Commit 0a658002 authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
Browse files

[PATCH] x86_64: Rewrite exception stack backtracing 



Exceptions and hardware interrupts can, to a certain degree, nest, so when
attempting to follow the sequence of stacks used in order to dump their
contents this has to be accounted for.  Also, IST stacks have their tops
stored in the TSS, so there's no need to add the stack size to get to their
ends.

Minor changes from AK.

Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 63518644

arch/x86_64/kernel/traps.c

+79 −68
Original line number Diff line number Diff line
@@ -120,15 +120,31 @@ int printk_address(unsigned long address) 
} 

#endif



unsigned long *in_exception_stack(int cpu, unsigned long stack) 

{ 

	int k;

static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,

					unsigned *usedp, const char **idp)

{

	static const char ids[N_EXCEPTION_STACKS][8] = {

		[DEBUG_STACK - 1] = "#DB",

		[NMI_STACK - 1] = "NMI",

		[DOUBLEFAULT_STACK - 1] = "#DF",

		[STACKFAULT_STACK - 1] = "#SS",

		[MCE_STACK - 1] = "#MC",

	};

	unsigned k;



	for (k = 0; k < N_EXCEPTION_STACKS; k++) {

		struct tss_struct *tss = &per_cpu(init_tss, cpu);

		unsigned long start = tss->ist[k] - EXCEPTION_STKSZ;

		unsigned long end;



		if (stack >= start && stack < tss->ist[k])

			return (unsigned long *)tss->ist[k];

		end = per_cpu(init_tss, cpu).ist[k];

		if (stack >= end)

			continue;

		if (stack >= end - EXCEPTION_STKSZ) {

			if (*usedp & (1U << k))

				break;

			*usedp |= 1U << k;

			*idp = ids[k];

			return (unsigned long *)end;

		}

	}

	return NULL;

}
@@ -137,78 +153,73 @@ unsigned long *in_exception_stack(int cpu, unsigned long stack) 
 * x86-64 can have upto three kernel stacks: 

 * process stack

 * interrupt stack

 * severe exception (double fault, nmi, stack fault) hardware stack

 * Check and process them in order.

 * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack

 */



void show_trace(unsigned long *stack)

{

	unsigned long addr;

	unsigned long *irqstack, *irqstack_end, *estack_end;

	const int cpu = safe_smp_processor_id();

	const unsigned cpu = safe_smp_processor_id();

	unsigned long *irqstack_end = (unsigned long *)cpu_pda[cpu].irqstackptr;

	int i;

	unsigned used = 0;



	printk("\nCall Trace:");

	i = 0; 



	estack_end = in_exception_stack(cpu, (unsigned long)stack); 

#define HANDLE_STACK(cond) \

	do while (cond) { \

		addr = *stack++; \

		if (kernel_text_address(addr)) { \

			/* \

			 * If the address is either in the text segment of the \

			 * kernel, or in the region which contains vmalloc'ed \

			 * memory, it *may* be the address of a calling \

			 * routine; if so, print it so that someone tracing \

			 * down the cause of the crash will be able to figure \

			 * out the call path that was taken. \

			 */ \

			i += printk_address(addr); \

			if (i > 50) { \

				printk("\n       "); \

				i = 0; \

			} \

			else \

				i += printk(" "); \

		} \

	} while (0)



	for(i = 0; ; ) {

		const char *id;

		unsigned long *estack_end;

		estack_end = in_exception_stack(cpu, (unsigned long)stack,

						&used, &id);



		if (estack_end) {

		while (stack < estack_end) { 

			addr = *stack++; 

			if (__kernel_text_address(addr)) {

				i += printk_address(addr);

				i += printk(" "); 

				if (i > 50) {

					printk("\n"); 

					i = 0;

				}

			}

		}

			i += printk(" <%s> ", id);

			HANDLE_STACK (stack < estack_end);

			i += printk(" <EOE> ");

		i += 7;

			stack = (unsigned long *) estack_end[-2];

			continue;

		}



	irqstack_end = (unsigned long *) (cpu_pda[cpu].irqstackptr);

	irqstack = (unsigned long *) (cpu_pda[cpu].irqstackptr - IRQSTACKSIZE + 64);

		if (irqstack_end) {

			unsigned long *irqstack;

			irqstack = irqstack_end -

				(IRQSTACKSIZE - 64) / sizeof(*irqstack);



			if (stack >= irqstack && stack < irqstack_end) {

		printk("<IRQ> ");  

		while (stack < irqstack_end) {

			addr = *stack++;

			/*

			 * If the address is either in the text segment of the

			 * kernel, or in the region which contains vmalloc'ed

			 * memory, it *may* be the address of a calling

			 * routine; if so, print it so that someone tracing

			 * down the cause of the crash will be able to figure

			 * out the call path that was taken.

			 */

			 if (__kernel_text_address(addr)) {

				 i += printk_address(addr);

				 i += printk(" "); 

				 if (i > 50) { 

					printk("\n       ");

					 i = 0;

				 } 

			}

		} 

				i += printk(" <IRQ> ");

				HANDLE_STACK (stack < irqstack_end);

				stack = (unsigned long *) (irqstack_end[-1]);

		printk(" <EOI> ");

		i += 7;

	} 



	while (((long) stack & (THREAD_SIZE-1)) != 0) {

		addr = *stack++;

		if (__kernel_text_address(addr)) {

			i += printk_address(addr);

			i += printk(" "); 

			if (i > 50) { 

				printk("\n       ");

					 i = 0;

				irqstack_end = NULL;

				i += printk(" <EOI> ");

				continue;

			}

		}

		break;

	}



	HANDLE_STACK (((long) stack & (THREAD_SIZE-1)) != 0);

#undef HANDLE_STACK

	printk("\n");

}

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