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x86_64: fix the check point in stack_overflow_check

PATCH New jia zhang 2 participants 2 messages Nov 23, 2008 x86

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jia zhang

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#0 lore raw

PATCH 1/1 x86_64: fix the check point in stack_overflow_check

stack_overflow_check() should consider the stack usage of pt_regs, and thus it could warn us in advance. Additionally, it looks a bit good that the warning time starts at INITIAL_JIFFIES.

Signed-off-by jia zhang <[email protected]>

---
Assume at the moment rsp get close to the check point before interrupt arrives. When interrupt really happens, thread_info will be partly overrode.

 arch/x86/kernel/irq_64.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
arch/x86/kernel/irq_64.c +4 -3
@@ -29,11 +29,12 @@
 static inline void stack_overflow_check(struct pt_regs *regs)
 {
 	u64 curbase = (u64)task_stack_page(current);
-	static unsigned long warned = -60*HZ;
+	static unsigned long warned = INITIAL_JIFFIES - 60*HZ;
 
 	if (regs->sp >= curbase && regs->sp <= curbase + THREAD_SIZE &&
-	    regs->sp <  curbase + sizeof(struct thread_info) + 128 &&
-	    time_after(jiffies, warned + 60*HZ)) {
+			regs->sp < curbase + sizeof(struct thread_info) +
+			sizeof(struct pt_regs) + 128 &&
+			time_after(jiffies, warned + 60*HZ)) {
 		printk("do_IRQ: %s near stack overflow (cur:%Lx,sp:%lx)\n",
 		       current->comm, curbase, regs->sp);
 		show_stack(NULL,NULL);
Applied
#1 lore raw

PATCH 1/1 x86: clean up stack overflow debug check

Quoted 21 lines · jia zhang

stack_overflow_check() should consider the stack usage of pt_regs, and thus it could warn us in advance. Additionally, it looks a bit good that the warning time starts at INITIAL_JIFFIES.

Signed-off-by jia zhang <[email protected]>

---
Assume at the moment rsp get close to the check point before interrupt arrives. When interrupt really happens, thread_info will be partly overrode.

 arch/x86/kernel/irq_64.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
arch/x86/kernel/irq_64.c +1 -1
@@ -29,11 +29,12 @@
 static inline void stack_overflow_check(struct pt_regs *regs)
 {
 	u64 curbase = (u64)task_stack_page(current);
-	static unsigned long warned = -60*HZ;
+	static unsigned long warned = INITIAL_JIFFIES - 60*HZ;

arch/x86/kernel/irq_64.c line 40

Quoted 10 lines
arch/x86/kernel/irq_64.c +3 -2
 
 	if (regs->sp >= curbase && regs->sp <= curbase + THREAD_SIZE &&
-	    regs->sp <  curbase + sizeof(struct thread_info) + 128 &&
-	    time_after(jiffies, warned + 60*HZ)) {
+			regs->sp < curbase + sizeof(struct thread_info) +
+			sizeof(struct pt_regs) + 128 &&
+			time_after(jiffies, warned + 60*HZ)) {
 		printk("do_IRQ: %s near stack overflow (cur:%Lx,sp:%lx)\n",
 		       current->comm, curbase, regs->sp);
 		show_stack(NULL,NULL);

applied to tip/x86/debug, thanks! I also applied the clean up patch below on top of your fix.

Ingo

----------------->

Quoted 1 line

From f377fa123d0ec621e8e361ecc3f2a8ee70e81a2e Mon Sep 17 00:00:00 2001

From: Ingo Molnar <[email protected]>
Date: Sun, 23 Nov 2008 09:02:26 +0100
Subject: [PATCH] x86: clean up stack overflow debug check

Impact: cleanup

Simplify the irq-sampled stack overflow debug check:

- eliminate an #idef

- use WARN_ONCE() to emit a single warning (all bets are off after the first such warning anyway)

Signed-off-by Ingo Molnar <[email protected]>
---
 arch/x86/kernel/irq_64.c |   25 ++++++++++---------------
 1 files changed, 10 insertions(+), 15 deletions(-)
arch/x86/kernel/irq_64.c +10 -15
index b842fc8..1d3d0e7 100644
@@ -18,7 +18,6 @@
 #include <asm/idle.h>
 #include <asm/smp.h>
 
-#ifdef CONFIG_DEBUG_STACKOVERFLOW
 /*
  * Probabilistic stack overflow check:
  *

@@ -28,20 +27,18 @@
  */
 static inline void stack_overflow_check(struct pt_regs *regs)
 {
+#ifdef CONFIG_DEBUG_STACKOVERFLOW
 	u64 curbase = (u64)task_stack_page(current);
-	static unsigned long warned = INITIAL_JIFFIES - 60*HZ;
-
-	if (regs->sp >= curbase && regs->sp <= curbase + THREAD_SIZE &&
-			regs->sp < curbase + sizeof(struct thread_info) +
-			sizeof(struct pt_regs) + 128 &&
-			time_after(jiffies, warned + 60*HZ)) {
-		printk("do_IRQ: %s near stack overflow (cur:%Lx,sp:%lx)\n",
-		       current->comm, curbase, regs->sp);
-		show_stack(NULL,NULL);
-		warned = jiffies;
-	}
-}
+
+	WARN_ONCE(regs->sp >= curbase &&
+		  regs->sp <= curbase + THREAD_SIZE &&
+		  regs->sp <  curbase + sizeof(struct thread_info) +
+					sizeof(struct pt_regs) + 128,
+
+		  "do_IRQ: %s near stack overflow (cur:%Lx,sp:%lx)\n",
+			current->comm, curbase, regs->sp);
 #endif
+}
 
 /*
  * do_IRQ handles all normal device IRQ's (the special

@@ -61,9 +58,7 @@ asmlinkage unsigned int do_IRQ(struct pt_regs *regs)
 	irq_enter();
 	irq = __get_cpu_var(vector_irq)[vector];
 
-#ifdef CONFIG_DEBUG_STACKOVERFLOW
 	stack_overflow_check(regs);
-#endif
 
 	desc = irq_to_desc(irq);
 	if (likely(desc))