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Mon 14 Oct 23:06:38 CEST 2024

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sbosse 2024-10-14 23:08:47 +02:00
parent 4e4a6fb542
commit d4cb87efd6
1 changed files with 187 additions and 0 deletions
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kernel/elf.c Normal file
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/*
Copyright (C) 2015-2019 The University of Notre Dame
This software is distributed under the GNU General Public License.
See the file LICENSE for details.
*/
#include "elf.h"
#include "fs.h"
#include "string.h"
#include "console.h"
#include "process.h"
#include "kernel/syscall.h"
#include "memorylayout.h"
struct elf_header {
char ident[16];
uint16_t type;
uint16_t machine;
uint32_t version;
uint32_t entry;
uint32_t program_offset;
uint32_t section_offset;
uint32_t flags;
uint16_t header_size;
uint16_t phentsize;
uint16_t phnum;
uint16_t shentsize;
uint16_t shnum;
uint16_t shstrndx;
};
#define ELF_HEADER_TYPE_NONE 0
#define ELF_HEADER_TYPE_OBJECT 1
#define ELF_HEADER_TYPE_EXECUTABLE 2
#define ELF_HEADER_TYPE_DYNAMIC 3
#define ELF_HEADER_TYPE_CORE 4
#define ELF_HEADER_MACHINE_I386 3
#define ELF_HEADER_MACHINE_ARM 40
#define ELF_HEADER_MACHINE_X86_64 62
#define ELF_HEADER_VERSION 1
struct elf_program {
uint32_t type;
uint32_t offset;
uint32_t vaddr;
uint32_t paddr;
uint32_t file_size;
uint32_t memory_size;
uint32_t flags;
uint32_t align;
};
#define ELF_PROGRAM_TYPE_LOADABLE 1
struct elf_section {
uint32_t name;
uint32_t type;
uint32_t flags;
uint32_t address;
uint32_t offset;
uint32_t size;
uint32_t link;
uint32_t info;
uint32_t alignment;
uint32_t entry_size;
};
#define ELF_SECTION_TYPE_NULL 0
#define ELF_SECTION_TYPE_PROGRAM 1
#define ELF_SECTION_TYPE_SYMBOL_TABLE 2
#define ELF_SECTION_TYPE_STRING_TABLE 3
#define ELF_SECTION_TYPE_RELA 4
#define ELF_SECTION_TYPE_HASH 5
#define ELF_SECTION_TYPE_DYNAMIC 6
#define ELF_SECTION_TYPE_NOTE 7
#define ELF_SECTION_TYPE_BSS 8
#define ELF_SECTION_FLAGS_WRITE 1
#define ELF_SECTION_FLAGS_MEMORY 2
#define ELF_SECTION_FLAGS_EXEC 8
#define ELF_SECTION_FLAGS_MERGE 16
#define ELF_SECTION_FLAGS_STRINGS 32
#define ELF_SECTION_FLAGS_INFO_LINK 64
#define ELF_SECTION_FLAGS_LINK_ORDER 128
#define ELF_SECTION_FLAGS_NONSTANDARD 256
#define ELF_SECTION_FLAGS_GROUP 512
#define ELF_SECTION_FLAGS_TLS 1024
/* Ensure that the current process has address space up to this value. */
static int elf_ensure_address_space( struct process *p, uint32_t addr )
{
/* Size of user data area, ignoring start addr */
uint32_t limit = addr - PROCESS_ENTRY_POINT;
/* Round up to next page size. */
uint32_t overflow = limit % PAGE_SIZE;
limit += (PAGE_SIZE-overflow);
/* Extend virtual memory if needed. */
if(limit > p->vm_data_size) {
return process_data_size_set(p,limit);
} else {
return 0;
}
/* Return zero on success. */
}
int elf_load(struct process *p, struct fs_dirent *d, addr_t * entry)
{
struct elf_header header;
struct elf_program program;
struct elf_section section;
int i;
uint32_t actual;
actual = fs_dirent_read(d, (char *) &header, sizeof(header), 0);
if(actual != sizeof(header))
goto noload;
if(strncmp(header.ident, "\177ELF", 4) || header.machine != ELF_HEADER_MACHINE_I386 || header.version != ELF_HEADER_VERSION)
goto noexec;
actual = fs_dirent_read(d, (char *) &program, sizeof(program), header.program_offset);
if(actual != sizeof(program))
goto noload;
// @blab+ fix first empty section with vaddr=0 (after newly needed objcopy removing unnessary symbols and sections)
if (program.vaddr==0) program.vaddr=header.entry;
//printf("elf: text %x bytes from offset %x at address %x length %x\n",program.file_size,program.offset,program.vaddr,program.memory_size);
if(program.type != ELF_PROGRAM_TYPE_LOADABLE || program.vaddr < PROCESS_ENTRY_POINT || program.memory_size > 0x8000000 || program.memory_size != program.file_size)
goto noexec;
process_data_size_set(p, program.memory_size);
actual = fs_dirent_read(d, (char *) program.vaddr, program.memory_size, program.offset);
if(actual != program.memory_size)
goto mustdie;
for(i = 0; i < header.shnum; i++) {
actual = fs_dirent_read(d, (char *) &section, sizeof(section), header.section_offset + i * header.shentsize);
if(actual != sizeof(section))
goto mustdie;
if(section.type == ELF_SECTION_TYPE_BSS) {
/* For BSS, just clear that address space to zero. */
actual = elf_ensure_address_space(p,section.address+section.size);
if(actual!=0) goto nomem;
memset((void *) section.address, section.size, 0);
} else if(section.type == ELF_SECTION_TYPE_PROGRAM && section.address!=0) {
/* For other loadable section types (usually data), load from file. */
actual = elf_ensure_address_space(p,section.address+section.size);
if(actual!=0) goto nomem;
actual = fs_dirent_read(d,(char*)section.address,section.size,section.offset);
if(actual != section.size) goto mustdie;
} else {
/* skip all other section types */
}
}
*entry = header.entry;
return 0;
noload:
printf("elf: failed to load correctly!\n");
return KERROR_NOT_FOUND;
noexec:
printf("elf: not a valid i386 ELF executable [%c%c%c%c:%x(%x):%x(%x):%d(%d)]\n",
header.ident[0],header.ident[1],header.ident[2],header.ident[3],
program.type,ELF_PROGRAM_TYPE_LOADABLE,program.vaddr,PROCESS_ENTRY_POINT,program.memory_size,program.file_size); // @blab+
return KERROR_NOT_EXECUTABLE;
nomem:
printf("elf: failed to allocate memory\n");
return KERROR_OUT_OF_MEMORY;
mustdie:
printf("elf: did not load correctly\n");
return KERROR_EXECUTION_FAILED;
}