(3/4) stack updates for x86

C-stack_usage_check-2.5.52+bk-6.patch
Check for stack overflows on entry to each funtion. Use gcc's -p profiling feature to do it.

Dave Hansen
[email protected]

# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher. # This patch includes the following deltas:
# ChangeSet 1.860.1.2 -> 1.866
# arch/i386/kernel/process.c 1.32.1.3 -> 1.38
# arch/i386/kernel/irq.c 1.23.1.2 -> 1.26
# Makefile 1.344 -> 1.346
# include/asm-i386/thread_info.h 1.10.1.2 -> 1.14
# arch/i386/Kconfig 1.13 -> 1.15
# arch/i386/kernel/entry.S 1.38.1.6 -> 1.49
# arch/i386/Makefile 1.24.2.7 -> 1.30
# arch/i386/boot/compressed/misc.c 1.9 -> 1.10
# arch/i386/kernel/init_task.c 1.6.1.1 -> 1.8
# arch/i386/kernel/i386_ksyms.c 1.36.2.4 -> 1.41
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 02/12/15 haveblue@elm3b96.(none) 1.859.1.2
# Merge elm3b96.(none):/work/dave/bk/linux-2.5-thread_info_infra

# into elm3b96.(none):/work/dave/bk/linux-2.5-overflow-detect
# --------------------------------------------
# 02/12/15	haveblue@elm3b96.(none)	1.865
# Merge elm3b96.(none):/work/dave/bk/linux-2.5-irq-stack
# into elm3b96.(none):/work/dave/bk/linux-2.5-irq-stack+overflow-detect
# --------------------------------------------
# 02/12/15	haveblue@elm3b96.(none)	1.866
# Merge elm3b96.(none):/work/dave/bk/linux-2.5-overflow-detect
# into elm3b96.(none):/work/dave/bk/linux-2.5-irq-stack+overflow-detect
# --------------------------------------------
#
diff -Nru a/arch/i386/Kconfig b/arch/i386/Kconfig
--- a/arch/i386/Kconfig	Sun Dec 15 21:16:27 2002
+++ b/arch/i386/Kconfig	Sun Dec 15 21:16:27 2002
@@ -1573,6 +1573,25 @@
 	  If you don't debug the kernel, you can say N, but we may not be able
 	  to solve problems without frame pointers.

+config X86_STACK_CHECK
+ bool "Detect stack overflows"
+ depends on FRAME_POINTER
+ help

+	  Say Y here to have the kernel attempt to detect when the per-task
+	  kernel stack overflows.  This is much more robust checking than
+	  the above overflow check, which will only occasionally detect
+	  an overflow.  The level of guarantee here is much greater.
+	
+	  Some older versions of gcc don't handle the -p option correctly.  
+	  Kernprof is affected by the same problem, which is described here:
+	  http://oss.sgi.com/projects/kernprof/faq.html#Q9
+	
+	  Basically, if you get oopses in __free_pages_ok during boot when
+	  you have this turned on, you need to fix gcc.  The Redhat 2.96 
+	  version and gcc-3.x seem to work.  

+
+ If not debugging a stack overflow problem, say N
+
config X86_EXTRA_IRQS
bool
depends on X86_LOCAL_APIC

diff -Nru a/arch/i386/Makefile b/arch/i386/Makefile
@@ -52,6 +52,10 @@
 MACHINE	:= mach-generic
 endif
 
+ifdef CONFIG_X86_STACK_CHECK
+CFLAGS += -p
+endif
+
 HEAD := arch/i386/kernel/head.o arch/i386/kernel/init_task.o
 
 libs-y 					+= arch/i386/lib/

diff -Nru a/arch/i386/boot/compressed/misc.c b/arch/i386/boot/compressed/misc.c
@@ -377,3 +377,7 @@
 	if (high_loaded) close_output_buffer_if_we_run_high(mv);
 	return high_loaded;
 }
+
+/* We don't actually check for stack overflows this early. */
+__asm__(".globl mcount ; mcount: ret\n");
+

diff -Nru a/arch/i386/kernel/i386_ksyms.c b/arch/i386/kernel/i386_ksyms.c
@@ -216,3 +216,8 @@
 EXPORT_SYMBOL(edd);
 EXPORT_SYMBOL(eddnr);
 #endif
+
+#ifdef CONFIG_X86_STACK_CHECK
+extern void mcount(void);
+EXPORT_SYMBOL(mcount);
+#endif

diff -Nru a/arch/i386/kernel/init_task.c b/arch/i386/kernel/init_task.c
@@ -16,6 +16,10 @@
 union thread_union init_irq_union
 	__attribute__((__section__(".data.init_task")));
 
+#ifdef CONFIG_X86_STACK_CHECK
+union thread_union stack_overflow_stack
+	__attribute__((__section__(".data.init_task")));
+#endif
 
 /*
  * Initial thread structure.

diff -Nru a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
@@ -158,7 +158,25 @@
 
 __setup("idle=", idle_setup);
 
-void show_regs(struct pt_regs * regs)
+void stack_overflow(unsigned long esp, unsigned long eip)
+{
+	int panicing = ((esp&(THREAD_SIZE-1)) <= STACK_PANIC);
+
+	printk( "esp: 0x%x masked: 0x%x STACK_PANIC:0x%x %d %d\n", 
+		esp, (esp&(THREAD_SIZE-1)), STACK_PANIC, (((esp&(THREAD_SIZE-1)) <= STACK_PANIC)), panicing );
+	
+	if (panicing)
+		print_symbol("stack overflow from %s\n", eip);
+	else
+		print_symbol("excessive stack use from %s\n", eip);
+	printk("esp: %p\n", (void*)esp);
+	show_trace((void*)esp);
+	
+	if (panicing)
+		panic("stack overflow\n");
+}
+
+asmlinkage void show_regs(struct pt_regs * regs)
 {
 	unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
 

diff -Nru a/include/asm-i386/thread_info.h b/include/asm-i386/thread_info.h
@@ -63,6 +63,8 @@
  */
 #define THREAD_ORDER 1 
 #define INIT_THREAD_SIZE       THREAD_SIZE
+#define STACK_PANIC		0x200ul
+#define STACK_WARN		((THREAD_SIZE)>>1)
 
 #ifndef __ASSEMBLY__