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authorIan Moffett <ian@osmora.org>2024-03-07 17:28:00 -0500
committerIan Moffett <ian@osmora.org>2024-03-07 17:28:32 -0500
commitbd5969fc876a10b18613302db7087ef3c40f18e1 (patch)
tree7c2b8619afe902abf99570df2873fbdf40a4d1a1 /lib/mlibc/options/rtdl/generic
parenta95b38b1b92b172e6cc4e8e56a88a30cc65907b0 (diff)
lib: Add mlibc
Signed-off-by: Ian Moffett <ian@osmora.org>
Diffstat (limited to 'lib/mlibc/options/rtdl/generic')
-rw-r--r--lib/mlibc/options/rtdl/generic/linker.cpp1872
-rw-r--r--lib/mlibc/options/rtdl/generic/linker.hpp402
-rw-r--r--lib/mlibc/options/rtdl/generic/main.cpp844
3 files changed, 3118 insertions, 0 deletions
diff --git a/lib/mlibc/options/rtdl/generic/linker.cpp b/lib/mlibc/options/rtdl/generic/linker.cpp
new file mode 100644
index 0000000..a519c35
--- /dev/null
+++ b/lib/mlibc/options/rtdl/generic/linker.cpp
@@ -0,0 +1,1872 @@
+#include <mlibc/arch-defs.hpp>
+#include <stdint.h>
+#include <string.h>
+
+// keep a list of optional generic relocation types
+enum {
+ R_OFFSET = (uintptr_t) -1,
+};
+
+
+#include <frg/manual_box.hpp>
+#include <frg/small_vector.hpp>
+#include <mlibc/allocator.hpp>
+#include <mlibc/debug.hpp>
+#include <mlibc/rtdl-sysdeps.hpp>
+#include <mlibc/rtdl-abi.hpp>
+#include <mlibc/thread.hpp>
+#include <abi-bits/fcntl.h>
+#include <internal-config.h>
+
+#include "elf.hpp"
+#include "linker.hpp"
+
+#if !MLIBC_MMAP_ALLOCATE_DSO
+uintptr_t libraryBase = 0x41000000;
+#endif
+
+constexpr bool verbose = false;
+constexpr bool stillSlightlyVerbose = false;
+constexpr bool logBaseAddresses = false;
+constexpr bool logRpath = false;
+constexpr bool logLdPath = false;
+constexpr bool eagerBinding = true;
+
+#if defined(__x86_64__) || defined(__i386__)
+constexpr inline bool tlsAboveTp = false;
+#elif defined(__aarch64__)
+constexpr inline bool tlsAboveTp = true;
+#elif defined(__riscv)
+constexpr inline bool tlsAboveTp = true;
+#else
+# error Unknown architecture
+#endif
+
+extern DebugInterface globalDebugInterface;
+extern uintptr_t __stack_chk_guard;
+
+extern frg::manual_box<frg::small_vector<frg::string_view, 4, MemoryAllocator>> libraryPaths;
+extern frg::manual_box<frg::vector<frg::string_view, MemoryAllocator>> preloads;
+
+#if MLIBC_STATIC_BUILD
+extern "C" size_t __init_array_start[];
+extern "C" size_t __init_array_end[];
+extern "C" size_t __preinit_array_start[];
+extern "C" size_t __preinit_array_end[];
+#endif
+
+size_t tlsMaxAlignment = 16;
+
+// This is the global "resolution timestamp" (RTS) counter.
+// It is incremented each time __dlapi_open() (i.e. dlopen()) is called.
+// Each DSO stores its objectRts (i.e. RTS at the time the object was loaded).
+// DSOs in the global scope also store a globalRts (i.e. RTS at the time the
+// object became global). This mechanism is used to determine which
+// part of the global scope is considered for symbol resolution.
+uint64_t rtsCounter = 2;
+
+bool trySeek(int fd, int64_t offset) {
+ off_t noff;
+ return mlibc::sys_seek(fd, offset, SEEK_SET, &noff) == 0;
+}
+
+bool tryReadExactly(int fd, void *data, size_t length) {
+ size_t offset = 0;
+ while(offset < length) {
+ ssize_t chunk;
+ if(mlibc::sys_read(fd, reinterpret_cast<char *>(data) + offset,
+ length - offset, &chunk))
+ return false;
+ __ensure(chunk > 0);
+ offset += chunk;
+ }
+ __ensure(offset == length);
+ return true;
+}
+
+void closeOrDie(int fd) {
+ if(mlibc::sys_close(fd))
+ __ensure(!"sys_close() failed");
+}
+
+uintptr_t alignUp(uintptr_t address, size_t align) {
+ return (address + align - 1) & ~(align - 1);
+}
+
+// --------------------------------------------------------
+// ObjectRepository
+// --------------------------------------------------------
+
+ObjectRepository::ObjectRepository()
+: loadedObjects{getAllocator()},
+ _nameMap{frg::hash<frg::string_view>{}, getAllocator()} {}
+
+SharedObject *ObjectRepository::injectObjectFromDts(frg::string_view name,
+ frg::string<MemoryAllocator> path, uintptr_t base_address,
+ elf_dyn *dynamic, uint64_t rts) {
+ __ensure(!findLoadedObject(name));
+
+ auto object = frg::construct<SharedObject>(getAllocator(),
+ name.data(), std::move(path), false, globalScope.get(), rts);
+ object->baseAddress = base_address;
+ object->dynamic = dynamic;
+ _parseDynamic(object);
+
+ _addLoadedObject(object);
+ _discoverDependencies(object, globalScope.get(), rts);
+
+ return object;
+}
+
+SharedObject *ObjectRepository::injectObjectFromPhdrs(frg::string_view name,
+ frg::string<MemoryAllocator> path, void *phdr_pointer,
+ size_t phdr_entry_size, size_t num_phdrs, void *entry_pointer,
+ uint64_t rts) {
+ __ensure(!findLoadedObject(name));
+
+ auto object = frg::construct<SharedObject>(getAllocator(),
+ name.data(), std::move(path), true, globalScope.get(), rts);
+ _fetchFromPhdrs(object, phdr_pointer, phdr_entry_size, num_phdrs, entry_pointer);
+ _parseDynamic(object);
+
+ _addLoadedObject(object);
+ _discoverDependencies(object, globalScope.get(), rts);
+
+ return object;
+}
+
+SharedObject *ObjectRepository::injectStaticObject(frg::string_view name,
+ frg::string<MemoryAllocator> path, void *phdr_pointer,
+ size_t phdr_entry_size, size_t num_phdrs, void *entry_pointer,
+ uint64_t rts) {
+ __ensure(!findLoadedObject(name));
+ auto object = frg::construct<SharedObject>(getAllocator(),
+ name.data(), std::move(path), true, globalScope.get(), rts);
+ _fetchFromPhdrs(object, phdr_pointer, phdr_entry_size, num_phdrs, entry_pointer);
+
+#if MLIBC_STATIC_BUILD
+ object->initArray = reinterpret_cast<InitFuncPtr*>(__init_array_start);
+ object->initArraySize = static_cast<size_t>((uintptr_t)__init_array_end -
+ (uintptr_t)__init_array_start);
+ object->preInitArray = reinterpret_cast<InitFuncPtr*>(__preinit_array_start);
+ object->preInitArraySize = static_cast<size_t>((uintptr_t)__preinit_array_end -
+ (uintptr_t)__preinit_array_start);
+#endif
+
+ _addLoadedObject(object);
+
+ return object;
+}
+
+frg::expected<LinkerError, SharedObject *> ObjectRepository::requestObjectWithName(frg::string_view name,
+ SharedObject *origin, Scope *localScope, bool createScope, uint64_t rts) {
+ if (auto obj = findLoadedObject(name))
+ return obj;
+
+ auto tryToOpen = [&] (const char *path) {
+ int fd;
+ if(auto x = mlibc::sys_open(path, O_RDONLY, 0, &fd); x) {
+ return -1;
+ }
+ return fd;
+ };
+
+ // TODO(arsen): this process can probably undergo heavy optimization, by
+ // preprocessing the rpath only once on parse
+ auto processRpath = [&] (frg::string_view path) {
+ frg::string<MemoryAllocator> sPath { getAllocator() };
+ if (path.starts_with("$ORIGIN")) {
+ frg::string_view dirname = origin->path;
+ auto lastsl = dirname.find_last('/');
+ if (lastsl != size_t(-1)) {
+ dirname = dirname.sub_string(0, lastsl);
+ } else {
+ dirname = ".";
+ }
+ sPath = frg::string<MemoryAllocator>{ getAllocator(), dirname };
+ sPath += path.sub_string(7, path.size() - 7);
+ } else {
+ sPath = frg::string<MemoryAllocator>{ getAllocator(), path };
+ }
+ if (sPath[sPath.size() - 1] != '/') {
+ sPath += '/';
+ }
+ sPath += name;
+ if (logRpath)
+ mlibc::infoLogger() << "rtdl: trying in rpath " << sPath << frg::endlog;
+ int fd = tryToOpen(sPath.data());
+ if (logRpath && fd >= 0)
+ mlibc::infoLogger() << "rtdl: found in rpath" << frg::endlog;
+ return frg::tuple { fd, std::move(sPath) };
+ };
+
+ frg::string<MemoryAllocator> chosenPath { getAllocator() };
+ int fd = -1;
+ if (origin && origin->runPath) {
+ size_t start = 0;
+ size_t idx = 0;
+ frg::string_view rpath { origin->runPath };
+ auto next = [&] () {
+ idx = rpath.find_first(':', start);
+ if (idx == (size_t)-1)
+ idx = rpath.size();
+ };
+ for (next(); idx < rpath.size(); next()) {
+ auto path = rpath.sub_string(start, idx - start);
+ start = idx + 1;
+ auto [fd_, fullPath] = processRpath(path);
+ if (fd_ != -1) {
+ fd = fd_;
+ chosenPath = std::move(fullPath);
+ break;
+ }
+ }
+ if (fd == -1) {
+ auto path = rpath.sub_string(start, rpath.size() - start);
+ auto [fd_, fullPath] = processRpath(path);
+ if (fd_ != -1) {
+ fd = fd_;
+ chosenPath = std::move(fullPath);
+ }
+ }
+ } else if (logRpath) {
+ mlibc::infoLogger() << "rtdl: no rpath set for object" << frg::endlog;
+ }
+
+ for(size_t i = 0; i < libraryPaths->size() && fd == -1; i++) {
+ auto ldPath = (*libraryPaths)[i];
+ auto path = frg::string<MemoryAllocator>{getAllocator(), ldPath} + '/' + name;
+ if(logLdPath)
+ mlibc::infoLogger() << "rtdl: Trying to load " << name << " from ldpath " << ldPath << "/" << frg::endlog;
+ fd = tryToOpen(path.data());
+ if(fd >= 0) {
+ chosenPath = std::move(path);
+ break;
+ }
+ }
+ if(fd == -1)
+ return LinkerError::notFound;
+
+ if (createScope) {
+ __ensure(localScope == nullptr);
+
+ // TODO: Free this when the scope is no longer needed.
+ localScope = frg::construct<Scope>(getAllocator());
+ }
+
+ __ensure(localScope != nullptr);
+
+ auto object = frg::construct<SharedObject>(getAllocator(),
+ name.data(), std::move(chosenPath), false, localScope, rts);
+
+ auto result = _fetchFromFile(object, fd);
+ closeOrDie(fd);
+ if(!result) {
+ frg::destruct(getAllocator(), object);
+ return result.error();
+ }
+
+ _parseDynamic(object);
+
+ _addLoadedObject(object);
+ _discoverDependencies(object, localScope, rts);
+
+ return object;
+}
+
+frg::expected<LinkerError, SharedObject *> ObjectRepository::requestObjectAtPath(frg::string_view path,
+ Scope *localScope, bool createScope, uint64_t rts) {
+ // TODO: Support SONAME correctly.
+ auto lastSlash = path.find_last('/') + 1;
+ auto name = path;
+ if (!lastSlash) {
+ name = name.sub_string(lastSlash, path.size() - lastSlash);
+ }
+ if (auto obj = findLoadedObject(name))
+ return obj;
+
+ if (createScope) {
+ __ensure(localScope == nullptr);
+
+ // TODO: Free this when the scope is no longer needed.
+ localScope = frg::construct<Scope>(getAllocator());
+ }
+
+ __ensure(localScope != nullptr);
+
+ auto object = frg::construct<SharedObject>(getAllocator(),
+ name.data(), path.data(), false, localScope, rts);
+
+ frg::string<MemoryAllocator> no_prefix(getAllocator(), path);
+
+ int fd;
+ if(mlibc::sys_open((no_prefix + '\0').data(), O_RDONLY, 0, &fd)) {
+ frg::destruct(getAllocator(), object);
+ return LinkerError::notFound;
+ }
+ auto result = _fetchFromFile(object, fd);
+ closeOrDie(fd);
+ if(!result) {
+ frg::destruct(getAllocator(), object);
+ return result.error();
+ }
+
+ _parseDynamic(object);
+
+ _addLoadedObject(object);
+ _discoverDependencies(object, localScope, rts);
+
+ return object;
+}
+
+SharedObject *ObjectRepository::findCaller(void *addr) {
+ uintptr_t target = reinterpret_cast<uintptr_t>(addr);
+
+ for (auto [name, object] : _nameMap) {
+ // Search all PT_LOAD segments for the specified address.
+ for(size_t j = 0; j < object->phdrCount; j++) {
+ auto phdr = (elf_phdr *)((uintptr_t)object->phdrPointer + j * object->phdrEntrySize);
+ if (phdr->p_type == PT_LOAD) {
+ uintptr_t start = object->baseAddress + phdr->p_vaddr;
+ uintptr_t end = start + phdr->p_memsz;
+ if (start <= target && target < end)
+ return object;
+ }
+ }
+ }
+
+ return nullptr;
+}
+
+SharedObject *ObjectRepository::findLoadedObject(frg::string_view name) {
+ auto it = _nameMap.get(name);
+ if (it)
+ return *it;
+
+ for (auto object : loadedObjects) {
+ // See if any object has a matching SONAME.
+ if (object->soName && name == object->soName)
+ return object;
+ }
+
+ // TODO: We should also look at the device and inode here as a fallback.
+ return nullptr;
+}
+
+// --------------------------------------------------------
+// ObjectRepository: Fetching methods.
+// --------------------------------------------------------
+
+void ObjectRepository::_fetchFromPhdrs(SharedObject *object, void *phdr_pointer,
+ size_t phdr_entry_size, size_t phdr_count, void *entry_pointer) {
+ __ensure(object->isMainObject);
+ object->phdrPointer = phdr_pointer;
+ object->phdrEntrySize = phdr_entry_size;
+ object->phdrCount = phdr_count;
+ if(verbose)
+ mlibc::infoLogger() << "rtdl: Loading " << object->name << frg::endlog;
+
+ // Note: the entry pointer is absolute and not relative to the base address.
+ object->entry = entry_pointer;
+
+ frg::optional<ptrdiff_t> dynamic_offset;
+ frg::optional<ptrdiff_t> tls_offset;
+
+ // segments are already mapped, so we just have to find the dynamic section
+ for(size_t i = 0; i < phdr_count; i++) {
+ auto phdr = (elf_phdr *)((uintptr_t)phdr_pointer + i * phdr_entry_size);
+ switch(phdr->p_type) {
+ case PT_PHDR:
+ // Determine the executable's base address (in the PIE case) by comparing
+ // the PHDR segment's load address against it's address in the ELF file.
