From: Segher Boessenkool <segher@kernel.crashing.org>
To: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Kees Cook <kees@kernel.org>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org, linux-alpha@vger.kernel.org,
linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org,
linux-m68k@vger.kernel.org, linux-mips@vger.kernel.org,
linux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
sparclinux@vger.kernel.org, llvm@lists.linux.dev,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH 05/17] powerpc: Add __attribute_const__ to ffs()-family implementations
Date: Fri, 15 Aug 2025 11:34:56 -0500 [thread overview]
Message-ID: <aJ9hsHj9lsHvvhcA@gate> (raw)
In-Reply-To: <7f4f4d07-38f7-444c-adff-ec2a2387e86b@linux.ibm.com>
Hi!
On Thu, Aug 07, 2025 at 03:16:35PM +0530, Madhavan Srinivasan wrote:
> making them eligible for compiler optimization.
You can instead use GCC for this. __builtin_ffs () exists since 2003,
and has this attribute built-in, as well as tens of other optimisations
that the kernel thing misses.
Of course using existing stuff instead of cobbling together something
half working prevents you from having a lot of fun ;-)
Segher
WARNING: multiple messages have this Message-ID (diff)
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Kees Cook <kees@kernel.org>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org, linux-alpha@vger.kernel.org,
linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org,
linux-m68k@vger.kernel.org, linux-mips@vger.kernel.org,
linux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
sparclinux@vger.kernel.org, llvm@lists.linux.dev,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH 05/17] powerpc: Add __attribute_const__ to ffs()-family implementations
Date: Fri, 15 Aug 2025 11:34:56 -0500 [thread overview]
Message-ID: <aJ9hsHj9lsHvvhcA@gate> (raw)
In-Reply-To: <7f4f4d07-38f7-444c-adff-ec2a2387e86b@linux.ibm.com>
Hi!
On Thu, Aug 07, 2025 at 03:16:35PM +0530, Madhavan Srinivasan wrote:
> making them eligible for compiler optimization.
You can instead use GCC for this. __builtin_ffs () exists since 2003,
and has this attribute built-in, as well as tens of other optimisations
that the kernel thing misses.
Of course using existing stuff instead of cobbling together something
half working prevents you from having a lot of fun ;-)
Segher
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linux-riscv@lists.infradead.org
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next prev parent reply other threads:[~2025-08-15 16:40 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-04 16:43 [PATCH 00/17] Add __attribute_const__ to ffs()-family implementations Kees Cook
2025-08-04 16:43 ` Kees Cook
2025-08-04 16:43 ` [PATCH 01/17] KUnit: Introduce ffs()-family tests Kees Cook
2025-08-04 16:43 ` Kees Cook
2025-08-04 16:43 ` [PATCH 02/17] bitops: Add __attribute_const__ to generic ffs()-family implementations Kees Cook
2025-08-04 16:43 ` Kees Cook
2025-08-04 16:43 ` [PATCH 03/17] csky: Add __attribute_const__ to " Kees Cook
2025-08-04 16:43 ` Kees Cook
2025-10-19 6:50 ` Guo Ren
2025-10-19 6:50 ` Guo Ren
2025-08-04 16:44 ` [PATCH 04/17] x86: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-04 16:44 ` [PATCH 05/17] powerpc: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-07 9:46 ` Madhavan Srinivasan
2025-08-07 9:46 ` Madhavan Srinivasan
2025-08-15 16:34 ` Segher Boessenkool [this message]
2025-08-15 16:34 ` Segher Boessenkool
2025-08-15 16:41 ` Segher Boessenkool
2025-08-15 16:41 ` Segher Boessenkool
2025-08-04 16:44 ` [PATCH 06/17] sh: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-04 16:44 ` [PATCH 07/17] alpha: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-04 16:44 ` [PATCH 08/17] hexagon: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-04 16:44 ` [PATCH 09/17] riscv: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-07 14:43 ` Alexandre Ghiti
2025-08-07 14:43 ` Alexandre Ghiti
2025-08-04 16:44 ` [PATCH 10/17] openrisc: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-04 17:15 ` Stafford Horne
2025-08-04 17:15 ` Stafford Horne
2025-08-04 16:44 ` [PATCH 11/17] m68k: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-05 8:12 ` Geert Uytterhoeven
2025-08-05 8:12 ` Geert Uytterhoeven
2025-08-04 16:44 ` [PATCH 12/17] mips: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-04 16:44 ` [PATCH 13/17] parisc: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-08 9:01 ` Helge Deller
2025-08-04 16:44 ` [PATCH 14/17] s390: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-06 10:33 ` Heiko Carstens
2025-08-06 10:33 ` Heiko Carstens
2025-08-04 16:44 ` [PATCH 15/17] xtensa: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-04 16:44 ` [PATCH 16/17] sparc: " Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-04 16:44 ` [PATCH 17/17] KUnit: ffs: Validate all the __attribute_const__ annotations Kees Cook
2025-08-04 16:44 ` Kees Cook
2025-08-15 14:16 ` [PATCH 00/17] Add __attribute_const__ to ffs()-family implementations Peter Zijlstra
2025-08-15 14:16 ` Peter Zijlstra
2025-10-09 1:07 ` patchwork-bot+linux-riscv
2025-10-09 1:07 ` patchwork-bot+linux-riscv
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