diff mbox series

[v5,10/12] arm64: BTI: Reset BTYPE when skipping emulated instructions

Message ID 20200122212144.6409-11-broonie@kernel.org (mailing list archive)
State New, archived
Headers show
Series arm64: ARMv8.5-A: Branch Target Identification support | expand

Commit Message

Mark Brown Jan. 22, 2020, 9:21 p.m. UTC 
From: Dave Martin <Dave.Martin@arm.com>

Since normal execution of any non-branch instruction resets the
PSTATE BTYPE field to 0, so do the same thing when emulating a
trapped instruction.

Branches don't trap directly, so we should never need to assign a
non-zero value to BTYPE here.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/kernel/traps.c | 2 ++
 1 file changed, 2 insertions(+)
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Patch

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 4fa8b92b8624..be71e5ef9ae0 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -332,6 +332,8 @@  void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
 
 	if (compat_user_mode(regs))
 		advance_itstate(regs);
+	else
+		regs->pstate &= ~PSR_BTYPE_MASK;
 }
 
 static LIST_HEAD(undef_hook);