In order to allow the use of non global stack protector canary, the stack canary needs to be located at a know offset defined in Makefile via -mstack-protector-guard-offset.
On powerpc/32, register r2 points to current task_struct at all time, the stack_canary located inside task_struct can be used directly if it is located in a known place. In order to allow that, this patch moves the stack_canary field out of the randomized area of task_struct. Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr> --- include/linux/sched.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 977cb57d7bc9..1d977b8a4bac 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -601,6 +601,10 @@ struct task_struct { /* -1 unrunnable, 0 runnable, >0 stopped: */ volatile long state; +#ifdef CONFIG_STACKPROTECTOR + /* Canary value for the -fstack-protector GCC feature: */ + unsigned long stack_canary; +#endif /* * This begins the randomizable portion of task_struct. Only * scheduling-critical items should be added above here. @@ -746,10 +750,6 @@ struct task_struct { pid_t pid; pid_t tgid; -#ifdef CONFIG_STACKPROTECTOR - /* Canary value for the -fstack-protector GCC feature: */ - unsigned long stack_canary; -#endif /* * Pointers to the (original) parent process, youngest child, younger sibling, * older sibling, respectively. (p->father can be replaced with -- 2.13.3