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/*
* 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/elf.h>
#include <sys/exec.h>
#include <sys/param.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/errno.h>
#include <vm/pmap.h>
#include <vm/physmem.h>
#include <vm/dynalloc.h>
#include <vm/vm.h>
#include <vm/map.h>
#include <string.h>
#include <machine/pcb.h>
#define PHDR(HDRP, IDX) \
(void *)((uintptr_t)HDRP + (HDRP)->e_phoff + (HDRP->e_phentsize * IDX))
struct elf_file {
char *data;
size_t size;
};
/*
* Load the file and give back an "elf_file"
* structure.
*/
static int
elf_get_file(const char *pathname, struct elf_file *res)
{
struct vnode *vp = NULL;
struct nameidata nd;
struct vattr vattr;
struct vop_getattr_args getattr_args;
struct sio_txn read_txn;
int status = 0;
nd.path = pathname;
nd.flags = 0;
if (res == NULL)
return -EINVAL;
if ((status = namei(&nd)) != 0)
return status;
vp = nd.vp;
getattr_args.res = &vattr;
getattr_args.vp = vp;
status = vfs_vop_getattr(nd.vp, &getattr_args);
if (status != 0)
goto done;
/* Can we use the size field? */
if (vattr.size == VNOVAL) {
status = -EIO;
goto done;
}
res->size = vattr.size;
res->data = dynalloc(sizeof(char) * res->size);
if (res->data == NULL) {
status = -ENOMEM;
goto done;
}
/* Read data into our buffer */
read_txn.buf = res->data;
read_txn.len = res->size;
read_txn.offset = 0;
vfs_vop_read(vp, &read_txn);
done:
if (vp != NULL) {
vfs_release_vnode(nd.vp);
}
return status;
}
/*
* Verify the validity of the ELF header.
* Returns 0 on success.
*/
static int
elf64_verify(Elf64_Ehdr *hdr)
{
const char *mag = &hdr->e_ident[EI_MAG0];
if (memcmp(mag, ELFMAG, SELFMAG) != 0) {
/* Bad magic */
return -ENOEXEC;
}
if (hdr->e_ident[EI_OSABI] != ELFOSABI_SYSV) {
/* ABI used is not System V */
return -ENOEXEC;
}
if (hdr->e_ident[EI_DATA] != ELFDATA2LSB) {
/* Not little-endian */
return -ENOEXEC;
}
if (hdr->e_ident[EI_CLASS] != ELFCLASS64) {
/* Not 64-bits */
return -ENOEXEC;
}
if (hdr->e_type != ET_EXEC) {
/* Not executable */
return -ENOEXEC;
}
if (hdr->e_phnum > MAX_PHDRS) {
/* Too many program headers */
return -ENOEXEC;
}
return 0;
}
void
elf_unload(struct proc *td, struct exec_prog *prog)
{
size_t map_len;
struct pcb *pcbp = &td->pcb;
struct auxval auxval = prog->auxval;
struct exec_range *loadmap = prog->loadmap;
for (size_t i = 0; i < auxval.at_phnum; ++i) {
map_len = (loadmap[i].end - loadmap[i].start);
vm_unmap(pcbp->addrsp, loadmap[i].start, map_len);
vm_free_frame(loadmap[i].start, map_len / DEFAULT_PAGESIZE);
}
}
int
elf64_load(const char *pathname, struct proc *td, struct exec_prog *prog)
{
vm_prot_t prot = (PROT_READ | PROT_USER);
Elf64_Ehdr *hdr;
Elf64_Phdr *phdr;
paddr_t physmem;
off_t misalign;
void *tmp;
size_t page_count, map_len;
struct elf_file file;
struct pcb *pcbp;
struct exec_range loadmap[MAX_PHDRS];
struct auxval *auxvalp;
int error = 0;
if ((error = elf_get_file(pathname, &file)) != 0)
return error;
hdr = (Elf64_Ehdr *)file.data;
if ((error = elf64_verify(hdr)) != 0)
return error;
pcbp = &td->pcb;
/* Load program headers */
for (size_t i = 0; i < hdr->e_phnum; ++i) {
phdr = PHDR(hdr, i);
switch (phdr->p_type) {
case PT_LOAD:
if (ISSET(phdr->p_flags, PF_W))
prot |= PROT_WRITE;
if (ISSET(phdr->p_flags, PF_X))
prot |= PROT_EXEC;
misalign = phdr->p_vaddr & (DEFAULT_PAGESIZE - 1);
map_len = ALIGN_UP(phdr->p_memsz + misalign, DEFAULT_PAGESIZE);
page_count = map_len / DEFAULT_PAGESIZE;
/* Try to allocate page frames */
physmem = vm_alloc_frame(page_count);
if (physmem == 0) {
error = -ENOMEM;
break;
}
error = vm_map(pcbp->addrsp, phdr->p_vaddr, physmem,
prot, map_len);
if (error != 0) {
break;
}
tmp = (void *)((uintptr_t)hdr + phdr->p_offset);
memcpy(PHYS_TO_VIRT(physmem), tmp, phdr->p_filesz);
loadmap[i].start = physmem;
loadmap[i].end = physmem + map_len;
}
}
memcpy(prog->loadmap, loadmap, sizeof(loadmap));
auxvalp = &prog->auxval;
auxvalp->at_entry = hdr->e_entry;
auxvalp->at_phent = hdr->e_phentsize;
auxvalp->at_phnum = hdr->e_phnum;
/* Did program header loading fail? */
if (error != 0) {
elf_unload(td, prog);
return error;
}
dynfree(file.data);
return 0;
}
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