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From:   Mark Brown <broonie@kernel.org>
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        Dave Martin <Dave.Martin@arm.com>,
        Mark Brown <broonie@kernel.org>
Subject: [PATCH v6 09/11] arm64: BTI: Reset BTYPE when skipping emulated instructions
Date:   Wed, 12 Feb 2020 19:29:04 +0000
Message-Id: <20200212192906.53366-10-broonie@kernel.org>
In-Reply-To: <20200212192906.53366-1-broonie@kernel.org>
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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(+)

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 3c07a7074145..52ed261e7739 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -335,6 +335,8 @@ 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);
-- 
2.20.1