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[v4,10/12] arm64: BTI: Reset BTYPE when skipping emulated instructions

Message ID 20191211154206.46260-11-broonie@kernel.org
State New
Headers show
Series arm64: ARMv8.5-A: Branch Target Identification support | expand

Commit Message

Mark Brown Dec. 11, 2019, 3:42 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>

Signed-off-by: Mark Brown <broonie@kernel.org>

---
 arch/arm64/kernel/traps.c | 2 ++
 1 file changed, 2 insertions(+)

-- 
2.20.1
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Patch

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index bf79d8024fbe..9fc05ae500e6 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 (regs->pstate & PSR_MODE32_BIT)
 		advance_itstate(regs);
+	else
+		regs->pstate &= ~PSR_BTYPE_MASK;
 }
 
 static LIST_HEAD(undef_hook);