+ object->baseAddress = reinterpret_cast<uintptr_t>(phdr_pointer) - phdr->p_vaddr;
+ if(verbose)
+ mlibc::infoLogger() << "rtdl: Executable is loaded at "
+ << (void *)object->baseAddress << frg::endlog;
+ break;
+ case PT_DYNAMIC:
+ dynamic_offset = phdr->p_vaddr;
+ break;
+ case PT_TLS: {
+ object->tlsSegmentSize = phdr->p_memsz;
+ object->tlsAlignment = phdr->p_align;
+ object->tlsImageSize = phdr->p_filesz;
+ tls_offset = phdr->p_vaddr;
+ break;
+ case PT_INTERP:
+ object->interpreterPath = frg::string<MemoryAllocator>{
+ (char*)(object->baseAddress + phdr->p_vaddr),
+ getAllocator()
+ };
+ } break;
+ default:
+ //FIXME warn about unknown phdrs
+ break;
+ }
+ }
+
+ if(dynamic_offset)
+ object->dynamic = (elf_dyn *)(object->baseAddress + *dynamic_offset);
+ if(tls_offset)
+ object->tlsImagePtr = (void *)(object->baseAddress + *tls_offset);
+}
+
+
+frg::expected<LinkerError, void> ObjectRepository::_fetchFromFile(SharedObject *object, int fd) {
+ __ensure(!object->isMainObject);
+
+ // read the elf file header
+ elf_ehdr ehdr;
+ if(!tryReadExactly(fd, &ehdr, sizeof(elf_ehdr)))
+ return LinkerError::fileTooShort;
+
+ if(ehdr.e_ident[0] != 0x7F
+ || ehdr.e_ident[1] != 'E'
+ || ehdr.e_ident[2] != 'L'
+ || ehdr.e_ident[3] != 'F')
+ return LinkerError::notElf;
+
+ if((ehdr.e_type != ET_EXEC && ehdr.e_type != ET_DYN)
+ || ehdr.e_machine != ELF_MACHINE
+ || ehdr.e_ident[EI_CLASS] != ELF_CLASS)
+ return LinkerError::wrongElfType;
+
+ // read the elf program headers
+ auto phdr_buffer = (char *)getAllocator().allocate(ehdr.e_phnum * ehdr.e_phentsize);
+ if(!phdr_buffer)
+ return LinkerError::outOfMemory;
+
+ if(!trySeek(fd, ehdr.e_phoff)) {
+ getAllocator().deallocate(phdr_buffer, ehdr.e_phnum * ehdr.e_phentsize);
+ return LinkerError::invalidProgramHeader;
+ }
+ if(!tryReadExactly(fd, phdr_buffer, ehdr.e_phnum * ehdr.e_phentsize)) {
+ getAllocator().deallocate(phdr_buffer, ehdr.e_phnum * ehdr.e_phentsize);
+ return LinkerError::invalidProgramHeader;
+ }
+
+ object->phdrPointer = phdr_buffer;
+ object->phdrCount = ehdr.e_phnum;
+ object->phdrEntrySize = ehdr.e_phentsize;
+
+ // Allocate virtual address space for the DSO.
+ constexpr size_t hugeSize = 0x200000;
+
+ uintptr_t highest_address = 0;
+ for(int i = 0; i < ehdr.e_phnum; i++) {
+ auto phdr = (elf_phdr *)(phdr_buffer + i * ehdr.e_phentsize);
+
+ if(phdr->p_type != PT_LOAD)
+ continue;
+
+ auto limit = phdr->p_vaddr + phdr->p_memsz;
+ if(limit > highest_address)
+ highest_address = limit;
+ }
+
+ __ensure(!(object->baseAddress & (hugeSize - 1)));
+
+ highest_address = (highest_address + mlibc::page_size - 1) & ~(mlibc::page_size - 1);
+
+#if MLIBC_MMAP_ALLOCATE_DSO
+ void *mappedAddr = nullptr;
+
+ if (mlibc::sys_vm_map(nullptr,
+ highest_address - object->baseAddress, PROT_NONE,
+ MAP_PRIVATE | MAP_ANONYMOUS, -1, 0, &mappedAddr)) {
+ mlibc::infoLogger() << "sys_vm_map failed when allocating address space for DSO \""
+ << object->name << "\""
+ << ", base " << (void *)object->baseAddress
+ << ", requested " << (highest_address - object->baseAddress) << " bytes"
+ << frg::endlog;
+ getAllocator().deallocate(phdr_buffer, ehdr.e_phnum * ehdr.e_phentsize);
+ return LinkerError::outOfMemory;
+ }
+
+ object->baseAddress = reinterpret_cast<uintptr_t>(mappedAddr);
+#else
+ object->baseAddress = libraryBase;
+ libraryBase += (highest_address + (hugeSize - 1)) & ~(hugeSize - 1);
+#endif
+
+ if(verbose || logBaseAddresses)
+ mlibc::infoLogger() << "rtdl: Loading " << object->name
+ << " at " << (void *)object->baseAddress << frg::endlog;
+
+ // Load all segments.
+ constexpr size_t pageSize = 0x1000;
+ for(int i = 0; i < ehdr.e_phnum; i++) {
+ auto phdr = (elf_phdr *)(phdr_buffer + i * ehdr.e_phentsize);
+
+ if(phdr->p_type == PT_LOAD) {
+ size_t misalign = phdr->p_vaddr & (pageSize - 1);
+ __ensure(phdr->p_memsz > 0);
+ __ensure(phdr->p_memsz >= phdr->p_filesz);
+
+ // If the following condition is violated, we cannot use mmap() the segment;
+ // however, GCC only generates ELF files that satisfy this.
+ __ensure(misalign == (phdr->p_offset & (pageSize - 1)));
+
+ auto map_address = object->baseAddress + phdr->p_vaddr - misalign;
+ auto backed_map_size = (phdr->p_filesz + misalign + pageSize - 1) & ~(pageSize - 1);
+ auto total_map_size = (phdr->p_memsz + misalign + pageSize - 1) & ~(pageSize - 1);
+
+ int prot = 0;
+ if(phdr->p_flags & PF_R)
+ prot |= PROT_READ;
+ if(phdr->p_flags & PF_W)
+ prot |= PROT_WRITE;
+ if(phdr->p_flags & PF_X)
+ prot |= PROT_EXEC;
+
+ #if MLIBC_MAP_DSO_SEGMENTS
+ void *map_pointer;
+ if(mlibc::sys_vm_map(reinterpret_cast<void *>(map_address),
+ backed_map_size, prot | PROT_WRITE,
+ MAP_PRIVATE | MAP_FIXED, fd, phdr->p_offset - misalign, &map_pointer))
+ __ensure(!"sys_vm_map failed");
+ if(total_map_size > backed_map_size)
+ if(mlibc::sys_vm_map(reinterpret_cast<void *>(map_address + backed_map_size),
+ total_map_size - backed_map_size, prot | PROT_WRITE,
+ MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS, -1, 0, &map_pointer))
+ __ensure(!"sys_vm_map failed");
+
+ if(mlibc::sys_vm_readahead)
+ if(mlibc::sys_vm_readahead(reinterpret_cast<void *>(map_address),
+ backed_map_size))
+ mlibc::infoLogger() << "mlibc: sys_vm_readahead() failed in ld.so"
+ << frg::endlog;
+
+ // Clear the trailing area at the end of the backed mapping.
+ // We do not clear the leading area; programs are not supposed to access it.
+ memset(reinterpret_cast<void *>(map_address + misalign + phdr->p_filesz),
+ 0, phdr->p_memsz - phdr->p_filesz);
+ #else
+ (void)backed_map_size;
+
+ void *map_pointer;
+ if(mlibc::sys_vm_map(reinterpret_cast<void *>(map_address),
+ total_map_size, prot | PROT_WRITE,
+ MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS, -1, 0, &map_pointer))
+ __ensure(!"sys_vm_map failed");
+
+ __ensure(trySeek(fd, phdr->p_offset));
+ __ensure(tryReadExactly(fd, reinterpret_cast<char *>(map_address) + misalign,
+ phdr->p_filesz));
+ #endif
+ // Take care of removing superfluous permissions.
+ if(mlibc::sys_vm_protect && ((prot & PROT_WRITE) == 0))
+ if(mlibc::sys_vm_protect(map_pointer, total_map_size, prot))
+ mlibc::infoLogger() << "mlibc: sys_vm_protect() failed in ld.so" << frg::endlog;
+ }else if(phdr->p_type == PT_TLS) {
+ object->tlsSegmentSize = phdr->p_memsz;
+ object->tlsAlignment = phdr->p_align;
+ object->tlsImageSize = phdr->p_filesz;
+ object->tlsImagePtr = (void *)(object->baseAddress + phdr->p_vaddr);
+ }else if(phdr->p_type == PT_DYNAMIC) {
+ object->dynamic = (elf_dyn *)(object->baseAddress + phdr->p_vaddr);
+ }else if(phdr->p_type == PT_INTERP
+ || phdr->p_type == PT_PHDR
+ || phdr->p_type == PT_NOTE
+ || phdr->p_type == PT_RISCV_ATTRIBUTES
+ || phdr->p_type == PT_GNU_EH_FRAME
+ || phdr->p_type == PT_GNU_RELRO
+ || phdr->p_type == PT_GNU_STACK
+ || phdr->p_type == PT_GNU_PROPERTY) {
+ // ignore the phdr
+ }else{
+ mlibc::panicLogger() << "Unexpected PHDR type 0x"
+ << frg::hex_fmt(phdr->p_type) << " in DSO " << object->name << frg::endlog;
+ }
+ }
+
+ return frg::success;
+}
+
+// --------------------------------------------------------
+// ObjectRepository: Parsing methods.
+// --------------------------------------------------------
+
+void ObjectRepository::_parseDynamic(SharedObject *object) {
+ if(!object->dynamic)
+ mlibc::infoLogger() << "ldso: Object '" << object->name
+ << "' does not have a dynamic section" << frg::endlog;
+ __ensure(object->dynamic);
+
+ // Fix up these offsets to addresses after the loop, since the
+ // addresses depend on the value of DT_STRTAB.
+ frg::optional<ptrdiff_t> runpath_offset;
+ /* If true, ignore the RPATH. */
+ bool runpath_found = false;
+ frg::optional<ptrdiff_t> soname_offset;
+
+ for(size_t i = 0; object->dynamic[i].d_tag != DT_NULL; i++) {
+ elf_dyn *dynamic = &object->dynamic[i];
+ switch(dynamic->d_tag) {
+ // handle hash table, symbol table and string table
+ case DT_HASH:
+ object->hashStyle = HashStyle::systemV;
+ object->hashTableOffset = dynamic->d_un.d_ptr;
+ break;
+ case DT_GNU_HASH:
+ object->hashStyle = HashStyle::gnu;
+ object->hashTableOffset = dynamic->d_un.d_ptr;
+ break;
+ case DT_STRTAB:
+ object->stringTableOffset = dynamic->d_un.d_ptr;
+ break;
+ case DT_STRSZ:
+ break; // we don't need the size of the string table
+ case DT_SYMTAB:
+ object->symbolTableOffset = dynamic->d_un.d_ptr;
+ break;
+ case DT_SYMENT:
+ __ensure(dynamic->d_un.d_val == sizeof(elf_sym));
+ break;
+ // handle lazy relocation table
+ case DT_PLTGOT:
+ object->globalOffsetTable = (void **)(object->baseAddress
+ + dynamic->d_un.d_ptr);
+ break;
+ case DT_JMPREL:
+ object->lazyRelocTableOffset = dynamic->d_un.d_ptr;
+ break;
+ case DT_PLTRELSZ:
+ object->lazyTableSize = dynamic->d_un.d_val;
+ break;
+ case DT_PLTREL:
+ if(dynamic->d_un.d_val == DT_RELA) {
+ object->lazyExplicitAddend = true;
+ }else{
+ __ensure(dynamic->d_un.d_val == DT_REL);
+ object->lazyExplicitAddend = false;
+ }
+ break;
+ // TODO: Implement this correctly!
+ case DT_SYMBOLIC:
+ object->symbolicResolution = true;
+ break;
+ case DT_BIND_NOW:
+ object->eagerBinding = true;
+ break;
+ case DT_FLAGS: {
+ if(dynamic->d_un.d_val & DF_SYMBOLIC)
+ object->symbolicResolution = true;
+ if(dynamic->d_un.d_val & DF_STATIC_TLS)
+ object->haveStaticTls = true;
+ if(dynamic->d_un.d_val & DF_BIND_NOW)
+ object->eagerBinding = true;
+
+ auto ignored = DF_BIND_NOW | DF_SYMBOLIC | DF_STATIC_TLS;
+#ifdef __riscv
+ // Work around https://sourceware.org/bugzilla/show_bug.cgi?id=24673.
+ ignored |= DF_TEXTREL;
+#else
+ if(dynamic->d_un.d_val & DF_TEXTREL)
+ mlibc::panicLogger() << "\e[31mrtdl: DF_TEXTREL is unimplemented" << frg::endlog;
+#endif
+ if(dynamic->d_un.d_val & ~ignored)
+ mlibc::infoLogger() << "\e[31mrtdl: DT_FLAGS(" << frg::hex_fmt{dynamic->d_un.d_val & ~ignored}
+ << ") is not implemented correctly!\e[39m"
+ << frg::endlog;
+ } break;
+ case DT_FLAGS_1:
+ if(dynamic->d_un.d_val & DF_1_NOW)
+ object->eagerBinding = true;
+ // The DF_1_PIE flag is informational only. It is used by e.g file(1).
+ // The DF_1_NODELETE flag has a similar effect to RTLD_NODELETE, both of which we
+ // ignore because we don't implement dlclose().
+ if(dynamic->d_un.d_val & ~(DF_1_NOW | DF_1_PIE | DF_1_NODELETE))
+ mlibc::infoLogger() << "\e[31mrtdl: DT_FLAGS_1(" << frg::hex_fmt{dynamic->d_un.d_val}
+ << ") is not implemented correctly!\e[39m"
+ << frg::endlog;
+ break;
+ case DT_RPATH:
+ if (runpath_found) {
+ /* Ignore RPATH if RUNPATH was present. */
+ break;
+ }
+ [[fallthrough]];
+ case DT_RUNPATH:
+ runpath_found = dynamic->d_tag == DT_RUNPATH;
+ runpath_offset = dynamic->d_un.d_val;
+ break;
+ case DT_INIT:
+ if(dynamic->d_un.d_ptr != 0)
+ object->initPtr = (InitFuncPtr)(object->baseAddress + dynamic->d_un.d_ptr);
+ break;
+ case DT_INIT_ARRAY:
+ if(dynamic->d_un.d_ptr != 0)
+ object->initArray = (InitFuncPtr *)(object->baseAddress + dynamic->d_un.d_ptr);
+ break;
+ case DT_INIT_ARRAYSZ:
+ object->initArraySize = dynamic->d_un.d_val;
+ break;
+ case DT_PREINIT_ARRAY:
+ if(dynamic->d_un.d_ptr != 0) {
+ // Only the main object is allowed pre-initializers.
+ __ensure(object->isMainObject);
+ object->preInitArray = (InitFuncPtr *)(object->baseAddress + dynamic->d_un.d_ptr);
+ }
+ break;
+ case DT_PREINIT_ARRAYSZ:
+ // Only the main object is allowed pre-initializers.
