1 /* SPDX-License-Identifier: GPL-2.0 */ 1
2 #ifndef _LINUX_TRACE_RECURSION_H
3 #define _LINUX_TRACE_RECURSION_H
4
5 #include <linux/interrupt.h>
6 #include <linux/sched.h>
7
8 #ifdef CONFIG_TRACING
9
10 /* Only current can touch trace_recursion */
11
12 /*
13 * For function tracing recursion:
14 * The order of these bits are important.
15 *
16 * When function tracing occurs, the followin
17 * If arch does not support a ftrace feature
18 * call internal function (uses INTERNAL bi
19 * The function callback, which can use the
20 * check for recursion.
21 */
22 enum {
23 /* Function recursion bits */
24 TRACE_FTRACE_BIT,
25 TRACE_FTRACE_NMI_BIT,
26 TRACE_FTRACE_IRQ_BIT,
27 TRACE_FTRACE_SIRQ_BIT,
28 TRACE_FTRACE_TRANSITION_BIT,
29
30 /* Internal use recursion bits */
31 TRACE_INTERNAL_BIT,
32 TRACE_INTERNAL_NMI_BIT,
33 TRACE_INTERNAL_IRQ_BIT,
34 TRACE_INTERNAL_SIRQ_BIT,
35 TRACE_INTERNAL_TRANSITION_BIT,
36
37 TRACE_BRANCH_BIT,
38 /*
39 * Abuse of the trace_recursion.
40 * As we need a way to maintain state if we ar
41 * graph in irq because we want to trace a par
42 * was called in irq context but we have irq t
43 * can only be modified by current, we can reu
44 */
45 TRACE_IRQ_BIT,
46
47 /* Used to prevent recursion recording
48 TRACE_RECORD_RECURSION_BIT,
49 };
50
51 #define trace_recursion_set(bit) do { (
52 #define trace_recursion_clear(bit) do { (
53 #define trace_recursion_test(bit) ((curr
54
55 #define TRACE_CONTEXT_BITS 4
56
57 #define TRACE_FTRACE_START TRACE_FTRACE_B
58
59 #define TRACE_LIST_START TRACE_INTERNAL
60
61 #define TRACE_CONTEXT_MASK ((1 << (TRACE_
62
63 /*
64 * Used for setting context
65 * NMI = 0
66 * IRQ = 1
67 * SOFTIRQ = 2
68 * NORMAL = 3
69 */
70 enum {
71 TRACE_CTX_NMI,
72 TRACE_CTX_IRQ,
73 TRACE_CTX_SOFTIRQ,
74 TRACE_CTX_NORMAL,
75 TRACE_CTX_TRANSITION,
76 };
77
78 static __always_inline int trace_get_context_b
79 {
80 unsigned char bit = interrupt_context_
81
82 return TRACE_CTX_NORMAL - bit;
83 }
84
85 #ifdef CONFIG_FTRACE_RECORD_RECURSION
86 extern void ftrace_record_recursion(unsigned l
87 # define do_ftrace_record_recursion(ip, pip)
88 do {
89 if (!trace_recursion_test(TRAC
90 trace_recursion_set(TR
91 ftrace_record_recursio
92 trace_recursion_clear(
93 }
94 } while (0)
95 #else
96 # define do_ftrace_record_recursion(ip, pip)
97 #endif
98
99 #ifdef CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING
100 # define trace_warn_on_no_rcu(ip)
101 ({
102 bool __ret = !rcu_is_watching(
103 if (__ret && !trace_recursion_
104 trace_recursion_set(TR
105 WARN_ONCE(true, "RCU n
106 trace_recursion_clear(
107 }
108 __ret;
109 })
110 #else
111 # define trace_warn_on_no_rcu(ip) false
112 #endif
113
114 /*
115 * Preemption is promised to be disabled when
116 */
117 static __always_inline int trace_test_and_set_
118
119 {
120 unsigned int val = READ_ONCE(current->
121 int bit;
122
123 if (trace_warn_on_no_rcu(ip))
124 return -1;
125
126 bit = trace_get_context_bit() + start;
127 if (unlikely(val & (1 << bit))) {
128 /*
129 * If an interrupt occurs duri
130 * happens in that interrupt b
131 * updated to reflect the new
132 * will think a recursion occu
133 * Let a single instance happe
134 * not drop those events.
135 */
136 bit = TRACE_CTX_TRANSITION + s
137 if (val & (1 << bit)) {
138 do_ftrace_record_recur
139 return -1;
140 }
141 }
142
143 val |= 1 << bit;
144 current->trace_recursion = val;
145 barrier();
146
147 preempt_disable_notrace();
148
149 return bit;
150 }
151
152 /*
153 * Preemption will be enabled (if it was previ
154 */
155 static __always_inline void trace_clear_recurs
156 {
157 preempt_enable_notrace();
158 barrier();
159 trace_recursion_clear(bit);
160 }
161
162 /**
163 * ftrace_test_recursion_trylock - tests for r
164 *
165 * Use this for ftrace callbacks. This will de
166 * tracing recursed in the same context (norma
167 *
168 * Returns: -1 if a recursion happened.
169 * >= 0 if no recursion.
170 */
171 static __always_inline int ftrace_test_recursi
172
173 {
174 return trace_test_and_set_recursion(ip
175 }
176
177 /**
178 * ftrace_test_recursion_unlock - called when
179 * @bit: The return of a successful ftrace_tes
180 *
181 * This is used at the end of a ftrace callbac
182 */
183 static __always_inline void ftrace_test_recurs
184 {
185 trace_clear_recursion(bit);
186 }
187
188 #endif /* CONFIG_TRACING */
189 #endif /* _LINUX_TRACE_RECURSION_H */
190
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.