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 DEFINE_PER_CPU(struct irq_stack *, hardirq_stack);
59 DEFINE_PER_CPU(struct irq_stack *, softirq_stack);
60
call_on_stack(void * func,void * stack)61 static void call_on_stack(void *func, void *stack)
62 {
63 asm volatile("xchgl %%ebx,%%esp \n"
64 "call *%%edi \n"
65 "movl %%ebx,%%esp \n"
66 : "=b" (stack)
67 : "0" (stack),
68 "D"(func)
69 : "memory", "cc", "edx", "ecx", "eax");
70 }
71
72 /* how to get the current stack pointer from C */
73 #define current_stack_pointer ({ \
74 unsigned long sp; \
75 asm("mov %%esp,%0" : "=g" (sp)); \
76 sp; \
77 })
78
current_stack(void)79 static inline void *current_stack(void)
80 {
81 return (void *)(current_stack_pointer & ~(THREAD_SIZE - 1));
82 }
83
84 static inline int
execute_on_irq_stack(int overflow,struct irq_desc * desc,int irq)85 execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
86 {
87 struct irq_stack *curstk, *irqstk;
88 u32 *isp, *prev_esp, arg1, arg2;
89
90 curstk = (struct irq_stack *) current_stack();
91 irqstk = __this_cpu_read(hardirq_stack);
92
93 /*
94 * this is where we switch to the IRQ stack. However, if we are
95 * already using the IRQ stack (because we interrupted a hardirq
96 * handler) we can't do that and just have to keep using the
97 * current stack (which is the irq stack already after all)
98 */
99 if (unlikely(curstk == irqstk))
100 return 0;
101
102 isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));
103
104 /* Save the next esp at the bottom of the stack */
105 prev_esp = (u32 *)irqstk;
106 *prev_esp = current_stack_pointer;
107
108 if (unlikely(overflow))
109 call_on_stack(print_stack_overflow, isp);
110
111 asm volatile("xchgl %%ebx,%%esp \n"
112 "call *%%edi \n"
113 "movl %%ebx,%%esp \n"
114 : "=a" (arg1), "=d" (arg2), "=b" (isp)
115 : "0" (irq), "1" (desc), "2" (isp),
116 "D" (desc->handle_irq)
117 : "memory", "cc", "ecx");
118 return 1;
119 }
120
121 /*
122 * allocate per-cpu stacks for hardirq and for softirq processing
123 */
irq_ctx_init(int cpu)124 void irq_ctx_init(int cpu)
125 {
126 struct irq_stack *irqstk;
127
128 if (per_cpu(hardirq_stack, cpu))
129 return;
130
131 irqstk = page_address(alloc_pages_node(cpu_to_node(cpu),
132 THREADINFO_GFP,
133 THREAD_SIZE_ORDER));
134 per_cpu(hardirq_stack, cpu) = irqstk;
135
136 irqstk = page_address(alloc_pages_node(cpu_to_node(cpu),
137 THREADINFO_GFP,
138 THREAD_SIZE_ORDER));
139 per_cpu(softirq_stack, cpu) = irqstk;
140
141 printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",
142 cpu, per_cpu(hardirq_stack, cpu), per_cpu(softirq_stack, cpu));
143 }
144
do_softirq_own_stack(void)145 void do_softirq_own_stack(void)
146 {
147 struct thread_info *curstk;
148 struct irq_stack *irqstk;
149 u32 *isp, *prev_esp;
150
151 curstk = current_stack();
152 irqstk = __this_cpu_read(softirq_stack);
153
154 /* build the stack frame on the softirq stack */
155 isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));
156
157 /* Push the previous esp onto the stack */
158 prev_esp = (u32 *)irqstk;
159 *prev_esp = current_stack_pointer;
160
161 call_on_stack(__do_softirq, isp);
162 }
163
handle_irq(unsigned irq,struct pt_regs * regs)164 bool handle_irq(unsigned irq, struct pt_regs *regs)
165 {
166 struct irq_desc *desc;
167 int overflow;
168
169 overflow = check_stack_overflow();
170
171 desc = irq_to_desc(irq);
172 if (unlikely(!desc))
173 return false;
174
175 if (user_mode_vm(regs) || !execute_on_irq_stack(overflow, desc, irq)) {
176 if (unlikely(overflow))
177 print_stack_overflow();
178 desc->handle_irq(irq, desc);
179 }
180
181 return true;
182 }
183