+ __ensure(object->isMainObject);
+ object->preInitArraySize = dynamic->d_un.d_val;
+ break;
+ case DT_DEBUG:
+#if ELF_CLASS == ELFCLASS32
+ dynamic->d_un.d_val = reinterpret_cast<Elf32_Word>(&globalDebugInterface);
+#elif ELF_CLASS == ELFCLASS64
+ dynamic->d_un.d_val = reinterpret_cast<Elf64_Xword>(&globalDebugInterface);
+#endif
+ break;
+ case DT_SONAME:
+ soname_offset = dynamic->d_un.d_val;
+ break;
+ // ignore unimportant tags
+ case DT_NEEDED: // we handle this later
+ case DT_FINI: case DT_FINI_ARRAY: case DT_FINI_ARRAYSZ:
+ case DT_RELA: case DT_RELASZ: case DT_RELAENT: case DT_RELACOUNT:
+ case DT_REL: case DT_RELSZ: case DT_RELENT: case DT_RELCOUNT:
+ case DT_RELR: case DT_RELRSZ: case DT_RELRENT:
+ case DT_VERSYM:
+ case DT_VERDEF: case DT_VERDEFNUM:
+ case DT_VERNEED: case DT_VERNEEDNUM:
+#ifdef __riscv
+ case DT_TEXTREL: // Work around https://sourceware.org/bugzilla/show_bug.cgi?id=24673.
+#endif
+ break;
+ case DT_TLSDESC_PLT: case DT_TLSDESC_GOT:
+ break;
+ default:
+ // Ignore unknown entries in the os-specific area as we don't use them.
+ if(dynamic->d_tag < DT_LOOS || dynamic->d_tag > DT_HIOS) {
+ mlibc::panicLogger() << "Unexpected dynamic entry "
+ << (void *)dynamic->d_tag << " in object" << frg::endlog;
+ }
+ }
+ }
+
+ if(runpath_offset) {
+ object->runPath = reinterpret_cast<const char *>(object->baseAddress
+ + object->stringTableOffset + *runpath_offset);
+ }
+ if(soname_offset) {
+ object->soName = reinterpret_cast<const char *>(object->baseAddress
+ + object->stringTableOffset + *soname_offset);
+ }
+}
+
+void ObjectRepository::_discoverDependencies(SharedObject *object,
+ Scope *localScope, uint64_t rts) {
+ if(object->isMainObject) {
+ for(auto preload : *preloads) {
+ frg::expected<LinkerError, SharedObject *> libraryResult;
+ if (preload.find_first('/') == size_t(-1)) {
+ libraryResult = requestObjectWithName(preload, object, globalScope.get(), false, 1);
+ } else {
+ libraryResult = requestObjectAtPath(preload, globalScope.get(), false, 1);
+ }
+ if(!libraryResult)
+ mlibc::panicLogger() << "rtdl: Could not load preload " << preload << frg::endlog;
+
+ if(verbose)
+ mlibc::infoLogger() << "rtdl: Preloading " << preload << frg::endlog;
+
+ object->dependencies.push_back(libraryResult.value());
+ }
+ }
+
+ // Load required dynamic libraries.
+ for(size_t i = 0; object->dynamic[i].d_tag != DT_NULL; i++) {
+ elf_dyn *dynamic = &object->dynamic[i];
+ if(dynamic->d_tag != DT_NEEDED)
+ continue;
+
+ const char *library_str = (const char *)(object->baseAddress
+ + object->stringTableOffset + dynamic->d_un.d_val);
+
+ auto library = requestObjectWithName(frg::string_view{library_str},
+ object, localScope, false, rts);
+ if(!library)
+ mlibc::panicLogger() << "Could not satisfy dependency " << library_str << frg::endlog;
+ object->dependencies.push(library.value());
+ }
+}
+
+void ObjectRepository::_addLoadedObject(SharedObject *object) {
+ _nameMap.insert(object->name, object);
+ loadedObjects.push_back(object);
+}
+
+// --------------------------------------------------------
+// SharedObject
+// --------------------------------------------------------
+
+SharedObject::SharedObject(const char *name, frg::string<MemoryAllocator> path,
+ bool is_main_object, Scope *local_scope, uint64_t object_rts)
+ : name(name, getAllocator()), path(std::move(path)),
+ interpreterPath(getAllocator()), soName(nullptr),
+ isMainObject(is_main_object), objectRts(object_rts), inLinkMap(false),
+ baseAddress(0), localScope(local_scope), dynamic(nullptr),
+ globalOffsetTable(nullptr), entry(nullptr), tlsSegmentSize(0),
+ tlsAlignment(0), tlsImageSize(0), tlsImagePtr(nullptr),
+ tlsInitialized(false), hashTableOffset(0), symbolTableOffset(0),
+ stringTableOffset(0), lazyRelocTableOffset(0), lazyTableSize(0),
+ lazyExplicitAddend(false), symbolicResolution(false),
+ eagerBinding(false), haveStaticTls(false),
+ dependencies(getAllocator()), tlsModel(TlsModel::null),
+ tlsOffset(0), globalRts(0), wasLinked(false),
+ scheduledForInit(false), onInitStack(false),
+ wasInitialized(false) { }
+
+SharedObject::SharedObject(const char *name, const char *path,
+ bool is_main_object, Scope *localScope, uint64_t object_rts)
+ : SharedObject(name,
+ frg::string<MemoryAllocator> { path, getAllocator() },
+ is_main_object, localScope, object_rts) {}
+
+void processLateRelocation(Relocation rel) {
+ // resolve the symbol if there is a symbol
+ frg::optional<ObjectSymbol> p;
+ if(rel.symbol_index()) {
+ auto symbol = (elf_sym *)(rel.object()->baseAddress + rel.object()->symbolTableOffset
+ + rel.symbol_index() * sizeof(elf_sym));
+ ObjectSymbol r(rel.object(), symbol);
+
+ p = Scope::resolveGlobalOrLocal(*globalScope, rel.object()->localScope,
+ r.getString(), rel.object()->objectRts, Scope::resolveCopy);
+ }
+
+ switch(rel.type()) {
+ case R_COPY:
+ __ensure(p);
+ memcpy(rel.destination(), (void *)p->virtualAddress(), p->symbol()->st_size);
+ break;
+
+// TODO: R_IRELATIVE also exists on other architectures but will likely need a different implementation.
+#if defined(__x86_64__) || defined(__i386__)
+ case R_IRELATIVE: {
+ uintptr_t addr = rel.object()->baseAddress + rel.addend_rel();
+ auto* fn = reinterpret_cast<uintptr_t (*)()>(addr);
+ rel.relocate(fn());
+ } break;
+#elif defined(__aarch64__)
+ case R_IRELATIVE: {
+ uintptr_t addr = rel.object()->baseAddress + rel.addend_rel();
+ auto* fn = reinterpret_cast<uintptr_t (*)(uint64_t)>(addr);
+ // TODO: the function should get passed AT_HWCAP value.
+ rel.relocate(fn(0));
+ } break;
+#endif
+
+ default:
+ break;
+ }
+}
+
+void processLateRelocations(SharedObject *object) {
+ frg::optional<uintptr_t> rel_offset;
+ frg::optional<size_t> rel_length;
+
+ frg::optional<uintptr_t> rela_offset;
+ frg::optional<size_t> rela_length;
+
+ for(size_t i = 0; object->dynamic[i].d_tag != DT_NULL; i++) {
+ elf_dyn *dynamic = &object->dynamic[i];
+
+ switch(dynamic->d_tag) {
+ case DT_REL:
+ rel_offset = dynamic->d_un.d_ptr;
+ break;
+ case DT_RELSZ:
+ rel_length = dynamic->d_un.d_val;
+ break;
+ case DT_RELENT:
+ __ensure(dynamic->d_un.d_val == sizeof(elf_rel));
+ break;
+ case DT_RELA:
+ rela_offset = dynamic->d_un.d_ptr;
+ break;
+ case DT_RELASZ:
+ rela_length = dynamic->d_un.d_val;
+ break;
+ case DT_RELAENT:
+ __ensure(dynamic->d_un.d_val == sizeof(elf_rela));
+ break;
+ }
+ }
+
+ if(rela_offset && rela_length) {
+ for(size_t offset = 0; offset < *rela_length; offset += sizeof(elf_rela)) {
+ auto reloc = (elf_rela *)(object->baseAddress + *rela_offset + offset);
+ auto r = Relocation(object, reloc);
+ processLateRelocation(r);
+ }
+ } else if(rel_offset && rel_length) {
+ for(size_t offset = 0; offset < *rel_length; offset += sizeof(elf_rel)) {
+ auto reloc = (elf_rel *)(object->baseAddress + *rel_offset + offset);
+ auto r = Relocation(object, reloc);
+ processLateRelocation(r);
+ }
+ }else{
+ __ensure(!rela_offset && !rela_length);
+ __ensure(!rel_offset && !rel_length);
+ }
+}
+
+void doInitialize(SharedObject *object) {
+ __ensure(object->wasLinked);
+ __ensure(!object->wasInitialized);
+
+ // if the object has dependencies we initialize them first
+ for(size_t i = 0; i < object->dependencies.size(); i++)
+ __ensure(object->dependencies[i]->wasInitialized);
+
+ if(verbose)
+ mlibc::infoLogger() << "rtdl: Initialize " << object->name << frg::endlog;
+
+ if(verbose)
+ mlibc::infoLogger() << "rtdl: Running DT_INIT function" << frg::endlog;
+ if(object->initPtr != nullptr)
+ object->initPtr();
+
+ if(verbose)
+ mlibc::infoLogger() << "rtdl: Running DT_INIT_ARRAY functions" << frg::endlog;
+ __ensure((object->initArraySize % sizeof(InitFuncPtr)) == 0);
+ for(size_t i = 0; i < object->initArraySize / sizeof(InitFuncPtr); i++)
+ object->initArray[i]();
+
+ if(verbose)
+ mlibc::infoLogger() << "rtdl: Object initialization complete" << frg::endlog;
+ object->wasInitialized = true;
+}
+
+// --------------------------------------------------------
+// RuntimeTlsMap
+// --------------------------------------------------------
+
+RuntimeTlsMap::RuntimeTlsMap()
+: initialPtr{0}, initialLimit{0}, indices{getAllocator()} { }
+
+void initTlsObjects(Tcb *tcb, const frg::vector<SharedObject *, MemoryAllocator> &objects, bool checkInitialized) {
+ // Initialize TLS segments that follow the static model.
+ for(auto object : objects) {
+ if(object->tlsModel == TlsModel::initial) {
+ if(checkInitialized && object->tlsInitialized)
+ continue;
+
+ char *tcb_ptr = reinterpret_cast<char *>(tcb);
+ auto tls_ptr = tcb_ptr + object->tlsOffset;
+ memset(tls_ptr, 0, object->tlsSegmentSize);
+ memcpy(tls_ptr, object->tlsImagePtr, object->tlsImageSize);
+
+ if (verbose) {
+ mlibc::infoLogger() << "rtdl: wrote tls image at " << (void *)tls_ptr
+ << ", size = 0x" << frg::hex_fmt{object->tlsSegmentSize} << frg::endlog;
+ }
+
+ if (checkInitialized)
+ object->tlsInitialized = true;
+ }
+ }
+}
+
+Tcb *allocateTcb() {
+ size_t tlsInitialSize = runtimeTlsMap->initialLimit;
+
+ // To make sure that both the TCB and TLS data are sufficiently aligned, allocate
+ // slightly more than necessary and adjust alignment afterwards.
+ size_t alignOverhead = frg::max(alignof(Tcb), tlsMaxAlignment);
+ size_t allocSize = tlsInitialSize + sizeof(Tcb) + alignOverhead;
+ auto allocation = reinterpret_cast<uintptr_t>(getAllocator().allocate(allocSize));
+ memset(reinterpret_cast<void *>(allocation), 0, allocSize);
+
+ uintptr_t tlsAddress, tcbAddress;
+ if constexpr (tlsAboveTp) {
+ // Here we must satisfy two requirements of the TCB and the TLS data:
+ // 1. One should follow the other immediately in memory. We do this so that
+ // we can simply add or subtract sizeof(Tcb) to obtain the address of the other.
+ // 2. Both should be sufficiently aligned.
+ // To do this, we will fix whichever address has stricter alignment requirements, and
+ // derive the other from it.
+ if (tlsMaxAlignment > alignof(Tcb)) {
+ tlsAddress = alignUp(allocation + sizeof(Tcb), tlsMaxAlignment);
+ tcbAddress = tlsAddress - sizeof(Tcb);
+ } else {
+ tcbAddress = alignUp(allocation, alignof(Tcb));
+ tlsAddress = tcbAddress + sizeof(Tcb);
+ }
+ __ensure((tlsAddress & (tlsMaxAlignment - 1)) == 0);
+ __ensure(tlsAddress == tcbAddress + sizeof(Tcb));
+ } else {
+ // The TCB should be aligned such that the preceding blocks are aligned too.
+ tcbAddress = alignUp(allocation + tlsInitialSize, alignOverhead);
+ tlsAddress = tcbAddress - tlsInitialSize;
+ }
+ __ensure((tcbAddress & (alignof(Tcb) - 1)) == 0);
+
+ if (verbose) {
+ mlibc::infoLogger() << "rtdl: tcb allocated at " << (void *)tcbAddress
+ << ", size = 0x" << frg::hex_fmt{sizeof(Tcb)} << frg::endlog;
+ mlibc::infoLogger() << "rtdl: tls allocated at " << (void *)tlsAddress
+ << ", size = 0x" << frg::hex_fmt{tlsInitialSize} << frg::endlog;
+ }
+
+ Tcb *tcb_ptr = new ((char *)tcbAddress) Tcb;
+ tcb_ptr->selfPointer = tcb_ptr;
+
+ tcb_ptr->stackCanary = __stack_chk_guard;
+ tcb_ptr->cancelBits = tcbCancelEnableBit;
+ tcb_ptr->didExit = 0;
+ tcb_ptr->isJoinable = 1;
+ memset(&tcb_ptr->returnValue, 0, sizeof(tcb_ptr->returnValue));
+ tcb_ptr->localKeys = frg::construct<frg::array<Tcb::LocalKey, PTHREAD_KEYS_MAX>>(getAllocator());
+ tcb_ptr->dtvSize = runtimeTlsMap->indices.size();
+ tcb_ptr->dtvPointers = frg::construct_n<void *>(getAllocator(), runtimeTlsMap->indices.size());
+ memset(tcb_ptr->dtvPointers, 0, sizeof(void *) * runtimeTlsMap->indices.size());
+ for(size_t i = 0; i < runtimeTlsMap->indices.size(); ++i) {
+ auto object = runtimeTlsMap->indices[i];
+ if(object->tlsModel != TlsModel::initial)
+ continue;
+ tcb_ptr->dtvPointers[i] = reinterpret_cast<char *>(tcb_ptr) + object->tlsOffset;
+ }
+
+ return tcb_ptr;
+}
+
+void *accessDtv(SharedObject *object) {
+ Tcb *tcb_ptr = mlibc::get_current_tcb();
+
+ // We might need to reallocate the DTV.
+ if(object->tlsIndex >= tcb_ptr->dtvSize) {
+ // TODO: need to protect runtimeTlsMap against concurrent access.
+ auto ndtv = frg::construct_n<void *>(getAllocator(), runtimeTlsMap->indices.size());
+ memset(ndtv, 0, sizeof(void *) * runtimeTlsMap->indices.size());
+ memcpy(ndtv, tcb_ptr->dtvPointers, sizeof(void *) * tcb_ptr->dtvSize);
+ frg::destruct_n(getAllocator(), tcb_ptr->dtvPointers, tcb_ptr->dtvSize);
+ tcb_ptr->dtvSize = runtimeTlsMap->indices.size();
+ tcb_ptr->dtvPointers = ndtv;
+ }
+
+ // We might need to fill in a new DTV entry.
