From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: Nathan Chancellor <nathan@kernel.org>
Cc: "Christophe Leroy (CS GROUP)" <chleroy@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@kernel.org>, Theodore Ts'o <tytso@mit.edu>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Bill Wendling <morbo@google.com>,
Justin Stitt <justinstitt@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Huacai Chen <chenhuacai@kernel.org>,
WANG Xuerui <kernel@xen0n.name>,
Madhavan Srinivasan <maddy@linux.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Nicholas Piggin <npiggin@gmail.com>,
Paul Walmsley <pjw@kernel.org>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Alexandre Ghiti <alex@ghiti.fr>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, loongarch@lists.linux.dev,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-s390@vger.kernel.org, llvm@lists.linux.dev
Subject: Re: [PATCH v2] random: vDSO: Avoid call to memset() when zeroing reserved in __cvdso_getrandom_data()
Date: Thu, 1 Oct 2026 12:48:10 +0200 [thread overview]
Message-ID: <ar46ap4jzLWyP92C@zx2c4.com> (raw)
In-Reply-To: <20261001102059.GA4176271@ax162>
On Thu, Oct 01, 2026 at 12:20:59PM +0200, Nathan Chancellor wrote:
> control. The change that introduced -max-store-memset only did it to
> "allow fine-tuning of the inlining threshold for performance analysis
> and optimization". If they decide to remove it for whatever reason,
> we're back to square one.
I suppose all the more reason to get -finline-stringops=memset added to
clang. Then the dual-default thing you came up with below will naturally
start choosing the first option when it becomes available.
> I know something like below would be uglier due to the ifdef but it
> would avoid changing anything for GCC while clearing up the issue at
> hand for clang in a guaranteed stable and succinct manner.
But then we're back to the byte-by-byte codegen that Christophe pointed
out.
> If that is not acceptable, something like the following does appear to
> work for me.
Okay, great, let's do that.
Does this commit seem okay with you? I used the diff you sent below and
adjusted the commit message: https://git.zx2c4.com/linux-rng/commit/?id=56ff95ee85715047eb5b5220243778af657778c8
Jason
next prev parent reply other threads:[~2026-10-01 10:48 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-25 21:46 Nathan Chancellor
2026-09-25 21:53 ` Nick Desaulniers
2026-09-25 21:56 ` Nick Desaulniers
2026-09-25 22:00 ` Nick Desaulniers
2026-09-25 22:19 ` Nathan Chancellor
2026-09-26 6:34 ` Christophe Leroy (CS GROUP)
2026-09-26 10:02 ` Jason A. Donenfeld
2026-09-26 10:55 ` Christophe Leroy (CS GROUP)
2026-09-26 12:29 ` Jason A. Donenfeld
2026-09-29 18:24 ` Nick Desaulniers
2026-09-30 13:38 ` Nathan Chancellor
2026-09-30 14:21 ` Jason A. Donenfeld
2026-09-30 14:44 ` Jason A. Donenfeld
2026-09-30 15:13 ` Nathan Chancellor
2026-09-30 15:16 ` Jason A. Donenfeld
2026-10-01 4:41 ` Christophe Leroy (CS GROUP)
2026-10-01 9:25 ` Jason A. Donenfeld
2026-10-01 10:20 ` Nathan Chancellor
2026-10-01 10:48 ` Jason A. Donenfeld [this message]
2026-10-01 11:03 ` Nathan Chancellor
2026-09-26 12:39 ` Nathan Chancellor
2026-09-26 9:39 ` Andreas Schwab
2026-09-26 12:19 ` Nathan Chancellor
2026-09-26 12:32 ` Jason A. Donenfeld
2026-09-26 12:49 ` Nathan Chancellor
2026-09-27 7:02 ` David Laight
2026-09-29 16:59 ` Nathan Chancellor
2026-09-29 17:44 ` David Laight
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