linux-kernel - Re: [PATCH RESEND] powerpc/tools: drop `-o pipefail` in gcc check scripts

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <caut6db7r6loimb2bk4zoqkqmfd3mhvzmv6ntsltf3tr4k4c2n@fbyhls233oys>
Date: Wed, 3 Dec 2025 09:29:25 +0530
From: Naveen N Rao <naveen@...nel.org>
To: Jan Stancek <jstancek@...hat.com>, 
	Michael Ellerman <mpe@...erman.id.au>, Madhavan Srinivasan <maddy@...ux.ibm.com>
Cc: linuxppc-dev@...ts.ozlabs.org, npiggin@...il.com, 
	christophe.leroy@...roup.eu, linux-kernel@...r.kernel.org, joe.lawrence@...hat.com
Subject: Re: [PATCH RESEND] powerpc/tools: drop `-o pipefail` in gcc check
 scripts

On Tue, Sep 23, 2025 at 05:32:16PM +0200, Jan Stancek wrote:
> We've been observing rare non-deterministic kconfig failures during
> olddefconfig, where ARCH_USING_PATCHABLE_FUNCTION_ENTRY was getting
> disabled and with it number of other config options that depend on it.
> 
> The reason is that gcc-check-fpatchable-function-entry.sh can fail
> if `grep -q` (or scripts/dummy-tools/gcc) is fast enough to exit while
> there is still someone writing on other side of pipe. `pipefail`
> propagates that error up to kconfig.
> 
> This can be seen for example with:
>   # (set -e; set -o pipefail; yes | grep -q y); echo $?
>   141
> 
> or by running the actual check script in loop extensively:
>   ----------------------------- 8< -------------------------------
>   function kconfig()
>   {
>     for i in `seq 1 100`; do
>       arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh \
>         ./scripts/dummy-tools/gcc -mlittle-endian \
>         || { echo "Oops"; exit 1; }
>     done
>   }
> 
>   for ((i=0; i<$(nproc); i++)); do kconfig & done
>   wait; echo "Done"
>   ----------------------------- >8 -------------------------------
> 
> Fixes: 0f71dcfb4aef ("powerpc/ftrace: Add support for -fpatchable-function-entry")
> Fixes: b71c9ffb1405 ("powerpc: Add arch/powerpc/tools directory")

The latter fixes tag should probably tag one of the below commits which 
actually introduced pipefail, or introduced it in Kconfig:
Fixes: 8c50b72a3b4f ("powerpc/ftrace: Add Kconfig & Make glue for mprofile-kernel")
  or:
Fixes: abba759796f9 ("powerpc/kbuild: move -mprofile-kernel check to Kconfig")

> Reported-by: Joe Lawrence <joe.lawrence@...hat.com>
> Acked-by: Joe Lawrence <joe.lawrence@...hat.com>
> Signed-off-by: Jan Stancek <jstancek@...hat.com>
> ---
>  arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh | 1 -
>  arch/powerpc/tools/gcc-check-mprofile-kernel.sh           | 1 -
>  2 files changed, 2 deletions(-)

Other than that, thanks for fixing this. This LGTM.
Reviewed-by: Naveen N Rao (AMD) <naveen@...nel.org>

Maddy/Michael,
Can you please pick this up?


Thanks,
Naveen