From 59eb4404a680cdd833b3e7a573f43fced916f571 Mon Sep 17 00:00:00 2001
From: Marc Fiuczynski <mef@cs.princeton.edu>
Date: Fri, 17 Dec 2004 20:41:32 +0000
Subject: [PATCH] Updated stack overflow handling support.

---
 arch/i386/kernel/entry.S   | 51 ++++++++++++++++----------------------
 arch/i386/kernel/process.c | 24 ++++++++++++------
 2 files changed, 38 insertions(+), 37 deletions(-)

diff --git a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S
index 4ca841e0a..dfbade1b9 100644
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -1043,48 +1043,41 @@ stack_overflowed:
 .text
 
 ENTRY(mcount)
+#warning stack check enabled
 	push %eax
 	movl $(THREAD_SIZE - 1),%eax
 	andl %esp,%eax
-	cmpl $STACK_WARN,%eax /* more than half the stack is used*/
+	cmpl $STACK_WARN,%eax
 	jle 1f
 2:
 	popl %eax
 	ret
 1:
+	/* prevent infinite recursion from call to mcount from the
+	 * stack_overflow function.  Need to revisit this code for
+	 * SMP based systems.
+	 */
 	lock; btsl $0,stack_overflowed
 	jc 2b
 
-	# switch to overflow stack
-	movl %esp,%eax
-	movl $(stack_overflow_stack + THREAD_SIZE - 4),%esp
+	/* prepare to jmp to stack_overflow directly, as if it were 
+	 * called directly by the caller of mcount.  
+	 */
+	pushl %ebp
+	pushl %ebx
+	pushl %esi
+	pushl %edi
 	
-	pushf
-	cli
-	pushl %eax
-
-	# push eip then esp of error for stack_overflow_panic
-	pushl 4(%eax)
-	pushl %eax
-
-	# update the task pointer and cpu in the overflow stack's thread_info.
-	GET_THREAD_INFO_WITH_ESP(%eax)
-	movl TI_task(%eax),%ebx
-	movl %ebx,stack_overflow_stack+TI_task
-	movl TI_cpu(%eax),%ebx
-	movl %ebx,stack_overflow_stack+TI_cpu
-
 	call stack_overflow
+	/* Note that stack_overflow() will clear the stack_overflowed
+	 * variable.
+	 */
 
-	# pop off call arguments
-	addl $8,%esp
-
-	popl %eax
-	popf
-	movl %eax,%esp
-	popl %eax
-	movl $0,stack_overflowed
+	popl %edi
+	popl %esi
+	popl %ebx
+	popl %ebp
+	
+	popl %eax	
 	ret
-
-#warning stack check enabled
 #endif
diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c
index 51c17cc52..e8a01f2b5 100644
--- a/arch/i386/kernel/process.c
+++ b/arch/i386/kernel/process.c
@@ -219,22 +219,30 @@ static int __init idle_setup (char *str)
 
 __setup("idle=", idle_setup);
 
-void stack_overflow(unsigned long esp, unsigned long eip)
+void stack_overflow(void)
 {
+        extern unsigned long stack_overflowed;
+        unsigned long esp = current_stack_pointer();
 	int panicing = ((esp&(THREAD_SIZE-1)) <= STACK_PANIC);
 
+	oops_in_progress = 1;
 	printk( "esp: 0x%lx masked: 0x%lx STACK_PANIC:0x%lx %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);
+		esp, (esp&(THREAD_SIZE-1)), STACK_PANIC, 
+		(((esp&(THREAD_SIZE-1)) <= STACK_PANIC)), panicing);
 	show_trace(current,(void*)esp);
 
 	if (panicing)
 	  panic("stack overflow\n");
+
+	oops_in_progress = 0;
+
+	/* Just let it happen once per task, as otherwise it goes nuts
+	 * in printing stack traces.  This means that I need to dump
+	 * the stack_overflowed boolean into the task or thread_info
+	 * structure.  For now just turn it off all together.
+	 */
+
+	/* stack_overflowed = 0; */
 }
 
 void show_regs(struct pt_regs * regs)
-- 
2.47.0