From dda5f312bb09e56e7a1c3e3851f2000eb2e9c879 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Mon, 5 Jun 2023 08:00:58 +0100 Subject: locking/atomic: arm: fix sync ops The sync_*() ops on arch/arm are defined in terms of the regular bitops with no special handling. This is not correct, as UP kernels elide barriers for the fully-ordered operations, and so the required ordering is lost when such UP kernels are run under a hypervsior on an SMP system. Fix this by defining sync ops with the required barriers. Note: On 32-bit arm, the sync_*() ops are currently only used by Xen, which requires ARMv7, but the semantics can be implemented for ARMv6+. Fixes: e54d2f61528165bb ("xen/arm: sync_bitops") Signed-off-by: Mark Rutland Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20230605070124.3741859-2-mark.rutland@arm.com --- arch/arm/lib/testchangebit.S | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/arm/lib/testchangebit.S') diff --git a/arch/arm/lib/testchangebit.S b/arch/arm/lib/testchangebit.S index 4ebecc67e6e0..f13fe9bc2399 100644 --- a/arch/arm/lib/testchangebit.S +++ b/arch/arm/lib/testchangebit.S @@ -10,3 +10,7 @@ .text testop _test_and_change_bit, eor, str + +#if __LINUX_ARM_ARCH__ >= 6 +sync_testop _sync_test_and_change_bit, eor, str +#endif -- cgit