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From: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: ardb@kernel.org, catalin.marinas@arm.com, james.morse@arm.com,
	joey.gouly@arm.com, mark.rutland@arm.com, maz@kernel.org,
	will@kernel.org
Subject: [PATCH 1/9] arm64: cpufeature: make cpus_have_cap() noinstr-safe
Date: Thu,  1 Sep 2022 16:13:55 +0100	[thread overview]
Message-ID: <20220901151403.1735836-2-mark.rutland@arm.com> (raw)
In-Reply-To: <20220901151403.1735836-1-mark.rutland@arm.com>

Currently it isn't safe to use cpus_have_cap() from noinstr code as
test_bit() is explicitly instrumented, and were cpus_have_cap() placed
out-of-line, cpus_have_cap() itself could be instrumented.

Make cpus_have_cap() noinstr safe by marking it __always_inline and
using arch_test_bit().

Aside from the prevention of instrumentation, there should be no
functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
---
 arch/arm64/include/asm/cpufeature.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index fd7d75a275f6c..630c337c77746 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -448,11 +448,11 @@ static __always_inline bool system_capabilities_finalized(void)
  *
  * Before the capability is detected, this returns false.
  */
-static inline bool cpus_have_cap(unsigned int num)
+static __always_inline bool cpus_have_cap(unsigned int num)
 {
 	if (num >= ARM64_NCAPS)
 		return false;
-	return test_bit(num, cpu_hwcaps);
+	return arch_test_bit(num, cpu_hwcaps);
 }
 
 /*
-- 
2.30.2


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  reply	other threads:[~2022-09-01 15:15 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-01 15:13 [PATCH 0/9] arm64: alternatives: improvements Mark Rutland
2022-09-01 15:13 ` Mark Rutland [this message]
2022-09-01 15:13 ` [PATCH 2/9] arm64: alternatives: kvm: prepare for cap changes Mark Rutland
2022-09-01 15:13 ` [PATCH 3/9] arm64: alternatives: proton-pack: " Mark Rutland
2022-09-02 16:19   ` Joey Gouly
2022-09-05  8:46     ` Mark Rutland
2022-09-01 15:13 ` [PATCH 4/9] arm64: alternatives: hoist print out of __apply_alternatives() Mark Rutland
2022-09-01 15:13 ` [PATCH 5/9] arm64: alternatives: make alt_region const Mark Rutland
2022-09-06 15:18   ` Ard Biesheuvel
2022-09-12  9:31     ` Mark Rutland
2022-09-12 10:13       ` Ard Biesheuvel
2022-09-12 12:13         ` Mark Rutland
2022-09-01 15:14 ` [PATCH 6/9] arm64: alternatives: have callbacks take a cap Mark Rutland
2022-09-02 15:54   ` Joey Gouly
2022-09-05  8:48     ` Mark Rutland
2022-09-01 15:14 ` [PATCH 7/9] arm64: alternatives: add alternative_has_feature_*() Mark Rutland
2022-09-01 15:14 ` [PATCH 8/9] arm64: alternatives: add shared NOP callback Mark Rutland
2022-09-01 15:14 ` [PATCH 9/9] HACK: arm64: alternatives: dump summary of alternatives Mark Rutland
2022-09-12 12:36   ` Mark Brown
2022-09-12 16:14     ` Mark Rutland

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