| // SPDX-License-Identifier: GPL-2.0 |
| #include <linux/compiler.h> |
| #include <elfutils/libdw.h> |
| #include <elfutils/libdwfl.h> |
| #include <inttypes.h> |
| #include <errno.h> |
| #include "debug.h" |
| #include "dso.h" |
| #include "unwind.h" |
| #include "unwind-libdw.h" |
| #include "machine.h" |
| #include "map.h" |
| #include "symbol.h" |
| #include "thread.h" |
| #include <linux/types.h> |
| #include <linux/zalloc.h> |
| #include "event.h" |
| #include "perf_regs.h" |
| #include "callchain.h" |
| |
| static char *debuginfo_path; |
| |
| static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata, |
| const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused, |
| const char *file_name, const char *debuglink_file __maybe_unused, |
| GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name) |
| { |
| const struct dso *dso = *userdata; |
| |
| assert(dso); |
| if (dso->symsrc_filename && strcmp (file_name, dso->symsrc_filename)) |
| *debuginfo_file_name = strdup(dso->symsrc_filename); |
| return -1; |
| } |
| |
| static const Dwfl_Callbacks offline_callbacks = { |
| .find_debuginfo = __find_debuginfo, |
| .debuginfo_path = &debuginfo_path, |
| .section_address = dwfl_offline_section_address, |
| // .find_elf is not set as we use dwfl_report_elf() instead. |
| }; |
| |
| static int __report_module(struct addr_location *al, u64 ip, |
| struct unwind_info *ui) |
| { |
| Dwfl_Module *mod; |
| struct dso *dso = NULL; |
| /* |
| * Some callers will use al->sym, so we can't just use the |
| * cheaper thread__find_map() here. |
| */ |
| thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al); |
| |
| if (al->map) |
| dso = map__dso(al->map); |
| |
| if (!dso) |
| return 0; |
| |
| mod = dwfl_addrmodule(ui->dwfl, ip); |
| if (mod) { |
| Dwarf_Addr s; |
| |
| dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL); |
| if (s != map__start(al->map) - map__pgoff(al->map)) |
| mod = 0; |
| } |
| |
| if (!mod) |
| mod = dwfl_report_elf(ui->dwfl, dso->short_name, dso->long_name, -1, |
| map__start(al->map) - map__pgoff(al->map), false); |
| if (!mod) { |
| char filename[PATH_MAX]; |
| |
| if (dso__build_id_filename(dso, filename, sizeof(filename), false)) |
| mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1, |
| map__start(al->map) - map__pgoff(al->map), false); |
| } |
| |
| if (mod) { |
| void **userdatap; |
| |
| dwfl_module_info(mod, &userdatap, NULL, NULL, NULL, NULL, NULL, NULL); |
| *userdatap = dso; |
| } |
| |
| return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1; |
| } |
| |
| static int report_module(u64 ip, struct unwind_info *ui) |
| { |
| struct addr_location al; |
| |
| return __report_module(&al, ip, ui); |
| } |
| |
| /* |
| * Store all entries within entries array, |
| * we will process it after we finish unwind. |
| */ |
| static int entry(u64 ip, struct unwind_info *ui) |
| |
| { |
| struct unwind_entry *e = &ui->entries[ui->idx++]; |
| struct addr_location al; |
| |
| if (__report_module(&al, ip, ui)) |
| return -1; |
| |
| e->ip = ip; |
| e->ms.maps = al.maps; |
| e->ms.map = al.map; |
| e->ms.sym = al.sym; |
| |
| pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", |
| al.sym ? al.sym->name : "''", |
| ip, |
| al.map ? map__map_ip(al.map, ip) : (u64) 0); |
| return 0; |
| } |
| |
| static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp) |
| { |
| /* We want only single thread to be processed. */ |
| if (*thread_argp != NULL) |
| return 0; |
| |
| *thread_argp = arg; |
| return dwfl_pid(dwfl); |
| } |
| |
| static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr, |
| Dwarf_Word *data) |
| { |
| struct addr_location al; |
| ssize_t size; |
| struct dso *dso; |
