1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/compiler.h>
3 #include <elfutils/libdw.h>
4 #include <elfutils/libdwfl.h>
10 #include "unwind-libdw.h"
15 #include <linux/types.h>
16 #include <linux/zalloc.h>
18 #include "perf_regs.h"
19 #include "callchain.h"
21 static char *debuginfo_path;
23 static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata,
24 const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused,
25 const char *file_name, const char *debuglink_file __maybe_unused,
26 GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name)
28 const struct dso *dso = *userdata;
31 if (dso->symsrc_filename && strcmp (file_name, dso->symsrc_filename))
32 *debuginfo_file_name = strdup(dso->symsrc_filename);
36 static const Dwfl_Callbacks offline_callbacks = {
37 .find_debuginfo = __find_debuginfo,
38 .debuginfo_path = &debuginfo_path,
39 .section_address = dwfl_offline_section_address,
40 // .find_elf is not set as we use dwfl_report_elf() instead.
43 static int __report_module(struct addr_location *al, u64 ip,
44 struct unwind_info *ui)
47 struct dso *dso = NULL;
49 * Some callers will use al->sym, so we can't just use the
50 * cheaper thread__find_map() here.
52 thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al);
60 mod = dwfl_addrmodule(ui->dwfl, ip);
65 dwfl_module_info(mod, &userdatap, &s, NULL, NULL, NULL, NULL, NULL);
67 if (s != al->map->start - al->map->pgoff)
72 mod = dwfl_report_elf(ui->dwfl, dso->short_name, dso->long_name, -1,
73 al->map->start - al->map->pgoff, false);
75 char filename[PATH_MAX];
77 if (dso__build_id_filename(dso, filename, sizeof(filename), false))
78 mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1,
79 al->map->start - al->map->pgoff, false);
82 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
85 static int report_module(u64 ip, struct unwind_info *ui)
87 struct addr_location al;
89 return __report_module(&al, ip, ui);
93 * Store all entries within entries array,
94 * we will process it after we finish unwind.
96 static int entry(u64 ip, struct unwind_info *ui)
99 struct unwind_entry *e = &ui->entries[ui->idx++];
100 struct addr_location al;
102 if (__report_module(&al, ip, ui))
106 e->ms.maps = al.maps;
110 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
111 al.sym ? al.sym->name : "''",
113 al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
117 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
119 /* We want only single thread to be processed. */
120 if (*thread_argp != NULL)
124 return dwfl_pid(dwfl);
127 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
130 struct addr_location al;
133 if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) {
134 pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
141 size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
142 addr, (u8 *) data, sizeof(*data));
144 return !(size == sizeof(*data));
147 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
150 struct unwind_info *ui = arg;
151 struct stack_dump *stack = &ui->sample->user_stack;
156 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
160 end = start + stack->size;
162 /* Check overflow. */
163 if (addr + sizeof(Dwarf_Word) < addr)
166 if (addr < start || addr + sizeof(Dwarf_Word) > end) {
167 ret = access_dso_mem(ui, addr, result);
169 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
170 " 0x%" PRIx64 "-0x%" PRIx64 "\n",
177 offset = addr - start;
178 *result = *(Dwarf_Word *)&stack->data[offset];
179 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
180 addr, (unsigned long)*result, offset);
184 static const Dwfl_Thread_Callbacks callbacks = {
185 .next_thread = next_thread,
186 .memory_read = memory_read,
187 .set_initial_registers = libdw__arch_set_initial_registers,
191 frame_callback(Dwfl_Frame *state, void *arg)
193 struct unwind_info *ui = arg;
197 if (!dwfl_frame_pc(state, &pc, NULL)) {
198 pr_err("%s", dwfl_errmsg(-1));
199 return DWARF_CB_ABORT;
202 // report the module before we query for isactivation
203 report_module(pc, ui);
205 if (!dwfl_frame_pc(state, &pc, &isactivation)) {
206 pr_err("%s", dwfl_errmsg(-1));
207 return DWARF_CB_ABORT;
213 return entry(pc, ui) || !(--ui->max_stack) ?
214 DWARF_CB_ABORT : DWARF_CB_OK;
217 int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
218 struct thread *thread,
219 struct perf_sample *data,
222 struct unwind_info *ui, ui_buf = {
225 .machine = thread->maps->machine,
228 .max_stack = max_stack,
231 int err = -EINVAL, i;
233 if (!data->user_regs.regs)
236 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);
242 ui->dwfl = dwfl_begin(&offline_callbacks);
246 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
250 err = report_module(ip, ui);
254 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui);
258 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui);
260 if (err && ui->max_stack != max_stack)
264 * Display what we got based on the order setup.
266 for (i = 0; i < ui->idx && !err; i++) {
269 if (callchain_param.order == ORDER_CALLER)
272 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
277 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));