From aa62c2091129af81a172350b718eb35d5448cebc 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 e8772c07cf5c..e51bbe79f5b5 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); -- 2.20.1