[PATCH 2/2] x86_64 stack usage debugging

[Eric Sandeen]

Applies to git & 2.6.17-rc6 after CONFIG_DEBUG_STACKOVERFLOW patch

uses same stack-zeroing mechanism as on i386 to discover maximum stack excursions.

Signed-off-by: Eric Sandeen <sandeen@xxxxxxx>

Index: linux/arch/x86_64/Kconfig.debug
===================================================================
--- linux.orig/arch/x86_64/Kconfig.debug	2006-06-13 08:54:36.923001750 -0500
+++ linux/arch/x86_64/Kconfig.debug	2006-06-13 08:59:32.941501750 -0500
@@ -42,6 +42,15 @@
 	  This option will cause messages to be printed if free stack space
 	  drops below a certain limit.
 
+config DEBUG_STACK_USAGE
+        bool "Stack utilization instrumentation"
+        depends on DEBUG_KERNEL
+        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.
+
+	  This option will slow down process creation somewhat.
+
 #config X86_REMOTE_DEBUG
 #       bool "kgdb debugging stub"
 
Index: linux/include/asm-x86_64/thread_info.h
===================================================================
--- linux.orig/include/asm-x86_64/thread_info.h	2006-03-19 23:53:29.000000000 -0600
+++ linux/include/asm-x86_64/thread_info.h	2006-06-13 08:59:32.953502500 -0500
@@ -73,8 +73,21 @@
 }
 
 /* thread information allocation */
+#ifdef CONFIG_DEBUG_STACK_USAGE
+#define alloc_thread_info(tsk)					\
+    ({								\
+	struct thread_info *ret;				\
+								\
+	ret = ((struct thread_info *) __get_free_pages(GFP_KERNEL,THREAD_ORDER)); \
+	if (ret)						\
+		memset(ret, 0, THREAD_SIZE);			\
+	ret;							\
+    })
+#else
 #define alloc_thread_info(tsk) \
 	((struct thread_info *) __get_free_pages(GFP_KERNEL,THREAD_ORDER))
+#endif
+
 #define free_thread_info(ti) free_pages((unsigned long) (ti), THREAD_ORDER)
 
 #else /* !__ASSEMBLY__ */
-
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