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
9 unsigned 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 }
20 EXPORT_SYMBOL_GPL(unwind_get_return_address);
21
22 unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
23 {
24 return NULL;
25 }
26
27 bool 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 }
49 EXPORT_SYMBOL_GPL(unwind_next_frame);
50
51 void __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 }
72 EXPORT_SYMBOL_GPL(__unwind_start);
73
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