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perf srcline: Make sentinel reading for binutils addr2line more robust

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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@huawei.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Changbin 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: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ian Rogers 2023-06-12 20:48:17 -07:00 committed by Arnaldo Carvalho de Melo
parent c7a0023a14
commit 8dc26b6f71
1 changed files with 53 additions and 8 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

61
tools/perf/util/srcline.c
View file

@ -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;
@ -518,20 +518,64 @@ 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 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));
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: