linux-kernel - Re: [PATCH 6/8] ARM: clang: Do not relay on lr register for stacktrace

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Message-ID: <YWhghNxpJD51ZDgD@shell.armlinux.org.uk>
Date:   Thu, 14 Oct 2021 17:53:24 +0100
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        "Naveen N . Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Ananth N Mavinakayanahalli <ananth@...ux.ibm.com>,
        Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
        Sven Schnelle <svens@...ux.ibm.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 6/8] ARM: clang: Do not relay on lr register for
 stacktrace

On Fri, Oct 08, 2021 at 09:29:08PM +0900, Masami Hiramatsu wrote:
> Currently the stacktrace on clang compiled arm kernel uses the 'lr'
> register to find the first frame address from pt_regs. However, that
> is wrong after calling another function, because the 'lr' register
> is used by 'bl' instruction and never be recovered.
> 
> As same as gcc arm kernel, directly use the frame pointer (x11) of
> the pt_regs to find the first frame address.

Can I ask that the subject line is corrected. It's "rely" not "relay".

Also, the frame pointer is called "r11" not "x11" if you want to use
the numerical register reference for 32-bit ARM registers.

Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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