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From:   Dave Martin <Dave.Martin@arm.com>
To:     linux-kernel@vger.kernel.org
Cc:     Andrew Jones <drjones@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
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Subject: [PATCH v2 11/12] arm64: BTI: Reset BTYPE when skipping emulated instructions
Date:   Thu, 10 Oct 2019 19:44:39 +0100
Message-Id: <1570733080-21015-12-git-send-email-Dave.Martin@arm.com>
In-Reply-To: <1570733080-21015-1-git-send-email-Dave.Martin@arm.com>
References: <1570733080-21015-1-git-send-email-Dave.Martin@arm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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>
---
 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 3af2768..4d8ce50 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -331,6 +331,8 @@ void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
 
 	if (regs->pstate & PSR_MODE32_BIT)
 		advance_itstate(regs);
+	else
+		regs->pstate &= ~(u64)PSR_BTYPE_MASK;
 }
 
 static LIST_HEAD(undef_hook);
-- 
2.1.4