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"
12 #include <linux/types.h>
14 #include "perf_regs.h"
15 #include "callchain.h"
18 static char *debuginfo_path;
20 static const Dwfl_Callbacks offline_callbacks = {
21 .find_debuginfo = dwfl_standard_find_debuginfo,
22 .debuginfo_path = &debuginfo_path,
23 .section_address = dwfl_offline_section_address,
26 static int __report_module(struct addr_location *al, u64 ip,
27 struct unwind_info *ui)
30 struct dso *dso = NULL;
32 thread__find_addr_location(ui->thread,
33 PERF_RECORD_MISC_USER,
34 MAP__FUNCTION, ip, al);
42 mod = dwfl_addrmodule(ui->dwfl, ip);
46 dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);
47 if (s != al->map->start)
52 mod = dwfl_report_elf(ui->dwfl, dso->short_name,
53 dso->long_name, -1, al->map->start,
56 return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
59 static int report_module(u64 ip, struct unwind_info *ui)
61 struct addr_location al;
63 return __report_module(&al, ip, ui);
67 * Store all entries within entries array,
68 * we will process it after we finish unwind.
70 static int entry(u64 ip, struct unwind_info *ui)
73 struct unwind_entry *e = &ui->entries[ui->idx++];
74 struct addr_location al;
76 if (__report_module(&al, ip, ui))
83 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
84 al.sym ? al.sym->name : "''",
86 al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
90 static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
92 /* We want only single thread to be processed. */
93 if (*thread_argp != NULL)
97 return dwfl_pid(dwfl);
100 static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
103 struct addr_location al;
106 thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
107 MAP__FUNCTION, addr, &al);
110 * We've seen cases (softice) where DWARF unwinder went
111 * through non executable mmaps, which we need to lookup
112 * in MAP__VARIABLE tree.
114 thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
115 MAP__VARIABLE, addr, &al);
119 pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
126 size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
127 addr, (u8 *) data, sizeof(*data));
129 return !(size == sizeof(*data));
132 static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
135 struct unwind_info *ui = arg;
136 struct stack_dump *stack = &ui->sample->user_stack;
141 ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
145 end = start + stack->size;
147 /* Check overflow. */
148 if (addr + sizeof(Dwarf_Word) < addr)
151 if (addr < start || addr + sizeof(Dwarf_Word) > end) {
152 ret = access_dso_mem(ui, addr, result);
154 pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
155 " 0x%" PRIx64 "-0x%" PRIx64 "\n",
162 offset = addr - start;
163 *result = *(Dwarf_Word *)&stack->data[offset];
164 pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
165 addr, (unsigned long)*result, offset);
169 static const Dwfl_Thread_Callbacks callbacks = {
170 .next_thread = next_thread,
171 .memory_read = memory_read,
172 .set_initial_registers = libdw__arch_set_initial_registers,
176 frame_callback(Dwfl_Frame *state, void *arg)
178 struct unwind_info *ui = arg;
182 if (!dwfl_frame_pc(state, &pc, NULL)) {
183 pr_err("%s", dwfl_errmsg(-1));
184 return DWARF_CB_ABORT;
187 // report the module before we query for isactivation
188 report_module(pc, ui);
190 if (!dwfl_frame_pc(state, &pc, &isactivation)) {
191 pr_err("%s", dwfl_errmsg(-1));
192 return DWARF_CB_ABORT;
198 return entry(pc, ui) || !(--ui->max_stack) ?
199 DWARF_CB_ABORT : DWARF_CB_OK;
202 int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
203 struct thread *thread,
204 struct perf_sample *data,
207 struct unwind_info *ui, ui_buf = {
210 .machine = thread->mg->machine,
213 .max_stack = max_stack,
216 int err = -EINVAL, i;
218 if (!data->user_regs.regs)
221 ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);
227 ui->dwfl = dwfl_begin(&offline_callbacks);
231 err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
235 err = report_module(ip, ui);
239 if (!dwfl_attach_state(ui->dwfl, EM_NONE, thread->tid, &callbacks, ui))
242 err = dwfl_getthread_frames(ui->dwfl, thread->tid, frame_callback, ui);
244 if (err && ui->max_stack != max_stack)
248 * Display what we got based on the order setup.
250 for (i = 0; i < ui->idx && !err; i++) {
253 if (callchain_param.order == ORDER_CALLER)
256 err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
261 pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));