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![Vincent Whitchurch](/assets/img/avatar_default.png)
Pass the full path including the symfs (if any) to libdw. Without this unwinding fails with errors like this when a symfs is used: unwind: failed with 'No such file or directory'" Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: kernel@axis.com Cc: Ian Rogers <irogers@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ingo Molnar <mingo@redhat.com> Link: https://lore.kernel.org/r/20230630-perf-libdw-symfs-v2-1-469760dd4d5b@axis.com Signed-off-by: Namhyung Kim <namhyung@kernel.org>
308 lines
7 KiB
C
308 lines
7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/compiler.h>
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#include <elfutils/libdw.h>
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#include <elfutils/libdwfl.h>
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#include <inttypes.h>
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#include <errno.h>
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#include "debug.h"
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#include "dso.h"
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#include "unwind.h"
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#include "unwind-libdw.h"
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#include "machine.h"
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#include "map.h"
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#include "symbol.h"
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#include "thread.h"
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#include <linux/types.h>
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#include <linux/zalloc.h>
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#include "event.h"
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#include "perf_regs.h"
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#include "callchain.h"
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static char *debuginfo_path;
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static int __find_debuginfo(Dwfl_Module *mod __maybe_unused, void **userdata,
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const char *modname __maybe_unused, Dwarf_Addr base __maybe_unused,
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const char *file_name, const char *debuglink_file __maybe_unused,
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GElf_Word debuglink_crc __maybe_unused, char **debuginfo_file_name)
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{
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const struct dso *dso = *userdata;
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assert(dso);
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if (dso->symsrc_filename && strcmp (file_name, dso->symsrc_filename))
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*debuginfo_file_name = strdup(dso->symsrc_filename);
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return -1;
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}
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static const Dwfl_Callbacks offline_callbacks = {
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.find_debuginfo = __find_debuginfo,
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.debuginfo_path = &debuginfo_path,
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.section_address = dwfl_offline_section_address,
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// .find_elf is not set as we use dwfl_report_elf() instead.
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};
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static int __report_module(struct addr_location *al, u64 ip,
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struct unwind_info *ui)
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{
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Dwfl_Module *mod;
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struct dso *dso = NULL;
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/*
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* Some callers will use al->sym, so we can't just use the
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* cheaper thread__find_map() here.
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*/
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thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al);
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if (al->map)
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dso = map__dso(al->map);
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if (!dso)
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return 0;
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mod = dwfl_addrmodule(ui->dwfl, ip);
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if (mod) {
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Dwarf_Addr s;
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dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);
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if (s != map__start(al->map) - map__pgoff(al->map))
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mod = 0;
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}
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if (!mod) {
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char filename[PATH_MAX];
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__symbol__join_symfs(filename, sizeof(filename), dso->long_name);
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mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1,
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map__start(al->map) - map__pgoff(al->map), false);
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}
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if (!mod) {
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char filename[PATH_MAX];
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if (dso__build_id_filename(dso, filename, sizeof(filename), false))
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mod = dwfl_report_elf(ui->dwfl, dso->short_name, filename, -1,
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map__start(al->map) - map__pgoff(al->map), false);
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}
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if (mod) {
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void **userdatap;
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dwfl_module_info(mod, &userdatap, NULL, NULL, NULL, NULL, NULL, NULL);
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*userdatap = dso;
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}
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return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
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}
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static int report_module(u64 ip, struct unwind_info *ui)
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{
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struct addr_location al;
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int res;
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addr_location__init(&al);
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res = __report_module(&al, ip, ui);
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addr_location__exit(&al);
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return res;
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}
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/*
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* Store all entries within entries array,
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* we will process it after we finish unwind.
