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UPSTREAM: arm64/sme: Don't flush SVE register state when handling SME traps

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Currently as part of handling a SME access trap we flush the SVE register
state. This is not needed and would corrupt register state if the task has
access to the SVE registers already. For non-streaming mode accesses the
required flushing will be done in the SVE access trap. For streaming
mode SVE register accesses the architecture guarantees that the register
state will be flushed when streaming mode is entered or exited so there is
no need for us to do so. Simply remove the register initialisation.

Bug: 254441685
Fixes: 8bd7f91c03d8 ("arm64/sme: Implement traps and syscall handling for SME")
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220817182324.638214-5-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
(cherry picked from commit 714f3cbd70a4db9f9b7fe5b8a032896ed33fb824)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: Ib4726fa39751d21b736a64c58a492548e536e043
This commit is contained in:
Mark Brown
2022-08-17 19:23:24 +01:00
committed by Treehugger Robot
parent b7538d55a3
commit 354a078d96
1 changed files with 0 additions and 11 deletions
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11
arch/arm64/kernel/fpsimd.c
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@@ -1452,17 +1452,6 @@ void do_sme_acc(unsigned int esr, struct pt_regs *regs)
fpsimd_bind_task_to_cpu();
}
/*
* If SVE was not already active initialise the SVE registers,
* any non-shared state between the streaming and regular SVE
* registers is architecturally guaranteed to be zeroed when
* we enter streaming mode. We do not need to initialize ZA
* since ZA must be disabled at this point and enabling ZA is
* architecturally defined to zero ZA.
*/
if (system_supports_sve() && !test_thread_flag(TIF_SVE))
sve_init_regs();
put_cpu_fpsimd_context();
}