[SPARC]: Add stack usage instrumentation

arch/sparc/Kconfig

@@ -380,11 +380,32 @@ source "drivers/char/watchdog/Kconfig"
 
 menu "Kernel hacking"
 
+config DEBUG_KERNEL
+	bool "Kernel debugging"
+	help
+	  Say Y here if you are developing drivers or trying to debug and
+	  identify kernel problems.
+
+config DEBUG_STACK_USAGE
+	bool "Enable 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 DEBUG_SLAB
 	bool "Debug memory allocations"
+	depends on DEBUG_KERNEL
+	help
+	  Say Y here to have the kernel do limited verification on memory
+	  allocation as well as poisoning memory on free to catch use of freed
+	  memory.
 
 config MAGIC_SYSRQ
 	bool "Magic SysRq key"
+	depends on DEBUG_KERNEL
 	help
 	  If you say Y here, you will have some control over the system even
 	  if the system crashes for example during kernel debugging (e.g., you
@@ -398,22 +419,30 @@ config MAGIC_SYSRQ
 
 config DEBUG_SPINLOCK
 	bool "Spinlock debugging"
+	depends on DEBUG_KERNEL
+	help
+	  Say Y here and build SMP to catch missing spinlock initialization
+	  and certain other kinds of spinlock errors commonly made.  This is
+	  best used in conjunction with the NMI watchdog so that spinlock
+	  deadlocks are also debuggable.
 
 config DEBUG_HIGHMEM
 	bool "Highmem debugging"
 	depends on DEBUG_KERNEL && HIGHMEM
 	help
-	  This options enables addition error checking for high memory systems.
-	  Disable for production systems.
+	  This options enables additional error checking for high memory
+	  systems.  Disable for production systems.
 
 config DEBUG_SPINLOCK_SLEEP
 	bool "Sleep-inside-spinlock checking"
+	depends on DEBUG_KERNEL
 	help
 	  If you say Y here, various routines which may sleep will become very
 	  noisy if they are called with a spinlock held.	
 
 config DEBUG_BUGVERBOSE
 	bool "Verbose BUG() reporting (adds 70K)"
+	depends on DEBUG_KERNEL
 	help
 	  Say Y here to make BUG() panics output the file name and line number
 	  of the BUG call as well as the EIP and oops trace.  This aids

arch/sparc/mm/srmmu.c

@@ -627,8 +627,15 @@ static void srmmu_unmapiorange(unsigned long virt_addr, unsigned int len)
  */
 struct thread_info *srmmu_alloc_thread_info(void)
 {
-	return (struct thread_info *)
-	    __get_free_pages(GFP_KERNEL, THREAD_INFO_ORDER);
+	struct thread_info *ret;
+
+	ret = (struct thread_info *)__get_free_pages(GFP_KERNEL,
+						     THREAD_INFO_ORDER);
+#ifdef CONFIG_DEBUG_STACK_USAGE
+	memset(ret, 0, PAGE_SIZE << THREAD_INFO_ORDER);
+#endif /* DEBUG_STACK_USAGE */
+
+	return ret;
 }
 
 static void srmmu_free_thread_info(struct thread_info *ti)

arch/sparc/mm/sun4c.c

@@ -1058,6 +1058,11 @@ static struct thread_info *sun4c_alloc_thread_info(void)
 #ifndef CONFIG_SUN4	
 	sun4c_put_pte(addr + PAGE_SIZE, BUCKET_PTE(pages + PAGE_SIZE));
 #endif
+
+#ifdef CONFIG_DEBUG_STACK_USAGE
+	memset((void *)addr, 0, PAGE_SIZE << THREAD_INFO_ORDER);
+#endif /* DEBUG_STACK_USAGE */
+
 	return (struct thread_info *) addr;
 }
 

include/asm-sparc/thread_info.h

@@ -79,9 +79,9 @@ register struct thread_info *current_thread_info_reg asm("g6");
 /*
  * thread information allocation
  */
-#ifdef CONFIG_SUN4
+#if PAGE_SHIFT == 13
 #define THREAD_INFO_ORDER  0
-#else
+#else /* PAGE_SHIFT */
 #define THREAD_INFO_ORDER  1
 #endif