Commit cb76c939 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Ingo Molnar
Browse files

x86/dumpstack: Add get_stack_info() interface 



valid_stack_ptr() is buggy: it assumes that all stacks are of size
THREAD_SIZE, which is not true for exception stacks.  So the
walk_stack() callbacks will need to know the location of the beginning
of the stack as well as the end.

Another issue is that in general the various features of a stack (type,
size, next stack pointer, description string) are scattered around in
various places throughout the stack dump code.

Encapsulate all that information in a single place with a new stack_info
struct and a get_stack_info() interface.

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/8164dd0db96b7e6a279fa17ae5e6dc375eecb4a9.1473905218.git.jpoimboe@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 9c003907

arch/x86/events/core.c

+1 −1
Original line number Diff line number Diff line
@@ -2251,7 +2251,7 @@ void arch_perf_update_userpage(struct perf_event *event, 
 * callchain support

 */



static int backtrace_stack(void *data, char *name)

static int backtrace_stack(void *data, const char *name)

{

	return 0;

}

arch/x86/include/asm/stacktrace.h

+37 −4
Original line number Diff line number Diff line
@@ -10,6 +10,39 @@ 
#include <linux/ptrace.h>

#include <asm/switch_to.h>



enum stack_type {

	STACK_TYPE_UNKNOWN,

	STACK_TYPE_TASK,

	STACK_TYPE_IRQ,

	STACK_TYPE_SOFTIRQ,

	STACK_TYPE_EXCEPTION,

	STACK_TYPE_EXCEPTION_LAST = STACK_TYPE_EXCEPTION + N_EXCEPTION_STACKS-1,

};



struct stack_info {

	enum stack_type type;

	unsigned long *begin, *end, *next_sp;

};



bool in_task_stack(unsigned long *stack, struct task_struct *task,

		   struct stack_info *info);



int get_stack_info(unsigned long *stack, struct task_struct *task,

		   struct stack_info *info, unsigned long *visit_mask);



void stack_type_str(enum stack_type type, const char **begin,

		    const char **end);



static inline bool on_stack(struct stack_info *info, void *addr, size_t len)

{

	void *begin = info->begin;

	void *end   = info->end;



	return (info->type != STACK_TYPE_UNKNOWN &&

		addr >= begin && addr < end &&

		addr + len > begin && addr + len <= end);

}



extern int kstack_depth_to_print;



struct thread_info;
@@ -20,27 +53,27 @@ typedef unsigned long (*walk_stack_t)(struct task_struct *task, 
				      unsigned long bp,

				      const struct stacktrace_ops *ops,

				      void *data,

				      unsigned long *end,

				      struct stack_info *info,

				      int *graph);



extern unsigned long

print_context_stack(struct task_struct *task,

		    unsigned long *stack, unsigned long bp,

		    const struct stacktrace_ops *ops, void *data,

		    unsigned long *end, int *graph);

		    struct stack_info *info, int *graph);



extern unsigned long

print_context_stack_bp(struct task_struct *task,

		       unsigned long *stack, unsigned long bp,

		       const struct stacktrace_ops *ops, void *data,

		       unsigned long *end, int *graph);

		       struct stack_info *info, int *graph);



/* Generic stack tracer with callbacks */



struct stacktrace_ops {

	int (*address)(void *data, unsigned long address, int reliable);

	/* On negative return stop dumping */

	int (*stack)(void *data, char *name);

	int (*stack)(void *data, const char *name);

	walk_stack_t	walk_stack;

};

arch/x86/kernel/dumpstack.c

+22 −18
Original line number Diff line number Diff line
@@ -25,6 +25,23 @@ unsigned int code_bytes = 64; 
int kstack_depth_to_print = 3 * STACKSLOTS_PER_LINE;

static int die_counter;



bool in_task_stack(unsigned long *stack, struct task_struct *task,

		   struct stack_info *info)

{

	unsigned long *begin = task_stack_page(task);

	unsigned long *end   = task_stack_page(task) + THREAD_SIZE;



	if (stack < begin || stack >= end)

		return false;



	info->type	= STACK_TYPE_TASK;

	info->begin	= begin;

	info->end	= end;

	info->next_sp	= NULL;



	return true;

}



static void printk_stack_address(unsigned long address, int reliable,

				 char *log_lvl)

{
@@ -46,24 +63,11 @@ void printk_address(unsigned long address) 
 * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack

 */



static inline int valid_stack_ptr(struct task_struct *task,

			void *p, unsigned int size, void *end)

