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1// SPDX-License-Identifier: GPL-2.02#include <linux/compiler.h>3#include <elfutils/libdw.h>4#include <elfutils/libdwfl.h>5#include <inttypes.h>6#include <errno.h>7#include "debug.h"8#include "dso.h"9#include "unwind.h"10#include "unwind-libdw.h"11#include "machine.h"12#include "map.h"13#include "symbol.h"14#include "thread.h"15#include <linux/types.h>16#include <linux/zalloc.h>17#include "event.h"18#include "perf_regs.h"19#include "callchain.h"20#include "util/env.h"21 22static char *debuginfo_path;23 24static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata,25 const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused,26 const char *file_name, const char *debuglink_file __maybe_unused,27 GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name)28{29 const struct dso *dso = *userdata;30 31 assert(dso);32 if (dso__symsrc_filename(dso) && strcmp(file_name, dso__symsrc_filename(dso)))33 *debuginfo_file_name = strdup(dso__symsrc_filename(dso));34 return -1;35}36 37static const Dwfl_Callbacks offline_callbacks = {38 .find_debuginfo = __find_debuginfo,39 .debuginfo_path = &debuginfo_path,40 .section_address = dwfl_offline_section_address,41 // .find_elf is not set as we use dwfl_report_elf() instead.42};43 44static int __report_module(struct addr_location *al, u64 ip,45 struct unwind_info *ui)46{47 Dwfl_Module *mod;48 struct dso *dso = NULL;49 Dwarf_Addr base;50 /*51 * Some callers will use al->sym, so we can't just use the52 * cheaper thread__find_map() here.53 */54 thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al);55 56 if (al->map)57 dso = map__dso(al->map);58 59 if (!dso)60 return 0;61 62 /*63 * The generated JIT DSO files only map the code segment without64 * ELF headers. Since JIT codes used to be packed in a memory65 * segment, calculating the base address using pgoff falls into66 * a different code in another DSO. So just use the map->start67 * directly to pick the correct one.68 */69 if (!strncmp(dso__long_name(dso), "/tmp/jitted-", 12))70 base = map__start(al->map);71 else72 base = map__start(al->map) - map__pgoff(al->map);73 74 mod = dwfl_addrmodule(ui->dwfl, ip);75 if (mod) {76 Dwarf_Addr s;77 78 dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);79 if (s != base)80 mod = NULL;81 }82 83 if (!mod) {84 char filename[PATH_MAX];85 86 __symbol__join_symfs(filename, sizeof(filename), dso__long_name(dso));87 mod = dwfl_report_elf(ui->dwfl, dso__short_name(dso), filename, -1,88 base, false);89 }90 if (!mod) {91 char filename[PATH_MAX];92 93 if (dso__build_id_filename(dso, filename, sizeof(filename), false))94 mod = dwfl_report_elf(ui->dwfl, dso__short_name(dso), filename, -1,95 base, false);96 }97 98 if (mod) {99 void **userdatap;100 101 dwfl_module_info(mod, &userdatap, NULL, NULL, NULL, NULL, NULL, NULL);102 *userdatap = dso;103 }104 105 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;106}107 108static int report_module(u64 ip, struct unwind_info *ui)109{110 struct addr_location al;111 int res;112 113 addr_location__init(&al);114 res = __report_module(&al, ip, ui);115 addr_location__exit(&al);116 return res;117}118 119/*120 * Store all entries within entries array,121 * we will process it after we finish unwind.122 */123static int entry(u64 ip, struct unwind_info *ui)124 125{126 struct unwind_entry *e = &ui->entries[ui->idx++];127 struct addr_location al;128 129 addr_location__init(&al);130 if (__report_module(&al, ip, ui)) {131 addr_location__exit(&al);132 return -1;133 }134 135 e->ip = ip;136 e->ms.maps = al.maps;137 e->ms.map = al.map;138 e->ms.sym = al.sym;139 140 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",141 al.sym ? al.sym->name : "''",142 ip,143 al.map ? map__map_ip(al.map, ip) : (u64) 0);144 addr_location__exit(&al);145 return 0;146}147 148static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)149{150 /* We want only single thread to be processed. */151 if (*thread_argp != NULL)152 return 0;153 154 *thread_argp = arg;155 return dwfl_pid(dwfl);156}157 158static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,159 Dwarf_Word *data)160{161 struct addr_location al;162 ssize_t size;163 struct dso *dso;164 165 addr_location__init(&al);166 if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) {167 pr_debug("unwind: no map for %lx\n", (unsigned long)addr);168 goto out_fail;169 }170 dso = map__dso(al.map);171 if (!dso)172 goto out_fail;173 174 size = dso__data_read_addr(dso, al.map, ui->machine, addr, (u8 *) data, sizeof(*data));175 176 addr_location__exit(&al);177 return !