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This commit is contained in:
Freya Murphy 2024-09-09 12:43:01 -04:00
parent 2ed2758216
commit 6ec6d858b5
Signed by: freya
GPG key ID: 744AB800E383AE52
1 changed files with 0 additions and 363 deletions
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#include <merror.h>
#include <mips.h>
#include <mips32.h>
#include <stdio.h>
#include <stdlib.h>
#include <elf.h>
#include <string.h>
#include <stddef.h>
#include "asm.h"
#include "mlimits.h"
#include "parse.h"
#include "parse_mips32.h"
extern char *current_file;
#define SHDR_STRTBL 0
#define SHDR_SYMTBL 1
#define SHDR_SECTIONS 2
static int parse_file(struct parser *parser)
{
while (1) {
struct expr expr;
if (parser_next(parser, &expr)) {
break;
}
if (expr.type == EXPR_INS)
if (sectbl_push(&parser->sec_tbl,
parser->sec_tbl.current, expr.ins))
return M_ERROR;
}
for (uint32_t i = 0; i < parser->ref_tbl.count; i++) {
struct reference *ref = &parser->ref_tbl.references[i];
struct symbol *sym;
struct mips32_instruction *ins;
if (symtbl_find(&parser->sym_tbl, &sym, ref->name)) {
ERROR("undefined symbol '%s'", ref->name);
return M_ERROR;
}
ins = &ref->section->ins[ref->index].mips32;
switch (ref->type) {
case REF_OFFESET:
ins->B_data.offset += sym->position -
(ref->section->start + ref->index);
break;
case REF_TARGET:
ins->J_data.target += sym->position;
break;
}
};
return M_SUCCESS;
}
static int assemble_phdr(struct assembler *asm, Elf32_Phdr **res,
uint32_t *res2)
{
struct parser *parser = asm->parser;
Elf32_Phdr *phdr = malloc(sizeof(Elf32_Phdr) *
parser->sec_tbl.count);
size_t ins_sz = sizeof(struct mips32_instruction);
if (phdr == NULL) {
ERROR("cannot alloc");
return M_ERROR;;
}
for (uint32_t i = 0; i < parser->sec_tbl.count; i++) {
Elf32_Phdr *hdr = &phdr[i];
struct section *sec = &parser->sec_tbl.sections[i];
hdr->p_type = PT_LOAD;
hdr->p_flags = PF_X | PF_W | PF_R; // FIXME: this is bad
hdr->p_offset = sec->start * ins_sz;
hdr->p_vaddr = sec->start * ins_sz;
hdr->p_paddr = 0x00;
hdr->p_filesz = sec->count * ins_sz;
hdr->p_memsz = sec->count * ins_sz;
hdr->p_align = sec->alignment;
}
*res = phdr;
*res2 = parser->sec_tbl.count;
return M_SUCCESS;
}
static int assemble_symtbl(struct assembler *asm, Elf32_Sym **res,
uint32_t *res2)
{
Elf32_Sym *stbl = malloc(sizeof(Elf32_Sym) * asm->parser->sym_tbl
.count);
if (stbl == NULL)
return M_ERROR;
for (uint32_t i = 0; i < asm->parser->sym_tbl.count; i++) {
struct symbol *sym = &asm->parser->sym_tbl.symbols[i];
size_t str_off;
if (strtbl_write_str(&asm->str_tbl, sym->name, &str_off)) {
free(stbl);
return M_ERROR;
}
int viz = STB_LOCAL;
switch (sym->flag) {
case SYM_LOCAL:
viz = STB_LOCAL;
break;
case SYM_GLOBAL:
case SYM_EXTERNAL:
viz = STB_GLOBAL;
break;
}
stbl[i] = (Elf32_Sym) {
.st_name = str_off,
.st_value = sym->position,
.st_size = 0,
.st_info = (unsigned char)
ELF32_ST_INFO(SYMINFO_BT_SELF,
SYMINFO_FLG_DIRECT),
.st_other = (unsigned char)
ELF32_ST_VISIBILITY(viz),
.st_shndx = 0, // FIXME: specify section
};
};
*res = stbl;
*res2 = asm->parser->sym_tbl.count;
return M_SUCCESS;
}
static int assemble_shdr(struct assembler *asm, Elf32_Shdr **res,
uint32_t *res2)
{
uint32_t entries = 2; // str table and sym tabel
entries += asm->parser->sec_tbl.count; // sections
Elf32_Shdr *shdr = malloc(sizeof(Elf32_Shdr) * entries);
size_t str_off;
if (strtbl_write_str(&asm->str_tbl, ".shstrtab", &str_off)) {
free(shdr);
return M_ERROR;
}
// string table
shdr[SHDR_STRTBL] = (Elf32_Shdr) {
.sh_name = str_off,
.sh_type = SHT_STRTAB,
.sh_flags = SHF_STRINGS,
.sh_addr = 0,
.sh_offset = 0,
.sh_size = 0,
.sh_link = 0,
.sh_info = 0,
.sh_addralign = 1,
.sh_entsize = 0,
};
if (strtbl_write_str(&asm->str_tbl, ".shsymtab", &str_off)) {
free(shdr);
return M_ERROR;
}
