linux-kernel - Re: [PATCH v2 00/11] unwind, perf: sframe user space unwinding, deferred perf callchains

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Message-ID: <20241003023702.4bam6cj5opcz24em@treble>
Date: Wed, 2 Oct 2024 19:37:02 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Peter Zijlstra <peterz@...radead.org>, x86@...nel.org,
	Ingo Molnar <mingo@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	linux-kernel@...r.kernel.org, Indu Bhagat <indu.bhagat@...cle.com>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	linux-perf-users@...r.kernel.org, Mark Brown <broonie@...nel.org>,
	linux-toolchains@...r.kernel.org, Jordan Rome <jordalgo@...a.com>,
	Sam James <sam@...too.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Subject: Re: [PATCH v2 00/11] unwind, perf: sframe user space unwinding,
 deferred perf callchains

On Wed, Oct 02, 2024 at 10:31:25PM -0400, Steven Rostedt wrote:
> +++ b/kernel/unwind/user.c
> @@ -177,7 +181,8 @@ int unwind_user_deferred(struct unwind_callback *callback, u64 *ctx_cookie)
>  
>  		cookie = __this_cpu_read(ctx_ctr);
>  		cookie &= ((1UL << 48) - 1);
> -		cookie |= ((cpu << 48) + 1);
> +		cookie |= cpu << 48;
> +		cookie++;
>  		__this_cpu_write(ctx_ctr, cookie);
>  
>  		current->unwind_ctx_cookie = cookie;
> 
> As the cookie never got incremented.

Ha, that might help ;-)

> That was just one issue. Things are still not working but I'll debug the
> rest later.

If you don't want to run on the bleeding edge, I'll be testing it soon
myself once I get the coding done for my v3.

-- 
Josh