From a87a2f8368f8a50b5492737c1524c2dfd69c7595 Mon Sep 17 00:00:00 2001 From: "T.J. Purtell" Date: Tue, 5 Nov 2013 17:07:18 +0000 Subject: [PATCH] arm64: compat: Clear the IT state independent of the 32-bit ARM or Thumb-2 mode The ARM architecture reference specifies that the IT state bits in the PSR must be all zeros in ARM mode or behavior is unspecified. If an ARM function is registered as a signal handler, and that signal is delivered inside a block of instructions following an IT instruction, some of the instructions at the beginning of the signal handler may be skipped if the IT state bits of the Program Status Register are not cleared by the kernel. Signed-off-by: T.J. Purtell [catalin.marinas@arm.com: code comment and commit log updated] Signed-off-by: Catalin Marinas --- arch/arm64/kernel/signal32.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c index e8772c07cf5c9..e51bbe79f5b5b 100644 --- a/arch/arm64/kernel/signal32.c +++ b/arch/arm64/kernel/signal32.c @@ -446,12 +446,13 @@ static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka, /* Check if the handler is written for ARM or Thumb */ thumb = handler & 1; - if (thumb) { + if (thumb) spsr |= COMPAT_PSR_T_BIT; - spsr &= ~COMPAT_PSR_IT_MASK; - } else { + else spsr &= ~COMPAT_PSR_T_BIT; - } + + /* The IT state must be cleared for both ARM and Thumb-2 */ + spsr &= ~COMPAT_PSR_IT_MASK; if (ka->sa.sa_flags & SA_RESTORER) { retcode = ptr_to_compat(ka->sa.sa_restorer); -- 2.39.5