+ if(!tcb_ptr->dtvPointers[object->tlsIndex]) {
+ __ensure(object->tlsModel == TlsModel::dynamic);
+
+ auto buffer = getAllocator().allocate(object->tlsSegmentSize);
+ __ensure(!(reinterpret_cast<uintptr_t>(buffer) & (object->tlsAlignment - 1)));
+ memset(buffer, 0, object->tlsSegmentSize);
+ memcpy(buffer, object->tlsImagePtr, object->tlsImageSize);
+ tcb_ptr->dtvPointers[object->tlsIndex] = buffer;
+
+ if (verbose) {
+ mlibc::infoLogger() << "rtdl: accessDtv wrote tls image at " << buffer
+ << ", size = 0x" << frg::hex_fmt{object->tlsSegmentSize} << frg::endlog;
+ }
+ }
+
+ return (void *)((char *)tcb_ptr->dtvPointers[object->tlsIndex] + TLS_DTV_OFFSET);
+}
+
+void *tryAccessDtv(SharedObject *object) {
+ Tcb *tcb_ptr = mlibc::get_current_tcb();
+
+ if (object->tlsIndex >= tcb_ptr->dtvSize)
+ return nullptr;
+ if (!tcb_ptr->dtvPointers[object->tlsIndex])
+ return nullptr;
+
+ return (void *)((char *)tcb_ptr->dtvPointers[object->tlsIndex] + TLS_DTV_OFFSET);
+}
+
+// --------------------------------------------------------
+// ObjectSymbol
+// --------------------------------------------------------
+
+ObjectSymbol::ObjectSymbol(SharedObject *object, const elf_sym *symbol)
+: _object(object), _symbol(symbol) { }
+
+const char *ObjectSymbol::getString() {
+ __ensure(_symbol->st_name != 0);
+ return (const char *)(_object->baseAddress
+ + _object->stringTableOffset + _symbol->st_name);
+}
+
+uintptr_t ObjectSymbol::virtualAddress() {
+ auto bind = ELF_ST_BIND(_symbol->st_info);
+ __ensure(bind == STB_GLOBAL || bind == STB_WEAK || bind == STB_GNU_UNIQUE);
+ __ensure(_symbol->st_shndx != SHN_UNDEF);
+ return _object->baseAddress + _symbol->st_value;
+}
+
+// --------------------------------------------------------
+// Scope
+// --------------------------------------------------------
+
+uint32_t elf64Hash(frg::string_view string) {
+ uint32_t h = 0, g;
+
+ for(size_t i = 0; i < string.size(); ++i) {
+ h = (h << 4) + (uint32_t)string[i];
+ g = h & 0xF0000000;
+ if(g)
+ h ^= g >> 24;
+ h &= 0x0FFFFFFF;
+ }
+
+ return h;
+}
+
+uint32_t gnuHash(frg::string_view string) {
+ uint32_t h = 5381;
+ for(size_t i = 0; i < string.size(); ++i)
+ h = (h << 5) + h + string[i];
+ return h;
+}
+
+// TODO: move this to some namespace or class?
+frg::optional<ObjectSymbol> resolveInObject(SharedObject *object, frg::string_view string) {
+ // Checks if the symbol can be used to satisfy the dependency.
+ auto eligible = [&] (ObjectSymbol cand) {
+ if(cand.symbol()->st_shndx == SHN_UNDEF)
+ return false;
+
+ auto bind = ELF_ST_BIND(cand.symbol()->st_info);
+ if(bind != STB_GLOBAL && bind != STB_WEAK && bind != STB_GNU_UNIQUE)
+ return false;
+
+ return true;
+ };
+
+ if (object->hashStyle == HashStyle::systemV) {
+ auto hash_table = (Elf64_Word *)(object->baseAddress + object->hashTableOffset);
+ Elf64_Word num_buckets = hash_table[0];
+ auto bucket = elf64Hash(string) % num_buckets;
+
+ auto index = hash_table[2 + bucket];
+ while(index != 0) {
+ ObjectSymbol cand{object, (elf_sym *)(object->baseAddress
+ + object->symbolTableOffset + index * sizeof(elf_sym))};
+ if(eligible(cand) && frg::string_view{cand.getString()} == string)
+ return cand;
+
+ index = hash_table[2 + num_buckets + index];
+ }
+
+ return frg::optional<ObjectSymbol>{};
+ }else{
+ __ensure(object->hashStyle == HashStyle::gnu);
+
+ struct GnuTable {
+ uint32_t nBuckets;
+ uint32_t symbolOffset;
+ uint32_t bloomSize;
+ uint32_t bloomShift;
+ };
+
+ auto hash_table = reinterpret_cast<const GnuTable *>(object->baseAddress
+ + object->hashTableOffset);
+ auto buckets = reinterpret_cast<const uint32_t *>(object->baseAddress
+ + object->hashTableOffset + sizeof(GnuTable)
+ + hash_table->bloomSize * sizeof(elf_addr));
+ auto chains = reinterpret_cast<const uint32_t *>(object->baseAddress
+ + object->hashTableOffset + sizeof(GnuTable)
+ + hash_table->bloomSize * sizeof(elf_addr)
+ + hash_table->nBuckets * sizeof(uint32_t));
+
+ // TODO: Use the bloom filter.
+
+ // The symbols of a given bucket are contiguous in the table.
+ auto hash = gnuHash(string);
+ auto index = buckets[hash % hash_table->nBuckets];
+
+ if(!index)
+ return frg::optional<ObjectSymbol>{};
+
+ while(true) {
+ // chains[] contains an array of hashes, parallel to the symbol table.
+ auto chash = chains[index - hash_table->symbolOffset];
+ if ((chash & ~1) == (hash & ~1)) {
+ ObjectSymbol cand{object, (elf_sym *)(object->baseAddress
+ + object->symbolTableOffset + index * sizeof(elf_sym))};
+ if(eligible(cand) && frg::string_view{cand.getString()} == string)
+ return cand;
+ }
+
+ // If we hit the end of the chain, the symbol is not present.
+ if(chash & 1)
+ return frg::optional<ObjectSymbol>{};
+ index++;
+ }
+ }
+}
+
+frg::optional<ObjectSymbol> Scope::_resolveNext(frg::string_view string,
+ SharedObject *target) {
+ // Skip objects until we find the target, and only look for symbols after that.
+ size_t i;
+ for (i = 0; i < _objects.size(); i++) {
+ if (_objects[i] == target)
+ break;
+ }
+
+ if (i == _objects.size()) {
+ mlibc::infoLogger() << "rtdl: object passed to Scope::resolveAfter was not found" << frg::endlog;
+ return frg::optional<ObjectSymbol>();
+ }
+
+ for (i = i + 1; i < _objects.size(); i++) {
+ if(_objects[i]->isMainObject)
+ continue;
+
+ frg::optional<ObjectSymbol> p = resolveInObject(_objects[i], string);
+ if(p)
+ return p;
+ }
+
+ return frg::optional<ObjectSymbol>();
+}
+
+Scope::Scope(bool isGlobal)
+: isGlobal{isGlobal}, _objects(getAllocator()) { }
+
+void Scope::appendObject(SharedObject *object) {
+ // Don't insert duplicates.
+ for (auto obj : _objects) {
+ if (obj == object)
+ return;
+ }
+
+ _objects.push(object);
+}
+
+frg::optional<ObjectSymbol> Scope::resolveGlobalOrLocal(Scope &globalScope,
+ Scope *localScope, frg::string_view string, uint64_t skipRts, ResolveFlags flags) {
+ auto sym = globalScope.resolveSymbol(string, skipRts, flags | skipGlobalAfterRts);
+ if(!sym && localScope)
+ sym = localScope->resolveSymbol(string, skipRts, flags | skipGlobalAfterRts);
+ return sym;
+}
+
+frg::optional<ObjectSymbol> Scope::resolveGlobalOrLocalNext(Scope &globalScope,
+ Scope *localScope, frg::string_view string, SharedObject *origin) {
+ auto sym = globalScope._resolveNext(string, origin);
+ if(!sym && localScope) {
+ sym = localScope->_resolveNext(string, origin);
+ }
+ return sym;
+}
+
+// TODO: let this return uintptr_t
+frg::optional<ObjectSymbol> Scope::resolveSymbol(frg::string_view string,
+ uint64_t skipRts, ResolveFlags flags) {
+ for (auto object : _objects) {
+ if((flags & resolveCopy) && object->isMainObject)
+ continue;
+ if((flags & skipGlobalAfterRts) && object->globalRts > skipRts) {
+ // globalRts should be monotone increasing for objects in the global scope,
+ // so as an optimization we can break early here.
+ // TODO: If we implement DT_SYMBOLIC, this assumption fails.
+ if(isGlobal)
+ break;
+ else
+ continue;
+ }
+
+ frg::optional<ObjectSymbol> p = resolveInObject(object, string);
+ if(p)
+ return p;
+ }
+
+ return frg::optional<ObjectSymbol>();
+}
+
+// --------------------------------------------------------
+// Loader
+// --------------------------------------------------------
+
+Loader::Loader(Scope *scope, SharedObject *mainExecutable, bool is_initial_link, uint64_t rts)
+: _mainExecutable{mainExecutable}, _loadScope{scope}, _isInitialLink{is_initial_link},
+ _linkRts{rts}, _linkBfs{getAllocator()}, _initQueue{getAllocator()} { }
+
+void Loader::_buildLinkBfs(SharedObject *root) {
+ __ensure(_linkBfs.size() == 0);
+
+ struct Token {};
+ using Set = frg::hash_map<SharedObject *, Token,
+ frg::hash<SharedObject *>, MemoryAllocator>;
+ Set set{frg::hash<SharedObject *>{}, getAllocator()};
+ _linkBfs.push(root);
+
+ // Loop over indices (not iterators) here: We are adding elements in the loop!
+ for(size_t i = 0; i < _linkBfs.size(); i++) {
+ auto current = _linkBfs[i];
+
+ // At this point the object is loaded and we can fill in its debug struct,
+ // the linked list fields will be filled later.
+ current->linkMap.base = current->baseAddress;
+ current->linkMap.name = current->path.data();
+ current->linkMap.dynv = current->dynamic;
+
+ __ensure((current->tlsAlignment & (current->tlsAlignment - 1)) == 0);
+
+ if (_isInitialLink && current->tlsAlignment > tlsMaxAlignment) {
+ tlsMaxAlignment = current->tlsAlignment;
+ }
+
+ for (auto dep : current->dependencies) {
+ if (!set.get(dep)) {
+ set.insert(dep, Token{});
+ _linkBfs.push(dep);
+ }
+ }
+ }
+}
+
+void Loader::linkObjects(SharedObject *root) {
+ _buildLinkBfs(root);
+ _buildTlsMaps();
+
+ // Promote objects to the desired scope.
+ for(auto object : _linkBfs) {
+ if (object->globalRts == 0 && _loadScope->isGlobal)
+ object->globalRts = _linkRts;
+
+ _loadScope->appendObject(object);
+ }
+
+ // Process regular relocations.
+ for(auto object : _linkBfs) {
+ // Some objects have already been linked before.
+ if(object->objectRts < _linkRts)
+ continue;
+
+ if(object->dynamic == nullptr)
+ continue;
+
+ if(verbose)
+ mlibc::infoLogger() << "rtdl: Linking " << object->name << frg::endlog;
+
+ __ensure(!object->wasLinked);
+
+ // TODO: Support this.
+ if(object->symbolicResolution)
+ mlibc::infoLogger() << "\e[31mrtdl: DT_SYMBOLIC is not implemented correctly!\e[39m"
+ << frg::endlog;
+
+ _processStaticRelocations(object);
+ _processLazyRelocations(object);
+ }
+
+ // Process copy relocations.
+ for(auto object : _linkBfs) {
+ if(!object->isMainObject)
+ continue;
+
+ // Some objects have already been linked before.
+ if(object->objectRts < _linkRts)
+ continue;
+
+ if(object->dynamic == nullptr)
+ continue;
+
+ processLateRelocations(object);
+ }
+
+ for(auto object : _linkBfs) {
+ object->wasLinked = true;
+
+ if(object->inLinkMap)
+ continue;
+
+ auto linkMap = reinterpret_cast<LinkMap*>(globalDebugInterface.head);
+
+ object->linkMap.prev = linkMap;
+ object->linkMap.next = linkMap->next;
+ if(linkMap->next)
+ linkMap->next->prev = &(object->linkMap);
+ linkMap->next = &(object->linkMap);
+ object->inLinkMap = true;
+ }
+}
+
+void Loader::_buildTlsMaps() {
+ if(_isInitialLink) {
+ __ensure(runtimeTlsMap->initialPtr == 0);
+ __ensure(runtimeTlsMap->initialLimit == 0);
+
+ __ensure(!_linkBfs.empty());
+ __ensure(_linkBfs.front()->isMainObject);
+
+ for(auto object : _linkBfs) {
+ __ensure(object->tlsModel == TlsModel::null);
+
+ if(object->tlsSegmentSize == 0)
+ continue;
+
+ // Allocate an index for the object.
+ object->tlsIndex = runtimeTlsMap->indices.size();
+ runtimeTlsMap->indices.push_back(object);
+
+ object->tlsModel = TlsModel::initial;
+
+ if constexpr (tlsAboveTp) {
+ // As per the comment in allocateTcb(), we may simply add sizeof(Tcb) to
+ // reach the TLS data.
+ object->tlsOffset = runtimeTlsMap->initialPtr + sizeof(Tcb);
+ runtimeTlsMap->initialPtr += object->tlsSegmentSize;
+
+ size_t misalign = runtimeTlsMap->initialPtr & (object->tlsAlignment - 1);
+ if(misalign)
+ runtimeTlsMap->initialPtr += object->tlsAlignment - misalign;
+ } else {
+ runtimeTlsMap->initialPtr += object->tlsSegmentSize;
+
+ size_t misalign = runtimeTlsMap->initialPtr & (object->tlsAlignment - 1);
+ if(misalign)
+ runtimeTlsMap->initialPtr += object->tlsAlignment - misalign;
+
+ object->tlsOffset = -runtimeTlsMap->initialPtr;
+ }
+
+ if(verbose)
+ mlibc::infoLogger() << "rtdl: TLS of " << object->name
+ << " mapped to 0x" << frg::hex_fmt{object->tlsOffset}
+ << ", size: " << object->tlsSegmentSize
+ << ", alignment: " << object->tlsAlignment << frg::endlog;
+ }
+
+ // Reserve some additional space for future libraries.
+ runtimeTlsMap->initialLimit = runtimeTlsMap->initialPtr + 64;
+ }else{
+ for(auto object : _linkBfs) {
+ if(object->tlsModel != TlsModel::null)
+ continue;
+ if(object->tlsSegmentSize == 0)
+ continue;
+
+ // Allocate an index for the object.
+ object->tlsIndex = runtimeTlsMap->indices.size();
+ runtimeTlsMap->indices.push_back(object);
+
+ // There are some libraries (e.g. Mesa) that require static TLS even though
+ // they expect to be dynamically loaded.
+ if(object->haveStaticTls) {
+ auto ptr = runtimeTlsMap->initialPtr + object->tlsSegmentSize;
+ size_t misalign = ptr & (object->tlsAlignment - 1);
+ if(misalign)
+ ptr += object->tlsAlignment - misalign;
+
+ if(ptr > runtimeTlsMap->initialLimit)
+ mlibc::panicLogger() << "rtdl: Static TLS space exhausted while while"
+ " allocating TLS for " << object->name << frg::endlog;
+
+ object->tlsModel = TlsModel::initial;
+
+ if constexpr (tlsAboveTp) {
+ size_t tcbSize = ((sizeof(Tcb) + tlsMaxAlignment - 1) & ~(tlsMaxAlignment - 1));
+
+ object->tlsOffset = runtimeTlsMap->initialPtr + tcbSize;
+ runtimeTlsMap->initialPtr = ptr;
+ } else {
+ runtimeTlsMap->initialPtr = ptr;
+ object->tlsOffset = -runtimeTlsMap->initialPtr;
+ }
+
+ if(verbose)
+ mlibc::infoLogger() << "rtdl: TLS of " << object->name
+ << " mapped to 0x" << frg::hex_fmt{object->tlsOffset}
+ << ", size: " << object->tlsSegmentSize
+ << ", alignment: " << object->tlsAlignment << frg::endlog;
+ }else{
+ object->tlsModel = TlsModel::dynamic;
+ }
+ }
+ }
+}
+
+void Loader::initObjects() {
+ initTlsObjects(mlibc::get_current_tcb(), _linkBfs, true);
+
+ if (_mainExecutable && _mainExecutable->preInitArray) {
+ if (verbose)
+ mlibc::infoLogger() << "rtdl: Running DT_PREINIT_ARRAY functions" << frg::endlog;
+
+ __ensure(_mainExecutable->isMainObject);
+ __ensure(!_mainExecutable->wasInitialized);
+ __ensure((_mainExecutable->preInitArraySize % sizeof(InitFuncPtr)) == 0);
+ for(size_t i = 0; i < _mainExecutable->preInitArraySize / sizeof(InitFuncPtr); i++)
+ _mainExecutable->preInitArray[i]();
+ }
+
+ // Convert the breadth-first representation to a depth-first post-order representation,
+ // so that every object is initialized *after* its dependencies.
