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- #include <linux/compiler.h>
- #include <elfutils/libdw.h>
- #include <elfutils/libdwfl.h>
- #include <inttypes.h>
- #include <errno.h>
- #include "debug.h"
- #include "unwind.h"
- #include "unwind-libdw.h"
- #include "machine.h"
- #include "thread.h"
- #include <linux/types.h>
- #include "event.h"
- #include "perf_regs.h"
- static char *debuginfo_path;
- static const Dwfl_Callbacks offline_callbacks = {
- .find_debuginfo = dwfl_standard_find_debuginfo,
- .debuginfo_path = &debuginfo_path,
- .section_address = dwfl_offline_section_address,
- };
- static int __report_module(struct addr_location *al, u64 ip,
- struct unwind_info *ui)
- {
- Dwfl_Module *mod;
- struct dso *dso = NULL;
- thread__find_addr_location(ui->thread,
- PERF_RECORD_MISC_USER,
- MAP__FUNCTION, ip, al);
- if (al->map)
- dso = al->map->dso;
- if (!dso)
- return 0;
- mod = dwfl_addrmodule(ui->dwfl, ip);
- if (mod) {
- Dwarf_Addr s;
- dwfl_module_info(mod, NULL, &s, NULL, NULL, NULL, NULL, NULL);
- if (s != al->map->start - al->map->pgoff)
- mod = 0;
- }
- if (!mod)
- mod = dwfl_report_elf(ui->dwfl, dso->short_name,
- (dso->symsrc_filename ? dso->symsrc_filename : dso->long_name), -1, al->map->start - al->map->pgoff,
- false);
- return mod && dwfl_addrmodule(ui->dwfl, ip) == mod ? 0 : -1;
- }
- static int report_module(u64 ip, struct unwind_info *ui)
- {
- struct addr_location al;
- return __report_module(&al, ip, ui);
- }
- static int entry(u64 ip, struct unwind_info *ui)
- {
- struct unwind_entry e;
- struct addr_location al;
- if (__report_module(&al, ip, ui))
- return -1;
- e.ip = ip;
- e.map = al.map;
- e.sym = al.sym;
- pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
- al.sym ? al.sym->name : "''",
- ip,
- al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
- return ui->cb(&e, ui->arg);
- }
- static pid_t next_thread(Dwfl *dwfl, void *arg, void **thread_argp)
- {
- /* We want only single thread to be processed. */
- if (*thread_argp != NULL)
- return 0;
- *thread_argp = arg;
- return dwfl_pid(dwfl);
- }
- static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
- Dwarf_Word *data)
- {
- struct addr_location al;
- ssize_t size;
- thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
- MAP__FUNCTION, addr, &al);
- if (!al.map) {
- pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
- return -1;
- }
- if (!al.map->dso)
- return -1;
- size = dso__data_read_addr(al.map->dso, al.map, ui->machine,
- addr, (u8 *) data, sizeof(*data));
- return !(size == sizeof(*data));
- }
- static bool memory_read(Dwfl *dwfl __maybe_unused, Dwarf_Addr addr, Dwarf_Word *result,
- void *arg)
- {
- struct unwind_info *ui = arg;
- struct stack_dump *stack = &ui->sample->user_stack;
- u64 start, end;
- int offset;
- int ret;
- ret = perf_reg_value(&start, &ui->sample->user_regs, PERF_REG_SP);
- if (ret)
- return false;
- end = start + stack->size;
- /* Check overflow. */
- if (addr + sizeof(Dwarf_Word) < addr)
- return false;
- if (addr < start || addr + sizeof(Dwarf_Word) > end) {
- ret = access_dso_mem(ui, addr, result);
- if (ret) {
- pr_debug("unwind: access_mem 0x%" PRIx64 " not inside range"
- " 0x%" PRIx64 "-0x%" PRIx64 "\n",
- addr, start, end);
- return false;
- }
- return true;
- }
- offset = addr - start;
- *result = *(Dwarf_Word *)&stack->data[offset];
- pr_debug("unwind: access_mem addr 0x%" PRIx64 ", val %lx, offset %d\n",
- addr, (unsigned long)*result, offset);
- return true;
- }
- static const Dwfl_Thread_Callbacks callbacks = {
- .next_thread = next_thread,
- .memory_read = memory_read,
- .set_initial_registers = libdw__arch_set_initial_registers,
- };
- static int
- frame_callback(Dwfl_Frame *state, void *arg)
- {
- struct unwind_info *ui = arg;
- Dwarf_Addr pc;
- if (!dwfl_frame_pc(state, &pc, NULL)) {
- pr_err("%s", dwfl_errmsg(-1));
- return DWARF_CB_ABORT;
- }
- return entry(pc, ui) || !(--ui->max_stack) ?
- DWARF_CB_ABORT : DWARF_CB_OK;
- }
- int unwind__get_entries(unwind_entry_cb_t cb, void *arg,
- struct thread *thread,
- struct perf_sample *data,
- int max_stack)
- {
- struct unwind_info ui = {
- .sample = data,
- .thread = thread,
- .machine = thread->mg->machine,
- .cb = cb,
- .arg = arg,
- .max_stack = max_stack,
- };
- Dwarf_Word ip;
- int err = -EINVAL;
- if (!data->user_regs.regs)
- return -EINVAL;
- ui.dwfl = dwfl_begin(&offline_callbacks);
- if (!ui.dwfl)
- goto out;
- err = perf_reg_value(&ip, &data->user_regs, PERF_REG_IP);
- if (err)
- goto out;
- err = report_module(ip, &ui);
- if (err)
- goto out;
- if (!dwfl_attach_state(ui.dwfl, EM_NONE, thread->tid, &callbacks, &ui))
- goto out;
- err = dwfl_getthread_frames(ui.dwfl, thread->tid, frame_callback, &ui);
- if (err && !ui.max_stack)
- err = 0;
- out:
- if (err)
- pr_debug("unwind: failed with '%s'\n", dwfl_errmsg(-1));
- dwfl_end(ui.dwfl);
- return 0;
- }
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