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