From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/4] arm64: prevent instrumentation of LL/SC atomics
Date: Tue, 17 Oct 2017 11:03:15 +0100 [thread overview]
Message-ID: <20171017100315.GA22140@arm.com> (raw)
In-Reply-To: <20171016132440.38098-3-mark.rutland@arm.com>
On Mon, Oct 16, 2017 at 02:24:38PM +0100, Mark Rutland wrote:
> While we build the LL/SC atomics as a C object file, this does not
> follow the AAPCS. This does not interoperate with other C code, and can
> only be called from special wrapper assembly.
>
> Bulding a kernel with CONFIG_KCOV and CONFIG_ARM64_LSE_ATOMICS results
> in the cmopiler inserting calls to __sanitizer_cov_trace_pc within the
cmopiler
> LL/SC atomics. As __sanitizer_cov_trace_pc is built per the AAPCS, these
> calls corrupt register values, resulting in failures at boot time.
>
> Avoid this (and other similar issues) by opting out of all compiler
> instrumentation. We can opt-in to specific instrumentation in future if
> we want to.
>
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> ---
> arch/arm64/lib/Makefile | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm64/lib/Makefile b/arch/arm64/lib/Makefile
> index a0abc142c92b..af77516f71b2 100644
> --- a/arch/arm64/lib/Makefile
> +++ b/arch/arm64/lib/Makefile
> @@ -17,5 +17,6 @@ CFLAGS_atomic_ll_sc.o := -fcall-used-x0 -ffixed-x1 -ffixed-x2 \
> -fcall-saved-x10 -fcall-saved-x11 -fcall-saved-x12 \
> -fcall-saved-x13 -fcall-saved-x14 -fcall-saved-x15 \
> -fcall-saved-x18
> +CC_INSTRUMENT_atomic_ll_sc.o := n
Does this mean we can lose the "notrace" definition of __LL_SC_INLINE
when generating the out-of-line atomics?
Will
next prev parent reply other threads:[~2017-10-17 10:03 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-16 13:24 [PATCH 0/4] Cleanup instrumentation avoidance Mark Rutland
2017-10-16 13:24 ` [PATCH 1/4] kbuild: allow global override of CC instrumentation Mark Rutland
2017-10-17 10:37 ` Will Deacon
2017-10-16 13:24 ` [PATCH 2/4] arm64: prevent instrumentation of LL/SC atomics Mark Rutland
2017-10-17 10:03 ` Will Deacon [this message]
2017-10-17 10:54 ` Mark Rutland
2017-10-17 10:58 ` Will Deacon
2017-10-17 11:10 ` Mark Rutland
2017-10-17 11:38 ` Will Deacon
2017-10-17 12:55 ` Mark Rutland
2017-10-18 14:16 ` Will Deacon
2017-10-16 13:24 ` [PATCH 3/4] kvm/arm64: simplify CC instrumentation opt-out Mark Rutland
2017-10-17 14:50 ` Christoffer Dall
2017-10-16 13:24 ` [PATCH 4/4] arm64: vdso: remove pointless gcov option Mark Rutland
2017-10-17 13:56 ` Mark Rutland
2017-10-16 13:35 ` [PATCH 0/4] Cleanup instrumentation avoidance Mark Rutland
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