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"
22 static char *debuginfo_path;
24 static const Dwfl_Callbacks offline_callbacks = {
25 .find_debuginfo = dwfl_standard_find_debuginfo,
26 .debuginfo_path = &debuginfo_path,
27 .section_address = dwfl_offline_section_address,
30 static int __report_module(struct addr_location *al, u64 ip,
31 struct unwind_info *ui)
34 struct dso *dso = NULL;
36 * Some callers will use al->sym, so we can't just use the
37 * cheaper thread__find_map() here.
39 thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al);
47 mod = dwfl_addrmodule(ui->dwfl, ip);
51 dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);
52 if (s != al->map->start - al->map->pgoff)
57 mod = dwfl_report_elf(ui->dwfl, dso->short_name,
58 (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start - al->map->pgoff,
61 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
64 static int report_module(u64 ip, struct unwind_info *ui)
66 struct addr_location al;
68 return __report_module(&al, ip, ui);
72 * Store all entries within entries array,
73 * we will process it after we finish unwind.
75 static int entry(u64 ip, struct unwind_info *ui)
78 struct unwind_entry *e = &ui->entries[ui->idx++];
79 struct addr_location al;
81 if (__report_module(&al, ip, ui))
88 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
89 al.sym ? al.sym->name : "''",
91 al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
95 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
97 /* We want only single thread to be processed. */
98 if (*thread_argp != NULL)
102 return dwfl_pid(dwfl);
105 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
108 struct addr_location al;
111 if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) {
112 pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
119 size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
120 addr, (u8 *) data, sizeof(*data));
122 return !(size == sizeof(*data));
125 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
128 struct unwind_info *ui = arg;
129 struct stack_dump *stack = &ui->sample->user_stack;
134 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
138 end = start + stack->size;
140 /* Check overflow. */
141 if (addr + sizeof(Dwarf_Word) < addr)
144 if (addr < start || addr + sizeof(Dwarf_Word) > end) {
145 ret = access_dso_mem(ui, addr, result);
147 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
148 " 0x%" PRIx64 "-0x%" PRIx64 "\n",
155 offset = addr - start;
156 *result = *(Dwarf_Word *)&stack->data[offset];
157 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
158 addr, (unsigned long)*result, offset);
162 static const Dwfl_Thread_Callbacks callbacks = {
163 .next_thread = next_thread,
164 .memory_read = memory_read,
165 .set_initial_registers = libdw__arch_set_initial_registers,
169 frame_callback(Dwfl_Frame *state, void *arg)
171 struct unwind_info *ui = arg;
175 if (!dwfl_frame_pc(state, &pc, NULL)) {
176 pr_err("%s", dwfl_errmsg(-1));
177 return DWARF_CB_ABORT;
180 // report the module before we query for isactivation
181 report_module(pc, ui);
183 if (!dwfl_frame_pc(state, &pc, &isactivation)) {
184 pr_err("%s", dwfl_errmsg(-1));
185 return DWARF_CB_ABORT;
191 return entry(pc, ui) || !(--ui->max_stack) ?
192 DWARF_CB_ABORT : DWARF_CB_OK;
195 int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
196 struct thread *thread,
197 struct perf_sample *data,
200 struct unwind_info *ui, ui_buf = {
203 .machine = thread->mg->machine,
206 .max_stack = max_stack,
209 int err = -EINVAL, i;
211 if (!data->user_regs.regs)
214 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);
220 ui->dwfl = dwfl_begin(&offline_callbacks);
224 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
228 err = report_module(ip, ui);
232 err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui);
236 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui);
238 if (err && ui->max_stack != max_stack)
242 * Display what we got based on the order setup.
244 for (i = 0; i < ui->idx && !err; i++) {
247 if (callchain_param.order == ORDER_CALLER)
250 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
255 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));