linux-kernel - Re: [PATCH V7 09/15] perf kcore_copy: Fix module map when there are no modules loaded

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Date:   Wed, 27 May 2020 12:44:30 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Leo Yan <leo.yan@...aro.org>, Jiri Olsa <jolsa@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V7 09/15] perf kcore_copy: Fix module map when there are
 no modules loaded

Em Tue, May 12, 2020 at 03:19:16PM +0300, Adrian Hunter escreveu:
> In the absence of any modules, no "modules" map is created, but there are
> other executable pages to map, due to eBPF JIT, kprobe or ftrace. Map them
> by recognizing that the first "module" symbol is not necessarily from a
> module, and adjust the map accordingly.

Applied,

- Arnaldo
 
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>  tools/perf/util/symbol-elf.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> index be5b493f8284..5e43054bffea 100644
> --- a/tools/perf/util/symbol-elf.c
> +++ b/tools/perf/util/symbol-elf.c
> @@ -1458,6 +1458,7 @@ struct kcore_copy_info {
>  	u64 first_symbol;
>  	u64 last_symbol;
>  	u64 first_module;
> +	u64 first_module_symbol;
>  	u64 last_module_symbol;
>  	size_t phnum;
>  	struct list_head phdrs;
> @@ -1534,6 +1535,8 @@ static int kcore_copy__process_kallsyms(void *arg, const char *name, char type,
>  		return 0;
>  
>  	if (strchr(name, '[')) {
> +		if (!kci->first_module_symbol || start < kci->first_module_symbol)
> +			kci->first_module_symbol = start;
>  		if (start > kci->last_module_symbol)
>  			kci->last_module_symbol = start;
>  		return 0;
> @@ -1731,6 +1734,10 @@ static int kcore_copy__calc_maps(struct kcore_copy_info *kci, const char *dir,
>  		kci->etext += page_size;
>  	}
>  
> +	if (kci->first_module_symbol &&
> +	    (!kci->first_module || kci->first_module_symbol < kci->first_module))
> +		kci->first_module = kci->first_module_symbol;
> +
>  	kci->first_module = round_down(kci->first_module, page_size);
>  
>  	if (kci->last_module_symbol) {
> -- 
> 2.17.1
> 

-- 

- Arnaldo