1// SPDX-License-Identifier: GPL-2.0-only
 2#include <linux/sched.h>
 3#include <linux/ftrace.h>
 4#include <asm/ptrace.h>
 5#include <asm/bitops.h>
 6#include <asm/stacktrace.h>
 7#include <asm/unwind.h>
 8
 9unsigned long unwind_get_return_address(struct unwind_state *state)
10{
11	unsigned long addr;
12
13	if (unwind_done(state))
14		return 0;
15
16	addr = READ_ONCE_NOCHECK(*state->sp);
17
18	return ftrace_graph_ret_addr(state->task, &state->graph_idx,
19				     addr, state->sp);
20}
21EXPORT_SYMBOL_GPL(unwind_get_return_address);
22
23unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
24{
25	return NULL;
26}
27
28bool unwind_next_frame(struct unwind_state *state)
29{
30	struct stack_info *info = &state->stack_info;
31
32	if (unwind_done(state))
33		return false;
34
35	do {
36		for (state->sp++; state->sp < info->end; state->sp++) {
37			unsigned long addr = READ_ONCE_NOCHECK(*state->sp);
38
39			if (__kernel_text_address(addr))
40				return true;
41		}
42
43		state->sp = PTR_ALIGN(info->next_sp, sizeof(long));
44
45	} while (!get_stack_info(state->sp, state->task, info,
46				 &state->stack_mask));
47
48	return false;
49}
50EXPORT_SYMBOL_GPL(unwind_next_frame);
51
52void __unwind_start(struct unwind_state *state, struct task_struct *task,
53		    struct pt_regs *regs, unsigned long *first_frame)
54{
55	memset(state, 0, sizeof(*state));
56
57	state->task = task;
58	state->sp   = PTR_ALIGN(first_frame, sizeof(long));
59
60	get_stack_info(first_frame, state->task, &state->stack_info,
61		       &state->stack_mask);
62
63	/*
64	 * The caller can provide the address of the first frame directly
65	 * (first_frame) or indirectly (regs->sp) to indicate which stack frame
66	 * to start unwinding at.  Skip ahead until we reach it.
67	 */
68	if (!unwind_done(state) &&
69	    (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
70	    !__kernel_text_address(*first_frame)))
71		unwind_next_frame(state);
72}
73EXPORT_SYMBOL_GPL(__unwind_start);