[v10,09/13] arm64: BTI: Reset BTYPE when skipping emulated instructions

Commit Message

Mark Brown March 16, 2020, 4:50 p.m. UTC

From: Dave Martin <[e-mail]>

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 <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>
---
 arch/arm64/kernel/traps.c | 2 ++
 1 file changed, 2 insertions(+)

Patch

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 3c986c8ca204..10d6451b2776 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);