Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 5 Apr 2023 16:40:24 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Florent Revest <revest@chromium.org>
Cc:     linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org,
        catalin.marinas@arm.com, will@kernel.org, mhiramat@kernel.org,
        mark.rutland@arm.com, ast@kernel.org, daniel@iogearbox.net,
        andrii@kernel.org, kpsingh@kernel.org, jolsa@kernel.org,
        xukuohai@huaweicloud.com, lihuafei1@huawei.com
Subject: Re: [PATCH v6 3/5] samples: ftrace: Save required argument
 registers in sample trampolines
Message-ID: <20230405164024.5f5c3b6b@gandalf.local.home>
In-Reply-To: <20230405180250.2046566-4-revest@chromium.org>
References: <20230405180250.2046566-1-revest@chromium.org>
        <20230405180250.2046566-4-revest@chromium.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Wed,  5 Apr 2023 20:02:48 +0200
Florent Revest <revest@chromium.org> wrote:

> The ftrace-direct-too sample traces the handle_mm_fault function whose
> signature changed since the introduction of the sample. Since:
> commit bce617edecad ("mm: do page fault accounting in handle_mm_fault")
> handle_mm_fault now has 4 arguments. Therefore, the sample trampoline
> should save 4 argument registers.
> 
> s390 saves all argument registers already so it does not need a change
> but x86_64 needs an extra push and pop.
> 
> This also evolves the signature of the tracing function to make it
> mirror the signature of the traced function.
>

Should probably add:

Cc: stable@vger.kernel.org
Fixes: bce617edecad ("mm: do page fault accounting in handle_mm_fault")

Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>

-- Steve