From: Dave Martin <Dave.Martin@arm.com>
Date: Mon, 16 Mar 2020 16:50:51 +0000 (+0000)
Subject: arm64: BTI: Reset BTYPE when skipping emulated instructions
X-Git-Tag: v5.8-rc1~213^2~2^2~16^2~6
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0537c4cd71e3c729c278c82f5b088460fb66fc33;p=thirdparty%2Flinux.git

arm64: BTI: Reset BTYPE when skipping emulated instructions

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: Mark Brown <broonie@kernel.org>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 3c986c8ca2041..10d6451b27761 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -340,6 +340,8 @@ 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);