1/*
2 * Stack trace management functions
3 *
4 * Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
5 */
6#include <linux/sched.h>
7#include <linux/sched/debug.h>
8#include <linux/sched/task_stack.h>
9#include <linux/stacktrace.h>
10#include <linux/export.h>
11#include <linux/uaccess.h>
12#include <asm/stacktrace.h>
13#include <asm/unwind.h>
14
15void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
16 struct task_struct *task, struct pt_regs *regs)
17{
18 struct unwind_state state;
19 unsigned long addr;
20
21 if (regs && !consume_entry(cookie, regs->ip))
22 return;
23
24 for (unwind_start(state: &state, task, regs, NULL); !unwind_done(state: &state);
25 unwind_next_frame(state: &state)) {
26 addr = unwind_get_return_address(state: &state);
27 if (!addr || !consume_entry(cookie, addr))
28 break;
29 }
30}
31
32int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
33 void *cookie, struct task_struct *task)
34{
35 struct unwind_state state;
36 struct pt_regs *regs;
37 unsigned long addr;
38
39 for (unwind_start(state: &state, task, NULL, NULL);
40 !unwind_done(state: &state) && !unwind_error(state: &state);
41 unwind_next_frame(state: &state)) {
42
43 regs = unwind_get_entry_regs(state: &state, NULL);
44 if (regs) {
45 /* Success path for user tasks */
46 if (user_mode(regs))
47 return 0;
48
49 /*
50 * Kernel mode registers on the stack indicate an
51 * in-kernel interrupt or exception (e.g., preemption
52 * or a page fault), which can make frame pointers
53 * unreliable.
54 */
55 if (IS_ENABLED(CONFIG_FRAME_POINTER))
56 return -EINVAL;
57 }
58
59 addr = unwind_get_return_address(state: &state);
60
61 /*
62 * A NULL or invalid return address probably means there's some
63 * generated code which __kernel_text_address() doesn't know
64 * about.
65 */
66 if (!addr)
67 return -EINVAL;
68
69 if (!consume_entry(cookie, addr))
70 return -EINVAL;
71 }
72
73 /* Check for stack corruption */
74 if (unwind_error(state: &state))
75 return -EINVAL;
76
77 return 0;
78}
79
80/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
81
82struct stack_frame_user {
83 const void __user *next_fp;
84 unsigned long ret_addr;
85};
86
87static int
88copy_stack_frame(const struct stack_frame_user __user *fp,
89 struct stack_frame_user *frame)
90{
91 int ret;
92
93 if (!__access_ok(ptr: fp, size: sizeof(*frame)))
94 return 0;
95
96 ret = 1;
97 pagefault_disable();
98 if (__get_user(frame->next_fp, &fp->next_fp) ||
99 __get_user(frame->ret_addr, &fp->ret_addr))
100 ret = 0;
101 pagefault_enable();
102
103 return ret;
104}
105
106void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
107 const struct pt_regs *regs)
108{
109 const void __user *fp = (const void __user *)regs->bp;
110
111 if (!consume_entry(cookie, regs->ip))
112 return;
113
114 while (1) {
115 struct stack_frame_user frame;
116
117 frame.next_fp = NULL;
118 frame.ret_addr = 0;
119 if (!copy_stack_frame(fp, frame: &frame))
120 break;
121 if ((unsigned long)fp < regs->sp)
122 break;
123 if (!frame.ret_addr)
124 break;
125 if (!consume_entry(cookie, frame.ret_addr))
126 break;
127 fp = frame.next_fp;
128 }
129}
130
131