/*
* Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Hyra nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/loader.h>
#include <sys/cdefs.h>
#include <sys/elf.h>
#include <sys/types.h>
#include <sys/syslog.h>
#include <sys/errno.h>
#include <sys/proc.h>
#include <vm/vm.h>
#include <vm/map.h>
#include <vm/physseg.h>
#include <vm/dynalloc.h>
#include <string.h>
#include <assert.h>
__MODULE_NAME("kern_loader");
__KERNEL_META("$Hyra$: kern_loader.c, Ian Marco Moffett, "
"Kernel ELF loader");
#if !defined(DEBUG)
#define DBG(...) __nothing
#else
#define DBG(...) KDEBUG(__VA_ARGS__)
#endif
#define PHDR(hdrptr, IDX) \
(void *)((uintptr_t)hdr + (hdrptr)->e_phoff + (hdrptr->e_phentsize*IDX))
int
loader_unload(struct vas vas, struct vm_range *exec_range)
{
size_t start, end;
start = exec_range->start;
end = exec_range->end;
/* FIXME: Figure out how to free physical memory too */
return vm_map_destroy(vas, start, (end - start));
}
uintptr_t
loader_init_stack(void *stack_top, struct exec_args args)
{
uintptr_t *sp = stack_top;
uintptr_t old_sp = 0;
size_t argc, envc, len;
char **argvp = args.argp;
char **envp = args.envp;
struct auxval auxv = args.auxv;
/* Copy strings */
old_sp = (uintptr_t)sp;
for (argc = 0; argvp[argc] != NULL; ++argc) {
len = strlen(argvp[argc]) + 1;
sp = (void *)((char *)sp - len);
memcpy((char *)sp, argvp[argc], len);
}
for (envc = 0; envp[envc] != NULL; ++envc) {
len = strlen(envp[envc]) + 1;
sp = (void *)((char *)sp - len);
memcpy((char *)sp, envp[envc], len);
}
/* Ensure the stack is aligned */
sp = (void *)__ALIGN_DOWN((uintptr_t)sp, 16);
if (((argc + envc + 1) & 1) != 0)
--sp;
AUXVAL(sp, AT_NULL, 0x0);
AUXVAL(sp, AT_SECURE, 0x0);
AUXVAL(sp, AT_ENTRY, auxv.at_entry);
AUXVAL(sp, AT_PHDR, auxv.at_phdr);
AUXVAL(sp, AT_PHNUM, auxv.at_phnum);
AUXVAL(sp, AT_PAGESIZE, vm_get_page_size());
STACK_PUSH(sp, 0);
/* Copy envp pointers */
sp -= envc;
for (int i = 0; i < envc; ++i) {
len = strlen(envp[i]) + 1;
old_sp -= len;
sp[i] = KERN_TO_USER(old_sp);
}
/* Copy argvp pointers */
STACK_PUSH(sp, 0);
sp -= argc;
for (int i = 0; i < argc; ++i) {
len = strlen(argvp[i]) + 1;
old_sp -= len;
sp[i] = KERN_TO_USER(old_sp);
}
STACK_PUSH(sp, argc);
return (uintptr_t)sp;
}
int loader_load(struct vas vas, const void *dataptr, struct auxval *auxv,
size_t load_base, char **ld_path, struct vm_range *prog_range)
{
const Elf64_Ehdr *hdr = dataptr;
Elf64_Phdr *phdr;
vm_prot_t prot = PROT_USER;
uintptr_t physmem;
size_t misalign, page_count, map_len;
int status;
uintptr_t start_addr = (uintptr_t)-1;
uintptr_t end_addr = 0;
const size_t GRANULE = vm_get_page_size();
void *tmp_ptr;
if (auxv == NULL) {
DBG("Auxval argument NULL\n");
return -1;
}
if (memcmp(hdr->e_ident, ELFMAG, 4) != 0) {
/* Bad ELF header */
DBG("ELF header bad! (Magic incorrect)\n");
return -1;
}
/* Parse program headers */
for (size_t i = 0; i < hdr->e_phnum; ++i) {
phdr = PHDR(hdr, i);
switch (phdr->p_type) {
case PT_LOAD:
if (__TEST(phdr->p_flags, PF_W))
prot |= PROT_WRITE;
if (__TEST(phdr->p_flags, PF_X)) {
prot |= PROT_EXEC;
}
misalign = phdr->p_vaddr & (GRANULE - 1);
page_count = __DIV_ROUNDUP(phdr->p_memsz + misalign, GRANULE);
physmem = vm_alloc_pageframe(page_count);
map_len = page_count * GRANULE;
/*
* Now we want to compute the start address of the
* program and the end address.
*/
if (start_addr == (uintptr_t)-1) {
start_addr = phdr->p_vaddr;
}
end_addr = __MAX(end_addr, phdr->p_vaddr + page_count*GRANULE);
/* Do we not have enough page frames? */
if (physmem == 0) {
DBG("Failed to allocate physical memory\n");
vm_free_pageframe(physmem, page_count);
return -ENOMEM;
}
status = vm_map_create(vas, phdr->p_vaddr + load_base, physmem, prot, map_len);
if (status != 0) {
return status;
}
/* Now we want to copy the data */
tmp_ptr = (void *)((uintptr_t)hdr + phdr->p_offset);
memcpy(PHYS_TO_VIRT(physmem), tmp_ptr, phdr->p_filesz);
break;
case PT_INTERP:
if (ld_path == NULL) {
break;
}
*ld_path = dynalloc(phdr->p_filesz);
if (ld_path == NULL) {
DBG("Failed to allocate memory for PT_INTERP path\n");
return -ENOMEM;
}
memcpy(*ld_path, (char *)hdr + phdr->p_offset, phdr->p_filesz);
break;
case PT_PHDR:
auxv->at_phdr = phdr->p_vaddr + load_base;
break;
}
}
auxv->at_entry = hdr->e_entry + load_base;
auxv->at_phent = hdr->e_phentsize;
auxv->at_phnum = hdr->e_phnum;
prog_range->start = start_addr;
prog_range->end = end_addr;
return 0;
}