add symbol parsinng (64 and 32 bit)
This commit is contained in:
Patrick Lipka
parent
12ee7a6ad7
commit
b9978801a3
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@ -64,5 +64,172 @@ static int add_symbol(uintptr_t addr, const char* name, size_t size){
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g_rvprof.symbols.data[g_rvprof.symbols.size].size = size;
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g_rvprof.symbols.size++;
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return 0;
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}
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// ELF symbol parsing
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static int parse_elf_symbols(const char* filepath){
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int fp = open(filepath, O_RDONLY);
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if (fp< 0) return -1;
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struct stat st;
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if (fstat(fp, &st) < 0){
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close(fp);
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return -1;
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}
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// sanity check: file size, max fort executables defined here: 1 GiB
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if (st.st_size < (off_t)sizeof(Elf64_Ehdr) || st.st_size > 1024*1024*1024){
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close(fp);
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return -1;
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}
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void* mapped = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fp, 0);
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close(fp);
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// check ELF magic with bounds checkuing
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if (st.st_size < 16){
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munmap(mapped, st.st_size);
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return -1;
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}
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unsigned char* elf_data = (unsigned char*)mapped;
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if (elf_data[0] != 0x7f || elf_data[1] != 'E' || elf_data[2] != 'L' || elf_data != 'F'){
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// not an ELF file
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munmap(mapped, st.st_size);
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return -1;
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}
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// 32 or 64 bit ELF ?
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int is_64bit = (elf_data[4] == 2);
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if(is_64bit){
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if(st.st_size < (off_t)sizeof(Elf64_Ehdr)){
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// mismatch
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munmap(mapped, st.st_size);
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return -1;
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}
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Elf64_Ehdr* ehdr = (Elf64_Ehdr*)mapped;
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// bounds checking: section header table
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if (ehdr->e_shoff == 0 || ehdr->e_shnum == 0 || ehdr->e_shoff + (ehdr->e_shnum * sizeof(Elf64_Shdr)) > (size_t)st.st_size){
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munmap(mapped, st.st_size);
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return -1;
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}
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Elf64_Shdr* shdrs = (Elf64_Shdr*)((char*)mapped + ehdr->e_shoff);
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// bounds checking: string table index
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if (ehdr->e_shstrndx >= ehdr->e_shnum){
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munmap(mapped, st.st_size);
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return -1;
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}
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// parse .symtab and .dynsym sections
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for (int i=0; i<ehdr->e_shnum; i++){
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Elf64_Shdr *shdr = &shdrs[i];
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if (shdr->sh_type == SHT_SYMTAB || shdr->sh_type == SHT_DYNSYM){
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// bounds checking: symbol table
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if (shdr->sh_offset + shdr->sh_size > (size_t)st.st_size) continue;
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if (shdr->sh_size == 0 || shdr->sh_size % sizeof(Elf64_Sym) != 0) continue;
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// find associated string table
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if (shdr->sh_link >= ehdr->e_shnum) continue;
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Elf64_Shdr* strtab_shdr = &shdrs[shdr->sh_link];
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// bounds checking: string table
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if (strtab_shdr->sh_offset + strtab_shdr->sh_size > (size_t)st.st_size) continue;
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if (strtab_shdr->sh_size == 0) continue;
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char* strtab = (char*)mapped + strtab_shdr->sh_offset;
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Elf64_Sym* symbols = (Elf64_Sym*)((char*)mapped + shdr->sh_offset);
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int num_syms = shdr->sh_size / sizeof(Elf64_Sym);
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for (int j=0; j<num_syms; j++){
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Elf64_Sym* sym = &symbols[j];
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// only process function symbols
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if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC) continue;
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if (sym->st_value == 0) continue;
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if (sym->st_name == 0) continue;
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if (sym->st_name >= strtab_shdr->sh_size) continue;
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char* name = &strtab[sym->st_name];
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// verify null termination within bounds
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int name_len = strnlen(name, strtab_shdr->sh_size - sym->st_name);
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if (name_len == 0 || name_len >= (int)(strtab_shdr->sh_size - sym->st_name)) continue;
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add_symbol(sym->st_value, name, sym->st_size);
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}
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}
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}
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} else{
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// 32-bit case (similar logic)
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if (st.st_size < (off_t)sizeof(Elf32_Ehdr)){
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munmap(mapped, st.st_size);
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return -1;
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}
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Elf32_Ehdr* ehdr = (Elf32_Ehdr*)mapped;
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if (ehdr->e_shoff == 0 || ehdr->e_shnum == 0 ||
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ehdr->e_shoff + (ehdr->e_shnum * sizeof(Elf32_Shdr)) > (size_t)st.st_size){
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munmap(mapped, st.st_size);
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return -1;
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}
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Elf32_Shdr* shdrs = (Elf32_Shdr*)((char*)mapped + ehdr->e_shoff);
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if (ehdr->e_shstrndx >= ehdr->e_shnum){
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munmap(mapped, st.st_size);
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return -1;
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}
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for (int i = 0; i < ehdr->e_shnum; i++){
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Elf32_Shdr* shdr = &shdrs[i];
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if (shdr->sh_type == SHT_SYMTAB || shdr->sh_type == SHT_DYNSYM){
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if (shdr->sh_offset + shdr->sh_size > (size_t)st.st_size) continue;
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if (shdr->sh_size == 0 || shdr->sh_size % sizeof(Elf32_Sym) != 0) continue;
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if (shdr->sh_link >= ehdr->e_shnum) continue;
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Elf32_Shdr* strtab_shdr = &shdrs[shdr->sh_link];
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if (strtab_shdr->sh_offset + strtab_shdr->sh_size > (size_t)st.st_size) continue;
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if (strtab_shdr->sh_size == 0) continue;
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char* strtab = (char*)mapped + strtab_shdr->sh_offset;
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Elf32_Sym* symbols = (Elf32_Sym*)((char*)mapped + shdr->sh_offset);
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int num_syms = shdr->sh_size / sizeof(Elf32_Sym);
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for (int j = 0; j < num_syms; j++){
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Elf32_Sym* sym = &symbols[j];
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if (ELF32_ST_TYPE(sym->st_info) != STT_FUNC) continue;
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if (sym->st_value == 0) continue;
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if (sym->st_name == 0) continue;
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if (sym->st_name >= strtab_shdr->sh_size) continue;
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char* name = &strtab[sym->st_name];
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int name_len = strnlen(name, strtab_shdr->sh_size - sym->st_name);
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if (name_len == 0 || name_len >= (int)(strtab_shdr->sh_size - sym->st_name)) continue;
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add_symbol(sym->st_value, name, sym->st_size);
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}
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}
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}
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}
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munmap(mapped, st.st_size);
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// sort symbols by address for quick binary search
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if (g_rvprof.symbols.size > 0){
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qsort(g_rvprof.symbols.data, g_rvprof.symbols.size, sizeof(symbol_entry_t), symbol_compare);
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g_rvprof.symbols_loaded = 1;
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}
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return 0;
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}
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