0,0 → 1,479 |
/* |
* Copyright (c) 2006 Sergey Bondari |
* Copyright (c) 2006 Jakub Jermar |
* Copyright (c) 2008 Jiri Svoboda |
* All rights reserved. |
* |
* Redistribution and use in source and binary forms, with or without |
* modification, are permitted provided that the following conditions |
* are met: |
* |
* - Redistributions of source code must retain the above copyright |
* notice, this list of conditions and the following disclaimer. |
* - 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. |
* - The name of the author may not be used to endorse or promote products |
* derived from this software without specific prior written permission. |
* |
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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. |
*/ |
|
/** @addtogroup generic |
* @{ |
*/ |
|
/** |
* @file |
* @brief Userspace ELF loader. |
* |
* This module allows loading ELF binaries (both executables and |
* shared objects) from VFS. The current implementation allocates |
* anonymous memory, fills it with segment data and then adjusts |
* the memory areas' flags to the final value. In the future, |
* the segments will be mapped directly from the file. |
*/ |
|
#include <stdio.h> |
#include <sys/types.h> |
#include <align.h> |
#include <assert.h> |
#include <as.h> |
#include <unistd.h> |
#include <fcntl.h> |
#include <smc.h> |
#include <loader/pcb.h> |
|
#include "elf.h" |
#include "elf_load.h" |
#include "arch.h" |
|
static char *error_codes[] = { |
"no error", |
"invalid image", |
"address space error", |
"incompatible image", |
"unsupported image type", |
"irrecoverable error" |
}; |
|
static unsigned int elf_load(elf_ld_t *elf, size_t so_bias); |
static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry); |
static int section_header(elf_ld_t *elf, elf_section_header_t *entry); |
static int load_segment(elf_ld_t *elf, elf_segment_header_t *entry); |
|
/** Read until the buffer is read in its entirety. */ |
static int my_read(int fd, char *buf, size_t len) |
{ |
int cnt = 0; |
do { |
buf += cnt; |
len -= cnt; |
cnt = read(fd, buf, len); |
} while ((cnt > 0) && ((len - cnt) > 0)); |
|
return cnt; |
} |
|
/** Load ELF binary from a file. |
* |
* Load an ELF binary from the specified file. If the file is |
* an executable program, it is loaded unbiased. If it is a shared |
* object, it is loaded with the bias @a so_bias. Some information |
* extracted from the binary is stored in a elf_info_t structure |
* pointed to by @a info. |
* |
* @param file_name Path to the ELF file. |
* @param so_bias Bias to use if the file is a shared object. |
* @param info Pointer to a structure for storing information |
* extracted from the binary. |
* |
* @return EOK on success or negative error code. |
*/ |
int elf_load_file(char *file_name, size_t so_bias, elf_info_t *info) |
{ |
elf_ld_t elf; |
|
int fd; |
int rc; |
|
// printf("open and read '%s'...\n", file_name); |
|
fd = open(file_name, O_RDONLY); |
if (fd < 0) { |
printf("failed opening file\n"); |
return -1; |
} |
|
elf.fd = fd; |
elf.info = info; |
|
rc = elf_load(&elf, so_bias); |
|
close(fd); |
|
return rc; |
} |
|
/** Run an ELF executable. |
* |
* Transfers control to the entry point of an ELF executable loaded |
* earlier with elf_load_file(). This function does not return. |
* |
* @param info Info structure filled earlier by elf_load_file() |
*/ |
void elf_run(elf_info_t *info, pcb_t *pcb) |
{ |
program_run(info->entry, pcb); |
|
/* not reached */ |
} |
|
/** Create the program control block (PCB). |
* |
* Fills the program control block @a pcb with information from |
* @a info. |
* |
* @param info Program info structure |
* @return EOK on success or negative error code |
*/ |
void elf_create_pcb(elf_info_t *info, pcb_t *pcb) |
{ |
pcb->entry = info->entry; |
pcb->dynamic = info->dynamic; |
} |
|
|
/** Load an ELF binary. |
* |
* The @a elf structure contains the loader state, including |