(size == sizeof(*data));178out_fail:179 addr_location__exit(&al);180 return -1;181}182 183static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,184 void *arg)185{186 struct unwind_info *ui = arg;187 const char *arch = perf_env__arch(ui->machine->env);188 struct stack_dump *stack = &ui->sample->user_stack;189 u64 start, end;190 int offset;191 int ret;192 193 ret = perf_reg_value(&start, &ui->sample->user_regs,194 perf_arch_reg_sp(arch));195 if (ret)196 return false;197 198 end = start + stack->size;199 200 /* Check overflow. */201 if (addr + sizeof(Dwarf_Word) < addr)202 return false;203 204 if (addr < start || addr + sizeof(Dwarf_Word) > end) {205 ret = access_dso_mem(ui, addr, result);206 if (ret) {207 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"208 " 0x%" PRIx64 "-0x%" PRIx64 "\n",209 addr, start, end);210 return false;211 }212 return true;213 }214 215 offset = addr - start;216 *result = *(Dwarf_Word *)&stack->data[offset];217 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",218 addr, (unsigned long)*result, offset);219 return true;220}221 222static const Dwfl_Thread_Callbacks callbacks = {223 .next_thread = next_thread,224 .memory_read = memory_read,225 .set_initial_registers = libdw__arch_set_initial_registers,226};227 228static int229frame_callback(Dwfl_Frame *state, void *arg)230{231 struct unwind_info *ui = arg;232 Dwarf_Addr pc;233 bool isactivation;234 235 if (!dwfl_frame_pc(state, &pc, NULL)) {236 if (!ui->best_effort)237 pr_err("%s", dwfl_errmsg(-1));238 return DWARF_CB_ABORT;239 }240 241 // report the module before we query for isactivation242 report_module(pc, ui);243 244 if (!dwfl_frame_pc(state, &pc, &isactivation)) {245 if (!ui->best_effort)246 pr_err("%s", dwfl_errmsg(-1));247 return DWARF_CB_ABORT;248 }249 250 if (!isactivation)251 --pc;252 253 return entry(pc, ui) || !(--ui->max_stack) ?254 DWARF_CB_ABORT : DWARF_CB_OK;255}256 257int unwind__get_entries(unwind_entry_cb_t cb, void *arg,258 struct thread *thread,259 struct perf_sample *data,260 int max_stack,261 bool best_effort)262{263 struct unwind_info *ui, ui_buf = {264 .sample = data,265 .thread = thread,266 .machine = maps__machine((thread__maps(thread))),267 .cb = cb,268 .arg = arg,269 .max_stack = max_stack,270 .best_effort = best_effort271 };272 const char *arch = perf_env__arch(ui_buf.machine->env);273 Dwarf_Word ip;274 int err = -EINVAL, i;275 276 if (!data->user_regs.regs)277 return -EINVAL;278 279 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);280 if (!ui)281 return -ENOMEM;282 283 *ui = ui_buf;284 285 ui->dwfl = dwfl_begin(&offline_callbacks);286 if (!ui->dwfl)287 goto out;288 289 err = perf_reg_value(&ip, &data->user_regs, perf_arch_reg_ip(arch));290 if (err)291 goto out;292 293 err = report_module(ip, ui);294 if (err)295 goto out;296 297 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread__tid(thread), &callbacks, ui);298 if (err)299 goto out;300 301 err = dwfl_getthread_frames(ui->dwfl, thread__tid(thread), frame_callback, ui);302 303 if (err && ui->max_stack != max_stack)304 err = 0;305 306 /*307 * Display what we got based on the order setup.308 */309 for (i = 0; i < ui->idx && !err; i++) {310 int j = i;311 312 if (callchain_param.order == ORDER_CALLER)313 j = ui->idx - i - 1;314 315 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;316 }317 318 out:319 if (err)320 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));321 322 dwfl_end(ui->dwfl);323 free(ui);324 return 0;325}326