1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/compiler.h>
3 #include <elfutils/libdw.h>
4 #include <elfutils/libdwfl.h>
9 #include "unwind-libdw.h"
14 #include <linux/types.h>
16 #include "perf_regs.h"
17 #include "callchain.h"
20 static char *debuginfo_path;
22 static const Dwfl_Callbacks offline_callbacks = {
23 .find_debuginfo = dwfl_standard_find_debuginfo,
24 .debuginfo_path = &debuginfo_path,
25 .section_address = dwfl_offline_section_address,
28 static int __report_module(struct addr_location *al, u64 ip,
29 struct unwind_info *ui)
32 struct dso *dso = NULL;
34 * Some callers will use al->sym, so we can't just use the
35 * cheaper thread__find_map() here.
37 thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al);
45 mod = dwfl_addrmodule(ui->dwfl, ip);
49 dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);
50 if (s != al->map->start - al->map->pgoff)
55 mod = dwfl_report_elf(ui->dwfl, dso->short_name,
56 (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start - al->map->pgoff,
59 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
62 static int report_module(u64 ip, struct unwind_info *ui)
64 struct addr_location al;
66 return __report_module(&al, ip, ui);
70 * Store all entries within entries array,
71 * we will process it after we finish unwind.
73 static int entry(u64 ip, struct unwind_info *ui)
76 struct unwind_entry *e = &ui->entries[ui->idx++];
77 struct addr_location al;
79 if (__report_module(&al, ip, ui))
86 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
87 al.sym ? al.sym->name : "''",
89 al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
93 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
95 /* We want only single thread to be processed. */
96 if (*thread_argp != NULL)
100 return dwfl_pid(dwfl);
103 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
106 struct addr_location al;
109 if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) {
110 pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
117 size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
118 addr, (u8 *) data, sizeof(*data));
120 return !(size == sizeof(*data));
123 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
126 struct unwind_info *ui = arg;
127 struct stack_dump *stack = &ui->sample->user_stack;
132 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
136 end = start + stack->size;
138 /* Check overflow. */
139 if (addr + sizeof(Dwarf_Word) < addr)
142 if (addr < start || addr + sizeof(Dwarf_Word) > end) {
143 ret = access_dso_mem(ui, addr, result);
145 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
146 " 0x%" PRIx64 "-0x%" PRIx64 "\n",
153 offset = addr - start;
154 *result = *(Dwarf_Word *)&stack->data[offset];
155 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
156 addr, (unsigned long)*result, offset);
160 static const Dwfl_Thread_Callbacks callbacks = {
161 .next_thread = next_thread,
162 .memory_read = memory_read,
163 .set_initial_registers = libdw__arch_set_initial_registers,
167 frame_callback(Dwfl_Frame *state, void *arg)
169 struct unwind_info *ui = arg;
173 if (!dwfl_frame_pc(state, &pc, NULL)) {
174 pr_err("%s", dwfl_errmsg(-1));
175 return DWARF_CB_ABORT;
178 // report the module before we query for isactivation
179 report_module(pc, ui);
181 if (!dwfl_frame_pc(state, &pc, &isactivation)) {
182 pr_err("%s", dwfl_errmsg(-1));
183 return DWARF_CB_ABORT;
189 return entry(pc, ui) || !(--ui->max_stack) ?
190 DWARF_CB_ABORT : DWARF_CB_OK;
193 int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
194 struct thread *thread,
195 struct perf_sample *data,
198 struct unwind_info *ui, ui_buf = {
201 .machine = thread->mg->machine,
204 .max_stack = max_stack,
207 int err = -EINVAL, i;
209 if (!data->user_regs.regs)
212 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);
218 ui->dwfl = dwfl_begin(&offline_callbacks);
222 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
226 err = report_module(ip, ui);
230 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui);
234 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui);
236 if (err && ui->max_stack != max_stack)
240 * Display what we got based on the order setup.
242 for (i = 0; i < ui->idx && !err; i++) {
245 if (callchain_param.order == ORDER_CALLER)
248 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
253 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));