* an open file, from which the binary will be loaded, |
* a pointer to the @c info structure etc. |
* |
* @param elf Pointer to loader state buffer. |
* @param so_bias Bias to use if the file is a shared object. |
* @return EE_OK on success or EE_xx error code. |
*/ |
static unsigned int elf_load(elf_ld_t *elf, size_t so_bias) |
{ |
elf_header_t header_buf; |
elf_header_t *header = &header_buf; |
int i, rc; |
|
rc = my_read(elf->fd, header, sizeof(elf_header_t)); |
if (rc < 0) { |
printf("read error\n"); |
return EE_INVALID; |
} |
|
elf->header = header; |
|
// printf("ELF-load:"); |
/* Identify ELF */ |
if (header->e_ident[EI_MAG0] != ELFMAG0 || |
header->e_ident[EI_MAG1] != ELFMAG1 || |
header->e_ident[EI_MAG2] != ELFMAG2 || |
header->e_ident[EI_MAG3] != ELFMAG3) { |
printf("invalid header\n"); |
return EE_INVALID; |
} |
|
/* Identify ELF compatibility */ |
if (header->e_ident[EI_DATA] != ELF_DATA_ENCODING || |
header->e_machine != ELF_MACHINE || |
header->e_ident[EI_VERSION] != EV_CURRENT || |
header->e_version != EV_CURRENT || |
header->e_ident[EI_CLASS] != ELF_CLASS) { |
printf("incompatible data/version/class\n"); |
return EE_INCOMPATIBLE; |
} |
|
if (header->e_phentsize != sizeof(elf_segment_header_t)) { |
printf("e_phentsize:%d != %d\n", header->e_phentsize, |
sizeof(elf_segment_header_t)); |
return EE_INCOMPATIBLE; |
} |
|
if (header->e_shentsize != sizeof(elf_section_header_t)) { |
printf("e_shentsize:%d != %d\n", header->e_shentsize, |
sizeof(elf_section_header_t)); |
return EE_INCOMPATIBLE; |
} |
|
/* Check if the object type is supported. */ |
if (header->e_type != ET_EXEC && header->e_type != ET_DYN) { |
printf("Object type %d is not supported\n", header->e_type); |
return EE_UNSUPPORTED; |
} |
|
/* Shared objects can be loaded with a bias */ |
// printf("Object type: %d\n", header->e_type); |
if (header->e_type == ET_DYN) |
elf->bias = so_bias; |
else |
elf->bias = 0; |
|
// printf("Bias set to 0x%x\n", elf->bias); |
elf->info->interp = NULL; |
elf->info->dynamic = NULL; |
|
// printf("parse segments\n"); |
|
/* Walk through all segment headers and process them. */ |
for (i = 0; i < header->e_phnum; i++) { |
elf_segment_header_t segment_hdr; |
|
/* Seek to start of segment header */ |
lseek(elf->fd, header->e_phoff |
+ i * sizeof(elf_segment_header_t), SEEK_SET); |
|
rc = my_read(elf->fd, &segment_hdr, |
sizeof(elf_segment_header_t)); |
if (rc < 0) { |
printf("read error\n"); |
return EE_INVALID; |
} |
|
rc = segment_header(elf, &segment_hdr); |
if (rc != EE_OK) |
return rc; |
} |
|
// printf("parse sections\n"); |
|
/* Inspect all section headers and proccess them. */ |
for (i = 0; i < header->e_shnum; i++) { |
elf_section_header_t section_hdr; |
|
/* Seek to start of section header */ |
lseek(elf->fd, header->e_shoff |
+ i * sizeof(elf_section_header_t), SEEK_SET); |
|
rc = my_read(elf->fd, §ion_hdr, |
sizeof(elf_section_header_t)); |
if (rc < 0) { |
printf("read error\n"); |
return EE_INVALID; |
} |
|
rc = section_header(elf, §ion_hdr); |
if (rc != EE_OK) |
return rc; |
} |
|
elf->info->entry = |
(entry_point_t)((uint8_t *)header->e_entry + elf->bias); |
|
// printf("done\n"); |
|
return EE_OK; |
} |
|
/** Print error message according to error code. |
* |
* @param rc Return code returned by elf_load(). |
* |
* @return NULL terminated description of error. |
*/ |
char *elf_error(unsigned int rc) |
{ |
assert(rc < sizeof(error_codes) / sizeof(char *)); |
|
return error_codes[rc]; |
} |
|
/** Process segment header. |
* |
* @param entry Segment header. |
* |
* @return EE_OK on success, error code otherwise. |
*/ |
static int segment_header(elf_ld_t *elf, elf_segment_header_t *entry) |
{ |
switch (entry->p_type) { |
case PT_NULL: |
case PT_PHDR: |
break; |
case PT_LOAD: |
return load_segment(elf, entry); |
break; |
case PT_INTERP: |
/* Assume silently interp == "/rtld.so" */ |
elf->info->interp = "/rtld.so"; |