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*/
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static int entry(u64 ip, struct unwind_info *ui)
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{
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struct unwind_entry *e = &ui->entries[ui->idx++];
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struct addr_location al;
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addr_location__init(&al);
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if (__report_module(&al, ip, ui)) {
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addr_location__exit(&al);
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return -1;
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}
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e->ip = ip;
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e->ms.maps = al.maps;
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e->ms.map = al.map;
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e->ms.sym = al.sym;
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pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
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al.sym ? al.sym->name : "''",
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ip,
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al.map ? map__map_ip(al.map, ip) : (u64) 0);
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addr_location__exit(&al);
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return 0;
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}
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static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
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{
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/* We want only single thread to be processed. */
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if (*thread_argp != NULL)
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return 0;
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*thread_argp = arg;
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return dwfl_pid(dwfl);
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}
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static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
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Dwarf_Word *data)
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{
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struct addr_location al;
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ssize_t size;
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struct dso *dso;
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addr_location__init(&al);
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if (!thread__find_map(ui->thread, PERF_RECORD_MISC_USER, addr, &al)) {
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pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
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goto out_fail;
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}
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dso = map__dso(al.map);
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if (!dso)
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goto out_fail;
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size = dso__data_read_addr(dso, al.map, ui->machine, addr, (u8 *) data, sizeof(*data));
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addr_location__exit(&al);
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return !(size == sizeof(*data));
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out_fail:
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addr_location__exit(&al);
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return -1;
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}
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static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
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void *arg)
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{
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struct unwind_info *ui = arg;
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struct stack_dump *stack = &ui->sample->user_stack;
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u64 start, end;
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int offset;
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int ret;
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ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
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if (ret)
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return false;
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end = start + stack->size;
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/* Check overflow. */
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if (addr + sizeof(Dwarf_Word) < addr)
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return false;
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if (addr < start || addr + sizeof(Dwarf_Word) > end) {
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ret = access_dso_mem(ui, addr, result);
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if (ret) {
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pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
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" 0x%" PRIx64 "-0x%" PRIx64 "\n",
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addr, start, end);
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return false;
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}
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return true;
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}
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offset = addr - start;
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*result = *(Dwarf_Word *)&stack->data[offset];
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pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
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addr, (unsigned long)*result, offset);
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return true;
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}
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static const Dwfl_Thread_Callbacks callbacks = {
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.next_thread = next_thread,
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.memory_read = memory_read,
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.set_initial_registers = libdw__arch_set_initial_registers,
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};
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static int
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frame_callback(Dwfl_Frame *state, void *arg)
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{
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struct unwind_info *ui = arg;
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Dwarf_Addr pc;
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bool isactivation;
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if (!dwfl_frame_pc(state, &pc, NULL)) {
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if (!ui->best_effort)
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pr_err("%s", dwfl_errmsg(-1));
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return DWARF_CB_ABORT;
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}
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// report the module before we query for isactivation
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report_module(pc, ui);
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if (!dwfl_frame_pc(state, &pc, &isactivation)) {
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if (!ui->best_effort)
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pr_err("%s", dwfl_errmsg(-1));
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return DWARF_CB_ABORT;
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}
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if (!isactivation)
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--pc;
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return entry(pc, ui) || !(--ui->max_stack) ?
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DWARF_CB_ABORT : DWARF_CB_OK;
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}
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int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
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struct thread *thread,
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struct perf_sample *data,
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int max_stack,
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bool best_effort)
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{
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struct unwind_info *ui, ui_buf = {
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.sample = data,
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.thread = thread,
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.machine = RC_CHK_ACCESS(thread__maps(thread))->machine,
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.cb = cb,
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.arg = arg,
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.max_stack = max_stack,
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.best_effort = best_effort
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};
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Dwarf_Word ip;
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int err = -EINVAL, i;
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if (!data->user_regs.regs)
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return -EINVAL;
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ui = zalloc(sizeof(ui_buf) + sizeof(ui_buf.entries[0]) * max_stack);
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if (!ui)
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return -ENOMEM;
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*ui = ui_buf;
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ui->dwfl = dwfl_begin(&offline_callbacks);
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if (!ui->dwfl)
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goto out;
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err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
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if (err)
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goto out;
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err = report_module(ip, ui);
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if (err)
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goto out;
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err = !dwfl_attach_state(ui->dwfl, EM_NONE, thread__tid(thread), &callbacks, ui);
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if (err)
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goto out;
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err = dwfl_getthread_frames(ui->dwfl, thread__tid(thread), frame_callback, ui);
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if (err && ui->max_stack != max_stack)
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err = 0;
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/*
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* Display what we got based on the order setup.
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*/
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for (i = 0; i < ui->idx && !err; i++) {
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int j = i;
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if (callchain_param.order == ORDER_CALLER)
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j = ui->idx - i - 1;
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err = ui->entries[j].ip ? ui->cb(&ui->entries[j], ui->arg) : 0;
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}
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out:
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if (err)
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pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));
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dwfl_end(ui->dwfl);
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free(ui);
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return 0;
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}
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