[PATCH] parisc,metag: Implement CONFIG_DEBUG_STACK_USAGE option

[Helge Deller]

On parisc and metag the stack grows upwards, so for those we need to
scan the stack downwards in order to calculate how much stack a process
has used.

Tested on a 64bit parisc kernel.

Signed-off-by: Helge Deller <del...@gmx.de>

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 084ed9f..71591f3 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2859,10 +2859,18 @@ static inline unsigned long stack_not_used(struct 
task_struct *p)
        unsigned long *n = end_of_stack(p);
 
        do {    /* Skip over canary */
+# ifdef CONFIG_STACK_GROWSUP
+               n--;
+# else
                n++;
+# endif
        } while (!*n);
 
+# ifdef CONFIG_STACK_GROWSUP
+       return (unsigned long)end_of_stack(p) - (unsigned long)n;
+# else
        return (unsigned long)n - (unsigned long)end_of_stack(p);
+# endif
 }
 #endif
 extern void set_task_stack_end_magic(struct task_struct *tsk);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index f28f7fa..901f96c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -546,7 +546,7 @@ config DEBUG_KMEMLEAK_DEFAULT_OFF
 
 config DEBUG_STACK_USAGE
        bool "Stack utilization instrumentation"
-       depends on DEBUG_KERNEL && !IA64 && !PARISC && !METAG
+       depends on DEBUG_KERNEL && !IA64
        help
          Enables the display of the minimum amount of free stack which each
          task has ever had available in the sysrq-T and sysrq-P debug output.