| |
| if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) { |
| pr_debug("unwind: no map for %lx\n", (unsigned long)addr); |
| return -1; |
| } |
| dso = map__dso(al.map); |
| if (!dso) |
| return -1; |
| |
| size = dso__data_read_addr(dso, al.map, ui->machine, addr, (u8 *) data, sizeof(*data)); |
| |
| return !(size == sizeof(*data)); |
| } |
| |
| static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result, |
| void *arg) |
| { |
| struct unwind_info *ui = arg; |
| struct stack_dump *stack = &ui->sample->user_stack; |
| u64 start, end; |
| int offset; |
| int ret; |
| |
| ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP); |
| if (ret) |
| return false; |
| |
| end = start + stack->size; |
| |
| /* Check overflow. */ |
| if (addr + sizeof(Dwarf_Word) < addr) |
| return false; |
| |
| if (addr < start || addr + sizeof(Dwarf_Word) > end) { |
| ret = access_dso_mem(ui, addr, result); |
| if (ret) { |
| pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range" |
| " 0x%" PRIx64 "-0x%" PRIx64 "\n", |
| addr, start, end); |
| return false; |
| } |
| return true; |
| } |
| |
| offset = addr - start; |
| *result = *(Dwarf_Word *)&stack->data[offset]; |
| pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n", |
| addr, (unsigned long)*result, offset); |
| return true; |
| } |
| |
| static const Dwfl_Thread_Callbacks callbacks = { |
| .next_thread = next_thread, |
| .memory_read = memory_read, |
| .set_initial_registers = libdw__arch_set_initial_registers, |
| }; |
| |
| static int |
| frame_callback(Dwfl_Frame *state, void *arg) |
| { |
| struct unwind_info *ui = arg; |
| Dwarf_Addr pc; |
| bool isactivation; |
| |
| if (!dwfl_frame_pc(state, &pc, NULL)) { |
| if (!ui->best_effort) |
| pr_err("%s", dwfl_errmsg(-1)); |
| return DWARF_CB_ABORT; |
| } |
| |
| // report the module before we query for isactivation |
| report_module(pc, ui); |
| |
| if (!dwfl_frame_pc(state, &pc, &isactivation)) { |
| if (!ui->best_effort) |
| pr_err("%s", dwfl_errmsg(-1)); |
| return DWARF_CB_ABORT; |
| } |
| |
| if (!isactivation) |
| --pc; |
| |
| return entry(pc, ui) || !(--ui->max_stack) ? |
| DWARF_CB_ABORT : DWARF_CB_OK; |
| } |
| |
| int unwind__get_entries(unwind_entry_cb_t cb, void *arg, |
| struct thread *thread, |
| struct perf_sample *data, |
| int max_stack, |
| bool best_effort) |
| { |
| struct unwind_info *ui, ui_buf = { |
| .sample = data, |
| .thread = thread, |
| .machine = RC_CHK_ACCESS(thread->maps)->machine, |
| .cb = cb, |
| .arg = arg, |
| .max_stack = max_stack, |
| .best_effort = best_effort |
| }; |
| Dwarf_Word ip; |
| int err = -EINVAL, i; |
| |
| if (!data->user_regs.regs) |
| return -EINVAL; |
| |
| ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack); |
| if (!ui) |
| return -ENOMEM; |
| |
| *ui = ui_buf; |
| |
| ui->dwfl = dwfl_begin(&offline_callbacks); |
| if (!ui->dwfl) |
| goto out; |
| |
| err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP); |
| if (err) |
| goto out; |
| |
| err = report_module(ip, ui); |
| if (err) |
| goto out; |
| |
| err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui); |
| if (err) |
| goto out; |
| |
| err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui); |
| |
| if (err && ui->max_stack != max_stack) |
| err = 0; |
| |
| /* |
| * Display what we got based on the order setup. |
| */ |
| for (i = 0; i < ui->idx && !err; i++) { |
| int j = i; |
| |
| if (callchain_param.order == ORDER_CALLER) |
| j = ui->idx - i - 1; |
| |
| err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0; |
| } |
| |
| out: |
| if (err) |
| pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1)); |
| |
| dwfl_end(ui->dwfl); |
| free(ui); |
| return 0; |
| } |