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update mld comments

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This commit is contained in:
Freya Murphy 2024-10-05 10:16:45 -04:00
parent 47d226cf36
commit 64a7a67f00
Signed by: freya
GPG key ID: 744AB800E383AE52
6 changed files with 58 additions and 25 deletions
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9
config.mk
View file

@ -12,12 +12,11 @@ PREFIX=/usr/local
# ======================== CONFIG OPTIONS ==
#
# MAX LEX LENGTH
# Specifies how long a ident, register,
# instruction name, or any type of variable
# length text can be inside the lexer
# MAX EXT LENGTH
# Specifies how long a stirng extension in a
# shdr entry name can be.
#
# CFLAGS+= -DMAX_LEX_LENGTH=24
# CFLAGS+= -DMAX_EXT_LENGTH=48
#
#
# MAX_ARG_LENGTH

2
include/melf.h
View file

@ -32,7 +32,7 @@ static const Elf32_Ehdr MIPS_ELF_EHDR =
.e_machine = B16(EM_MIPS),
.e_version = B32(EV_CURRENT),
.e_entry = 0x00,
.e_flags = 0x00, // B32(EF_MIPS_ARCH_32R6),
.e_flags = B32(EF_MIPS_ARCH_32R6 | EF_MIPS_NAN2008 | EF_MIPS_ABI_O32),
.e_ehsize = B16(sizeof(Elf32_Ehdr)),
.e_phentsize = B16(sizeof(Elf32_Phdr)),
.e_shentsize = B16(sizeof(Elf32_Shdr)),

9
include/mlimits.h
View file

@ -3,12 +3,11 @@
#ifndef __MLIMITS_H__
#define __MLIMITS_H__
/* Specifies how long a ident, register,
* instruction name, or any type of variable
* length text can be inside the lexer.
/* Specifies how long a stirng extension in a
* shdr entry name can be.
*/
#ifndef MAX_LEX_LENGTH
#define MAX_LEX_LENGTH 24
#ifndef MAX_EXT_LENGTH
#define MAX_EXT_LENGTH 48
#endif
/* Specifices how many max arguments a

5
masm/asm.c
View file

@ -9,7 +9,6 @@
#include "asm.h"
#include "gen.h"
#include "mlimits.h"
#include "tab.h"
extern char *current_file;
@ -202,14 +201,14 @@ static int assemble_shdr(struct assembler *assembler, Elf32_Shdr **res,
for (uint32_t i = 0; i < assembler->section_len; i++) {
struct elf_section *sec = &assembler->sections[i];
const char *prefix = ".reltab";
char reltab_name[MAX_LEX_LENGTH + strlen(prefix)];
char reltab_name[MAX_EXT_LENGTH + strlen(prefix)];
if (sec->reltab_len == 0)
continue;
strcpy(reltab_name, prefix);
strncat(reltab_name, sec->data->name.str,
MAX_LEX_LENGTH - strlen(prefix));
MAX_EXT_LENGTH - strlen(prefix));
if (strtab_write_str(&assembler->shstrtab,
reltab_name, &str_off)) {