+ for(auto object : _linkBfs) {
+ if(!object->scheduledForInit)
+ _scheduleInit(object);
+ }
+
+ for(auto object : _initQueue) {
+ if(!object->wasInitialized)
+ doInitialize(object);
+ }
+}
+
+// TODO: Use an explicit vector to reduce stack usage to O(1)?
+void Loader::_scheduleInit(SharedObject *object) {
+ // Here we detect cyclic dependencies.
+ __ensure(!object->onInitStack);
+ object->onInitStack = true;
+
+ __ensure(!object->scheduledForInit);
+ object->scheduledForInit = true;
+
+ for(size_t i = 0; i < object->dependencies.size(); i++) {
+ if(!object->dependencies[i]->scheduledForInit)
+ _scheduleInit(object->dependencies[i]);
+ }
+
+ _initQueue.push(object);
+ object->onInitStack = false;
+}
+
+void Loader::_processRelocations(Relocation &rel) {
+ // copy and irelative relocations have to be performed after all other relocations
+ if(rel.type() == R_COPY || rel.type() == R_IRELATIVE)
+ return;
+
+ // resolve the symbol if there is a symbol
+ frg::optional<ObjectSymbol> p;
+ if(rel.symbol_index()) {
+ auto symbol = (elf_sym *)(rel.object()->baseAddress + rel.object()->symbolTableOffset
+ + rel.symbol_index() * sizeof(elf_sym));
+ ObjectSymbol r(rel.object(), symbol);
+
+ p = Scope::resolveGlobalOrLocal(*globalScope, rel.object()->localScope,
+ r.getString(), rel.object()->objectRts, 0);
+ if(!p) {
+ if(ELF_ST_BIND(symbol->st_info) != STB_WEAK)
+ mlibc::panicLogger() << "Unresolved load-time symbol "
+ << r.getString() << " in object " << rel.object()->name << frg::endlog;
+
+ if(verbose)
+ mlibc::infoLogger() << "rtdl: Unresolved weak load-time symbol "
+ << r.getString() << " in object " << rel.object()->name << frg::endlog;
+ }
+ }
+
+ switch(rel.type()) {
+ case R_NONE:
+ break;
+
+ case R_JUMP_SLOT: {
+ __ensure(!rel.addend_norel());
+ uintptr_t symbol_addr = p ? p->virtualAddress() : 0;
+ rel.relocate(symbol_addr);
+ } break;
+
+#if !defined(__riscv)
+ // on some architectures, R_GLOB_DAT can be defined to other relocations
+ case R_GLOB_DAT: {
+ __ensure(rel.symbol_index());
+ uintptr_t symbol_addr = p ? p->virtualAddress() : 0;
+ rel.relocate(symbol_addr + rel.addend_norel());
+ } break;
+#endif
+
+ case R_ABSOLUTE: {
+ __ensure(rel.symbol_index());
+ uintptr_t symbol_addr = p ? p->virtualAddress() : 0;
+ rel.relocate(symbol_addr + rel.addend_rel());
+ } break;
+
+ case R_RELATIVE: {
+ __ensure(!rel.symbol_index());
+ rel.relocate(rel.object()->baseAddress + rel.addend_rel());
+ } break;
+
+ // DTPMOD and DTPREL are dynamic TLS relocations (for __tls_get_addr()).
+ // TPOFF is a relocation to the initial TLS model.
+ case R_TLS_DTPMOD: {
+ // sets the first `sizeof(uintptr_t)` bytes of `struct __abi_tls_entry`
+ // this means that we can just use the `SharedObject *` to resolve whatever we need
+ __ensure(!rel.addend_rel());
+ if(rel.symbol_index()) {
+ __ensure(p);
+ rel.relocate(elf_addr(p->object()));
+ }else{
+ if(stillSlightlyVerbose)
+ mlibc::infoLogger() << "rtdl: Warning: TLS_DTPMOD64 with no symbol in object "
+ << rel.object()->name << frg::endlog;
+ rel.relocate(elf_addr(rel.object()));
+ }
+ } break;
+ case R_TLS_DTPREL: {
+ __ensure(rel.symbol_index());
+ __ensure(p);
+ rel.relocate(p->symbol()->st_value + rel.addend_rel() - TLS_DTV_OFFSET);
+ } break;
+ case R_TLS_TPREL: {
+ uintptr_t off = rel.addend_rel();
+ uintptr_t tls_offset = 0;
+
+ if(rel.symbol_index()) {
+ __ensure(p);
+ if(p->object()->tlsModel != TlsModel::initial)
+ mlibc::panicLogger() << "rtdl: In object " << rel.object()->name
+ << ": Static TLS relocation to symbol " << p->getString()
+ << " in dynamically loaded object "
+ << p->object()->name << frg::endlog;
+ off += p->symbol()->st_value;
+ tls_offset = p->object()->tlsOffset;
+ }else{
+ if(stillSlightlyVerbose)
+ mlibc::infoLogger() << "rtdl: Warning: TPOFF64 with no symbol"
+ " in object " << rel.object()->name << frg::endlog;
+ if(rel.object()->tlsModel != TlsModel::initial)
+ mlibc::panicLogger() << "rtdl: In object " << rel.object()->name
+ << ": Static TLS relocation to dynamically loaded object "
+ << rel.object()->name << frg::endlog;
+ tls_offset = rel.object()->tlsOffset;
+ }
+
+ if constexpr (tlsAboveTp) {
+ off += tls_offset - sizeof(Tcb);
+ } else {
+ off += tls_offset;
+ }
+
+ rel.relocate(off);
+ } break;
+ default:
+ mlibc::panicLogger() << "Unexpected relocation type "
+ << (void *) rel.type() << frg::endlog;
+ }
+}
+
+void Loader::_processStaticRelocations(SharedObject *object) {
+ frg::optional<uintptr_t> rela_offset;
+ frg::optional<size_t> rela_length;
+
+ frg::optional<uintptr_t> rel_offset;
+ frg::optional<size_t> rel_length;
+
+ frg::optional<uintptr_t> relr_offset;
+ frg::optional<size_t> relr_length;
+
+ for(size_t i = 0; object->dynamic[i].d_tag != DT_NULL; i++) {
+ elf_dyn *dynamic = &object->dynamic[i];
+
+ switch(dynamic->d_tag) {
+ case DT_RELA:
+ rela_offset = dynamic->d_un.d_ptr;
+ break;
+ case DT_RELASZ:
+ rela_length = dynamic->d_un.d_val;
+ break;
+ case DT_RELAENT:
+ __ensure(dynamic->d_un.d_val == sizeof(elf_rela));
+ break;
+ case DT_REL:
+ rel_offset = dynamic->d_un.d_ptr;
+ break;
+ case DT_RELSZ:
+ rel_length = dynamic->d_un.d_val;
+ break;
+ case DT_RELENT:
+ __ensure(dynamic->d_un.d_val == sizeof(elf_rel));
+ break;
+ case DT_RELR:
+ relr_offset = dynamic->d_un.d_ptr;
+ break;
+ case DT_RELRSZ:
+ relr_length = dynamic->d_un.d_val;
+ break;
+ case DT_RELRENT:
+ __ensure(dynamic->d_un.d_val == sizeof(elf_relr));
+ break;
+ }
+ }
+
+ if(rela_offset && rela_length) {
+ __ensure(!rel_offset && !rel_length);
+
+ for(size_t offset = 0; offset < *rela_length; offset += sizeof(elf_rela)) {
+ auto reloc = (elf_rela *)(object->baseAddress + *rela_offset + offset);
+ auto r = Relocation(object, reloc);
+
+ _processRelocations(r);
+ }
+ }else if(rel_offset && rel_length) {
+ __ensure(!rela_offset && !rela_length);
+
+ for(size_t offset = 0; offset < *rel_length; offset += sizeof(elf_rel)) {
+ auto reloc = (elf_rel *)(object->baseAddress + *rel_offset + offset);
+ auto r = Relocation(object, reloc);
+
+ _processRelocations(r);
+ }
+ }
+
+ if(relr_offset && relr_length) {
+ elf_addr *addr = nullptr;
+
+ for(size_t offset = 0; offset < *relr_length; offset += sizeof(elf_relr)) {
+ auto entry = *(elf_relr *)(object->baseAddress + *relr_offset + offset);
+
+ // Even entry indicates the beginning address.
+ if(!(entry & 1)) {
+ addr = (elf_addr *)(object->baseAddress + entry);
+ __ensure(addr);
+ *addr++ += object->baseAddress;
+ }else {
+ // Odd entry indicates entry is a bitmap of the subsequent locations to be relocated.
+ for(int i = 0; entry; ++i) {
+ if(entry & 1) {
+ addr[i] += object->baseAddress;
+ }
+ entry >>= 1;
+ }
+
+ // Each entry describes at max 63 (on 64bit) or 31 (on 32bit) subsequent locations.
+ addr += CHAR_BIT * sizeof(elf_relr) - 1;
+ }
+ }
+ }
+}
+
+// TODO: TLSDESC relocations aren't aarch64 specific
+#ifdef __aarch64__
+extern "C" void *__mlibcTlsdescStatic(void *);
+extern "C" void *__mlibcTlsdescDynamic(void *);
+#endif
+
+void Loader::_processLazyRelocations(SharedObject *object) {
+ if(object->globalOffsetTable == nullptr) {
+ __ensure(object->lazyRelocTableOffset == 0);
+ return;
+ }
+ object->globalOffsetTable[1] = object;
+ object->globalOffsetTable[2] = (void *)&pltRelocateStub;
+
+ if(!object->lazyTableSize)
+ return;
+
+ // adjust the addresses of JUMP_SLOT relocations
+ __ensure(object->lazyExplicitAddend.has_value());
+ size_t rel_size = (*object->lazyExplicitAddend) ? sizeof(elf_rela) : sizeof(elf_rel);
+
+ for(size_t offset = 0; offset < object->lazyTableSize; offset += rel_size) {
+ elf_info type;
+ elf_info symbol_index;
+
+ uintptr_t rel_addr;
+ uintptr_t addend [[maybe_unused]] = 0;
+
+ if(*object->lazyExplicitAddend) {
+ auto reloc = (elf_rela *)(object->baseAddress + object->lazyRelocTableOffset + offset);
+ type = ELF_R_TYPE(reloc->r_info);
+ symbol_index = ELF_R_SYM(reloc->r_info);
+ rel_addr = object->baseAddress + reloc->r_offset;
+ addend = reloc->r_addend;
+ } else {
+ auto reloc = (elf_rel *)(object->baseAddress + object->lazyRelocTableOffset + offset);
+ type = ELF_R_TYPE(reloc->r_info);
+ symbol_index = ELF_R_SYM(reloc->r_info);
+ rel_addr = object->baseAddress + reloc->r_offset;
+ }
+
+ switch (type) {
+ case R_JUMP_SLOT:
+ if(eagerBinding) {
+ auto symbol = (elf_sym *)(object->baseAddress + object->symbolTableOffset
+ + symbol_index * sizeof(elf_sym));
+ ObjectSymbol r(object, symbol);
+ auto p = Scope::resolveGlobalOrLocal(*globalScope, object->localScope, r.getString(), object->objectRts, 0);
+
+ if(!p) {
+ if(ELF_ST_BIND(symbol->st_info) != STB_WEAK)
+ mlibc::panicLogger() << "rtdl: Unresolved JUMP_SLOT symbol "
+ << r.getString() << " in object " << object->name << frg::endlog;
+
+ if(verbose)
+ mlibc::infoLogger() << "rtdl: Unresolved weak JUMP_SLOT symbol "
+ << r.getString() << " in object " << object->name << frg::endlog;
+ *((uintptr_t *)rel_addr) = 0;
+ }else{
+ *((uintptr_t *)rel_addr) = p->virtualAddress();
+ }
+ }else{
+ *((uintptr_t *)rel_addr) += object->baseAddress;
+ }
+ break;
+#if defined(__x86_64__)
+ case R_X86_64_IRELATIVE: {
+ auto ptr = object->baseAddress + addend;
+ auto target = reinterpret_cast<uintptr_t (*)(void)>(ptr)();
+ *((uintptr_t *)rel_addr) = target;
+ break;
+ }
+#endif
+// TODO: TLSDESC relocations aren't aarch64 specific
+#if defined(__aarch64__)
+ case R_AARCH64_TLSDESC: {
+ size_t symValue = 0;
+ SharedObject *target = nullptr;
+
+ if (symbol_index) {
+ auto symbol = (elf_sym *)(object->baseAddress + object->symbolTableOffset
+ + symbol_index * sizeof(elf_sym));
+ ObjectSymbol r(object, symbol);
+ auto p = Scope::resolveGlobalOrLocal(*globalScope, object->localScope, r.getString(), object->objectRts, 0);
+
+ if (!p) {
+ __ensure(ELF_ST_BIND(symbol->st_info) != STB_WEAK);
+ mlibc::panicLogger() << "rtdl: Unresolved TLSDESC for symbol "
+ << r.getString() << " in object " << object->name << frg::endlog;
+ } else {
+ target = p->object();
+ if (p->symbol())
+ symValue = p->symbol()->st_value;
+ }
+ } else {
+ target = object;
+ }
+
+ __ensure(target);
+
+ if (target->tlsModel == TlsModel::initial) {
+ ((uint64_t *)rel_addr)[0] = reinterpret_cast<uintptr_t>(&__mlibcTlsdescStatic);
+ // TODO: guard the subtraction of TCB size with `if constexpr (tlsAboveTp)`
+ // for the arch-generic case
+ __ensure(tlsAboveTp == true);
+ ((uint64_t *)rel_addr)[1] = symValue + target->tlsOffset + addend - sizeof(Tcb);
+ } else {
+ struct TlsdescData {
+ uintptr_t tlsIndex;
+ uintptr_t addend;
+ };
+
+ // Access DTV for object to force the entry to be allocated and initialized
+ accessDtv(target);
+
+ __ensure(target->tlsIndex < mlibc::get_current_tcb()->dtvSize);
+
+ // TODO: We should free this when the DSO gets destroyed
+ auto data = frg::construct<TlsdescData>(getAllocator());
+ data->tlsIndex = target->tlsIndex;
+ data->addend = symValue + addend;
+
+ ((uint64_t *)rel_addr)[0] = reinterpret_cast<uintptr_t>(&__mlibcTlsdescDynamic);
+ ((uint64_t *)rel_addr)[1] = reinterpret_cast<uintptr_t>(data);
+ }
+ } break;
+#endif
+ default:
+ mlibc::panicLogger() << "unimplemented lazy relocation type " << type << frg::endlog;
+ break;
+ }
+ }
+}
+
diff --git a/lib/mlibc/options/rtdl/generic/linker.hpp b/lib/mlibc/options/rtdl/generic/linker.hpp
new file mode 100644
index 0000000..ad84ca9
--- /dev/null
+++ b/lib/mlibc/options/rtdl/generic/linker.hpp
@@ -0,0 +1,402 @@
+
+#include <frg/hash_map.hpp>
+#include <frg/optional.hpp>
+#include <frg/string.hpp>
+#include <frg/vector.hpp>
+#include <frg/expected.hpp>
+#include <mlibc/allocator.hpp>
+#include <mlibc/tcb.hpp>
+
+#include "elf.hpp"
+
+struct ObjectRepository;
+struct Scope;
+struct Loader;
+struct SharedObject;
+
+extern uint64_t rtsCounter;
+
+enum class TlsModel {
+ null,
+ initial,
+ dynamic
+};
+
+enum class LinkerError {
+ success,
+ notFound,
+ fileTooShort,
+ notElf,
+ wrongElfType,
+ outOfMemory,
+ invalidProgramHeader
+};
+
+// --------------------------------------------------------
+// ObjectRepository
+// --------------------------------------------------------
+
+struct ObjectRepository {
+ ObjectRepository();
+
+ ObjectRepository(const ObjectRepository &) = delete;
+
+ ObjectRepository &operator= (const ObjectRepository &) = delete;
+
+ // This is primarily used to create a SharedObject for the RTDL itself.
