From: Ard Biesheuvel <ardb@kernel.org> To: linux-crypto@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, will@kernel.org, mark.rutland@arm.com, catalin.marinas@arm.com, herbert@gondor.apana.org.au, Ard Biesheuvel <ardb@kernel.org>, Dave Martin <dave.martin@arm.com>, Eric Biggers <ebiggers@google.com> Subject: [PATCH v2 1/9] arm64: assembler: add cond_yield macro Date: Wed, 3 Feb 2021 12:36:18 +0100 [thread overview] Message-ID: <20210203113626.220151-2-ardb@kernel.org> (raw) In-Reply-To: <20210203113626.220151-1-ardb@kernel.org> Add a macro cond_yield that branches to a specified label when called if the TIF_NEED_RESCHED flag is set and decreasing the preempt count would make the task preemptible again, resulting in a schedule to occur. This can be used by kernel mode SIMD code that keeps a lot of state in SIMD registers, which would make chunking the input in order to perform the cond_resched() check from C code disproportionately costly. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- arch/arm64/include/asm/assembler.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index bf125c591116..27b1ea721c2d 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -745,6 +745,22 @@ USER(\label, ic ivau, \tmp2) // invalidate I line PoU .Lyield_out_\@ : .endm + /* + * Check whether preempt-disabled code should yield as soon as it + * is able. This is the case if re-enabling preemption a single + * time results in a preempt count of zero, and the TIF_NEED_RESCHED + * flag is set. (Note that the latter is stored negated in the + * top word of the thread_info::preempt_count field) + */ + .macro cond_yield, lbl:req, tmp:req +#ifdef CONFIG_PREEMPTION + get_current_task \tmp + ldr \tmp, [\tmp, #TSK_TI_PREEMPT] + sub \tmp, \tmp, #PREEMPT_DISABLE_OFFSET + cbz \tmp, \lbl +#endif + .endm + /* * This macro emits a program property note section identifying * architecture features which require special handling, mainly for -- 2.30.0
WARNING: multiple messages have this Message-ID (diff)
From: Ard Biesheuvel <ardb@kernel.org> To: linux-crypto@vger.kernel.org Cc: mark.rutland@arm.com, herbert@gondor.apana.org.au, Eric Biggers <ebiggers@google.com>, catalin.marinas@arm.com, Dave Martin <dave.martin@arm.com>, will@kernel.org, Ard Biesheuvel <ardb@kernel.org>, linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 1/9] arm64: assembler: add cond_yield macro Date: Wed, 3 Feb 2021 12:36:18 +0100 [thread overview] Message-ID: <20210203113626.220151-2-ardb@kernel.org> (raw) In-Reply-To: <20210203113626.220151-1-ardb@kernel.org> Add a macro cond_yield that branches to a specified label when called if the TIF_NEED_RESCHED flag is set and decreasing the preempt count would make the task preemptible again, resulting in a schedule to occur. This can be used by kernel mode SIMD code that keeps a lot of state in SIMD registers, which would make chunking the input in order to perform the cond_resched() check from C code disproportionately costly. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- arch/arm64/include/asm/assembler.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index bf125c591116..27b1ea721c2d 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -745,6 +745,22 @@ USER(\label, ic ivau, \tmp2) // invalidate I line PoU .Lyield_out_\@ : .endm + /* + * Check whether preempt-disabled code should yield as soon as it + * is able. This is the case if re-enabling preemption a single + * time results in a preempt count of zero, and the TIF_NEED_RESCHED + * flag is set. (Note that the latter is stored negated in the + * top word of the thread_info::preempt_count field) + */ + .macro cond_yield, lbl:req, tmp:req +#ifdef CONFIG_PREEMPTION + get_current_task \tmp + ldr \tmp, [\tmp, #TSK_TI_PREEMPT] + sub \tmp, \tmp, #PREEMPT_DISABLE_OFFSET + cbz \tmp, \lbl +#endif + .endm + /* * This macro emits a program property note section identifying * architecture features which require special handling, mainly for -- 2.30.0 _______________________________________________ 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:[~2021-02-03 11:37 UTC|newest] Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-02-03 11:36 [PATCH v2 0/9] arm64: rework NEON yielding to avoid scheduling from asm code Ard Biesheuvel 2021-02-03 11:36 ` Ard Biesheuvel 2021-02-03 11:36 ` Ard Biesheuvel [this message] 2021-02-03 11:36 ` [PATCH v2 1/9] arm64: assembler: add cond_yield macro Ard Biesheuvel 2021-02-03 11:36 ` [PATCH v2 2/9] crypto: arm64/sha1-ce - simplify NEON yield Ard Biesheuvel 2021-02-03 11:36 ` Ard Biesheuvel 2021-02-03 11:36 ` [PATCH v2 3/9] crypto: arm64/sha2-ce " Ard Biesheuvel 2021-02-03 11:36 ` Ard Biesheuvel 2021-02-03 11:36 ` [PATCH v2 4/9] crypto: arm64/sha3-ce " Ard Biesheuvel 2021-02-03 11:36 ` Ard Biesheuvel 2021-02-03 11:36 ` [PATCH v2 5/9] crypto: arm64/sha512-ce " Ard Biesheuvel 2021-02-03 11:36 ` Ard Biesheuvel 2021-02-03 11:36 ` [PATCH v2 6/9] crypto: arm64/aes-neonbs - remove NEON yield calls Ard Biesheuvel 2021-02-03 11:36 ` Ard Biesheuvel 2021-02-03 11:36 ` [PATCH v2 7/9] crypto: arm64/aes-ce-mac - simplify NEON yield Ard Biesheuvel 2021-02-03 11:36 ` Ard Biesheuvel 2021-02-03 11:36 ` [PATCH v2 8/9] crypto: arm64/crc-t10dif - move NEON yield to C code Ard Biesheuvel 2021-02-03 11:36 ` Ard Biesheuvel 2021-02-03 11:36 ` [PATCH v2 9/9] arm64: assembler: remove conditional NEON yield macros Ard Biesheuvel 2021-02-03 11:36 ` Ard Biesheuvel 2021-02-03 21:31 ` (subset) Re: [PATCH v2 0/9] arm64: rework NEON yielding to avoid scheduling from asm code Will Deacon 2021-02-03 21:31 ` Will Deacon 2021-02-04 2:44 ` Herbert Xu 2021-02-04 2:44 ` Herbert Xu 2021-02-04 8:29 ` Ard Biesheuvel 2021-02-04 8:29 ` Ard Biesheuvel 2021-02-04 11:10 ` Herbert Xu 2021-02-04 11:10 ` Herbert Xu 2021-02-04 13:03 ` Will Deacon 2021-02-04 13:03 ` Will Deacon 2021-02-04 19:45 ` Herbert Xu 2021-02-04 19:45 ` Herbert Xu 2021-02-04 10:33 ` Will Deacon 2021-02-04 10:33 ` Will Deacon 2021-02-10 7:23 ` Herbert Xu 2021-02-10 7:23 ` Herbert Xu
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=20210203113626.220151-2-ardb@kernel.org \ --to=ardb@kernel.org \ --cc=catalin.marinas@arm.com \ --cc=dave.martin@arm.com \ --cc=ebiggers@google.com \ --cc=herbert@gondor.apana.org.au \ --cc=linux-arm-kernel@lists.infradead.org \ --cc=linux-crypto@vger.kernel.org \ --cc=mark.rutland@arm.com \ --cc=will@kernel.org \ /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: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.