{

	void *t = task_stack_page(task);

	if (end) {

		if (p < end && p >= (end-THREAD_SIZE))

			return 1;

		else

			return 0;

	}

	return p >= t && p < t + THREAD_SIZE - size;

}



unsigned long

print_context_stack(struct task_struct *task,

		unsigned long *stack, unsigned long bp,

		const struct stacktrace_ops *ops, void *data,

		unsigned long *end, int *graph)

		struct stack_info *info, int *graph)

{

	struct stack_frame *frame = (struct stack_frame *)bp;
@@ -75,7 +79,7 @@ print_context_stack(struct task_struct *task, 
	    PAGE_SIZE)

		stack = (unsigned long *)task_stack_page(task);



	while (valid_stack_ptr(task, stack, sizeof(*stack), end)) {

	while (on_stack(info, stack, sizeof(*stack))) {

		unsigned long addr = *stack;



		if (__kernel_text_address(addr)) {
@@ -114,12 +118,12 @@ unsigned long 
print_context_stack_bp(struct task_struct *task,

		       unsigned long *stack, unsigned long bp,

		       const struct stacktrace_ops *ops, void *data,

		       unsigned long *end, int *graph)

		       struct stack_info *info, int *graph)

{

	struct stack_frame *frame = (struct stack_frame *)bp;

	unsigned long *retp = &frame->return_address;



	while (valid_stack_ptr(task, retp, sizeof(*retp), end)) {

	while (on_stack(info, stack, sizeof(*stack) * 2)) {

		unsigned long addr = *retp;

		unsigned long real_addr;
@@ -138,7 +142,7 @@ print_context_stack_bp(struct task_struct *task, 
}

EXPORT_SYMBOL_GPL(print_context_stack_bp);



static int print_trace_stack(void *data, char *name)

static int print_trace_stack(void *data, const char *name)

{

	printk("%s <%s> ", (char *)data, name);

	return 0;

arch/x86/kernel/dumpstack_32.c

+81 −25
Original line number Diff line number Diff line
@@ -16,61 +16,117 @@ 


#include <asm/stacktrace.h>



static void *is_irq_stack(void *p, void *irq)

void stack_type_str(enum stack_type type, const char **begin, const char **end)

{

	if (p < irq || p >= (irq + THREAD_SIZE))

		return NULL;

	return irq + THREAD_SIZE;

	switch (type) {

	case STACK_TYPE_IRQ:

	case STACK_TYPE_SOFTIRQ:

		*begin = "IRQ";

		*end   = "EOI";

		break;

	default:

		*begin = NULL;

		*end   = NULL;

	}

}



static bool in_hardirq_stack(unsigned long *stack, struct stack_info *info)

{

	unsigned long *begin = (unsigned long *)this_cpu_read(hardirq_stack);

	unsigned long *end   = begin + (THREAD_SIZE / sizeof(long));



	if (stack < begin || stack >= end)

		return false;



	info->type	= STACK_TYPE_IRQ;

	info->begin	= begin;

	info->end	= end;



	/*

	 * See irq_32.c -- the next stack pointer is stored at the beginning of

	 * the stack.

	 */

	info->next_sp	= (unsigned long *)*begin;



static void *is_hardirq_stack(unsigned long *stack)

	return true;

}



static bool in_softirq_stack(unsigned long *stack, struct stack_info *info)

{

	void *irq = this_cpu_read(hardirq_stack);

	unsigned long *begin = (unsigned long *)this_cpu_read(softirq_stack);

	unsigned long *end   = begin + (THREAD_SIZE / sizeof(long));



	if (stack < begin || stack >= end)

		return false;



	info->type	= STACK_TYPE_SOFTIRQ;

	info->begin	= begin;

	info->end	= end;



	/*

	 * The next stack pointer is stored at the beginning of the stack.

	 * See irq_32.c.

	 */

	info->next_sp	= (unsigned long *)*begin;



	return is_irq_stack(stack, irq);

	return true;

}



static void *is_softirq_stack(unsigned long *stack)

int get_stack_info(unsigned long *stack, struct task_struct *task,

		   struct stack_info *info, unsigned long *visit_mask)

{

	void *irq = this_cpu_read(softirq_stack);

	if (!stack)

		goto unknown;



	task = task ? : current;



	if (in_task_stack(stack, task, info))

		return 0;



	if (task != current)

		goto unknown;



	if (in_hardirq_stack(stack, info))

		return 0;



	return is_irq_stack(stack, irq);

	if (in_softirq_stack(stack, info))

		return 0;



unknown:

	info->type = STACK_TYPE_UNKNOWN;

	return -EINVAL;

