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SubjectRe: [PATCH] Subject: perf jit: Fix incorrect file name in DWARF line table
On Wed, May 31, 2023 at 7:35 AM elisabeth <paniii94@gmail.com> wrote:
>
> Fix an issue where an incorrect file name was added in the DWARF line table
> due to not checking the filename against the repeated name marker (/xff/0).
> This can be seen with `objdump --dwarf=line` on the ELF file after perf inject.
>
> Signed-off-by: elisabeth <paniii94@gmail.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Namhyung Kim <namhyung@kernel.org>
> ---
> tools/perf/util/genelf_debug.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/genelf_debug.c b/tools/perf/util/genelf_debug.c
> index aa5dcc56b2ac..2928b59bb9a5 100644
> --- a/tools/perf/util/genelf_debug.c
> +++ b/tools/perf/util/genelf_debug.c
> @@ -349,6 +349,7 @@ static void emit_lineno_info(struct buffer_ext *be,
> */
>
> /* start state of the state machine we take care of */
> + char const repeated_name_marker[] = {'\xff', '\0'};

Can you please mention that it's from the jitdump format
either by renaming or adding a comment?


> unsigned long last_vma = 0;
> char const *cur_filename = NULL;
> unsigned long cur_file_idx = 0;
> @@ -363,7 +364,8 @@ static void emit_lineno_info(struct buffer_ext *be,
> /*
> * check if filename changed, if so add it
> */
> - if (!cur_filename || strcmp(cur_filename, ent->name)) {
> + if ((!cur_filename || strcmp(cur_filename, ent->name)) &&
> + memcmp(repeated_name_marker, ent->name, sizeof(repeated_name_marker)) != 0) {

I think you can just use strcmp().

Thanks,
Namhyung


> emit_lne_define_filename(be, ent->name);
> cur_filename = ent->name;
> emit_set_file(be, ++cur_file_idx);
> --
> 2.34.1
>

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