Messages in this thread | | | Subject | Re: [PATCH] Fix max-stack calculators to skip canary | From | Joe Perches <> | Date | Tue, 22 Apr 2008 10:33:14 -0700 |
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On Tue, 2008-04-22 at 12:18 -0500, Eric Sandeen wrote: > Index: linux-2.6.25/kernel/exit.c > =================================================================== > --- linux-2.6.25.orig/kernel/exit.c 2008-04-20 22:34:16.000000000 -0500 > +++ linux-2.6.25/kernel/exit.c 2008-04-22 11:38:05.769412824 -0500 > @@ -826,6 +826,8 @@ static void check_stack_usage(void) > unsigned long *n = end_of_stack(current); > unsigned long free; > > + n++; /* skip over canary at end */ > + > while (*n == 0) > n++; > free = (unsigned long)n - (unsigned long)end_of_stack(current); > Index: linux-2.6.25/kernel/sched.c > =================================================================== > --- linux-2.6.25.orig/kernel/sched.c 2008-04-20 22:34:19.000000000 -0500 > +++ linux-2.6.25/kernel/sched.c 2008-04-22 11:48:06.975407495 -0500 > @@ -5190,6 +5190,8 @@ void sched_show_task(struct task_struct > #ifdef CONFIG_DEBUG_STACK_USAGE > { > unsigned long *n = end_of_stack(p); > + > + n++; /* skip over canary at end */ > while (!*n) > n++; > free = (unsigned long)n - (unsigned long)end_of_stack(p); >
Wouldn't it be better to have exactly the same code? How about using a statement expression macro?
#define DEBUG_STACK_FREE(process) \ ({ \ unsigned long *n = end_of_stack(process); \ do { /* Skip over canary */\ n++; \ } while (!*n); \ (unsigned long)n - (unsigned long)end_of_stack(process); \ })
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