}



void dump_trace(struct task_struct *task, struct pt_regs *regs,

		unsigned long *stack, unsigned long bp,

		const struct stacktrace_ops *ops, void *data)

{

	unsigned long visit_mask = 0;

	int graph = 0;

	u32 *prev_esp;



	task = task ? : current;

	stack = stack ? : get_stack_pointer(task, regs);

	bp = bp ? : (unsigned long)get_frame_pointer(task, regs);



	for (;;) {

		void *end_stack;

		const char *begin_str, *end_str;

		struct stack_info info;



		end_stack = is_hardirq_stack(stack);

		if (!end_stack)

			end_stack = is_softirq_stack(stack);

		if (get_stack_info(stack, task, &info, &visit_mask))

			break;



		bp = ops->walk_stack(task, stack, bp, ops, data,

				     end_stack, &graph);

		stack_type_str(info.type, &begin_str, &end_str);



		/* Stop if not on irq stack */

		if (!end_stack)

		if (begin_str && ops->stack(data, begin_str) < 0)

			break;



		/* The previous esp is saved on the bottom of the stack */

		prev_esp = (u32 *)(end_stack - THREAD_SIZE);

		stack = (unsigned long *)*prev_esp;

		if (!stack)

			break;

		bp = ops->walk_stack(task, stack, bp, ops, data, &info, &graph);



		if (ops->stack(data, "IRQ") < 0)

		if (end_str && ops->stack(data, end_str) < 0)

			break;



		stack = info.next_sp;



		touch_nmi_watchdog();

	}

}

arch/x86/kernel/dumpstack_64.c

+91 −78
Original line number Diff line number Diff line
@@ -28,76 +28,109 @@ static unsigned long exception_stack_sizes[N_EXCEPTION_STACKS] = { 
	[DEBUG_STACK - 1]			= DEBUG_STKSZ

};



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

					 char **idp)

void stack_type_str(enum stack_type type, const char **begin, const char **end)

{

	unsigned long begin, end;

	BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);



	switch (type) {

	case STACK_TYPE_IRQ:

		*begin = "IRQ";

		*end   = "EOI";

		break;

	case STACK_TYPE_EXCEPTION ... STACK_TYPE_EXCEPTION_LAST:

		*begin = exception_stack_names[type - STACK_TYPE_EXCEPTION];

		*end   = "EOE";

		break;

	default:

		*begin = NULL;

		*end   = NULL;

	}

}



static bool in_exception_stack(unsigned long *stack, struct stack_info *info,

			       unsigned long *visit_mask)

{

	unsigned long *begin, *end;

	struct pt_regs *regs;

	unsigned k;



	BUILD_BUG_ON(N_EXCEPTION_STACKS != 4);



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

		end   = raw_cpu_ptr(&orig_ist)->ist[k];

		begin = end - exception_stack_sizes[k];

		end   = (unsigned long *)raw_cpu_ptr(&orig_ist)->ist[k];

		begin = end - (exception_stack_sizes[k] / sizeof(long));

		regs  = (struct pt_regs *)end - 1;



		if (stack < begin || stack >= end)

			continue;



		/*

		 * Make sure we only iterate through an exception stack once.

		 * If it comes up for the second time then there's something

		 * wrong going on - just break and return NULL:

		 * Make sure we don't iterate through an exception stack more

		 * than once.  If it comes up a second time then there's

		 * something wrong going on - just break out and report an

		 * unknown stack type.

		 */

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

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

			break;

		*usedp |= 1U << k;

		*visit_mask |= 1U << k;



		*idp = exception_stack_names[k];

		return (unsigned long *)end;

		info->type	= STACK_TYPE_EXCEPTION + k;

		info->begin	= begin;

		info->end	= end;

		info->next_sp	= (unsigned long *)regs->sp;



		return true;

	}



	return NULL;

	return false;

}



static inline int

in_irq_stack(unsigned long *stack, unsigned long *irq_stack,

	     unsigned long *irq_stack_end)

static bool in_irq_stack(unsigned long *stack, struct stack_info *info)

{

	return (stack >= irq_stack && stack < irq_stack_end);

}

	unsigned long *end   = (unsigned long *)this_cpu_read(irq_stack_ptr);

	unsigned long *begin = end - (IRQ_STACK_SIZE / sizeof(long));



enum stack_type {

	STACK_IS_UNKNOWN,

	STACK_IS_NORMAL,

	STACK_IS_EXCEPTION,

	STACK_IS_IRQ,

};

	if (stack < begin || stack >= end)

		return false;



	info->type	= STACK_TYPE_IRQ;

	info->begin	= begin;

	info->end	= end;



	/*

	 * The next stack pointer is the first thing pushed by the entry code

	 * after switching to the irq stack.

