x86: Check stack overflow in detail

Currently, only kernel stack is checked for the overflow, which is not sufficient for systems that need a high reliability. To enhance it, it is required to check the IRQ and exception stacks, as well. This patch checks all the stack types and will cause messages of stacks in detail when free stack space drops below a certain limit except user stack. Signed-off-by: Mitsuo Hayasaka <[email protected]> Cc: [email protected] Cc: Randy Dunlap <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]>
mrcsosa · Dec 5, 2011 · 37fe6a4 · 37fe6a4
1 parent 69682b6
commit 37fe6a4
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Showing 2 changed files with 28 additions and 8 deletions.
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
@@ -63,8 +63,11 @@ config DEBUG_STACKOVERFLOW
 	bool "Check for stack overflows"
 	depends on DEBUG_KERNEL
 	---help---
-	  This option will cause messages to be printed if free stack space
-	  drops below a certain limit.
+	  Say Y here if you want to check the overflows of kernel, IRQ
+	  and exception stacks. This option will cause messages of the
+	  stacks in detail when free stack space drops below a certain
+	  limit.
+	  If in doubt, say "N".
 
 config X86_PTDUMP
 	bool "Export kernel pagetable layout to userspace via debugfs"

diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
@@ -36,18 +36,35 @@ EXPORT_PER_CPU_SYMBOL(irq_regs);
 static inline void stack_overflow_check(struct pt_regs *regs)
 {
 #ifdef CONFIG_DEBUG_STACKOVERFLOW
+	struct orig_ist *oist;
+	u64 irq_stack_top, irq_stack_bottom;
+	u64 estack_top, estack_bottom;
 	u64 curbase = (u64)task_stack_page(current);
 
 	if (user_mode_vm(regs))
 		return;
 
-	WARN_ONCE(regs->sp >= curbase &&
-		  regs->sp <= curbase + THREAD_SIZE &&
-		  regs->sp <  curbase + sizeof(struct thread_info) +
-					sizeof(struct pt_regs) + 128,
+	if (regs->sp >= curbase &&
+	    regs->sp <= curbase + THREAD_SIZE &&
+	    regs->sp >= curbase + sizeof(struct thread_info) +
+				  sizeof(struct pt_regs) + 128)
+		return;
+
+	irq_stack_top = (u64)__get_cpu_var(irq_stack_union.irq_stack);
+	irq_stack_bottom = (u64)__get_cpu_var(irq_stack_ptr);
+	if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom)
+		return;
+
+	oist = &__get_cpu_var(orig_ist);
+	estack_top = (u64)oist->ist[0] - EXCEPTION_STKSZ;
+	estack_bottom = (u64)oist->ist[N_EXCEPTION_STACKS - 1];
+	if (regs->sp >= estack_top && regs->sp <= estack_bottom)
+		return;
 
-		  "do_IRQ: %s near stack overflow (cur:%Lx,sp:%lx)\n",
-			current->comm, curbase, regs->sp);
+	WARN_ONCE(1, "do_IRQ(): %s has overflown the kernel stack (cur:%Lx,sp:%lx,irq stk top-bottom:%Lx-%Lx,exception stk top-bottom:%Lx-%Lx)\n",
+		current->comm, curbase, regs->sp,
+		irq_stack_top, irq_stack_bottom,
+		estack_top, estack_bottom);
 #endif
 }