[PATCH] x86_64: x86_64 stack usage debugging

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@sgi.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 22 insertions, 0 deletions

diff --git a/arch/x86_64/Kconfig.debug b/arch/x86_64/Kconfig.debug
index 087a04868b25..1d92ab56c0f9 100644
--- a/arch/x86_64/Kconfig.debug
+++ b/arch/x86_64/Kconfig.debug
@@ -42,6 +42,15 @@ config DEBUG_STACKOVERFLOW
           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"
 
diff --git a/include/asm-x86_64/thread_info.h b/include/asm-x86_64/thread_info.h
index b5e88216fd80..2029b00351f3 100644
--- a/include/asm-x86_64/thread_info.h
+++ b/include/asm-x86_64/thread_info.h
@@ -73,8 +73,21 @@ static inline struct thread_info *stack_thread_info(void)
 }
 
 /* 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__ */