Subject: powerpc/stackprotector: work around stack-guard init from atomic From: Sebastian Andrzej Siewior Date: Tue Mar 26 18:31:29 2019 +0100 From: Sebastian Andrzej Siewior This is invoked from the secondary CPU in atomic context. On x86 we use tsc instead. On Power we XOR it against mftb() so lets use stack address as the initial value. Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner --- arch/powerpc/include/asm/stackprotector.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- Index: linux-6.8.2-rt10/arch/powerpc/include/asm/stackprotector.h =================================================================== --- linux-6.8.2-rt10.orig/arch/powerpc/include/asm/stackprotector.h +++ linux-6.8.2-rt10/arch/powerpc/include/asm/stackprotector.h @@ -19,8 +19,13 @@ */ static __always_inline void boot_init_stack_canary(void) { - unsigned long canary = get_random_canary(); + unsigned long canary; +#ifndef CONFIG_PREEMPT_RT + canary = get_random_canary(); +#else + canary = ((unsigned long)&canary) & CANARY_MASK; +#endif current->stack_canary = canary; #ifdef CONFIG_PPC64 get_paca()->canary = canary;