1#include <linux/sched.h>
 2#include <linux/ftrace.h>
 3#include <asm/ptrace.h>
 4#include <asm/bitops.h>
 5#include <asm/stacktrace.h>
 6#include <asm/unwind.h>
 7
 8unsigned long unwind_get_return_address(struct unwind_state *state)
 9{
10	unsigned long addr;
11
12	if (unwind_done(state))
13		return 0;
14
15	addr = READ_ONCE_NOCHECK(*state->sp);
16
17	return ftrace_graph_ret_addr(state->task, &state->graph_idx,
18				     addr, state->sp);
19}
20EXPORT_SYMBOL_GPL(unwind_get_return_address);
21
22bool unwind_next_frame(struct unwind_state *state)
23{
24	struct stack_info *info = &state->stack_info;
25
26	if (unwind_done(state))
27		return false;
28
29	do {
30		for (state->sp++; state->sp < info->end; state->sp++) {
31			unsigned long addr = READ_ONCE_NOCHECK(*state->sp);
32
33			if (__kernel_text_address(addr))
34				return true;
35		}
36
37		state->sp = info->next_sp;
38
39	} while (!get_stack_info(state->sp, state->task, info,
40				 &state->stack_mask));
41
42	return false;
43}
44EXPORT_SYMBOL_GPL(unwind_next_frame);
45
46void __unwind_start(struct unwind_state *state, struct task_struct *task,
47		    struct pt_regs *regs, unsigned long *first_frame)
48{
49	memset(state, 0, sizeof(*state));
50
51	state->task = task;
52	state->sp   = first_frame;
53
54	get_stack_info(first_frame, state->task, &state->stack_info,
55		       &state->stack_mask);
56
57	/*
58	 * The caller can provide the address of the first frame directly
59	 * (first_frame) or indirectly (regs->sp) to indicate which stack frame
60	 * to start unwinding at.  Skip ahead until we reach it.
61	 */
62	if (!unwind_done(state) &&
63	    (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
64	    !__kernel_text_address(*first_frame)))
65		unwind_next_frame(state);
66}
67EXPORT_SYMBOL_GPL(__unwind_start);