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 unwind_recover_ret_addr(state, addr, state->sp);
19}
20EXPORT_SYMBOL_GPL(unwind_get_return_address);
21
22unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
23{
24	return NULL;
25}
26
27bool unwind_next_frame(struct unwind_state *state)
28{
29	struct stack_info *info = &state->stack_info;
30
31	if (unwind_done(state))
32		return false;
33
34	do {
35		for (state->sp++; state->sp < info->end; state->sp++) {
36			unsigned long addr = READ_ONCE_NOCHECK(*state->sp);
37
38			if (__kernel_text_address(addr))
39				return true;
40		}
41
42		state->sp = PTR_ALIGN(info->next_sp, sizeof(long));
43
44	} while (!get_stack_info(state->sp, state->task, info,
45				 &state->stack_mask));
46
47	return false;
48}
49EXPORT_SYMBOL_GPL(unwind_next_frame);
50
51void __unwind_start(struct unwind_state *state, struct task_struct *task,
52		    struct pt_regs *regs, unsigned long *first_frame)
53{
54	memset(state, 0, sizeof(*state));
55
56	state->task = task;
57	state->sp   = PTR_ALIGN(first_frame, sizeof(long));
58
59	get_stack_info(first_frame, state->task, &state->stack_info,
60		       &state->stack_mask);
61
62	/*
63	 * The caller can provide the address of the first frame directly
64	 * (first_frame) or indirectly (regs->sp) to indicate which stack frame
65	 * to start unwinding at.  Skip ahead until we reach it.
66	 */
67	if (!unwind_done(state) &&
68	    (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
69	    !__kernel_text_address(*first_frame)))
70		unwind_next_frame(state);
71}
72EXPORT_SYMBOL_GPL(__unwind_start);
73