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Date: Mon, 12 Jun 2023 16:11:19 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Changbin Du <changbin.du@...wei.com>,
Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Nathan Chancellor <nathan@...nel.org>,
Nick Desaulniers <ndesaulniers@...gle.com>,
Tom Rix <trix@...hat.com>, linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
Changbin Du <changbin.du@...wei.com>
Subject: Re: [PATCH v1 2/2] perf srcline: Make sentinel reading for binutils
addr2line more robust
Em Fri, Jun 09, 2023 at 04:54:19PM -0700, Ian Rogers escreveu:
> 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: Changbin Du <changbin.du@...wei.com>
Changbin,
Did this fix the problem you reported? If so can I have your
Tested-by?
Thanks,
- Arnaldo
> Signed-off-by: Ian Rogers <irogers@...gle.com>
> ---
> tools/perf/util/srcline.c | 61 ++++++++++++++++++++++++++++++++++-----
> 1 file changed, 53 insertions(+), 8 deletions(-)
>
> diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
> index fc85cdd6c8f9..c99a001453b4 100644
> --- a/tools/perf/util/srcline.c
> +++ b/tools/perf/util/srcline.c
> @@ -406,7 +406,7 @@ 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;
> @@ -461,10 +461,10 @@ 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;
> @@ -516,20 +516,64 @@ 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] == ',') {
> - zfree(&line);
> - return 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
> + 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));
>
> 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;
>
> @@ -633,8 +677,9 @@ 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:
> --
> 2.41.0.162.gfafddb0af9-goog
>
--
- Arnaldo
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