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![Jan Kratochvil](/assets/img/avatar_default.png)
elfutils needs to be provided main binary and separate debug info file respectively. Providing separate debug info file instead of the main binary is not sufficient. One needs to try both supplied filename and its possible cache by its build-id depending on the use case. Signed-off-by: Jan Kratochvil <jan.kratochvil@redhat.com> Tested-by: Jiri Olsa <jolsa@redhat.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ian Rogers <irogers@google.com> Cc: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
282 lines
6.3 KiB
C
282 lines
6.3 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 = al->map->dso;
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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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void **userdatap;
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dwfl_module_info(mod, &userdatap, &s, NULL, NULL, NULL, NULL, NULL);
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*userdatap = dso;
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if (s != al->map->start - al->map->pgoff)
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mod = 0;
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}
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if (!mod)
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mod = dwfl_report_elf(ui->dwfl, dso->short_name, dso->long_name, -1,
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al->map->start - al->map->pgoff, false);
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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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al->map->start - al->map->pgoff, false);
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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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return __report_module(&al, ip, ui);
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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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if (__report_module(&al, ip, ui))
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return -1;
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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 ? al.map->map_ip(al.map, ip) : (u64) 0);
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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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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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return -1;
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}
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if (!al.map->dso)
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return -1;
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size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
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addr, (u8 *) data, sizeof(*data));
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return !(size == sizeof(*data));
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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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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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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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{
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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 = thread->maps->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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};
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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, &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, 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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