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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, false))
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, false))
28 break;
29 }
30}
31
32/*
33 * This function returns an error if it detects any unreliable features of the
34 * stack. Otherwise it guarantees that the stack trace is reliable.
35 *
36 * If the task is not 'current', the caller *must* ensure the task is inactive.
37 */
38int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
39 void *cookie, struct task_struct *task)
40{
41 struct unwind_state state;
42 struct pt_regs *regs;
43 unsigned long addr;
44
45 for (unwind_start(&state, task, NULL, NULL);
46 !unwind_done(&state) && !unwind_error(&state);
47 unwind_next_frame(&state)) {
48
49 regs = unwind_get_entry_regs(&state, NULL);
50 if (regs) {
51 /* Success path for user tasks */
52 if (user_mode(regs))
53 return 0;
54
55 /*
56 * Kernel mode registers on the stack indicate an
57 * in-kernel interrupt or exception (e.g., preemption
58 * or a page fault), which can make frame pointers
59 * unreliable.
60 */
61
62 if (IS_ENABLED(CONFIG_FRAME_POINTER))
63 return -EINVAL;
64 }
65
66 addr = unwind_get_return_address(&state);
67
68 /*
69 * A NULL or invalid return address probably means there's some
70 * generated code which __kernel_text_address() doesn't know
71 * about.
72 */
73 if (!addr)
74 return -EINVAL;
75
76 if (!consume_entry(cookie, addr, false))
77 return -EINVAL;
78 }
79
80 /* Check for stack corruption */
81 if (unwind_error(&state))
82 return -EINVAL;
83
84 /* Success path for non-user tasks, i.e. kthreads and idle tasks */
85 if (!(task->flags & (PF_KTHREAD | PF_IDLE)))
86 return -EINVAL;
87
88 return 0;
89}
90
91/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
92
93struct stack_frame_user {
94 const void __user *next_fp;
95 unsigned long ret_addr;
96};
97
98static int
99copy_stack_frame(const void __user *fp, struct stack_frame_user *frame)
100{
101 int ret;
102
103 if (__range_not_ok(fp, sizeof(*frame), TASK_SIZE))
104 return 0;
105
106 ret = 1;
107 pagefault_disable();
108 if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
109 ret = 0;
110 pagefault_enable();
111
112 return ret;
113}
114
115void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
116 const struct pt_regs *regs)
117{
118 const void __user *fp = (const void __user *)regs->bp;
119
120 if (!consume_entry(cookie, regs->ip, false))
121 return;
122
123 while (1) {
124 struct stack_frame_user frame;
125
126 frame.next_fp = NULL;
127 frame.ret_addr = 0;
128 if (!copy_stack_frame(fp, &frame))
129 break;
130 if ((unsigned long)fp < regs->sp)
131 break;
132 if (!frame.ret_addr)
133 break;
134 if (!consume_entry(cookie, frame.ret_addr, false))
135 break;
136 fp = frame.next_fp;
137 }
138}
139
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