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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/stacktrace.h>
8#include <linux/export.h>
9#include <linux/uaccess.h>
10#include <asm/stacktrace.h>
11#include <asm/unwind.h>
12
13static int save_stack_address(struct stack_trace *trace, unsigned long addr,
14 bool nosched)
15{
16 if (nosched && in_sched_functions(addr))
17 return 0;
18
19 if (trace->skip > 0) {
20 trace->skip--;
21 return 0;
22 }
23
24 if (trace->nr_entries >= trace->max_entries)
25 return -1;
26
27 trace->entries[trace->nr_entries++] = addr;
28 return 0;
29}
30
31static void __save_stack_trace(struct stack_trace *trace,
32 struct task_struct *task, struct pt_regs *regs,
33 bool nosched)
34{
35 struct unwind_state state;
36 unsigned long addr;
37
38 if (regs)
39 save_stack_address(trace, regs->ip, nosched);
40
41 for (unwind_start(&state, task, regs, NULL); !unwind_done(&state);
42 unwind_next_frame(&state)) {
43 addr = unwind_get_return_address(&state);
44 if (!addr || save_stack_address(trace, addr, nosched))
45 break;
46 }
47
48 if (trace->nr_entries < trace->max_entries)
49 trace->entries[trace->nr_entries++] = ULONG_MAX;
50}
51
52/*
53 * Save stack-backtrace addresses into a stack_trace buffer.
54 */
55void save_stack_trace(struct stack_trace *trace)
56{
57 __save_stack_trace(trace, current, NULL, false);
58}
59EXPORT_SYMBOL_GPL(save_stack_trace);
60
61void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
62{
63 __save_stack_trace(trace, current, regs, false);
64}
65
66void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
67{
68 if (!try_get_task_stack(tsk))
69 return;
70
71 __save_stack_trace(trace, tsk, NULL, true);
72
73 put_task_stack(tsk);
74}
75EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
76
77/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
78
79struct stack_frame_user {
80 const void __user *next_fp;
81 unsigned long ret_addr;
82};
83
84static int
85copy_stack_frame(const void __user *fp, struct stack_frame_user *frame)
86{
87 int ret;
88
89 if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
90 return 0;
91
92 ret = 1;
93 pagefault_disable();
94 if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
95 ret = 0;
96 pagefault_enable();
97
98 return ret;
99}
100
101static inline void __save_stack_trace_user(struct stack_trace *trace)
102{
103 const struct pt_regs *regs = task_pt_regs(current);
104 const void __user *fp = (const void __user *)regs->bp;
105
106 if (trace->nr_entries < trace->max_entries)
107 trace->entries[trace->nr_entries++] = regs->ip;
108
109 while (trace->nr_entries < trace->max_entries) {
110 struct stack_frame_user frame;
111
112 frame.next_fp = NULL;
113 frame.ret_addr = 0;
114 if (!copy_stack_frame(fp, &frame))
115 break;
116 if ((unsigned long)fp < regs->sp)
117 break;
118 if (frame.ret_addr) {
119 trace->entries[trace->nr_entries++] =
120 frame.ret_addr;
121 }
122 if (fp == frame.next_fp)
123 break;
124 fp = frame.next_fp;
125 }
126}
127
128void save_stack_trace_user(struct stack_trace *trace)
129{
130 /*
131 * Trace user stack if we are not a kernel thread
132 */
133 if (current->mm) {
134 __save_stack_trace_user(trace);
135 }
136 if (trace->nr_entries < trace->max_entries)
137 trace->entries[trace->nr_entries++] = ULONG_MAX;
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/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 if (IS_ENABLED(CONFIG_FRAME_POINTER))
62 return -EINVAL;
63 }
64
65 addr = unwind_get_return_address(&state);
66
67 /*
68 * A NULL or invalid return address probably means there's some
69 * generated code which __kernel_text_address() doesn't know
70 * about.
71 */
72 if (!addr)
73 return -EINVAL;
74
75 if (!consume_entry(cookie, addr, false))
76 return -EINVAL;
77 }
78
79 /* Check for stack corruption */
80 if (unwind_error(&state))
81 return -EINVAL;
82
83 return 0;
84}
85
86/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
87
88struct stack_frame_user {
89 const void __user *next_fp;
90 unsigned long ret_addr;
91};
92
93static int
94copy_stack_frame(const struct stack_frame_user __user *fp,
95 struct stack_frame_user *frame)
96{
97 int ret;
98
99 if (__range_not_ok(fp, sizeof(*frame), TASK_SIZE))
100 return 0;
101
102 ret = 1;
103 pagefault_disable();
104 if (__get_user(frame->next_fp, &fp->next_fp) ||
105 __get_user(frame->ret_addr, &fp->ret_addr))
106 ret = 0;
107 pagefault_enable();
108
109 return ret;
110}
111
112void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
113 const struct pt_regs *regs)
114{
115 const void __user *fp = (const void __user *)regs->bp;
116
117 if (!consume_entry(cookie, regs->ip, false))
118 return;
119
120 while (1) {
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 break;
131 if (!consume_entry(cookie, frame.ret_addr, false))
132 break;
133 fp = frame.next_fp;
134 }
135}
136