#include <linux/export.h>#include <linux/sched.h>#include <linux/stacktrace.h> #include <asm/stacktrace.h> #if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)/* * Unwind the current stack frame and store the new register values in the * structure passed as argument. Unwinding is equivalent to a function return, * hence the new PC value rather than LR should be used for backtrace. * * With framepointer enabled, a simple function prologue looks like this: *	mov	ip, sp *	stmdb	sp!, {fp, ip, lr, pc} *	sub	fp, ip, #4 * * A simple function epilogue looks like this: *	ldm	sp, {fp, sp, pc} * * Note that with framepointer enabled, even the leaf functions have the same * prologue and epilogue, therefore we can ignore the LR value in this case. */int notrace unwind_frame(struct stackframe *frame){	unsigned long high, low;	unsigned long fp = frame->fp; 	/* only go to a higher address on the stack */	low = frame->sp;	high = ALIGN(low, THREAD_SIZE); 	/* check current frame pointer is within bounds */	if (fp < (low + 12) || fp + 4 >= high)		return -EINVAL; 	/* restore the registers from the stack frame */	frame->fp = *(unsigned long *)(fp - 12);	frame->sp = *(unsigned long *)(fp - 8);	frame->pc = *(unsigned long *)(fp - 4); 	return 0;}#endif void notrace walk_stackframe(struct stackframe *frame,		     int (*fn)(struct stackframe *, void *), void *data){	while (1) {		int ret; 		if (fn(frame, data))			break;		ret = unwind_frame(frame);		if (ret < 0)			break;	}}EXPORT_SYMBOL(walk_stackframe); #ifdef CONFIG_STACKTRACEstruct stack_trace_data {	struct stack_trace *trace;	unsigned int no_sched_functions;	unsigned int skip;}; static int save_trace(struct stackframe *frame, void *d){	struct stack_trace_data *data = d;	struct stack_trace *trace = data->trace;	unsigned long addr = frame->pc; 	if (data->no_sched_functions && in_sched_functions(addr))		return 0;	if (data->skip) {		data->skip--;		return 0;	} 	trace->entries[trace->nr_entries++] = addr; 	return trace->nr_entries >= trace->max_entries;} void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace){	struct stack_trace_data data;	struct stackframe frame; 	data.trace = trace;	data.skip = trace->skip; 	if (tsk != current) {#ifdef CONFIG_SMP		/*		 * What guarantees do we have here that 'tsk' is not		 * running on another CPU?  For now, ignore it as we		 * can't guarantee we won't explode.		 */		if (trace->nr_entries < trace->max_entries)			trace->entries[trace->nr_entries++] = ULONG_MAX;		return;#else		data.no_sched_functions = 1;		frame.fp = thread_saved_fp(tsk);		frame.sp = thread_saved_sp(tsk);		frame.lr = 0;		/* recovered from the stack */		frame.pc = thread_saved_pc(tsk);#endif	} else {		register unsigned long current_sp asm ("sp"); 		data.no_sched_functions = 0;		frame.fp = (unsigned long)__builtin_frame_address(0);		frame.sp = current_sp;		frame.lr = (unsigned long)__builtin_return_address(0);		frame.pc = (unsigned long)save_stack_trace_tsk;	} 	walk_stackframe(&frame, save_trace, &data);	if (trace->nr_entries < trace->max_entries)		trace->entries[trace->nr_entries++] = ULONG_MAX;} void save_stack_trace(struct stack_trace *trace){	save_stack_trace_tsk(current, trace);}EXPORT_SYMBOL_GPL(save_stack_trace);#endif