1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
|
/*
* Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
*
* This file contains the lowest level x86-specific interrupt
* entry, irq-stacks and irq statistics code. All the remaining
* irq logic is done by the generic kernel/irq/ code and
* by the x86-specific irq controller code. (e.g. i8259.c and
* io_apic.c.)
*/
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
#include <linux/percpu.h>
#include <asm/apic.h>
DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
EXPORT_PER_CPU_SYMBOL(irq_stat);
DEFINE_PER_CPU(struct pt_regs *, irq_regs);
EXPORT_PER_CPU_SYMBOL(irq_regs);
#ifdef CONFIG_DEBUG_STACKOVERFLOW
/* Debugging check for stack overflow: is there less than 1KB free? */
static int check_stack_overflow(void)
{
long sp;
__asm__ __volatile__("andl %%esp,%0" :
"=r" (sp) : "0" (THREAD_SIZE - 1));
return sp < (sizeof(struct thread_info) + STACK_WARN);
}
static void print_stack_overflow(void)
{
printk(KERN_WARNING "low stack detected by irq handler\n");
dump_stack();
}
#else
static inline int check_stack_overflow(void) { return 0; }
static inline void print_stack_overflow(void) { }
#endif
/*
* per-CPU IRQ handling contexts (thread information and stack)
*/
union irq_ctx {
struct thread_info tinfo;
u32 stack[THREAD_SIZE/sizeof(u32)];
} __attribute__((aligned(THREAD_SIZE)));
static DEFINE_PER_CPU(union irq_ctx *, hardirq_ctx);
static DEFINE_PER_CPU(union irq_ctx *, softirq_ctx);
static DEFINE_PER_CPU_PAGE_ALIGNED(union irq_ctx, hardirq_stack);
static DEFINE_PER_CPU_PAGE_ALIGNED(union irq_ctx, softirq_stack);
static void call_on_stack(void *func, void *stack)
{
asm volatile("xchgl %%ebx,%%esp \n"
"call *%%edi \n"
"movl %%ebx,%%esp \n"
: "=b" (stack)
: "0" (stack),
"D"(func)
: "memory", "cc", "edx", "ecx", "eax");
}
static inline int
execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
{
union irq_ctx *curctx, *irqctx;
u32 *isp, arg1, arg2;
curctx = (union irq_ctx *) current_thread_info();
irqctx = __get_cpu_var(hardirq_ctx);
/*
* this is where we switch to the IRQ stack. However, if we are
* already using the IRQ stack (because we interrupted a hardirq
* handler) we can't do that and just have to keep using the
* current stack (which is the irq stack already after all)
*/
if (unlikely(curctx == irqctx))
return 0;
/* build the stack frame on the IRQ stack */
isp = (u32 *) ((char *)irqctx + sizeof(*irqctx));
irqctx->tinfo.task = curctx->tinfo.task;
irqctx->tinfo.previous_esp = current_stack_pointer;
/*
* Copy the softirq bits in preempt_count so that the
* softirq checks work in the hardirq context.
*/
irqctx->tinfo.preempt_count =
(irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
(curctx->tinfo.preempt_count & SOFTIRQ_MASK);
if (unlikely(overflow))
call_on_stack(print_stack_overflow, isp);
asm volatile("xchgl %%ebx,%%esp \n"
"call *%%edi \n"
"movl %%ebx,%%esp \n"
: "=a" (arg1), "=d" (arg2), "=b" (isp)
: "0" (irq), "1" (desc), "2" (isp),
"D" (desc->handle_irq)
: "memory", "cc", "ecx");
return 1;
}
/*
* allocate per-cpu stacks for hardirq and for softirq processing
*/
void __cpuinit irq_ctx_init(int cpu)
{
union irq_ctx *irqctx;
if (per_cpu(hardirq_ctx, cpu))
return;
irqctx = &per_cpu(hardirq_stack, cpu);
irqctx->tinfo.task = NULL;
irqctx->tinfo.exec_domain = NULL;
irqctx->tinfo.cpu = cpu;
irqctx->tinfo.preempt_count = HARDIRQ_OFFSET;
irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
per_cpu(hardirq_ctx, cpu) = irqctx;
irqctx = &per_cpu(softirq_stack, cpu);
irqctx->tinfo.task = NULL;
irqctx->tinfo.exec_domain = NULL;
irqctx->tinfo.cpu = cpu;
irqctx->tinfo.preempt_count = 0;
irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
per_cpu(softirq_ctx, cpu) = irqctx;
printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",
cpu, per_cpu(hardirq_ctx, cpu), per_cpu(softirq_ctx, cpu));
}
void irq_ctx_exit(int cpu)
{
per_cpu(hardirq_ctx, cpu) = NULL;
}
asmlinkage void do_softirq(void)
{
unsigned long flags;
struct thread_info *curctx;
union irq_ctx *irqctx;
u32 *isp;
if (in_interrupt())
return;
local_irq_save(flags);
if (local_softirq_pending()) {
curctx = current_thread_info();
irqctx = __get_cpu_var(softirq_ctx);
irqctx->tinfo.task = curctx->task;
irqctx->tinfo.previous_esp = current_stack_pointer;
/* build the stack frame on the softirq stack */
isp = (u32 *) ((char *)irqctx + sizeof(*irqctx));
call_on_stack(__do_softirq, isp);
/*
* Shouldnt happen, we returned above if in_interrupt():
*/
WARN_ON_ONCE(softirq_count());
}
local_irq_restore(flags);
}
bool handle_irq(unsigned irq, struct pt_regs *regs)
{
struct irq_desc *desc;
int overflow;
overflow = check_stack_overflow();
desc = irq_to_desc(irq);
if (unlikely(!desc))
return false;
if (!execute_on_irq_stack(overflow, desc, irq)) {
if (unlikely(overflow))
print_stack_overflow();
desc->handle_irq(irq, desc);
}
return true;
}
|