	 */

	info->next_sp = (unsigned long *)*(end - 1);



static enum stack_type

analyze_stack(struct task_struct *task, unsigned long *stack,

	      unsigned long **stack_end, unsigned long *irq_stack,

	      unsigned *used, char **id)

	return true;

}



int get_stack_info(unsigned long *stack, struct task_struct *task,

		   struct stack_info *info, unsigned long *visit_mask)

{

	unsigned long addr;

	if (!stack)

		goto unknown;



	task = task ? : current;



	addr = ((unsigned long)stack & (~(THREAD_SIZE - 1)));

	if ((unsigned long)task_stack_page(task) == addr)

		return STACK_IS_NORMAL;

	if (in_task_stack(stack, task, info))

		return 0;



	*stack_end = in_exception_stack((unsigned long)stack, used, id);

	if (*stack_end)

		return STACK_IS_EXCEPTION;

	if (task != current)

		goto unknown;



	if (!irq_stack)

		return STACK_IS_NORMAL;

	if (in_exception_stack(stack, info, visit_mask))

		return 0;



	*stack_end = irq_stack;

	irq_stack -= (IRQ_STACK_SIZE / sizeof(long));

	if (in_irq_stack(stack, info))

		return 0;



	if (in_irq_stack(stack, irq_stack, *stack_end))

		return STACK_IS_IRQ;

	return 0;



	return STACK_IS_UNKNOWN;

unknown:

	info->type = STACK_TYPE_UNKNOWN;

	return -EINVAL;

}



/*
@@ -111,8 +144,8 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs, 
		unsigned long *stack, unsigned long bp,

		const struct stacktrace_ops *ops, void *data)

{

	unsigned long *irq_stack = (unsigned long *)this_cpu_read(irq_stack_ptr);

	unsigned used = 0;

	unsigned long visit_mask = 0;

	struct stack_info info;

	int graph = 0;

	int done = 0;
@@ -126,57 +159,37 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs, 
	 * exceptions

	 */

	while (!done) {

		unsigned long *stack_end;

		enum stack_type stype;

		char *id;

		const char *begin_str, *end_str;



		stype = analyze_stack(task, stack, &stack_end, irq_stack, &used,

				      &id);

		get_stack_info(stack, task, &info, &visit_mask);



		/* Default finish unless specified to continue */

		done = 1;



		switch (stype) {

		switch (info.type) {



		/* Break out early if we are on the thread stack */

		case STACK_IS_NORMAL:

		case STACK_TYPE_TASK:

			break;



		case STACK_IS_EXCEPTION:

		case STACK_TYPE_IRQ:

		case STACK_TYPE_EXCEPTION ... STACK_TYPE_EXCEPTION_LAST:



			if (ops->stack(data, id) < 0)

			stack_type_str(info.type, &begin_str, &end_str);



			if (ops->stack(data, begin_str) < 0)

				break;



			bp = ops->walk_stack(task, stack, bp, ops,

					     data, stack_end, &graph);

			ops->stack(data, "EOE");

			/*

			 * We link to the next stack via the

			 * second-to-last pointer (index -2 to end) in the

			 * exception stack:

			 */

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

			done = 0;

			break;

					     data, &info, &graph);



		case STACK_IS_IRQ:

			ops->stack(data, end_str);



			if (ops->stack(data, "IRQ") < 0)

				break;

			bp = ops->walk_stack(task, stack, bp,

				     ops, data, stack_end, &graph);

			/*

			 * We link to the next stack (which would be

			 * the process stack normally) the last

			 * pointer (index -1 to end) in the IRQ stack:

			 */

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

			irq_stack = NULL;

			ops->stack(data, "EOI");

			stack = info.next_sp;

			done = 0;

			break;



		case STACK_IS_UNKNOWN:

		default:

			ops->stack(data, "UNK");

			break;

		}
@@ -185,7 +198,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs, 
	/*

	 * This handles the process stack:

	 */

	bp = ops->walk_stack(task, stack, bp, ops, data, NULL, &graph);

	bp = ops->walk_stack(task, stack, bp, ops, data, &info, &graph);

}

EXPORT_SYMBOL(dump_trace);

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