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| author | James Morse <james.morse@arm.com> | 2019-06-18 18:17:33 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-31 08:27:05 +0300 |
| commit | 05959ed85e34240ba3980c784d7634a4ebc753f5 (patch) | |
| tree | c010a608ef03f00139075b6dacce10fe134e8fd5 | |
| parent | 007b01a27d4d5628d686d64c1b13356a7f21aad7 (diff) | |
| download | linux-05959ed85e34240ba3980c784d7634a4ebc753f5.tar.xz | |
arm64: assembler: Switch ESB-instruction with a vanilla nop if !ARM64_HAS_RAS
[ Upstream commit 2b68a2a963a157f024c67c0697b16f5f792c8a35 ]
The ESB-instruction is a nop on CPUs that don't implement the RAS
extensions. This lets us use it in places like the vectors without
having to use alternatives.
If someone disables CONFIG_ARM64_RAS_EXTN, this instruction still has
its RAS extensions behaviour, but we no longer read DISR_EL1 as this
register does depend on alternatives.
This could go wrong if we want to synchronize an SError from a KVM
guest. On a CPU that has the RAS extensions, but the KConfig option
was disabled, we consume the pending SError with no chance of ever
reading it.
Hide the ESB-instruction behind the CONFIG_ARM64_RAS_EXTN option,
outputting a regular nop if the feature has been disabled.
Reported-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | arch/arm64/include/asm/assembler.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index f90f5d83b228..5a97ac853168 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -112,7 +112,11 @@ * RAS Error Synchronization barrier */ .macro esb +#ifdef CONFIG_ARM64_RAS_EXTN hint #16 +#else + nop +#endif .endm /* |