break; |
case PT_DYNAMIC: |
case PT_SHLIB: |
case PT_NOTE: |
case PT_LOPROC: |
case PT_HIPROC: |
default: |
printf("segment p_type %d unknown\n", entry->p_type); |
return EE_UNSUPPORTED; |
break; |
} |
return EE_OK; |
} |
|
/** Load segment described by program header entry. |
* |
* @param elf Loader state. |
* @param entry Program header entry describing segment to be loaded. |
* |
* @return EE_OK on success, error code otherwise. |
*/ |
int load_segment(elf_ld_t *elf, elf_segment_header_t *entry) |
{ |
void *a; |
int flags = 0; |
uintptr_t bias; |
uintptr_t base; |
size_t mem_sz; |
int rc; |
|
// printf("load segment at addr 0x%x, size 0x%x\n", entry->p_vaddr, |
// entry->p_memsz); |
|
bias = elf->bias; |
|
if (entry->p_align > 1) { |
if ((entry->p_offset % entry->p_align) != |
(entry->p_vaddr % entry->p_align)) { |
printf("align check 1 failed offset%%align=%d, " |
"vaddr%%align=%d\n", |
entry->p_offset % entry->p_align, |
entry->p_vaddr % entry->p_align |
); |
return EE_INVALID; |
} |
} |
|
/* Final flags that will be set for the memory area */ |
|
if (entry->p_flags & PF_X) |
flags |= AS_AREA_EXEC; |
if (entry->p_flags & PF_W) |
flags |= AS_AREA_WRITE; |
if (entry->p_flags & PF_R) |
flags |= AS_AREA_READ; |
flags |= AS_AREA_CACHEABLE; |
|
base = ALIGN_DOWN(entry->p_vaddr, PAGE_SIZE); |
mem_sz = entry->p_memsz + (entry->p_vaddr - base); |
|
// printf("map to p_vaddr=0x%x-0x%x...\n", entry->p_vaddr + bias, |
// entry->p_vaddr + bias + ALIGN_UP(entry->p_memsz, PAGE_SIZE)); |
|
/* |
* For the course of loading, the area needs to be readable |
* and writeable. |
*/ |
a = as_area_create((uint8_t *)base + bias, mem_sz, |
AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE); |
if (a == (void *)(-1)) { |
printf("memory mapping failed\n"); |
return EE_MEMORY; |
} |
|
// printf("as_area_create(0x%lx, 0x%x, %d) -> 0x%lx\n", |
// entry->p_vaddr+bias, entry->p_memsz, flags, (uintptr_t)a); |
|
/* |
* Load segment data |
*/ |
// printf("seek to %d\n", entry->p_offset); |
rc = lseek(elf->fd, entry->p_offset, SEEK_SET); |
if (rc < 0) { |
printf("seek error\n"); |
return EE_INVALID; |
} |
|
// printf("read 0x%x bytes to address 0x%x\n", entry->p_filesz, entry->p_vaddr+bias); |
/* rc = read(fd, (void *)(entry->p_vaddr + bias), entry->p_filesz); |
if (rc < 0) { printf("read error\n"); return EE_INVALID; }*/ |
|
/* Long reads are not possible yet. Load segment picewise */ |
|
unsigned left, now; |
uint8_t *dp; |
|
left = entry->p_filesz; |
dp = (uint8_t *)(entry->p_vaddr + bias); |
|
while (left > 0) { |
now = 16384; |
if (now > left) now = left; |
|
// printf("read %d...", now); |
rc = my_read(elf->fd, dp, now); |
// printf("->%d\n", rc); |
|
if (rc < 0) { |
printf("read error\n"); |
return EE_INVALID; |
} |
|
left -= now; |
dp += now; |
} |
|
// printf("set area flags to %d\n", flags); |
rc = as_area_change_flags((uint8_t *)entry->p_vaddr + bias, flags); |
if (rc != 0) { |
printf("failed to set memory area flags\n"); |
return EE_MEMORY; |
} |
|
if (flags & AS_AREA_EXEC) { |
/* Enforce SMC coherence for the segment */ |
if (smc_coherence(entry->p_vaddr + bias, entry->p_filesz)) |
return EE_MEMORY; |
} |
|
return EE_OK; |
} |
|
/** Process section header. |
* |
* @param elf Loader state. |
* @param entry Segment header. |
* |
* @return EE_OK on success, error code otherwise. |
*/ |
static int section_header(elf_ld_t *elf, elf_section_header_t *entry) |
{ |
switch (entry->sh_type) { |
case SHT_PROGBITS: |
if (entry->sh_flags & SHF_TLS) { |
/* .tdata */ |
} |
break; |
case SHT_NOBITS: |
if (entry->sh_flags & SHF_TLS) { |
/* .tbss */ |
} |
break; |
case SHT_DYNAMIC: |
/* Record pointer to dynamic section into info structure */ |
elf->info->dynamic = |
(void *)((uint8_t *)entry->sh_addr + elf->bias); |
printf("dynamic section found at 0x%x\n", |
(uintptr_t)elf->info->dynamic); |
break; |
default: |
break; |
} |
|
return EE_OK; |
} |
|
/** @} |
*/ |