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Commit 6a330a3c authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Arnaldo Carvalho de Melo
Browse files

perf probe: Support comp_dir to find an absolute source path 



Gcc generates DW_AT_comp_dir and stores relative source path if building kernel
without O= option. In that case, perf probe --line sometimes doesn't work
without --source option, because it tries to access relative source path.

This adds DW_AT_comp_dir support to perf probe for finding an absolute source
path when no --source option.

LKML-Reference: <4C36EBE7.3060802@hitachi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 7cf0b79e

tools/perf/util/probe-event.c

+22 −12
Original line number Diff line number Diff line
@@ -201,28 +201,38 @@ static int try_to_find_kprobe_trace_events(struct perf_probe_event *pev, 
 * a newly allocated path on success.

 * Return 0 if file was found and readable, -errno otherwise.

 */

static int get_real_path(const char *raw_path, char **new_path)

static int get_real_path(const char *raw_path, const char *comp_dir,

			 char **new_path)

{

	if (!symbol_conf.source_prefix) {

	const char *prefix = symbol_conf.source_prefix;



	if (!prefix) {

		if (raw_path[0] != '/' && comp_dir)

			/* If not an absolute path, try to use comp_dir */

			prefix = comp_dir;

		else {

			if (access(raw_path, R_OK) == 0) {

				*new_path = strdup(raw_path);

				return 0;

			} else

				return -errno;

		}

	}



	*new_path = malloc((strlen(symbol_conf.source_prefix) +

			    strlen(raw_path) + 2));

	*new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));

	if (!*new_path)

		return -ENOMEM;



	for (;;) {

		sprintf(*new_path, "%s/%s", symbol_conf.source_prefix,

			raw_path);

		sprintf(*new_path, "%s/%s", prefix, raw_path);



		if (access(*new_path, R_OK) == 0)

			return 0;



		if (!symbol_conf.source_prefix)

			/* In case of searching comp_dir, don't retry */

			return -errno;



		switch (errno) {

		case ENAMETOOLONG:

		case ENOENT:
@@ -318,7 +328,7 @@ int show_line_range(struct line_range *lr) 


	/* Convert source file path */

	tmp = lr->path;

	ret = get_real_path(tmp, &lr->path);

	ret = get_real_path(tmp, lr->comp_dir, &lr->path);

	free(tmp);	/* Free old path */

	if (ret < 0) {

		pr_warning("Failed to find source file. (%d)\n", ret);

tools/perf/util/probe-event.h

+1 −0
Original line number Diff line number Diff line
@@ -86,6 +86,7 @@ struct line_range { 
	int			end;		/* End line number */

	int			offset;		/* Start line offset */

	char			*path;		/* Real path name */

	char			*comp_dir;	/* Compile directory */

	struct list_head	line_list;	/* Visible lines */

};

tools/perf/util/probe-finder.c

+21 −0
Original line number Diff line number Diff line
@@ -144,6 +144,15 @@ static const char *cu_find_realpath(Dwarf_Die *cu_die, const char *fname) 
	return src;

}



/* Get DW_AT_comp_dir (should be NULL with older gcc) */

static const char *cu_get_comp_dir(Dwarf_Die *cu_die)

{

	Dwarf_Attribute attr;

	if (dwarf_attr(cu_die, DW_AT_comp_dir, &attr) == NULL)

		return NULL;

	return dwarf_formstring(&attr);

}



/* Compare diename and tname */

static bool die_compare_name(Dwarf_Die *dw_die, const char *tname)

{
@@ -1374,6 +1383,7 @@ int find_line_range(int fd, struct line_range *lr) 
	size_t cuhl;

	Dwarf_Die *diep;

	Dwarf *dbg;

	const char *comp_dir;



	dbg = dwarf_begin(fd, DWARF_C_READ);

	if (!dbg) {
@@ -1409,6 +1419,17 @@ int find_line_range(int fd, struct line_range *lr) 
		}

		off = noff;

	}



	/* Store comp_dir */

	if (lf.found) {

		comp_dir = cu_get_comp_dir(&lf.cu_die);

		if (comp_dir) {

			lr->comp_dir = strdup(comp_dir);

			if (!lr->comp_dir)

				ret = -ENOMEM;

		}

	}



	pr_debug("path: %s\n", lr->path);

	dwarf_end(dbg);