29
mld/link.c
View file

@ -47,6 +47,7 @@ static int load_objects(struct linker *linker)
skip_obj:
}
// load runtime object if not set to be freestanding
if (linker->args->freestanding == false) {
#define _STR(x) _STR2(x)
#define _STR2(x) #x
@ -69,6 +70,9 @@ skip_obj:
*/
static int relocate_segment_name(struct linker *linker, const char *name)
{
// find each segment with the provided segment name,
// and then relocate them
for (size_t i = 0; i < linker->obj_len; i++) {
struct object *obj = &linker->objects[i];
for (size_t j = 0; j < obj->segment_len; j++) {
@ -122,6 +126,7 @@ static int relocate_segment_name(struct linker *linker, const char *name)
M_SUCCESS) {
if (segtab_ent_push(ent, seg))
return M_ERROR;
// otherwise create a new segment table entry
} else {
// update vaddr to be page aligned
uint32_t m = seg->new_vaddr % SEC_ALIGN;
@ -134,7 +139,7 @@ static int relocate_segment_name(struct linker *linker, const char *name)
linker->data_vaddr += add;
}
// else create a new segment
// create a new segment
if (segtab_push(&linker->segments, NULL, seg))
return M_ERROR;
}
@ -146,6 +151,9 @@ static int relocate_segment_name(struct linker *linker, const char *name)
static int relocate_segments(struct linker *linker)
{
// for each object, find each different
// unique segment name
for (size_t i = 0; i < linker->obj_len; i++) {
struct object *obj = &linker->objects[i];
for (size_t j = 0; j < obj->segment_len; j++) {
@ -154,6 +162,9 @@ static int relocate_segments(struct linker *linker)
// check if the segment has already been relocated
if (seg->new_vaddr != 0)
continue;
// relocate each segment with that segment
// name
if(relocate_segment_name(linker, seg->name))
return M_ERROR;
}
@ -165,6 +176,14 @@ static int relocate_segments(struct linker *linker)
static int relocate_symbol(struct linker *linker, struct object *obj,
struct symbol_table *symtab, const Elf32_Sym *sym)
{
// given the symbol and the object its in
// 1. make sure the symbol is valid
// 2. get the segment in the object that the symbol is in
// 3. get tthe segment table entry that the segment is also
// in. This allows us to get the offset into the segment_table
// 4. the new shndx is the offset + 1 (since segments start at
// shndx 1
size_t shndx = B16(sym->st_shndx);
if (shndx == 0 || shndx == SHN_ABS)
return M_SUCCESS; // ignore this symbol
@ -177,11 +196,15 @@ static int relocate_symbol(struct linker *linker, struct object *obj,
return M_ERROR;
}
// make sure the symbol name is
// in bounds
if (B32(sym->st_name) >= symtab->strtab->len) {
ERROR("symbol name out of bounds");
return M_ERROR;
}
// find the segment that this symbol
// is contained in
struct segment *sec = NULL;
for (size_t i = 0; i < obj->phdr_len; i++) {
if (obj->phdr_to_shdr_mapping[i] == shndx) {
@ -245,13 +268,17 @@ static int relocate_symbol(struct linker *linker, struct object *obj,
static int relocate_symbols(struct linker *linker)
{
// relocate in each object
for (size_t i = 0; i < linker->obj_len; i++) {
struct object *obj = &linker->objects[i];
// look though each shdr entry and find
// any symbol tables
for (size_t j = 0; j < obj->shdr_len; j++) {
struct symbol_table *symtab = &obj->symtabs[j];
if (symtab->len < 1)
continue;
// for each symbol in the table, relocate it
for (size_t k = 0; k < symtab->len; k++) {
const Elf32_Sym *sym = &symtab->syms[k];
if (relocate_symbol(linker, obj, symtab, sym))

29
mld/link.h
View file

@ -92,11 +92,6 @@ struct symbol_table {
struct symbol_table_mapping *map;
};
///
/// symbol table map
/// (metadata for each symbol)
///
int symtab_init(struct symbol_table *symtab);
void symtab_free(struct symbol_table *symtab);
@ -104,6 +99,13 @@ int symtab_push(struct symbol_table *symtab, const Elf32_Sym *sym);
int symtab_get(struct symbol_table *symtab, Elf32_Sym **sym, const char *name,
int32_t obj_idx);
///
/// symbol table map
/// (metadata for each symbol)
/// stores each object that a symbol
/// is in
///
struct symbol_table_mapping {
uint32_t len;
uint32_t size;
@ -163,6 +165,9 @@ int segment_load(struct object *object, struct segment *segment, size_t index);
///
/// segment table
/// holds each segment that
/// share the same name
/// (i.e. all .text segments)
///
struct segment_table_entry {
@ -172,6 +177,7 @@ struct segment_table_entry {
uint32_t off;
uint32_t vaddr;
// weak segment pointers. we do not own these!!!
// (but we own the array)
struct segment **parts;
};
@ -181,9 +187,10 @@ void segtab_ent_free(struct segment_table_entry *ent);
int segtab_ent_push(struct segment_table_entry *ent, struct segment *seg);
uint32_t segtab_ent_size(struct segment_table_entry *ent);
// holds each segment by name
// and all the segment parts from each of the
// object files
///
/// segment table
/// holds each segment table entry by name
///
struct segment_table {
uint32_t len;
uint32_t size;
@ -215,14 +222,16 @@ struct object {
Elf32_Ehdr *ehdr;
// section header table
Elf32_Shdr *shdr;
Elf32_Shdr *shdr; // weak
size_t shdr_len;
// program table
Elf32_Phdr *phdr;
Elf32_Phdr *phdr; // owned
size_t phdr_len;
// phdr <=> shdr mappings
// need a way to find any assoiciated
// phdr with a shdr, and also reverse
uint32_t *phdr_to_shdr_mapping;
// object meta