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1 #ifndef LINUX_HARDIRQ_H
2 #define LINUX_HARDIRQ_H
3 
4 #include <linux/preempt.h>
5 #include <linux/lockdep.h>
6 #include <linux/ftrace_irq.h>
7 #include <linux/vtime.h>
8 #include <asm/hardirq.h>
9 
10 /*
11  * We put the hardirq and softirq counter into the preemption
12  * counter. The bitmask has the following meaning:
13  *
14  * - bits 0-7 are the preemption count (max preemption depth: 256)
15  * - bits 8-15 are the softirq count (max # of softirqs: 256)
16  *
17  * The hardirq count can in theory reach the same as NR_IRQS.
18  * In reality, the number of nested IRQS is limited to the stack
19  * size as well. For archs with over 1000 IRQS it is not practical
20  * to expect that they will all nest. We give a max of 10 bits for
21  * hardirq nesting. An arch may choose to give less than 10 bits.
22  * m68k expects it to be 8.
23  *
24  * - bits 16-25 are the hardirq count (max # of nested hardirqs: 1024)
25  * - bit 26 is the NMI_MASK
26  * - bit 27 is the PREEMPT_ACTIVE flag
27  *
28  * PREEMPT_MASK: 0x000000ff
29  * SOFTIRQ_MASK: 0x0000ff00
30  * HARDIRQ_MASK: 0x03ff0000
31  *     NMI_MASK: 0x04000000
32  */
33 #define PREEMPT_BITS	8
34 #define SOFTIRQ_BITS	8
35 #define NMI_BITS	1
36 
37 #define MAX_HARDIRQ_BITS 10
38 
39 #ifndef HARDIRQ_BITS
40 # define HARDIRQ_BITS	MAX_HARDIRQ_BITS
41 #endif
42 
43 #if HARDIRQ_BITS > MAX_HARDIRQ_BITS
44 #error HARDIRQ_BITS too high!
45 #endif
46 
47 #define PREEMPT_SHIFT	0
48 #define SOFTIRQ_SHIFT	(PREEMPT_SHIFT + PREEMPT_BITS)
49 #define HARDIRQ_SHIFT	(SOFTIRQ_SHIFT + SOFTIRQ_BITS)
50 #define NMI_SHIFT	(HARDIRQ_SHIFT + HARDIRQ_BITS)
51 
52 #define __IRQ_MASK(x)	((1UL << (x))-1)
53 
54 #define PREEMPT_MASK	(__IRQ_MASK(PREEMPT_BITS) << PREEMPT_SHIFT)
55 #define SOFTIRQ_MASK	(__IRQ_MASK(SOFTIRQ_BITS) << SOFTIRQ_SHIFT)
56 #define HARDIRQ_MASK	(__IRQ_MASK(HARDIRQ_BITS) << HARDIRQ_SHIFT)
57 #define NMI_MASK	(__IRQ_MASK(NMI_BITS)     << NMI_SHIFT)
58 
59 #define PREEMPT_OFFSET	(1UL << PREEMPT_SHIFT)
60 #define SOFTIRQ_OFFSET	(1UL << SOFTIRQ_SHIFT)
61 #define HARDIRQ_OFFSET	(1UL << HARDIRQ_SHIFT)
62 #define NMI_OFFSET	(1UL << NMI_SHIFT)
63 
64 #define SOFTIRQ_DISABLE_OFFSET	(2 * SOFTIRQ_OFFSET)
65 
66 #ifndef PREEMPT_ACTIVE
67 #define PREEMPT_ACTIVE_BITS	1
68 #define PREEMPT_ACTIVE_SHIFT	(NMI_SHIFT + NMI_BITS)
69 #define PREEMPT_ACTIVE	(__IRQ_MASK(PREEMPT_ACTIVE_BITS) << PREEMPT_ACTIVE_SHIFT)
70 #endif
71 
72 #if PREEMPT_ACTIVE < (1 << (NMI_SHIFT + NMI_BITS))
73 #error PREEMPT_ACTIVE is too low!
74 #endif
75 
76 #define hardirq_count()	(preempt_count() & HARDIRQ_MASK)
77 #define softirq_count()	(preempt_count() & SOFTIRQ_MASK)
78 #define irq_count()	(preempt_count() & (HARDIRQ_MASK | SOFTIRQ_MASK \
79 				 | NMI_MASK))
80 
81 /*
82  * Are we doing bottom half or hardware interrupt processing?
