linux-kernel - Re: [PATCH 1/5] ARC: uapi: Stop leaking CONFIG_ARC_HAS

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: <9ecebf46-c230-4074-9001-7ba9d65634f1@app.fastmail.com>
Date: Tue, 30 Dec 2025 22:23:08 +0100
From: "Arnd Bergmann" <arnd@...db.de>
To: Thomas Weißschuh <thomas.weissschuh@...utronix.de>,
 "Vineet Gupta" <vgupta@...nel.org>, "Russell King" <linux@...linux.org.uk>,
 "Dinh Nguyen" <dinguyen@...nel.org>, "Thomas Gleixner" <tglx@...utronix.de>,
 "Ingo Molnar" <mingo@...hat.com>, "Borislav Petkov" <bp@...en8.de>,
 "Dave Hansen" <dave.hansen@...ux.intel.com>, x86@...nel.org,
 "H. Peter Anvin" <hpa@...or.com>
Cc: linux-snps-arc@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/5] ARC: uapi: Stop leaking CONFIG_ARC_HAS_SWAPE reference to
 userspace

On Tue, Dec 30, 2025, at 08:10, Thomas Weißschuh wrote:
> UAPI headers are not supposed to leak references to kconfig symbols.
> These won't be set when building userspace. Hide the kconfig reference
> behind 'if defined(__KERNEL__)', so it will be stripped by
> headers_install.sh. The result for userspace will be the same, but the
> exception in headers_install.sh can also be removed.
>
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>

Acked-by: Arnd Bergmann <arnd@...db.de>

Same as for the nios2 version, I think the nicer solution would
be to use the asm-generic header for uapi and move this one
to arch/arc/include/asm/swab.h for kernel-internal use.

In theory, using 'select ARCH_USE_BUILTIN_BSWAP' in Kconfig should
let the compiler pick the best swap instruction, which would
be even less code, but I'm not sure if there was a reason that
nios2 and arc don't already do this.

      Arnd