linux-kernel - Re: [PATCH] trace-cmd: Leave out absolute addresses to fix bogus symbol resolutions

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Date:	Tue, 15 Sep 2015 18:30:22 +0200
From:	Jan Kiszka <jan.kiszka@...mens.com>
To:	Steven Rostedt <rostedt@...dmis.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] trace-cmd: Leave out absolute addresses to fix bogus
 symbol resolutions

On 2015-07-31 16:04, Jan Kiszka wrote:
> On x86, page_fault_* tracepoints report userspace address via kernel
> symbols because all the per-cpu variable offsets are in kallsyms,
> occupying the lower address space. Fix this by skipping over absolute
> addresses while processing kallsyms.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
> ---
>  trace-util.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/trace-util.c b/trace-util.c
> index 8a81dd0..da20e4c 100644
> --- a/trace-util.c
> +++ b/trace-util.c
> @@ -434,8 +434,12 @@ void parse_proc_kallsyms(struct pevent *pevent,
>  		if (mod)
>  			mod[strlen(mod) - 1] = 0;
>  
> -		/* Hack for arm arch that adds a lot of bogus '$a' functions */
> -		if (func[0] != '$')
> +		/*
> +		 * Hacks for
> +		 *  - arm arch that adds a lot of bogus '$a' functions
> +		 *  - x86-64 that reports per-cpu variable offsets as absolute
> +		 */
> +		if (func[0] != '$' && ch != 'A')
>  			pevent_register_function(pevent, func, addr, mod);
>  		free(func);
>  		free(mod);
> 

Ping.

Jan

-- 
Siemens AG, Corporate Technology, CT RTC ITP SES-DE
Corporate Competence Center Embedded Linux
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