+ SharedObject *injectObjectFromDts(frg::string_view name,
+ frg::string<MemoryAllocator> path,
+ uintptr_t base_address, elf_dyn *dynamic, uint64_t rts);
+
+ // This is used to create a SharedObject for the executable that we want to link.
+ SharedObject *injectObjectFromPhdrs(frg::string_view name,
+ frg::string<MemoryAllocator> path, void *phdr_pointer,
+ size_t phdr_entry_size, size_t num_phdrs, void *entry_pointer,
+ uint64_t rts);
+
+ SharedObject *injectStaticObject(frg::string_view name,
+ frg::string<MemoryAllocator> path, void *phdr_pointer,
+ size_t phdr_entry_size, size_t num_phdrs, void *entry_pointer,
+ uint64_t rts);
+
+ frg::expected<LinkerError, SharedObject *> requestObjectWithName(frg::string_view name,
+ SharedObject *origin, Scope *localScope, bool createScope, uint64_t rts);
+
+ frg::expected<LinkerError, SharedObject *> requestObjectAtPath(frg::string_view path,
+ Scope *localScope, bool createScope, uint64_t rts);
+
+ SharedObject *findCaller(void *address);
+
+ SharedObject *findLoadedObject(frg::string_view name);
+
+ // Used by dl_iterate_phdr: stores objects in the order they are loaded.
+ frg::vector<SharedObject *, MemoryAllocator> loadedObjects;
+
+private:
+ void _fetchFromPhdrs(SharedObject *object, void *phdr_pointer,
+ size_t phdr_entry_size, size_t num_phdrs, void *entry_pointer);
+
+ frg::expected<LinkerError, void> _fetchFromFile(SharedObject *object, int fd);
+
+ void _parseDynamic(SharedObject *object);
+
+ void _discoverDependencies(SharedObject *object, Scope *localScope, uint64_t rts);
+
+ void _addLoadedObject(SharedObject *object);
+
+ frg::hash_map<frg::string_view, SharedObject *,
+ frg::hash<frg::string_view>, MemoryAllocator> _nameMap;
+};
+
+// --------------------------------------------------------
+// SharedObject
+// --------------------------------------------------------
+
+enum class HashStyle {
+ none,
+ systemV,
+ gnu
+};
+
+using InitFuncPtr = void (*)();
+
+// The ABI of this struct is fixed by GDB
+struct DebugInterface {
+ int ver;
+ void *head;
+ void (*brk)(void);
+ int state;
+ void *base;
+};
+
+// The ABI of this struct is fixed by GDB
+struct LinkMap {
+ uintptr_t base = 0;
+ const char *name = nullptr;
+ elf_dyn *dynv = nullptr;
+ LinkMap *next = nullptr, *prev = nullptr;
+};
+
+struct SharedObject {
+ // path is copied
+ SharedObject(const char *name, frg::string<MemoryAllocator> path,
+ bool is_main_object, Scope *localScope, uint64_t object_rts);
+
+ SharedObject(const char *name, const char *path, bool is_main_object,
+ Scope *localScope, uint64_t object_rts);
+
+ frg::string<MemoryAllocator> name;
+ frg::string<MemoryAllocator> path;
+ frg::string<MemoryAllocator> interpreterPath;
+ const char *soName;
+ bool isMainObject;
+ uint64_t objectRts;
+
+ // link map for debugging
+ LinkMap linkMap;
+ bool inLinkMap;
+
+ // base address this shared object was loaded to
+ uintptr_t baseAddress;
+
+ Scope *localScope;
+
+ // pointers to the dynamic table, GOT and entry point
+ elf_dyn *dynamic = nullptr;
+ void **globalOffsetTable;
+ void *entry;
+
+ // object initialization information
+ InitFuncPtr initPtr = nullptr;
+ InitFuncPtr *initArray = nullptr;
+ InitFuncPtr *preInitArray = nullptr;
+ size_t initArraySize = 0;
+ size_t preInitArraySize = 0;
+
+
+ // TODO: read this from the PHDR
+ size_t tlsSegmentSize, tlsAlignment, tlsImageSize;
+ void *tlsImagePtr;
+ bool tlsInitialized;
+
+ // symbol and string table of this shared object
+ HashStyle hashStyle = HashStyle::none;
+ uintptr_t hashTableOffset;
+ uintptr_t symbolTableOffset;
+ uintptr_t stringTableOffset;
+
+ const char *runPath = nullptr;
+
+ // save the lazy JUMP_SLOT relocation table
+ uintptr_t lazyRelocTableOffset;
+ size_t lazyTableSize;
+ frg::optional<bool> lazyExplicitAddend;
+
+ bool symbolicResolution;
+ bool eagerBinding;
+ bool haveStaticTls;
+
+ // vector of dependencies
+ frg::vector<SharedObject *, MemoryAllocator> dependencies;
+
+ TlsModel tlsModel;
+ size_t tlsIndex;
+ size_t tlsOffset;
+
+ uint64_t globalRts;
+ bool wasLinked;
+
+ bool scheduledForInit;
+ bool onInitStack;
+ bool wasInitialized;
+
+ // PHDR related stuff, we only set these for the main executable
+ void *phdrPointer = nullptr;
+ size_t phdrEntrySize = 0;
+ size_t phdrCount = 0;
+};
+
+struct Relocation {
+ Relocation(SharedObject *object, elf_rela *r)
+ : object_{object}, type_{Addend::Explicit} {
+ offset_ = r->r_offset;
+ info_ = r->r_info;
+ addend_ = r->r_addend;
+ }
+
+ Relocation(SharedObject *object, elf_rel *r)
+ : object_{object}, type_{Addend::Implicit} {
+ offset_ = r->r_offset;
+ info_ = r->r_info;
+ }
+
+ SharedObject *object() {
+ return object_;
+ }
+
+ elf_info type() const {
+ return ELF_R_TYPE(info_);
+ }
+
+ elf_info symbol_index() const {
+ return ELF_R_SYM(info_);
+ }
+
+ elf_addr addend_rel() {
+ switch(type_) {
+ case Addend::Explicit:
+ return addend_;
+ case Addend::Implicit: {
+ auto ptr = reinterpret_cast<elf_addr *>(object_->baseAddress + offset_);
+ return *ptr;
+ }
+ }
+ __builtin_unreachable();
+ }
+
+ elf_addr addend_norel() {
+ switch(type_) {
+ case Addend::Explicit:
+ return addend_;
+ case Addend::Implicit:
+ return 0;
+ }
+ __builtin_unreachable();
+ }
+
+ void *destination() {
+ return reinterpret_cast<void *>(object_->baseAddress + offset_);
+ }
+
+ void relocate(elf_addr addr) {
+ auto ptr = destination();
+ memcpy(ptr, &addr, sizeof(addr));
+ }
+
+private:
+ enum class Addend {
+ Implicit,
+ Explicit
+ };
+
+ SharedObject *object_;
+ Addend type_;
+
+ elf_addr offset_;
+ elf_info info_;
+ elf_addend addend_ = 0;
+};
+
+void processCopyRelocations(SharedObject *object);
+
+// --------------------------------------------------------
+// RuntimeTlsMap
+// --------------------------------------------------------
+
+struct RuntimeTlsMap {
+ RuntimeTlsMap();
+
+ // Amount of initialLimit that has already been allocated.
+ size_t initialPtr;
+
+ // Size of the inital TLS segment.
+ size_t initialLimit;
+
+ // TLS indices.
+ frg::vector<SharedObject *, MemoryAllocator> indices;
+};
+
+extern frg::manual_box<RuntimeTlsMap> runtimeTlsMap;
+
+Tcb *allocateTcb();
+void initTlsObjects(Tcb *tcb, const frg::vector<SharedObject *, MemoryAllocator> &objects, bool checkInitialized);
+void *accessDtv(SharedObject *object);
+// Tries to access the DTV, if not allocated, or object doesn't have
+// PT_TLS, return nullptr.
+void *tryAccessDtv(SharedObject *object);
+
+// --------------------------------------------------------
+// ObjectSymbol
+// --------------------------------------------------------
+
+struct ObjectSymbol {
+ ObjectSymbol(SharedObject *object, const elf_sym *symbol);
+
+ SharedObject *object() {
+ return _object;
+ }
+
+ const elf_sym *symbol() {
+ return _symbol;
+ }
+
+ const char *getString();
+
+ uintptr_t virtualAddress();
+
+private:
+ SharedObject *_object;
+ const elf_sym *_symbol;
+};
+
+frg::optional<ObjectSymbol> resolveInObject(SharedObject *object, frg::string_view string);
+
+// --------------------------------------------------------
+// Scope
+// --------------------------------------------------------
+
+struct Scope {
+ using ResolveFlags = uint32_t;
+ static inline constexpr ResolveFlags resolveCopy = 1;
+ static inline constexpr ResolveFlags skipGlobalAfterRts = 1 << 1;
+
+ static frg::optional<ObjectSymbol> resolveGlobalOrLocal(Scope &globalScope,
+ Scope *localScope, frg::string_view string, uint64_t skipRts, ResolveFlags flags);
+ static frg::optional<ObjectSymbol> resolveGlobalOrLocalNext(Scope &globalScope,
+ Scope *localScope, frg::string_view string, SharedObject *origin);
+
+ Scope(bool isGlobal = false);
+
+ void appendObject(SharedObject *object);
+
+ frg::optional<ObjectSymbol> resolveSymbol(frg::string_view string, uint64_t skipRts, ResolveFlags flags);
+
+ bool isGlobal;
+
+private:
+ frg::optional<ObjectSymbol> _resolveNext(frg::string_view string, SharedObject *target);
+public: // TODO: Make this private again. (Was made public for __dlapi_reverse()).
+ frg::vector<SharedObject *, MemoryAllocator> _objects;
+};
+
+extern frg::manual_box<Scope> globalScope;
+
+// --------------------------------------------------------
+// Loader
+// --------------------------------------------------------
+
+class Loader {
+public:
+ Loader(Scope *scope, SharedObject *mainExecutable, bool is_initial_link, uint64_t rts);
+
+public:
+ void linkObjects(SharedObject *root);
+
+private:
+ void _buildLinkBfs(SharedObject *root);
+ void _buildTlsMaps();
+
+ void _processStaticRelocations(SharedObject *object);
+ void _processLazyRelocations(SharedObject *object);
+
+ void _processRelocations(Relocation &rel);
+
+public:
+ void initObjects();
+
+private:
+ void _scheduleInit(SharedObject *object);
+
+private:
+ SharedObject *_mainExecutable;
+ Scope *_loadScope;
+ bool _isInitialLink;
+ uint64_t _linkRts;
+
+ frg::vector<SharedObject *, MemoryAllocator> _linkBfs;
+
+ frg::vector<SharedObject *, MemoryAllocator> _initQueue;
+};
+
+// --------------------------------------------------------
+// Namespace scope functions
+// --------------------------------------------------------
+
+extern "C" void pltRelocateStub() __attribute__((__visibility__("hidden")));
+
+// --------------------------------------------------------
+// RTDL interface
+// --------------------------------------------------------
+
+void *rtdl_auxvector();
+
diff --git a/lib/mlibc/options/rtdl/generic/main.cpp b/lib/mlibc/options/rtdl/generic/main.cpp
new file mode 100644
index 0000000..3cff1e4
--- /dev/null
+++ b/lib/mlibc/options/rtdl/generic/main.cpp
@@ -0,0 +1,844 @@
+
+#include <elf.h>
+#include <link.h>
+
+#include <frg/manual_box.hpp>
+#include <frg/small_vector.hpp>
+
+#include <abi-bits/auxv.h>
+#include <mlibc/debug.hpp>
+#include <mlibc/rtdl-sysdeps.hpp>
+#include <mlibc/rtdl-config.hpp>
+#include <mlibc/rtdl-abi.hpp>
+#include <mlibc/stack_protector.hpp>
+#include <internal-config.h>
+#include <abi-bits/auxv.h>
+
+#include "elf.hpp"
+#include "linker.hpp"
+
+#if __MLIBC_POSIX_OPTION
+#include <dlfcn.h>
+#endif
+
+#define HIDDEN __attribute__((__visibility__("hidden")))
+#define EXPORT __attribute__((__visibility__("default")))
+
+static constexpr bool logEntryExit = false;
+static constexpr bool logStartup = false;
+static constexpr bool logDlCalls = false;
+
+#ifndef MLIBC_STATIC_BUILD
+extern HIDDEN void *_GLOBAL_OFFSET_TABLE_[];
+extern HIDDEN elf_dyn _DYNAMIC[];
+#endif
+
+namespace mlibc {
+ // Declared in options/internal/mlibc/tcb.hpp.
+ bool tcb_available_flag = false;
+}
+
+mlibc::RtdlConfig rtdlConfig;
+
+bool ldShowAuxv = false;
+
+uintptr_t *entryStack;
+frg::manual_box<ObjectRepository> initialRepository;
+frg::manual_box<Scope> globalScope;
+
+frg::manual_box<RuntimeTlsMap> runtimeTlsMap;
+
+// We use a small vector of size 4 to avoid memory allocation for the default library paths
+frg::manual_box<frg::small_vector<frg::string_view, 4, MemoryAllocator>> libraryPaths;
+
+frg::manual_box<frg::vector<frg::string_view, MemoryAllocator>> preloads;
+
+static SharedObject *executableSO;
+extern HIDDEN char __ehdr_start[];
+
+// Global debug interface variable
+DebugInterface globalDebugInterface;
+
+#ifndef MLIBC_STATIC_BUILD
+
+// Use a PC-relative instruction sequence to find our runtime load address.
+uintptr_t getLdsoBase() {
+#if defined(__x86_64__) || defined(__i386__) || defined(__aarch64__)
+ // On x86_64, the first GOT entry holds the link-time address of _DYNAMIC.
+ // TODO: This isn't guaranteed on AArch64, so this might fail with some linkers.
+ auto linktime_dynamic = reinterpret_cast<uintptr_t>(_GLOBAL_OFFSET_TABLE_[0]);
+ auto runtime_dynamic = reinterpret_cast<uintptr_t>(_DYNAMIC);
+ return runtime_dynamic - linktime_dynamic;
+#elif defined(__riscv)
+ return reinterpret_cast<uintptr_t>(&__ehdr_start);
+#endif
+}
+
+// Relocates the dynamic linker (i.e. this DSO) itself.
