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Commit ab255e72 authored by Jean Pihet's avatar Jean Pihet Committed by Will Deacon
Browse files

perf: parse the .debug_frame section in case .eh_frame is not present 



On ARM the debug info is not present in the .eh_frame sections but
in .debug_frame instead, in dwarf format.
Use libunwind to load and parse the debug info.

Dependencies:
 . if present, libunwind >= 1.1 is needed to prevent a segfault when
   parsing the dwarf info,
 . libunwind needs to be configured with --enable-debug-frame. Note:
   --enable-debug-frame is automatically selected on ARM.

Acked-by: default avatarJiri Olsa <jolsa@redhat.com>
Signed-off-by: default avatarJean Pihet <jean.pihet@linaro.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 405ffbd4

tools/perf/util/unwind.c

+59 −16
Original line number Diff line number Diff line
@@ -39,6 +39,15 @@ UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as, 


#define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table)



extern int

UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug,

				 unw_word_t ip,

				 unw_word_t segbase,

				 const char *obj_name, unw_word_t start,

				 unw_word_t end);



#define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame)



#define DW_EH_PE_FORMAT_MASK	0x0f	/* format of the encoded value */

#define DW_EH_PE_APPL_MASK	0x70	/* how the value is to be applied */
@@ -245,8 +254,9 @@ static int unwind_spec_ehframe(struct dso *dso, struct machine *machine, 
	return 0;

}



static int read_unwind_spec(struct dso *dso, struct machine *machine,

			    u64 *table_data, u64 *segbase, u64 *fde_count)

static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine,

				     u64 *table_data, u64 *segbase,

				     u64 *fde_count)

{

	int ret = -EINVAL, fd;

	u64 offset;
@@ -255,6 +265,7 @@ static int read_unwind_spec(struct dso *dso, struct machine *machine, 
	if (fd < 0)

		return -EINVAL;



	/* Check the .eh_frame section for unwinding info */

	offset = elf_section_offset(fd, ".eh_frame_hdr");

	close(fd);
@@ -263,10 +274,29 @@ static int read_unwind_spec(struct dso *dso, struct machine *machine, 
					  table_data, segbase,

					  fde_count);



	/* TODO .debug_frame check if eh_frame_hdr fails */

	return ret;

}



#ifndef NO_LIBUNWIND_DEBUG_FRAME

static int read_unwind_spec_debug_frame(struct dso *dso,

					struct machine *machine, u64 *offset)

{

	int fd = dso__data_fd(dso, machine);



	if (fd < 0)

		return -EINVAL;



	/* Check the .debug_frame section for unwinding info */

	*offset = elf_section_offset(fd, ".debug_frame");

	close(fd);



	if (*offset)

		return 0;



	return -EINVAL;

}

#endif



static struct map *find_map(unw_word_t ip, struct unwind_info *ui)

{

	struct addr_location al;
@@ -291,10 +321,9 @@ find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi, 


	pr_debug("unwind: find_proc_info dso %s\n", map->dso->name);



	if (read_unwind_spec(map->dso, ui->machine,

			     &table_data, &segbase, &fde_count))

		return -EINVAL;



	/* Check the .eh_frame section for unwinding info */

	if (!read_unwind_spec_eh_frame(map->dso, ui->machine,

				       &table_data, &segbase, &fde_count)) {

		memset(&di, 0, sizeof(di));

		di.format   = UNW_INFO_FORMAT_REMOTE_TABLE;

		di.start_ip = map->start;
@@ -307,6 +336,20 @@ find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi, 
						 need_unwind_info, arg);

	}



#ifndef NO_LIBUNWIND_DEBUG_FRAME

	/* Check the .debug_frame section for unwinding info */

	if (!read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) {

		memset(&di, 0, sizeof(di));

		dwarf_find_debug_frame(0, &di, ip, 0, map->dso->name,

				       map->start, map->end);

		return dwarf_search_unwind_table(as, ip, &di, pi,

						 need_unwind_info, arg);

	}

#endif



	return -EINVAL;

}



static int access_fpreg(unw_addr_space_t __maybe_unused as,

			unw_regnum_t __maybe_unused num,

			unw_fpreg_t __maybe_unused *val,