83  * Are we in a softirq context? Interrupt context?
84  * in_softirq - Are we currently processing softirq or have bh disabled?
85  * in_serving_softirq - Are we currently processing softirq?
86  */
87 #define in_irq()		(hardirq_count())
88 #define in_softirq()		(softirq_count())
89 #define in_interrupt()		(irq_count())
90 #define in_serving_softirq()	(softirq_count() & SOFTIRQ_OFFSET)
91 
92 /*
93  * Are we in NMI context?
94  */
95 #define in_nmi()	(preempt_count() & NMI_MASK)
96 
97 #if defined(CONFIG_PREEMPT_COUNT)
98 # define PREEMPT_CHECK_OFFSET 1
99 #else
100 # define PREEMPT_CHECK_OFFSET 0
101 #endif
102 
103 /*
104  * Are we running in atomic context?  WARNING: this macro cannot
105  * always detect atomic context; in particular, it cannot know about
106  * held spinlocks in non-preemptible kernels.  Thus it should not be
107  * used in the general case to determine whether sleeping is possible.
108  * Do not use in_atomic() in driver code.
109  */
110 #define in_atomic()	((preempt_count() & ~PREEMPT_ACTIVE) != 0)
111 
112 /*
113  * Check whether we were atomic before we did preempt_disable():
114  * (used by the scheduler, *after* releasing the kernel lock)
115  */
116 #define in_atomic_preempt_off() \
117 		((preempt_count() & ~PREEMPT_ACTIVE) != PREEMPT_CHECK_OFFSET)
118 
119 #ifdef CONFIG_PREEMPT_COUNT
120 # define preemptible()	(preempt_count() == 0 && !irqs_disabled())
121 #else
122 # define preemptible()	0
123 #endif
124 
125 #if defined(CONFIG_SMP) || defined(CONFIG_GENERIC_HARDIRQS)
126 extern void synchronize_irq(unsigned int irq);
127 #else
128 # define synchronize_irq(irq)	barrier()
129 #endif
130 
131 #if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU)
132 
rcu_nmi_enter(void)133 static inline void rcu_nmi_enter(void)
134 {
135 }
136 
rcu_nmi_exit(void)137 static inline void rcu_nmi_exit(void)
138 {
139 }
140 
141 #else
142 extern void rcu_nmi_enter(void);
143 extern void rcu_nmi_exit(void);
144 #endif
145 
146 /*
147  * It is safe to do non-atomic ops on ->hardirq_context,
148  * because NMI handlers may not preempt and the ops are
149  * always balanced, so the interrupted value of ->hardirq_context
150  * will always be restored.
151  */
152 #define __irq_enter()					\
153 	do {						\
154 		account_irq_enter_time(current);	\
155 		add_preempt_count(HARDIRQ_OFFSET);	\
156 		trace_hardirq_enter();			\
157 	} while (0)
158 
159 /*
160  * Enter irq context (on NO_HZ, update jiffies):
161  */
162 extern void irq_enter(void);
163 
164 /*
165  * Exit irq context without processing softirqs:
166  */
167 #define __irq_exit()					\
168 	do {						\
169 		trace_hardirq_exit();			\
170 		account_irq_exit_time(current);		\
171 		sub_preempt_count(HARDIRQ_OFFSET);	\
172 	} while (0)
173 
174 /*
175  * Exit irq context and process softirqs if needed:
176  */
177 extern void irq_exit(void);
178 
179 #define nmi_enter()						\
180 	do {							\
181 		lockdep_off();					\
182 		ftrace_nmi_enter();				\
183 		BUG_ON(in_nmi());				\
184 		add_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET);	\
185 		rcu_nmi_enter();				\
186 		trace_hardirq_enter();				\
187 	} while (0)
188 
189 #define nmi_exit()						\
190 	do {							\
191 		trace_hardirq_exit();				\
192 		rcu_nmi_exit();					\
193 		BUG_ON(!in_nmi());				\
194 		sub_preempt_count(NMI_OFFSET + HARDIRQ_OFFSET);	\
195 		ftrace_nmi_exit();				\
196 		lockdep_on();					\
197 	} while (0)
198 
199 #endif /* LINUX_HARDIRQ_H */
200