+// Assumptions:
+// - There are no references to external symbols.
+// Note that this code is fragile in the sense that it must not contain relocations itself.
+// TODO: Use tooling to verify this at compile time.
+extern "C" void relocateSelf() {
+ size_t rela_offset = 0;
+ size_t rela_size = 0;
+ size_t rel_offset = 0;
+ size_t rel_size = 0;
+ size_t relr_offset = 0;
+ size_t relr_size = 0;
+ for(size_t i = 0; _DYNAMIC[i].d_tag != DT_NULL; i++) {
+ auto ent = &_DYNAMIC[i];
+ switch(ent->d_tag) {
+ case DT_REL: rel_offset = ent->d_un.d_ptr; break;
+ case DT_RELSZ: rel_size = ent->d_un.d_val; break;
+ case DT_RELA: rela_offset = ent->d_un.d_ptr; break;
+ case DT_RELASZ: rela_size = ent->d_un.d_val; break;
+ case DT_RELR: relr_offset = ent->d_un.d_ptr; break;
+ case DT_RELRSZ: relr_size = ent->d_un.d_val; break;
+ }
+ }
+
+ auto ldso_base = getLdsoBase();
+
+ __ensure((rel_offset != 0) ^ (rela_offset != 0));
+
+ for(size_t disp = 0; disp < rela_size; disp += sizeof(elf_rela)) {
+ auto reloc = reinterpret_cast<elf_rela *>(ldso_base + rela_offset + disp);
+
+ auto type = ELF_R_TYPE(reloc->r_info);
+ if(ELF_R_SYM(reloc->r_info))
+ __builtin_trap();
+
+ auto p = reinterpret_cast<uint64_t *>(ldso_base + reloc->r_offset);
+ switch(type) {
+ case R_RELATIVE:
+ *p = ldso_base + reloc->r_addend;
+ break;
+ default:
+ __builtin_trap();
+ }
+ }
+
+ for(size_t disp = 0; disp < rel_size; disp += sizeof(elf_rel)) {
+ auto reloc = reinterpret_cast<elf_rel *>(ldso_base + rel_offset + disp);
+
+ auto type = ELF_R_TYPE(reloc->r_info);
+ if(ELF_R_SYM(reloc->r_info))
+ __builtin_trap();
+
+ auto p = reinterpret_cast<uint64_t *>(ldso_base + reloc->r_offset);
+ switch(type) {
+ case R_RELATIVE:
+ *p += ldso_base;
+ break;
+ default:
+ __builtin_trap();
+ }
+ }
+
+ elf_addr *addr = nullptr;
+ for(size_t disp = 0; disp < relr_size; disp += sizeof(elf_relr)) {
+ auto entry = *(elf_relr *)(ldso_base + relr_offset + disp);
+
+ // Even entry indicates the beginning address.
+ if(!(entry & 1)) {
+ addr = (elf_addr *)(ldso_base + entry);
+ __ensure(addr);
+ *addr++ += ldso_base;
+ }else {
+ // Odd entry indicates entry is a bitmap of the subsequent locations to be relocated.
+ for(int i = 0; entry; ++i) {
+ if(entry & 1) {
+ addr[i] += ldso_base;
+ }
+ entry >>= 1;
+ }
+
+ // Each entry describes at max 63 (on 64bit) or 31 (on 32bit) subsequent locations.
+ addr += CHAR_BIT * sizeof(elf_relr) - 1;
+ }
+ }
+}
+#endif
+
+extern "C" void *lazyRelocate(SharedObject *object, unsigned int rel_index) {
+ __ensure(object->lazyExplicitAddend);
+ auto reloc = (elf_rela *)(object->baseAddress + object->lazyRelocTableOffset
+ + rel_index * sizeof(elf_rela));
+ auto type = ELF_R_TYPE(reloc->r_info);
+ auto symbol_index = ELF_R_SYM(reloc->r_info);
+
+ __ensure(type == R_X86_64_JUMP_SLOT);
+ __ensure(ELF_CLASS == ELFCLASS64);
+
+ auto symbol = (elf_sym *)(object->baseAddress + object->symbolTableOffset
+ + symbol_index * sizeof(elf_sym));
+ ObjectSymbol r(object, symbol);
+ auto p = Scope::resolveGlobalOrLocal(*globalScope, object->localScope, r.getString(), object->objectRts, 0);
+ if(!p)
+ mlibc::panicLogger() << "Unresolved JUMP_SLOT symbol" << frg::endlog;
+
+ //mlibc::infoLogger() << "Lazy relocation to " << symbol_str
+ // << " resolved to " << pointer << frg::endlog;
+
+ *(uint64_t *)(object->baseAddress + reloc->r_offset) = p->virtualAddress();
+ return (void *)p->virtualAddress();
+}
+
+extern "C" [[ gnu::visibility("default") ]] void *__rtdl_allocateTcb() {
+ auto tcb = allocateTcb();
+ initTlsObjects(tcb, globalScope->_objects, false);
+ return tcb;
+}
+
+extern "C" {
+ [[ gnu::visibility("hidden") ]] void dl_debug_state() {
+ // This function is used to signal changes in the debugging link map,
+ // GDB just sets a breakpoint on this function and we can call it
+ // everytime we update the link map. We don't need to implement
+ // anything besides defining and calling it.
+ }
+}
+
+extern "C" [[gnu::alias("dl_debug_state"), gnu::visibility("default")]] void _dl_debug_state() noexcept;
+
+// This symbol can be used by GDB to find the global interface structure
+[[ gnu::visibility("default") ]] DebugInterface *_dl_debug_addr = &globalDebugInterface;
+
+static frg::vector<frg::string_view, MemoryAllocator> parseList(frg::string_view paths, frg::string_view separators) {
+ frg::vector<frg::string_view, MemoryAllocator> list{getAllocator()};
+
+ size_t p = 0;
+ while(p < paths.size()) {
+ size_t s; // Offset of next colon or end of string.
+ if(size_t cs = paths.find_first_of(separators, p); cs != size_t(-1)) {
+ s = cs;
+ }else{
+ s = paths.size();
+ }
+
+ auto path = paths.sub_string(p, s - p);
+ p = s + 1;
+
+ if(path.size() == 0)
+ continue;
+
+ if(path.ends_with("/")) {
+ size_t i = path.size() - 1;
+ while(i > 0 && path[i] == '/')
+ i--;
+ path = path.sub_string(0, i + 1);
+ }
+
+ if(path == "/")
+ path = "";
+
+ list.push_back(path);
+ }
+
+ return list;
+}
+
+extern "C" void *interpreterMain(uintptr_t *entry_stack) {
+ if(logEntryExit)
+ mlibc::infoLogger() << "Entering ld.so" << frg::endlog;
+ entryStack = entry_stack;
+ runtimeTlsMap.initialize();
+ libraryPaths.initialize(getAllocator());
+ preloads.initialize(getAllocator());
+
+ void *phdr_pointer = 0;
+ size_t phdr_entry_size = 0;
+ size_t phdr_count = 0;
+ void *entry_pointer = 0;
+ void *stack_entropy = nullptr;
+
+ const char *execfn = "(executable)";
+
+#ifndef MLIBC_STATIC_BUILD
+ using ctor_fn = void(*)(void);
+
+ ctor_fn *ldso_ctors = nullptr;
+ size_t num_ldso_ctors = 0;
+
+ auto ldso_base = getLdsoBase();
+ if(logStartup) {
+ mlibc::infoLogger() << "ldso: Own base address is: 0x"
+ << frg::hex_fmt(ldso_base) << frg::endlog;
+ mlibc::infoLogger() << "ldso: Own dynamic section is at: " << _DYNAMIC << frg::endlog;
+ }
+
+#ifdef __x86_64__
+ // These entries are reserved on x86_64.
+ // TODO: Use a fake PLT stub that reports an error message?
+ _GLOBAL_OFFSET_TABLE_[1] = 0;
+ _GLOBAL_OFFSET_TABLE_[2] = 0;
+#endif
+
+ // Validate our own dynamic section.
+ // Here, we make sure that the dynamic linker does not need relocations itself.
+ uintptr_t strtab_offset = 0;
+ uintptr_t soname_str = 0;
+ for(size_t i = 0; _DYNAMIC[i].d_tag != DT_NULL; i++) {
+ auto ent = &_DYNAMIC[i];
+ switch(ent->d_tag) {
+ case DT_STRTAB: strtab_offset = ent->d_un.d_ptr; break;
+ case DT_SONAME: soname_str = ent->d_un.d_val; break;
+ case DT_INIT_ARRAY: ldso_ctors = reinterpret_cast<ctor_fn *>(ent->d_un.d_ptr + ldso_base); break;
+ case DT_INIT_ARRAYSZ: num_ldso_ctors = ent->d_un.d_val / sizeof(ctor_fn); break;
+ case DT_HASH:
+ case DT_GNU_HASH:
+ case DT_STRSZ:
+ case DT_SYMTAB:
+ case DT_SYMENT:
+ case DT_RELA:
+ case DT_RELASZ:
+ case DT_RELAENT:
+ case DT_RELACOUNT:
+ case DT_DEBUG:
+ case DT_REL:
+ case DT_RELSZ:
+ case DT_RELENT:
+ case DT_RELCOUNT:
+ case DT_RELR:
+ case DT_RELRSZ:
+ case DT_RELRENT:
+ continue;
+ default:
+ __ensure(!"Unexpected dynamic entry in program interpreter");
+ }
+ }
+ __ensure(strtab_offset);
+ __ensure(soname_str);
+
+ // Find the auxiliary vector by skipping args and environment.
+ auto aux = entryStack;
+ aux += *aux + 1; // First, we skip argc and all args.
+ __ensure(!*aux);
+ aux++;
+ while(*aux) { // Loop through the environment.
+ auto env = reinterpret_cast<char *>(*aux);
+ frg::string_view view{env};
+ size_t s = view.find_first('=');
+
+ if(s == size_t(-1))
+ mlibc::panicLogger() << "rtdl: environment '" << env << "' is missing a '='" << frg::endlog;
+
+ auto name = view.sub_string(0, s);
+ auto value = const_cast<char *>(view.data() + s + 1);
+
+ if(name == "LD_SHOW_AUXV" && *value && *value != '0') {
+ ldShowAuxv = true;
+ }else if(name == "LD_LIBRARY_PATH" && *value) {
+ for(auto path : parseList(value, ":;"))
+ libraryPaths->push_back(path);
+ }else if(name == "LD_PRELOAD" && *value) {
+ *preloads = parseList(value, " :");
+ }
+
+ aux++;
+ }
+ aux++;
+
+ // Add default library paths
+ libraryPaths->push_back("/lib");
+ libraryPaths->push_back("/lib64");
+ libraryPaths->push_back("/usr/lib");
+ libraryPaths->push_back("/usr/lib64");
+
+ // Parse the actual vector.
+ while(true) {
+ auto value = aux + 1;
+ if(!(*aux))
+ break;
+
+ if(ldShowAuxv) {
+ switch(*aux) {
+ case AT_PHDR: mlibc::infoLogger() << "AT_PHDR: 0x" << frg::hex_fmt{*value} << frg::endlog; break;
+ case AT_PHENT: mlibc::infoLogger() << "AT_PHENT: " << *value << frg::endlog; break;
+ case AT_PHNUM: mlibc::infoLogger() << "AT_PHNUM: " << *value << frg::endlog; break;
+ case AT_ENTRY: mlibc::infoLogger() << "AT_ENTRY: 0x" << frg::hex_fmt{*value} << frg::endlog; break;
+ case AT_PAGESZ: mlibc::infoLogger() << "AT_PAGESZ: " << *value << frg::endlog; break;
+ case AT_BASE: mlibc::infoLogger() << "AT_BASE: 0x" << frg::hex_fmt{*value} << frg::endlog; break;
+ case AT_FLAGS: mlibc::infoLogger() << "AT_FLAGS: 0x" << frg::hex_fmt{*value} << frg::endlog; break;
+ case AT_NOTELF: mlibc::infoLogger() << "AT_NOTELF: " << frg::hex_fmt{*value} << frg::endlog; break;
+ case AT_UID: mlibc::infoLogger() << "AT_UID: " << *value << frg::endlog; break;
+ case AT_EUID: mlibc::infoLogger() << "AT_EUID: " << *value << frg::endlog; break;
+ case AT_GID: mlibc::infoLogger() << "AT_GID: " << *value << frg::endlog; break;
+ case AT_EGID: mlibc::infoLogger() << "AT_EGID: " << *value << frg::endlog; break;
+#ifdef AT_PLATFORM
+ case AT_PLATFORM: mlibc::infoLogger() << "AT_PLATFORM: " << reinterpret_cast<const char *>(*value) << frg::endlog; break;
+#endif
+#ifdef AT_HWCAP
+ case AT_HWCAP: mlibc::infoLogger() << "AT_HWCAP: " << frg::hex_fmt{*value} << frg::endlog; break;
+#endif
+#ifdef AT_CLKTCK
+ case AT_CLKTCK: mlibc::infoLogger() << "AT_CLKTCK: " << *value << frg::endlog; break;
+#endif
+#ifdef AT_FPUCW
+ case AT_FPUCW: mlibc::infoLogger() << "AT_FPUCW: " << frg::hex_fmt{*value} << frg::endlog; break;
+#endif
+#ifdef AT_SECURE
+ case AT_SECURE: mlibc::infoLogger() << "AT_SECURE: " << *value << frg::endlog; break;
+#endif
+#ifdef AT_RANDOM
+ case AT_RANDOM: mlibc::infoLogger() << "AT_RANDOM: 0x" << frg::hex_fmt{*value} << frg::endlog; break;
+#endif
+#ifdef AT_EXECFN
+ case AT_EXECFN: mlibc::infoLogger() << "AT_EXECFN: " << reinterpret_cast<const char *>(*value) << frg::endlog; break;
+#endif
+#ifdef AT_SYSINFO_EHDR
+ case AT_SYSINFO_EHDR: mlibc::infoLogger() << "AT_SYSINFO_EHDR: 0x" << frg::hex_fmt{*value} << frg::endlog; break;
+#endif
+ }
+ }
+
+ // TODO: Whitelist auxiliary vector entries here?
+ switch(*aux) {
+ case AT_PHDR: phdr_pointer = reinterpret_cast<void *>(*value); break;
+ case AT_PHENT: phdr_entry_size = *value; break;
+ case AT_PHNUM: phdr_count = *value; break;
+ case AT_ENTRY: entry_pointer = reinterpret_cast<void *>(*value); break;
+ case AT_EXECFN: execfn = reinterpret_cast<const char *>(*value); break;
+ case AT_RANDOM: stack_entropy = reinterpret_cast<void*>(*value); break;
+ case AT_SECURE: rtdlConfig.secureRequired = reinterpret_cast<uintptr_t>(*value); break;
+ }
+
+ aux += 2;
+ }
+ globalDebugInterface.base = reinterpret_cast<void*>(ldso_base);
+
+// This is here because libgcc will add a global constructor on glibc Linux
+// (which is what it believes we are due to the aarch64-linux-gnu toolchain)
+// in order to check if LSE atomics are supported.
+//
+// This is not necessary on a custom Linux toolchain and is purely an artifact of
+// using the host toolchain.
