From mboxrd@z Thu Jan 1 00:00:00 1970 From: rabin@rab.in (Rabin Vincent) Date: Mon, 21 Apr 2014 20:07:44 +0200 Subject: [PATCH] ARM: fix v7-M signal return Message-ID: <1398103664-23078-1-git-send-email-rabin@rab.in> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org According to the ARM ARM, the behaviour is UNDPREDICTABLE if the PC read from the exception return stack is not half word aligned. See the pseudo code for ExceptionReturn() and PopStack(). The signal handler's address has the bit 0 set, and setup_return() directly writes this to regs->ARM_pc. Mask out bit 0 before the exception return to get predictable behaviour. Signed-off-by: Rabin Vincent --- arch/arm/kernel/entry-header.S | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index 1420725..ef72f4b 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -133,6 +133,7 @@ biceq r5, V7M_xPSR_FRAMEPTRALIGN @ write basic exception frame + bic r4, r4, #1 stmdb r2!, {r1, r3-r5} ldmia sp, {r1, r3-r5} .if \ret_r0 -- 1.9.1