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Date: Sun, 14 Sep 2014 23:23:05 -0500 From: Chuck Ebbert <cebbert.lkml@...il.com> To: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Cc: Aaron Tomlin <atomlin@...hat.com>, Helge Deller <deller@....de>, James Hogan <james.hogan@...tec.com> Subject: [RFC/PATCH] Fix end_of_stack() and stack_not_used() for archs using CONFIG_STACK_GROWSUP When looking at Aaron's patches adding extra checks of the stack canary, I realized the code almost certainly never worked if the stack grows up. Something like this is needed, I think. Not-Signed-Off-By: Chuck Ebbert <cebbert.lkml@...il.com> --- Not even compile tested. diff --git a/include/linux/sched.h b/include/linux/sched.h index 5c2c885..da7f597 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2610,7 +2610,11 @@ static inline void setup_thread_stack(struct task_struct *p, struct task_struct static inline unsigned long *end_of_stack(struct task_struct *p) { +#ifdef CONFIG_STACK_GROWSUP + return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1; +#else return (unsigned long *)(task_thread_info(p) + 1); +#endif } #endif @@ -2629,13 +2633,21 @@ static inline unsigned long stack_not_used(struct task_struct *p) { unsigned long *n = end_of_stack(p); +#ifdef CONFIG_STACK_GROWSUP + do { /* Skip over canary */ + n--; + } while (!*n); + + return (unsigned long)end_of_stack(p) - (unsigned long)n; +#else do { /* Skip over canary */ n++; } while (!*n); return (unsigned long)n - (unsigned long)end_of_stack(p); -} #endif +} +#endif /* CONFIG_DEBUG_STACK_USAGE */ /* set thread flags in other task's structures * - see asm/thread_info.h for TIF_xxxx flags available -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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