+#if defined(__aarch64__) && defined(__gnu_linux__)
+ for (size_t i = 0; i < num_ldso_ctors; i++) {
+ if(logStartup)
+ mlibc::infoLogger() << "ldso: Running own constructor at "
+ << reinterpret_cast<void *>(ldso_ctors[i])
+ << frg::endlog;
+ ldso_ctors[i]();
+ }
+#else
+ if (num_ldso_ctors > 0) {
+ mlibc::panicLogger() << "ldso: Found unexpected own global constructor(s), init_array starts at: "
+ << ldso_ctors
+ << frg::endlog;
+ }
+#endif
+
+#else
+ auto ehdr = reinterpret_cast<elf_ehdr*>(__ehdr_start);
+ phdr_pointer = reinterpret_cast<void*>((uintptr_t)ehdr->e_phoff + (uintptr_t)ehdr);
+ phdr_entry_size = ehdr->e_phentsize;
+ phdr_count = ehdr->e_phnum;
+ entry_pointer = reinterpret_cast<void*>(ehdr->e_entry);
+#endif
+ __ensure(phdr_pointer);
+ __ensure(entry_pointer);
+
+ if(logStartup)
+ mlibc::infoLogger() << "ldso: Executable PHDRs are at " << phdr_pointer
+ << frg::endlog;
+
+ // perform the initial dynamic linking
+ initialRepository.initialize();
+
+ globalScope.initialize(true);
+
+ // Add the dynamic linker, as well as the exectuable to the repository.
+#ifndef MLIBC_STATIC_BUILD
+ auto ldso_soname = reinterpret_cast<const char *>(ldso_base + strtab_offset + soname_str);
+ auto ldso = initialRepository->injectObjectFromDts(ldso_soname,
+ frg::string<MemoryAllocator> { getAllocator() },
+ ldso_base, _DYNAMIC, 1);
+ ldso->phdrPointer = phdr_pointer;
+ ldso->phdrCount = phdr_count;
+ ldso->phdrEntrySize = phdr_entry_size;
+
+ // TODO: support non-zero base addresses?
+ executableSO = initialRepository->injectObjectFromPhdrs(execfn,
+ frg::string<MemoryAllocator> { execfn, getAllocator() },
+ phdr_pointer, phdr_entry_size, phdr_count, entry_pointer, 1);
+
+ // We can't initialise the ldso object after the executable SO,
+ // so we have to set the ldso path after loading both.
+ ldso->path = executableSO->interpreterPath;
+
+#else
+ executableSO = initialRepository->injectStaticObject(execfn,
+ frg::string<MemoryAllocator>{ execfn, getAllocator() },
+ phdr_pointer, phdr_entry_size, phdr_count, entry_pointer, 1);
+ globalDebugInterface.base = (void*)executableSO->baseAddress;
+#endif
+
+ globalDebugInterface.head = &executableSO->linkMap;
+ executableSO->inLinkMap = true;
+ Loader linker{globalScope.get(), executableSO, true, 1};
+ linker.linkObjects(executableSO);
+
+ mlibc::initStackGuard(stack_entropy);
+
+ auto tcb = allocateTcb();
+ if(mlibc::sys_tcb_set(tcb))
+ __ensure(!"sys_tcb_set() failed");
+ tcb->tid = mlibc::this_tid();
+ mlibc::tcb_available_flag = true;
+
+ globalDebugInterface.ver = 1;
+ globalDebugInterface.brk = &dl_debug_state;
+ globalDebugInterface.state = 0;
+ dl_debug_state();
+
+ linker.initObjects();
+
+ if(logEntryExit)
+ mlibc::infoLogger() << "Leaving ld.so, jump to "
+ << (void *)executableSO->entry << frg::endlog;
+ return executableSO->entry;
+}
+
+const char *lastError;
+
+extern "C" [[ gnu::visibility("default") ]] uintptr_t *__dlapi_entrystack() {
+ return entryStack;
+}
+
+extern "C" [[ gnu::visibility("default") ]]
+const char *__dlapi_error() {
+ auto error = lastError;
+ lastError = nullptr;
+ return error;
+}
+
+extern "C" [[ gnu::visibility("default") ]]
+void *__dlapi_get_tls(struct __abi_tls_entry *entry) {
+ return reinterpret_cast<char *>(accessDtv(entry->object)) + entry->offset;
+}
+
+extern "C" [[ gnu::visibility("default") ]]
+const mlibc::RtdlConfig &__dlapi_get_config() {
+ return rtdlConfig;
+}
+
+#if __MLIBC_POSIX_OPTION
+
+extern "C" [[ gnu::visibility("default") ]]
+void *__dlapi_open(const char *file, int flags, void *returnAddress) {
+ if (logDlCalls)
+ mlibc::infoLogger() << "rtdl: __dlapi_open(" << (file ? file : "nullptr") << ")" << frg::endlog;
+
+ if (flags & RTLD_DEEPBIND)
+ mlibc::infoLogger() << "rtdl: dlopen(RTLD_DEEPBIND) is unsupported" << frg::endlog;
+
+ if(!file)
+ return executableSO;
+
+ // TODO: Thread-safety!
+ auto rts = rtsCounter++;
+
+ SharedObject *object;
+ if (flags & RTLD_NOLOAD) {
+ object = initialRepository->findLoadedObject(file);
+ if (object && object->globalRts == 0 && (flags & RTLD_GLOBAL)) {
+ // The object was opened with RTLD_LOCAL, but we are called with RTLD_NOLOAD | RTLD_GLOBAL.
+ // According to the man page, we should promote to the global scope here.
+ object->globalRts = rts;
+ globalScope->appendObject(object);
+ }
+ } else {
+ bool isGlobal = flags & RTLD_GLOBAL;
+ Scope *newScope = isGlobal ? globalScope.get() : nullptr;
+
+ frg::expected<LinkerError, SharedObject *> objectResult;
+ if (frg::string_view{file}.find_first('/') == size_t(-1)) {
+ // In order to know which RUNPATH / RPATH to process, we must find the calling object.
+ SharedObject *origin = initialRepository->findCaller(returnAddress);
+ if (!origin) {
+ mlibc::panicLogger() << "rtdl: unable to determine calling object of dlopen "
+ << "(ra = " << returnAddress << ")" << frg::endlog;
+ }
+
+ objectResult = initialRepository->requestObjectWithName(file, origin, newScope, !isGlobal, rts);
+ } else {
+ objectResult = initialRepository->requestObjectAtPath(file, newScope, !isGlobal, rts);
+ }
+
+ if(!objectResult) {
+ switch (objectResult.error()) {
+ case LinkerError::success:
+ __builtin_unreachable();
+ case LinkerError::notFound:
+ lastError = "Cannot locate requested DSO";
+ break;
+ case LinkerError::fileTooShort:
+ lastError = "File too short";
+ break;
+ case LinkerError::notElf:
+ lastError = "File is not an ELF file";
+ break;
+ case LinkerError::wrongElfType:
+ lastError = "File has wrong ELF type";
+ break;
+ case LinkerError::outOfMemory:
+ lastError = "Out of memory";
+ break;
+ case LinkerError::invalidProgramHeader:
+ lastError = "File has invalid program header";
+ break;
+ }
+ return nullptr;
+ }
+ object = objectResult.value();
+
+ Loader linker{object->localScope, nullptr, false, rts};
+ linker.linkObjects(object);
+ linker.initObjects();
+ }
+
+ dl_debug_state();
+
+ return object;
+}
+
+extern "C" [[ gnu::visibility("default") ]]
+void *__dlapi_resolve(void *handle, const char *string, void *returnAddress) {
+ if (logDlCalls) {
+ const char *name;
+ bool quote = false;
+ if (handle == RTLD_DEFAULT) {
+ name = "RTLD_DEFAULT";
+ } else if (handle == RTLD_NEXT) {
+ name = "RTLD_NEXT";
+ } else {
+ name = ((SharedObject *)handle)->name.data();
+ quote = true;
+ }
+
+ mlibc::infoLogger() << "rtdl: __dlapi_resolve(" << (quote ? "\"" : "") << name
+ << (quote ? "\"" : "") << ", \"" << string << "\")" << frg::endlog;
+ }
+
+ frg::optional<ObjectSymbol> target;
+
+ if (handle == RTLD_DEFAULT) {
+ target = globalScope->resolveSymbol(string, 0, 0);
+ } else if (handle == RTLD_NEXT) {
+ SharedObject *origin = initialRepository->findCaller(returnAddress);
+ if (!origin) {
+ mlibc::panicLogger() << "rtdl: unable to determine calling object of dlsym "
+ << "(ra = " << returnAddress << ")" << frg::endlog;
+ }
+
+ target = Scope::resolveGlobalOrLocalNext(*globalScope, origin->localScope, string, origin);
+ } else {
+ // POSIX does not unambiguously state how dlsym() is supposed to work; it just
+ // states that "The symbol resolution algorithm used shall be dependency order
+ // as described in dlopen()".
+ //
+ // Linux libc's lookup the symbol in the given DSO and all of its dependencies
+ // in breadth-first order. That is also what we implement here.
+ //
+ // Note that this *differs* from the algorithm that is used for relocations
+ // (since the algorithm used for relocations takes (i) the global scope,
+ // and (ii) the local scope of the DSO into account (which can contain more objects
+ // than just the dependencies of the DSO, if the DSO was loaded as a dependency
+ // of a dlopen()ed DSO).
+
+ frg::vector<SharedObject *, MemoryAllocator> queue{getAllocator()};
+
+ struct Token { };
+ frg::hash_map<
+ SharedObject *, Token,
+ frg::hash<SharedObject *>, MemoryAllocator
+ > visited{frg::hash<SharedObject *>{}, getAllocator()};
+
+ auto root = reinterpret_cast<SharedObject *>(handle);
+ visited.insert(root, Token{});
+ queue.push_back(root);
+
+ for(size_t i = 0; i < queue.size(); i++) {
+ auto current = queue[i];
+
+ target = resolveInObject(current, string);
+ if(target)
+ break;
+
+ for(auto dep : current->dependencies) {
+ if(visited.get(dep))
+ continue;
+ visited.insert(dep, Token{});
+ queue.push_back(dep);
+ }
+ }
+ }
+
+ if (!target) {
+ if (logDlCalls)
+ mlibc::infoLogger() << "rtdl: could not resolve \"" << string << "\"" << frg::endlog;
+
+ lastError = "Cannot resolve requested symbol";
+ return nullptr;
+ }
+ return reinterpret_cast<void *>(target->virtualAddress());
+}
+
+struct __dlapi_symbol {
+ const char *file;
+ void *base;
+ const char *symbol;
+ void *address;
+};
+
+extern "C" [[ gnu::visibility("default") ]]
+int __dlapi_reverse(const void *ptr, __dlapi_symbol *info) {
+ if (logDlCalls)
+ mlibc::infoLogger() << "rtdl: __dlapi_reverse(" << ptr << ")" << frg::endlog;
+
+ for(size_t i = 0; i < initialRepository->loadedObjects.size(); i++) {
+ auto object = initialRepository->loadedObjects[i];
+
+ auto eligible = [&] (ObjectSymbol cand) {
+ if(cand.symbol()->st_shndx == SHN_UNDEF)
+ return false;
+
+ auto bind = ELF_ST_BIND(cand.symbol()->st_info);
+ if(bind != STB_GLOBAL && bind != STB_WEAK)
+ return false;
+
+ return true;
+ };
+
+ auto hash_table = (Elf64_Word *)(object->baseAddress + object->hashTableOffset);
+ auto num_symbols = hash_table[1];
+ for(size_t i = 0; i < num_symbols; i++) {
+ ObjectSymbol cand{object, (elf_sym *)(object->baseAddress
+ + object->symbolTableOffset + i * sizeof(elf_sym))};
+ if(eligible(cand) && cand.virtualAddress() == reinterpret_cast<uintptr_t>(ptr)) {
+ if (logDlCalls)
+ mlibc::infoLogger() << "rtdl: Found symbol " << cand.getString() << " in object "
+ << object->path << frg::endlog;
+
+ info->file = object->path.data();
+ info->base = reinterpret_cast<void *>(object->baseAddress);
+ info->symbol = cand.getString();
+ info->address = reinterpret_cast<void *>(cand.virtualAddress());
+ return 0;
+ }
+ }
+ }
+
+ // Not found, find the DSO it should be in.
+ for(size_t i = 0; i < initialRepository->loadedObjects.size(); i++) {
+ auto object = initialRepository->loadedObjects[i];
+
+ for(size_t j = 0; j < object->phdrCount; j++) {
+ auto phdr = (elf_phdr *)((uintptr_t)object->phdrPointer + j * object->phdrEntrySize);
+ if(phdr->p_type != PT_LOAD) {
+ continue;
+ }
+ uintptr_t start = object->baseAddress + phdr->p_vaddr;
+ uintptr_t end = start + phdr->p_memsz;
+ if(reinterpret_cast<uintptr_t>(ptr) >= start && reinterpret_cast<uintptr_t>(ptr) < end) {
+ mlibc::infoLogger() << "rtdl: Found DSO " << object->path << frg::endlog;
+ info->file = object->path.data();
+ info->base = reinterpret_cast<void *>(object->baseAddress);
+ info->symbol = nullptr;
+ info->address = 0;
+ return 0;
+ }
+ }
+ }
+
+ if (logDlCalls)
+ mlibc::infoLogger() << "rtdl: Could not find symbol in __dlapi_reverse()" << frg::endlog;
+
+ return -1;
+}
+
+extern "C" [[ gnu::visibility("default") ]]
+int __dlapi_close(void *) {
+ if (logDlCalls)
+ mlibc::infoLogger() << "mlibc: dlclose() is a no-op" << frg::endlog;
+ return 0;
+}
+
+#endif
+
+extern "C" [[ gnu::visibility("default") ]]
+int __dlapi_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void*), void *data) {
+ int last_return = 0;
+ for (auto object : initialRepository->loadedObjects) {
+ struct dl_phdr_info info;
+ info.dlpi_addr = object->baseAddress;
+ info.dlpi_name = object->name.data();
+
+ if(object->isMainObject) {
+ info.dlpi_name = "";
+ } else {
+ info.dlpi_name = object->name.data();
+ }
+ info.dlpi_phdr = static_cast<ElfW(Phdr)*>(object->phdrPointer);
+ info.dlpi_phnum = object->phdrCount;
+ info.dlpi_adds = rtsCounter;
+ info.dlpi_subs = 0; // TODO(geert): implement dlclose().
+ if (object->tlsModel != TlsModel::null)
+ info.dlpi_tls_modid = object->tlsIndex;
+ else
+ info.dlpi_tls_modid = 0;
+ info.dlpi_tls_data = tryAccessDtv(object);
+
+ last_return = callback(&info, sizeof(struct dl_phdr_info), data);
+ if(last_return)
+ return last_return;
+ }
+
+ return last_return;
+}
+
+extern "C" [[ gnu::visibility("default") ]]
+void __dlapi_enter(uintptr_t *entry_stack) {
+#if MLIBC_STATIC_BUILD
+ interpreterMain(entry_stack);
+#else
+ (void)entry_stack;
+#endif
+}
+
+// XXX(qookie):
+// This is here because libgcc will call into __getauxval on glibc Linux
+// (which is what it believes we are due to the aarch64-linux-gnu toolchain)
+// in order to find AT_HWCAP to discover if LSE atomics are supported.
+//
+// This is not necessary on a custom Linux toolchain and is purely an artifact of
+// using the host toolchain.
+
+// __gnu_linux__ is the define checked by libgcc
+#if defined(__aarch64__) && defined(__gnu_linux__) && !defined(MLIBC_STATIC_BUILD)
+
+extern "C" unsigned long __getauxval(unsigned long type) {
+ // Find the auxiliary vector by skipping args and environment.
+ auto aux = entryStack;
+ aux += *aux + 1; // Skip argc and all arguments
+ __ensure(!*aux);
+ aux++;
+ while(*aux) // Now, we skip the environment.
+ aux++;
+ aux++;
+
+ // Parse the auxiliary vector.
+ while(true) {
+ auto value = aux + 1;
+ if(*aux == AT_NULL) {
+ return 0;
+ }else if(*aux == type) {
+ return *value;
+ }
+ aux += 2;
+ }
+}
+
+#endif