diff options
Diffstat (limited to 'lib/mlibc/options/rtdl/generic/linker.cpp')
| -rw-r--r-- | lib/mlibc/options/rtdl/generic/linker.cpp | 1872 |
1 files changed, 1872 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; + } + } +} + |