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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, task, regs, NULL); !unwind_done(&state);
25 unwind_next_frame(&state)) {
26 addr = unwind_get_return_address(&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, task, NULL, NULL);
40 !unwind_done(&state) && !unwind_error(&state);
41 unwind_next_frame(&state)) {
42
43 regs = unwind_get_entry_regs(&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);
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))
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(fp, 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))
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
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/stacktrace.h>
8#include <linux/module.h>
9#include <linux/uaccess.h>
10#include <asm/stacktrace.h>
11
12static int save_stack_stack(void *data, char *name)
13{
14 return 0;
15}
16
17static int
18__save_stack_address(void *data, unsigned long addr, bool reliable, bool nosched)
19{
20 struct stack_trace *trace = data;
21#ifdef CONFIG_FRAME_POINTER
22 if (!reliable)
23 return 0;
24#endif
25 if (nosched && in_sched_functions(addr))
26 return 0;
27 if (trace->skip > 0) {
28 trace->skip--;
29 return 0;
30 }
31 if (trace->nr_entries < trace->max_entries) {
32 trace->entries[trace->nr_entries++] = addr;
33 return 0;
34 } else {
35 return -1; /* no more room, stop walking the stack */
36 }
37}
38
39static int save_stack_address(void *data, unsigned long addr, int reliable)
40{
41 return __save_stack_address(data, addr, reliable, false);
42}
43
44static int
45save_stack_address_nosched(void *data, unsigned long addr, int reliable)
46{
47 return __save_stack_address(data, addr, reliable, true);
48}
49
50static const struct stacktrace_ops save_stack_ops = {
51 .stack = save_stack_stack,
52 .address = save_stack_address,
53 .walk_stack = print_context_stack,
54};
55
56static const struct stacktrace_ops save_stack_ops_nosched = {
57 .stack = save_stack_stack,
58 .address = save_stack_address_nosched,
59 .walk_stack = print_context_stack,
60};
61
62/*
63 * Save stack-backtrace addresses into a stack_trace buffer.
64 */
65void save_stack_trace(struct stack_trace *trace)
66{
67 dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace);
68 if (trace->nr_entries < trace->max_entries)
69 trace->entries[trace->nr_entries++] = ULONG_MAX;
70}
71EXPORT_SYMBOL_GPL(save_stack_trace);
72
73void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
74{
75 dump_trace(current, regs, NULL, 0, &save_stack_ops, trace);
76 if (trace->nr_entries < trace->max_entries)
77 trace->entries[trace->nr_entries++] = ULONG_MAX;
78}
79
80void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
81{
82 dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
83 if (trace->nr_entries < trace->max_entries)
84 trace->entries[trace->nr_entries++] = ULONG_MAX;
85}
86EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
87
88/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
89
90struct stack_frame_user {
91 const void __user *next_fp;
92 unsigned long ret_addr;
93};
94
95static int
96copy_stack_frame(const void __user *fp, struct stack_frame_user *frame)
97{
98 int ret;
99
100 if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
101 return 0;
102
103 ret = 1;
104 pagefault_disable();
105 if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
106 ret = 0;
107 pagefault_enable();
108
109 return ret;
110}
111
112static inline void __save_stack_trace_user(struct stack_trace *trace)
113{
114 const struct pt_regs *regs = task_pt_regs(current);
115 const void __user *fp = (const void __user *)regs->bp;
116
117 if (trace->nr_entries < trace->max_entries)
118 trace->entries[trace->nr_entries++] = regs->ip;
119
120 while (trace->nr_entries < trace->max_entries) {
121 struct stack_frame_user frame;
122
123 frame.next_fp = NULL;
124 frame.ret_addr = 0;
125 if (!copy_stack_frame(fp, &frame))
126 break;
127 if ((unsigned long)fp < regs->sp)
128 break;
129 if (frame.ret_addr) {
130 trace->entries[trace->nr_entries++] =
131 frame.ret_addr;
132 }
133 if (fp == frame.next_fp)
134 break;
135 fp = frame.next_fp;
136 }
137}
138
139void save_stack_trace_user(struct stack_trace *trace)
140{
141 /*
142 * Trace user stack if we are not a kernel thread
143 */
144 if (current->mm) {
145 __save_stack_trace_user(trace);
146 }
147 if (trace->nr_entries < trace->max_entries)
148 trace->entries[trace->nr_entries++] = ULONG_MAX;
149}
150