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/*
* Copyright (c) 2025 Ian Marco Moffett and L5 engineers
* 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 the project 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/types.h>
#include <sys/elf.h>
#include <sys/syslog.h>
#include <sys/errno.h>
#include <os/omar.h>
#include <os/elfload.h>
#include <vm/vm.h>
#include <vm/mmu.h>
#include <vm/map.h>
#include <vm/physseg.h>
#include <string.h>
#if defined(__x86_64__)
#define _EM_MACH EM_X86_64
#else
#error "ELF loader not ported to platform"
#endif /* __x86_64__ */
/*
* Verify an ELF64 using its header
*
* @eh: ELF64 header
*
* Returns zero on success, otherwise a less than
* zero value on error or invalid binary.
*/
static int
elf64_verify(Elf64_Ehdr *eh)
{
int error;
if (eh == NULL) {
return -EINVAL;
}
/* The magic must match */
error = memcmp(&eh->e_ident[EI_MAG0], ELFMAG, SELFMAG);
if (error != 0) {
printf("elf64_verify: bad ELF magic\n");
return -ENOEXEC;
}
/* Must be for this platform */
if (eh->e_machine != _EM_MACH) {
printf("elf64_verify: bad target machine\n");
return -ENOEXEC;
}
/* Version must be valid */
if (eh->e_ident[EI_VERSION] != EV_CURRENT) {
printf("elf64_verify: bad version\n");
return -ENOEXEC;
}
return 0;
}
/*
* Do the actual ELF64 loading
*
* @eh: ELF header to load
* @p: Process to load program as
*
* Returns zero on success, otherwise a less
* than zero value on failure.
*
* XXX: We'll need to handler unloading here
*/
static int
elf64_do_load(Elf64_Ehdr *eh, struct proc *proc)
{
static const size_t PSIZE = DEFAULT_PAGESIZE;
struct md_pcb *pcbp;
struct mmu_map spec;
Elf64_Phdr *phdr, *phdr_base;
paddr_t frame;
size_t npges, len, misalign;
uintptr_t tmp;
int error, prot;
if (eh == NULL || proc == NULL) {
return -EINVAL;
}
pcbp = &proc->pcb;
#define PHDR_I(PHDR_BASE, INDEX) \
PTR_OFFSET(PHDR_BASE, eh->e_phentsize*(INDEX))
phdr_base = PTR_OFFSET(eh, eh->e_phoff);
for (int i = 0; i < eh->e_phnum; ++i) {
prot = 0;
phdr = PHDR_I(phdr_base, i);
/* What segment type is this? */
switch (phdr->p_type) {
case PT_LOAD:
if (ISSET(phdr->p_flags, PF_R))
prot |= PROT_READ;
if (ISSET(phdr->p_flags, PF_W))
prot |= PROT_WRITE;
if (ISSET(phdr->p_flags, PF_X))
prot |= PROT_EXEC;
if (phdr->p_memsz == 0 && phdr->p_filesz == 0) {
continue;
}
/* Re-align the length */
misalign = phdr->p_memsz & (PSIZE - 1);
len = phdr->p_memsz;
len = ALIGN_UP(len + misalign, PSIZE);
frame = vm_alloc_frame(1);
if (frame == 0) {
printf("elf64_do_load: could not alloc frame\n");
return -ENOMEM;
}
/* Copy the segment data */
tmp = (uintptr_t)PTR_OFFSET(eh, phdr->p_offset);
memset(PHYS_TO_VIRT(frame), tmp, phdr->p_memsz);
/* Map the segment */
spec.va = phdr->p_vaddr;
spec.pa = frame;
error = vm_map(
&pcbp->vas,
&spec,
phdr->p_memsz,
prot
);
if (error < 0) {
printf("elf64_do_load: failed to map segment\n");
return error;
}
}
}
return 0;
}
/*
* Load an ELF binary
*/
int
elf_load(const char *path, struct proc *proc, struct loaded_elf *res)
{
Elf64_Ehdr *eh;
int error;
ssize_t len;
char *data;
if (path == NULL || proc == NULL) {
return -EINVAL;
}
if (res == NULL) {
return -EINVAL;
}
len = initrd_open(path, &data);
if (len < 0) {
printf("elf_load: failed to open \"%s\"\n", path);
return len;
}
eh = (Elf64_Ehdr *)data;
if ((error = elf64_verify(eh)) != 0) {
return error;
}
res->entrypoint = eh->e_entry;
return 0;
}
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