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authorMark Brown <broonie@kernel.org>2023-01-10 19:34:36 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2023-01-12 17:09:21 +0000
commitb2482807fbd48a299512d161e38262fd7d973aa0 (patch)
tree1b32f3d798a38b640fde57b22021660b3c4dba52 /drivers
parentfcd3d2c082b2a19da2326b2b38ba5a05536dcd32 (diff)
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arm64/sme: Optimise SME exit on syscall entry
Our ABI says that we exit streaming mode on syscall entry. Currently we check if we are in streaming mode before doing this but since we have a SMSTOP SM instruction which will clear SVCR.SM in a single atomic operation we can save ourselves the read of the system register and check of the flag and just unconditionally do the SMSTOP SM. If we are not in streaming mode it results in a noop change to SVCR, if we are in streaming mode we will exit as desired. No functional change. Signed-off-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20230110-arm64-sme-syscall-smstop-v1-1-ac94235fd810@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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