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? */ 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 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 54 static inline int check_stack_overflow(void) { return 0; } 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 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 static inline void *current_stack(void) 73 { 74 return (void *)(current_stack_pointer() & ~(THREAD_SIZE - 1)); 75 } 76 77 static inline int 78 execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq) 79 { 80 struct irq_stack *curstk, *irqstk; 81 u32 *isp, *prev_esp, arg1, arg2; 82 83 curstk = (struct irq_stack *) current_stack(); 84 irqstk = __this_cpu_read(hardirq_stack); 85 86 /* 87 * this is where we switch to the IRQ stack. However, if we are 88 * already using the IRQ stack (because we interrupted a hardirq 89 * handler) we can't do that and just have to keep using the 90 * current stack (which is the irq stack already after all) 91 */ 92 if (unlikely(curstk == irqstk)) 93 return 0; 94 95 isp = (u32 *) ((char *)irqstk + sizeof(*irqstk)); 96 97 /* Save the next esp at the bottom of the stack */ 98 prev_esp = (u32 *)irqstk; 99 *prev_esp = current_stack_pointer(); 100 101 if (unlikely(overflow)) 102 call_on_stack(print_stack_overflow, isp); 103 104 asm volatile("xchgl %%ebx,%%esp \n" 105 "call *%%edi \n" 106 "movl %%ebx,%%esp \n" 107 : "=a" (arg1), "=d" (arg2), "=b" (isp) 108 : "0" (irq), "1" (desc), "2" (isp), 109 "D" (desc->handle_irq) 110 : "memory", "cc", "ecx"); 111 return 1; 112 } 113 114 /* 115 * allocate per-cpu stacks for hardirq and for softirq processing 116 */ 117 void irq_ctx_init(int cpu) 118 { 119 struct irq_stack *irqstk; 120 121 if (per_cpu(hardirq_stack, cpu)) 122 return; 123 124 irqstk = page_address(alloc_pages_node(cpu_to_node(cpu), 125 THREADINFO_GFP, 126 THREAD_SIZE_ORDER)); 127 per_cpu(hardirq_stack, cpu) = irqstk; 128 129 irqstk = page_address(alloc_pages_node(cpu_to_node(cpu), 130 THREADINFO_GFP, 131 THREAD_SIZE_ORDER)); 132 per_cpu(softirq_stack, cpu) = irqstk; 133 134 printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n", 135 cpu, per_cpu(hardirq_stack, cpu), per_cpu(softirq_stack, cpu)); 136 } 137 138 void do_softirq_own_stack(void) 139 { 140 struct thread_info *curstk; 141 struct irq_stack *irqstk; 142 u32 *isp, *prev_esp; 143 144 curstk = current_stack(); 145 irqstk = __this_cpu_read(softirq_stack); 146 147 /* build the stack frame on the softirq stack */ 148 isp = (u32 *) ((char *)irqstk + sizeof(*irqstk)); 149 150 /* Push the previous esp onto the stack */ 151 prev_esp = (u32 *)irqstk; 152 *prev_esp = current_stack_pointer(); 153 154 call_on_stack(__do_softirq, isp); 155 } 156 157 bool handle_irq(unsigned irq, struct pt_regs *regs) 158 { 159 struct irq_desc *desc; 160 int overflow; 161 162 overflow = check_stack_overflow(); 163 164 desc = irq_to_desc(irq); 165 if (unlikely(!desc)) 166 return false; 167 168 if (user_mode_vm(regs) || !execute_on_irq_stack(overflow, desc, irq)) { 169 if (unlikely(overflow)) 170 print_stack_overflow(); 171 desc->handle_irq(irq, desc); 172 } 173 174 return true; 175 } 176