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;
MIME-Version: 1.0
References: <20220815110240.18293-1-chenzhongjin@huawei.com>
In-Reply-To: <20220815110240.18293-1-chenzhongjin@huawei.com>
From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Mon, 22 Aug 2022 13:20:32 +0200
Message-ID: <CACRpkdZsdggUptPkPhzzu8vv9moSO+rjvZxZRb1VqJ2xWjY=HQ@mail.gmail.com>
Subject: Re: [RESEND PATCH] ARM: Recover kretprobes return address for EABI
 stack unwinder
To:     Chen Zhongjin <chenzhongjin@huawei.com>
Cc:     linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-arch@vger.kernel.org, linux@armlinux.org.uk, arnd@arndb.de,
        ardb@kernel.org, rmk+kernel@armlinux.org.uk, rostedt@goodmis.org,
        nick.hawkins@hpe.com, john@phrozen.org, mhiramat@kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Mon, Aug 15, 2022 at 1:06 PM Chen Zhongjin <chenzhongjin@huawei.com> wrote:

> 'fed240d9c974 ("ARM: Recover kretprobe modified return address in stacktrace")'
> has implemented kretprobes return address recovery for FP
> unwinder, this patch makes it works for EABI unwinder.
>
> It saves __kretprobe_trampoline address in LR on stack to identify
> and recover the correct return address in EABI unwinder.
>
> Since EABI doesn't use r11 as frame pointer, we need to use SP to
> identify different kretprobes addresses. Here the value of SP has fixed
> distance to conventional FP position so it's fine to use it.
>
> Passed kunit kprobes_test on QEMU.
>
> Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>

This looks correct to me FWIW I understand the assembly
but I'm vaguely unfamiliar with the kprobe API, but anyway:
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Would you please drop it into Russell's patch tracker?

Yours,
Linus Walleij