Commit 8dc26b6f authored by Ian Rogers's avatar Ian Rogers Committed by Arnaldo Carvalho de Melo
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perf srcline: Make sentinel reading for binutils addr2line more robust 



The addr2line process is sent an address then multiple function,
filename:line "records" are read. To detect the end of output a ',' is
sent and for llvm-addr2line a ',' is then read back showing the end of
addrline's output.

For binutils addr2line the ',' translates to address 0 and we expect the
bogus filename marker "??:0" (see filename_split) to be sent from
addr2line.

For some kernels address 0 may have a mapping and so a seemingly valid
inline output is given and breaking the sentinel discovery:

  ```
  $ addr2line -e vmlinux -f -i
  ,
  __per_cpu_start
  ./arch/x86/kernel/cpu/common.c:1850
  ```

To avoid this problem enable the address dumping for addr2line (the -a
option). If an address of 0x0000000000000000 is read then this is the
sentinel value working around the problem above.

The filename_split still needs to check for "??:0" as bogus non-zero
addresses also need handling.

Reported-by: default avatarChangbin Du <changbin.du@huawei.com>
Signed-off-by: default avatarIan Rogers <irogers@google.com>
Tested-by: default avatarChangbin Du <changbin.du@huawei.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tom Rix <trix@redhat.com>
Cc: llvm@lists.linux.dev
Link: https://lore.kernel.org/r/20230613034817.1356114-3-irogers@google.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent c7a0023a

tools/perf/util/srcline.c

+53 −8
Original line number Diff line number Diff line
@@ -408,7 +408,7 @@ static struct child_process *addr2line_subprocess_init(const char *addr2line_pat 
	const char *argv[] = {

		addr2line_path ?: "addr2line",

		"-e", binary_path,

		"-i", "-f", NULL

		"-a", "-i", "-f", NULL

	};

	struct child_process *a2l = zalloc(sizeof(*a2l));

	int start_command_status = 0;
@@ -463,10 +463,10 @@ static enum a2l_style addr2line_configure(struct child_process *a2l, const char 
			style = LLVM;

			cached = true;

			lines = 1;

		} else if (ch == '?') {

		} else if (ch == '0') {

			style = GNU_BINUTILS;

			cached = true;

			lines = 2;

			lines = 3;

		} else {

			if (!symbol_conf.disable_add2line_warn) {

				char *output = NULL;
@@ -518,13 +518,56 @@ static int read_addr2line_record(struct io *io, 
	if (line_nr != NULL)

		*line_nr = 0;



	/*

	 * Read the first line. Without an error this will be either an address

	 * like 0x1234 or for llvm-addr2line the sentinal ',' character.

	 */

	if (io__getline(io, &line, &line_len) < 0 || !line_len)

		goto error;



	if (style == LLVM && line_len == 2 && line[0] == ',') {

	if (style == LLVM) {

		if (line_len == 2 && line[0] == ',') {

			zfree(&line);

			return 0;

		}

	} else {

		int zero_count = 0, non_zero_count = 0;



		/* The address should always start 0x. */

		if (line_len < 2 || line[0] != '0' || line[1] != 'x')

			goto error;



		for (size_t i = 2; i < line_len; i++) {

			if (line[i] == '0')

				zero_count++;

			else if (line[i] != '\n')

				non_zero_count++;

		}

		if (!non_zero_count) {

			int ch;



			if (!zero_count) {

				/* Line was erroneous just '0x'. */

				goto error;

			}

			/*

			 * Line was 0x0..0, the sentinel for binutils. Remove

			 * the function and filename lines.

			 */

			zfree(&line);

			do {

				ch = io__get_char(io);

			} while (ch > 0 && ch != '\n');

			do {

				ch = io__get_char(io);

			} while (ch > 0 && ch != '\n');

			return 0;

		}

	}



	/* Read the second function name line. */

	if (io__getline(io, &line, &line_len) < 0 || !line_len)

		goto error;



	if (function != NULL)

		*function = strdup(strim(line));
@@ -532,6 +575,7 @@ static int read_addr2line_record(struct io *io, 
	zfree(&line);

	line_len = 0;



	/* Read the third filename and line number line. */

	if (io__getline(io, &line, &line_len) < 0 || !line_len)

		goto error;
@@ -635,8 +679,9 @@ static int addr2line(const char *dso_name, u64 addr, 
		goto out;

	case 0:

		/*

		 * The first record was invalid, so return failure, but first read another

		 * record, since we asked a junk question and have to clear the answer out.

		 * The first record was invalid, so return failure, but first

		 * read another record, since we sent a sentinel ',' for the

		 * sake of detected the last inlined function.

		 */

		switch (read_addr2line_record(&io, a2l_style, NULL, NULL, NULL)) {

		case -1: