// SPDX-License-Identifier: GPL-2.0-only/* * Copyright (C) 2008 ARM Limited * Copyright (C) 2014 Regents of the University of California */ #include <linux/export.h>#include <linux/kallsyms.h>#include <linux/sched.h>#include <linux/sched/debug.h>#include <linux/sched/task_stack.h>#include <linux/stacktrace.h>#include <linux/ftrace.h> #include <asm/stacktrace.h> #ifdef CONFIG_FRAME_POINTER /* * This disables KASAN checking when reading a value from another task's stack, * since the other task could be running on another CPU and could have poisoned * the stack in the meantime. */#define READ_ONCE_TASK_STACK(task, x)			\({							\	unsigned long val;				\	unsigned long addr = x;				\	if ((task) == current)				\		val = READ_ONCE(addr);			\	else						\		val = READ_ONCE_NOCHECK(addr);		\	val;						\}) extern asmlinkage void handle_exception(void);extern unsigned long ret_from_exception_end; static inline int fp_is_valid(unsigned long fp, unsigned long sp){	unsigned long low, high; 	low = sp + sizeof(struct stackframe);	high = ALIGN(sp, THREAD_SIZE); 	return !(fp < low || fp > high || fp & 0x07);} void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,			     bool (*fn)(void *, unsigned long), void *arg){	unsigned long fp, sp, pc;	int graph_idx = 0;	int level = 0; 	if (regs) {		fp = frame_pointer(regs);		sp = user_stack_pointer(regs);		pc = instruction_pointer(regs);	} else if (task == NULL || task == current) {		fp = (unsigned long)__builtin_frame_address(0);		sp = current_stack_pointer;		pc = (unsigned long)walk_stackframe;		level = -1;	} else {		/* task blocked in __switch_to */		fp = task->thread.s[0];		sp = task->thread.sp;		pc = task->thread.ra;	} 	for (;;) {		struct stackframe *frame; 		if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc))))			break; 		if (unlikely(!fp_is_valid(fp, sp)))			break; 		/* Unwind stack frame */		frame = (struct stackframe *)fp - 1;		sp = fp;		if (regs && (regs->epc == pc) && fp_is_valid(frame->ra, sp)) {			/* We hit function where ra is not saved on the stack */			fp = frame->ra;			pc = regs->ra;		} else {			fp = READ_ONCE_TASK_STACK(task, frame->fp);			pc = READ_ONCE_TASK_STACK(task, frame->ra);			pc = ftrace_graph_ret_addr(task, &graph_idx, pc,						   &frame->ra);			if (pc >= (unsigned long)handle_exception &&			    pc < (unsigned long)&ret_from_exception_end) {				if (unlikely(!fn(arg, pc)))					break; 				pc = ((struct pt_regs *)sp)->epc;				fp = ((struct pt_regs *)sp)->s0;			}		} 	}} #else /* !CONFIG_FRAME_POINTER */ void notrace walk_stackframe(struct task_struct *task,	struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg){	unsigned long sp, pc;	unsigned long *ksp; 	if (regs) {		sp = user_stack_pointer(regs);		pc = instruction_pointer(regs);	} else if (task == NULL || task == current) {		sp = current_stack_pointer;		pc = (unsigned long)walk_stackframe;	} else {		/* task blocked in __switch_to */		sp = task->thread.sp;		pc = task->thread.ra;	} 	if (unlikely(sp & 0x7))		return; 	ksp = (unsigned long *)sp;	while (!kstack_end(ksp)) {		if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))			break;		pc = READ_ONCE_NOCHECK(*ksp++);	}} #endif /* CONFIG_FRAME_POINTER */ static bool print_trace_address(void *arg, unsigned long pc){	const char *loglvl = arg; 	print_ip_sym(loglvl, pc);	return true;} noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,		    const char *loglvl){	walk_stackframe(task, regs, print_trace_address, (void *)loglvl);} void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl){	pr_cont("%sCall Trace:\n", loglvl);	dump_backtrace(NULL, task, loglvl);} static bool save_wchan(void *arg, unsigned long pc){	if (!in_sched_functions(pc)) {		unsigned long *p = arg;		*p = pc;		return false;	}	return true;} unsigned long __get_wchan(struct task_struct *task){	unsigned long pc = 0; 	if (!try_get_task_stack(task))		return 0;	walk_stackframe(task, NULL, save_wchan, &pc);	put_task_stack(task);	return pc;} noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,		     struct task_struct *task, struct pt_regs *regs){	walk_stackframe(task, regs, consume_entry, cookie);} /* * Get the return address for a single stackframe and return a pointer to the * next frame tail. */static unsigned long unwind_user_frame(stack_trace_consume_fn consume_entry,				       void *cookie, unsigned long fp,				       unsigned long reg_ra){	struct stackframe buftail;	unsigned long ra = 0;	unsigned long __user *user_frame_tail =		(unsigned long __user *)(fp - sizeof(struct stackframe)); 	/* Check accessibility of one struct frame_tail beyond */	if (!access_ok(user_frame_tail, sizeof(buftail)))		return 0;	if (__copy_from_user_inatomic(&buftail, user_frame_tail,				      sizeof(buftail)))		return 0; 	ra = reg_ra ? : buftail.ra; 	fp = buftail.fp;	if (!ra || !consume_entry(cookie, ra))		return 0; 	return fp;} void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,			  const struct pt_regs *regs){	unsigned long fp = 0; 	fp = regs->s0;	if (!consume_entry(cookie, regs->epc))		return; 	fp = unwind_user_frame(consume_entry, cookie, fp, regs->ra);	while (fp && !(fp & 0x7))		fp = unwind_user_frame(consume_entry, cookie, fp, 0);}