// symbol table
shdr[SHDR_SYMTBL] = (Elf32_Shdr) {
.sh_name = str_off,
.sh_type = SHT_SYMTAB,
.sh_flags = 0,
.sh_addr = 0,
.sh_offset = 0,
.sh_size = 0,
.sh_link = 0,
.sh_info = 0,
.sh_addralign = 1,
.sh_entsize = sizeof(Elf32_Sym),
};
// for each section
for (uint32_t i = 0; i < asm->parser->sec_tbl.count; i++) {
struct section *sec = &asm->parser->sec_tbl.sections[i];
char name[MAX_LEX_LENGTH+1] = ".";
strcat(name, sec->name);
if (strtbl_write_str(&asm->str_tbl, name, &str_off)) {
free(shdr);
return M_ERROR;
}
shdr[i+SHDR_SECTIONS] = (Elf32_Shdr) {
.sh_name = str_off,
.sh_type = SHT_PROGBITS,
.sh_flags = SHF_WRITE | SHF_ALLOC | SHF_EXECINSTR,
.sh_addr = 0,
.sh_offset = 0,
.sh_size = 0,
.sh_link = 0,
.sh_info = 0,
.sh_addralign = sec->alignment,
.sh_entsize = sizeof(struct mips32_instruction),
};
}
*res = shdr;
*res2 = entries;
return M_SUCCESS;
}
static int assemble_file(struct assembler *asm)
{
Elf32_Phdr *phdr;
Elf32_Shdr *shdr;
Elf32_Sym *symtbl;
uint32_t phdr_len;
uint32_t shdr_len;
uint32_t symtbl_len;
if (assemble_symtbl(asm, &symtbl, &symtbl_len))
return M_ERROR;
if (assemble_phdr(asm, &phdr, &phdr_len)) {
free(symtbl);
return M_ERROR;
}
if (assemble_shdr(asm, &shdr, &shdr_len)) {
free(symtbl);
free(phdr);
return M_ERROR;
};
Elf32_Ehdr ehdr = {
.e_ident = {
[EI_MAG0] = ELFMAG0,
[EI_MAG1] = ELFMAG1,
[EI_MAG2] = ELFMAG2,
[EI_MAG3] = ELFMAG3,
[EI_CLASS] = ELFCLASS32,
[EI_DATA] = ELFDATA2LSB,
[EI_VERSION] = EV_CURRENT,
[EI_OSABI] = ELFOSABI_STANDALONE,
[EI_ABIVERSION] = 0x00,
[EI_PAD] = 0x00,
},
.e_type = ET_REL,
.e_machine = EM_MIPS,
.e_version = EV_CURRENT,
.e_entry = 0x00,
.e_phoff = 0x00,
.e_shoff = 0x00,
.e_flags = EF_MIPS_ARCH_32R6,
.e_ehsize = sizeof(Elf32_Ehdr),
.e_phentsize = 0x20,
.e_phnum = phdr_len,
.e_shentsize = 0x28,
.e_shnum = shdr_len,
.e_shstrndx = 0x00, // str table is always inx 0
};
uint32_t ptr = 0;
// we must now correct offets and sizes inside the ehdr, phdr,
// and shdr
ptr += sizeof(Elf32_Ehdr);
// phdr
ehdr.e_phoff = ptr;
ptr += phdr_len * sizeof(Elf32_Phdr);
// sections
for (uint32_t i = 0; i < asm->parser->sec_tbl.count; i++) {
phdr[i].p_offset = ptr;
phdr[i].p_vaddr = ptr;
shdr[i+SHDR_SECTIONS].sh_offset = ptr;
shdr[i+SHDR_SECTIONS].sh_size = phdr[i].p_filesz;
ptr += phdr[i].p_filesz;
}
// strtbl
shdr[SHDR_STRTBL].sh_offset = ptr;
shdr[SHDR_STRTBL].sh_size = asm->str_tbl.size;
ptr += asm->str_tbl.size;
// symtbl
ehdr.e_shoff = ptr;
shdr[SHDR_SYMTBL].sh_offset = ptr;
shdr[SHDR_SYMTBL].sh_size = symtbl_len * sizeof(Elf32_Sym);
ptr += symtbl_len * sizeof(Elf32_Sym);
FILE *out = fopen("/home/freya/out.o", "w");
// ehdr
fwrite(&ehdr, sizeof(Elf32_Ehdr), 1, out);
// phdr
fwrite(phdr, sizeof(Elf32_Phdr), phdr_len, out);
// sections
for (uint32_t i = 0; i < asm->parser->sec_tbl.count; i++) {
struct section *sec = &asm->parser->sec_tbl.sections[i];
for (uint32_t j = 0; j < sec->count; j++) {
struct mips32_instruction *ins = &sec->ins[j].mips32;
fwrite(ins, sizeof(struct mips32_instruction),
1, out);
}
}
// str tbl
fwrite(asm->str_tbl.ptr, asm->str_tbl.size, 1, out);
// sym tbl
fwrite(symtbl, sizeof(Elf32_Sym), symtbl_len, out);
// shdr
fwrite(shdr, sizeof(Elf32_Shdr), shdr_len, out);
fclose(out);
free(shdr);
free(phdr);
free(symtbl);
return M_SUCCESS;
}
int assemble_file_mips32(char *path)
{
struct lexer lexer;
struct parser parser;
current_file = path;
int res = M_SUCCESS;
if (lexer_init(current_file, &lexer))
return M_ERROR;
if (mips32_parser_init(&lexer, &parser))
return M_ERROR;
if (res == M_SUCCESS)
res = parse_file(&parser);
struct assembler assembler;
assembler.parser = &parser;
strtbl_init(&assembler.str_tbl);
if (res == M_SUCCESS)
res = assemble_file(&assembler);
strtbl_free(&assembler.str_tbl);
lexer_free(&lexer);
parser_free(&parser);
return res;
}