dbg: add backtrace command
This commit is contained in:
K. Lange
parent
fe6402ba18
commit
67a228e6ef
108
apps/dbg.c
108
apps/dbg.c
@ -193,6 +193,7 @@ static int find_symbol(pid_t pid, uintptr_t addr_in, char ** name, uintptr_t *ad
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uintptr_t current_xname = NULL;
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char * current_name = NULL;
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char * current_obj = NULL;
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uintptr_t best_base = 0;
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/* Can we cheat and peek at ld.so? */
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uintptr_t their_symbol_table = data_read_ptr(pid, __ld_symbol_table());
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@ -224,39 +225,66 @@ static int find_symbol(pid_t pid, uintptr_t addr_in, char ** name, uintptr_t *ad
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if (current_xname) {
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current_name = read_string(pid, current_xname);
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}
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}
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/* Figure out where this object is in the objects map */
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uintptr_t their_objects_table = data_read_ptr(pid, __ld_objects_table());
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data_read_bytes(pid, their_objects_table, (char*)&map, sizeof(hashmap_t));
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if (addr_in < 0x40000000) {
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current_obj = strdup("ld.so");
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}
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intptr_t cmax = INTPTR_MAX;
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uintptr_t best_name = 0;
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for (size_t i = 0; i < map.size; ++i) {
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uintptr_t ptr;
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hashmap_entry_t entry;
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data_read_bytes(pid, (uintptr_t)map.entries + sizeof(uintptr_t) * i, (char*)&ptr, sizeof(uintptr_t));
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while (ptr) {
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data_read_bytes(pid, ptr, (char*)&entry, sizeof(hashmap_entry_t));
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if (entry.value) {
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elf_t obj;
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data_read_bytes(pid, (uintptr_t)entry.value, (char*)&obj, sizeof(elf_t));
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if (addr_in >= obj.base) {
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intptr_t x = addr_in - (uintptr_t)obj.base;
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if (x < cmax) {
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cmax = x;
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best_name = (uintptr_t)entry.key;
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}
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/* Figure out where this object is in the objects map */
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uintptr_t their_objects_table = data_read_ptr(pid, __ld_objects_table());
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if (!current_obj && their_objects_table) {
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hashmap_t map;
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data_read_bytes(pid, their_objects_table, (char*)&map, sizeof(hashmap_t));
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intptr_t cmax = INTPTR_MAX;
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uintptr_t best_name = 0;
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for (size_t i = 0; i < map.size; ++i) {
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uintptr_t ptr;
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hashmap_entry_t entry;
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data_read_bytes(pid, (uintptr_t)map.entries + sizeof(uintptr_t) * i, (char*)&ptr, sizeof(uintptr_t));
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while (ptr) {
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data_read_bytes(pid, ptr, (char*)&entry, sizeof(hashmap_entry_t));
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if (entry.value) {
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elf_t obj;
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data_read_bytes(pid, (uintptr_t)entry.value, (char*)&obj, sizeof(elf_t));
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if (addr_in >= obj.base) {
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intptr_t x = addr_in - (uintptr_t)obj.base;
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if (x < cmax) {
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cmax = x;
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best_name = (uintptr_t)entry.key;
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best_base = obj.base;
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}
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}
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ptr = (uintptr_t)entry.next;
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}
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ptr = (uintptr_t)entry.next;
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}
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}
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if (best_name) {
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current_obj = read_string(pid, best_name);
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}
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}
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FILE * f = binary_obj;
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if (current_obj) {
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/* Try to open that */
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struct stat stat_buf;
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char path[1024];
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sprintf(path, "/lib/%s", current_obj);
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if (stat(path, &stat_buf)) {
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sprintf(path, "/usr/lib/%s", current_obj);
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if (stat(path, &stat_buf)) goto _bail;
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}
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f = fopen(path, "r");
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} else {
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_bail:
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current_obj = strdup(binary_path);
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best_base = 0;
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}
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fseek(f, 0, SEEK_SET);
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Elf64_Header header;
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@ -288,15 +316,14 @@ static int find_symbol(pid_t pid, uintptr_t addr_in, char ** name, uintptr_t *ad
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for (unsigned int i = 0; i < sectionHeader.sh_size / sizeof(Elf64_Sym); ++i) {
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if (!symtab[i].st_value) continue;
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if (addr_in >= (uintptr_t)symtab[i].st_value) {
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intptr_t x = addr_in - (uintptr_t)symtab[i].st_value;
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//if ((symtab[i].st_info & 0xF) != STT_NOTYPE && (symtab[i].st_info & 0xF) != STT_FUNC) continue;
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if (addr_in >= ((uintptr_t)symtab[i].st_value + best_base)) {
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intptr_t x = addr_in - ((uintptr_t)symtab[i].st_value + best_base);
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if (x < current_max) {
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if (current_name) free(current_name);
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if (current_obj) free(current_obj);
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current_max = x;
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current_addr = symtab[i].st_value;
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current_addr = symtab[i].st_value + best_base;
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current_name = strdup(strtab + symtab[i].st_name);
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current_obj = strdup(binary_path);
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}
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}
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}
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@ -313,6 +340,7 @@ static int find_symbol(pid_t pid, uintptr_t addr_in, char ** name, uintptr_t *ad
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*objname = current_obj;
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if (current_name) return 1;
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if (f != binary_obj) fclose(f);
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return 0;
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}
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@ -337,6 +365,32 @@ static void show_libs(pid_t pid) {
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}
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}
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static void attempt_backtrace(pid_t pid, struct regs * regs) {
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/* We already printed the top, now let's try to dig down */
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uintptr_t ip = regs->rip;
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uintptr_t bp = regs->rbp;
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int depth = 0;
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int max_depth = 20;
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while (bp && ip && depth < max_depth && ip < 0xFFFfff0000000000UL) {
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char * name = NULL;
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char * objname = NULL;
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uintptr_t addr = 0;
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if (find_symbol(pid, ip - 1, &name, &addr, &objname)) {
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fprintf(stderr, "<0x%016zx> %s+%#zx in %s\n",
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ip,
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name, ip - addr, objname);
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free(name);
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free(objname);
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}
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ip = data_read_ptr(pid, bp + sizeof(uintptr_t));
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bp = data_read_ptr(pid, bp);
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depth++;
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}
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}
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static void show_commandline(pid_t pid, int status, struct regs * regs) {
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@ -400,6 +454,8 @@ static void show_commandline(pid_t pid, int status, struct regs * regs) {
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} else {
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fprintf(stderr, "Don't know how to show '%s'\n", arg);
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}
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} else if (!strcmp(buf, "bt") || !strcmp(buf, "backtrace")) {
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attempt_backtrace(pid, regs);
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} else if (!strcmp(buf, "continue") || !strcmp(buf,"c")) {
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int signum = WSTOPSIG(status);
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if (signum == SIGINT) signum = 0;
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