From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, will@kernel.org, maz@kernel.org,
catalin.marinas@arm.com, ard.biesheuvel@linaro.org,
mark.rutland@arm.com, Suzuki K Poulose <suzuki.poulose@arm.com>
Subject: [PATCH v3 2/7] arm64: fpsimd: Make sure SVE setup is complete before SIMD is used
Date: Mon, 13 Jan 2020 23:30:18 +0000 [thread overview]
Message-ID: <20200113233023.928028-3-suzuki.poulose@arm.com> (raw)
In-Reply-To: <20200113233023.928028-1-suzuki.poulose@arm.com>
In-kernel users of NEON rely on may_use_simd() to check if the SIMD
can be used. However, we must initialize the SVE before SIMD can
be used. Add a sanity check to make sure that we have completed the
SVE setup before anyone uses the SIMD.
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
Changes since v2:
- Add WARN_ON() in may_use_simd() if invoked before caps
are finalized()
---
arch/arm64/include/asm/simd.h | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/simd.h b/arch/arm64/include/asm/simd.h
index 7434844036d3..89cba2622b79 100644
--- a/arch/arm64/include/asm/simd.h
+++ b/arch/arm64/include/asm/simd.h
@@ -26,6 +26,8 @@ DECLARE_PER_CPU(bool, fpsimd_context_busy);
static __must_check inline bool may_use_simd(void)
{
/*
+ * We must make sure that the SVE has been initialized properly
+ * before using the SIMD in kernel.
* fpsimd_context_busy is only set while preemption is disabled,
* and is clear whenever preemption is enabled. Since
* this_cpu_read() is atomic w.r.t. preemption, fpsimd_context_busy
@@ -33,8 +35,10 @@ static __must_check inline bool may_use_simd(void)
* migrated, and if it's clear we cannot be migrated to a CPU
* where it is set.
*/
- return !in_irq() && !irqs_disabled() && !in_nmi() &&
- !this_cpu_read(fpsimd_context_busy);
+ return !WARN_ON(!system_capabilities_finalized()) &&
+ system_supports_fpsimd() &&
+ !in_irq() && !irqs_disabled() && !in_nmi() &&
+ !this_cpu_read(fpsimd_context_busy);
}
#else /* ! CONFIG_KERNEL_MODE_NEON */
--
2.24.1
next prev parent reply other threads:[~2020-01-13 23:31 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-13 23:30 [PATCH v3 0/7] arm64: Fix support for no FP/SIMD Suzuki K Poulose
2020-01-13 23:30 ` [PATCH v3 1/7] arm64: Introduce system_capabilities_finalized() marker Suzuki K Poulose
2020-01-13 23:30 ` Suzuki K Poulose [this message]
2020-01-14 11:56 ` [PATCH v3 2/7] arm64: fpsimd: Make sure SVE setup is complete before SIMD is used Catalin Marinas
2020-01-13 23:30 ` [PATCH v3 3/7] arm64: cpufeature: Fix the type of no FP/SIMD capability Suzuki K Poulose
2020-01-13 23:30 ` [PATCH v3 4/7] arm64: cpufeature: Set the FP/SIMD compat HWCAP bits properly Suzuki K Poulose
2020-01-13 23:30 ` [PATCH v3 5/7] arm64: ptrace: nofpsimd: Fail FP/SIMD regset operations Suzuki K Poulose
2020-01-14 11:57 ` Catalin Marinas
2020-01-13 23:30 ` [PATCH v3 6/7] arm64: signal: nofpsimd: Handle fp/simd context for signal frames Suzuki K Poulose
2020-01-14 11:57 ` Catalin Marinas
2020-01-13 23:30 ` [PATCH v3 7/7] arm64: nofpsmid: Handle TIF_FOREIGN_FPSTATE flag cleanly Suzuki K Poulose
2020-01-14 8:30 ` [PATCH v3 0/7] arm64: Fix support for no FP/SIMD Ard Biesheuvel
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=20200113233023.928028-3-suzuki.poulose@arm.com \
--to=suzuki.poulose@arm.com \
--cc=ard.biesheuvel@linaro.org \
--cc=catalin.marinas@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=maz@kernel.org \
--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: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).