From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Tri Vo <trong@android.com>
Cc: irogers@google.com, Nick Desaulniers <ndesaulniers@google.com>,
stefan@agner.ch, Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: CONFIG_FRAME_POINTER support for Clang
Date: Fri, 31 May 2019 00:13:46 +0100 [thread overview]
Message-ID: <20190530231346.ede52pjznj3pgfll@shell.armlinux.org.uk> (raw)
In-Reply-To: <CANA+-vBHL9a9fXDWxALXXuJk6r8ObZZjhrGp-p5JUnfOThEV5g@mail.gmail.com>
On Thu, May 30, 2019 at 03:56:06PM -0700, Tri Vo wrote:
> Hello Russell,
>
> I'm trying to implement support for CONFIG_FRAME_POINTER when building Linux
> with Clang compiler.
>
> Currently, CONFIG_FRAME_POINTER relies on function prologue that is emitted by
> GCC using -mapcs flag. However, APCS is obsolete and Clang doesn't support it.
>
> So in order to accommodate Clang-emitted frame layout, I'm thinking of
> providing Clang-specific implementation of code that relies on frame pointer,
> most notably in these files:
> lib/backtrace.S
> arch/arm/kernel/stacktrace.c
> arch/arm/net/bpf_jit_32.c
What format stack frames does Clang use? I don't use clang, never seen
any clang ARM assembly, so I've no idea on this.
> This will likely involve putting "#ifdef CC_IS_CLANG" statements in the source
> code. Is that OK?
>
> Another caveat is that Clang implementation of backtracing won't be able to
> dump saved registers or dump precise pc value of the caller, because IIUC that
> information is derived from APCS's fixed prologue.
>
> What do you think about this approach?
>
> Thanks,
> Tri
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-05-30 23:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-30 22:56 CONFIG_FRAME_POINTER support for Clang Tri Vo
2019-05-30 22:58 ` Nick Desaulniers
2019-05-30 23:12 ` Ian Rogers
2019-05-30 23:14 ` Russell King - ARM Linux admin
2019-05-30 23:13 ` Russell King - ARM Linux admin [this message]
2019-05-31 0:03 ` Tri Vo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190530231346.ede52pjznj3pgfll@shell.armlinux.org.uk \
--to=linux@armlinux.org.uk \
--cc=irogers@google.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=ndesaulniers@google.com \
--cc=stefan@agner.ch \
--cc=trong@android.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox