linux-kernel - Re: [PATCH 1/2] perf annotate: Fallback to objdump when capstone fails

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Date: Thu, 25 Apr 2024 11:02:06 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Ian Rogers <irogers@...gle.com>, Kan Liang <kan.liang@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org
Subject: Re: [PATCH 1/2] perf annotate: Fallback to objdump when capstone
 fails

On Wed, Apr 24, 2024 at 05:51:56PM -0700, Namhyung Kim wrote:
> I found some cases that capstone failed to disassemble.  Probably my
> capstone is an old version but anyway there's a chance it can fail.  And
> then it silently stopped in the middle.  In my case, it didn't
> understand "RDPKRU" instruction.
> 
> Let's check if the capstone disassemble reached to the end of the
> function.  And fallback to objdump if not.

Thanks, applied to perf-tools-next,

- Arnaldo
 
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  tools/perf/util/disasm.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
> index 92937809be85..412101f2cf2a 100644
> --- a/tools/perf/util/disasm.c
> +++ b/tools/perf/util/disasm.c
> @@ -1542,6 +1542,20 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
>  		offset += insn[i].size;
>  	}
>  
> +	/* It failed in the middle: probably due to unknown instructions */
> +	if (offset != len) {
> +		struct list_head *list = &notes->src->source;
> +
> +		/* Discard all lines and fallback to objdump */
> +		while (!list_empty(list)) {
> +			dl = list_first_entry(list, struct disasm_line, al.node);
> +
> +			list_del_init(&dl->al.node);
> +			disasm_line__free(dl);
> +		}
> +		count = -1;
> +	}
> +
>  out:
>  	if (needs_cs_close)
>  		cs_close(&handle);
> -- 
> 2.44.0.769.g3c40516874-goog