1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Stack trace management functions
4 *
5 * Copyright (C) 2022 Loongson Technology Corporation Limited
6 */
7#include <linux/sched.h>
8#include <linux/stacktrace.h>
9#include <linux/uaccess.h>
10
11#include <asm/stacktrace.h>
12#include <asm/unwind.h>
13
14void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
15 struct task_struct *task, struct pt_regs *regs)
16{
17 unsigned long addr;
18 struct pt_regs dummyregs;
19 struct unwind_state state;
20
21 if (!regs) {
22 regs = &dummyregs;
23
24 if (task == current) {
25 regs->regs[3] = (unsigned long)__builtin_frame_address(0);
26 regs->csr_era = (unsigned long)__builtin_return_address(0);
27 } else {
28 regs->regs[3] = thread_saved_fp(task);
29 regs->csr_era = thread_saved_ra(task);
30 }
31 regs->regs[1] = 0;
32 regs->regs[22] = 0;
33 }
34
35 for (unwind_start(&state, task, regs);
36 !unwind_done(state: &state); unwind_next_frame(state: &state)) {
37 addr = unwind_get_return_address(state: &state);
38 if (!addr || !consume_entry(cookie, addr))
39 break;
40 }
41}
42
43int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
44 void *cookie, struct task_struct *task)
45{
46 unsigned long addr;
47 struct pt_regs dummyregs;
48 struct pt_regs *regs = &dummyregs;
49 struct unwind_state state;
50
51 if (task == current) {
52 regs->regs[3] = (unsigned long)__builtin_frame_address(0);
53 regs->csr_era = (unsigned long)__builtin_return_address(0);
54 regs->regs[22] = 0;
55 } else {
56 regs->regs[3] = thread_saved_fp(task);
57 regs->csr_era = thread_saved_ra(task);
58 regs->regs[22] = task->thread.reg22;
59 }
60 regs->regs[1] = 0;
61
62 for (unwind_start(&state, task, regs);
63 !unwind_done(state: &state) && !unwind_error(state: &state); unwind_next_frame(state: &state)) {
64 addr = unwind_get_return_address(state: &state);
65
66 /*
67 * A NULL or invalid return address probably means there's some
68 * generated code which __kernel_text_address() doesn't know about.
69 */
70 if (!addr)
71 return -EINVAL;
72
73 if (!consume_entry(cookie, addr))
74 return -EINVAL;
75 }
76
77 /* Check for stack corruption */
78 if (unwind_error(state: &state))
79 return -EINVAL;
80
81 return 0;
82}
83
84static int
85copy_stack_frame(unsigned long fp, struct stack_frame *frame)
86{
87 int ret = 1;
88 unsigned long err;
89 unsigned long __user *user_frame_tail;
90
91 user_frame_tail = (unsigned long *)(fp - sizeof(struct stack_frame));
92 if (!access_ok(user_frame_tail, sizeof(*frame)))
93 return 0;
94
95 pagefault_disable();
96 err = (__copy_from_user_inatomic(to: frame, from: user_frame_tail, n: sizeof(*frame)));
97 if (err || (unsigned long)user_frame_tail >= frame->fp)
98 ret = 0;
99 pagefault_enable();
100
101 return ret;
102}
103
104void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
105 const struct pt_regs *regs)
106{
107 unsigned long fp = regs->regs[22];
108
109 while (fp && !((unsigned long)fp & 0xf)) {
110 struct stack_frame frame;
111
112 frame.fp = 0;
113 frame.ra = 0;
114 if (!copy_stack_frame(fp, frame: &frame))
115 break;
116 if (!frame.ra)
117 break;
118 if (!consume_entry(cookie, frame.ra))
119 break;
120 fp = frame.fp;
121 }
122}
123

source code of linux/arch/loongarch/kernel/stacktrace.c