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 /* 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 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 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 if (unlikely(overflow)) 104 call_on_stack(print_stack_overflow, isp); 105 106 asm volatile("xchgl %%ebx,%%esp \n" 107 "call *%%edi \n" 108 "movl %%ebx,%%esp \n" 109 : "=a" (arg1), "=d" (arg2), "=b" (isp) 110 : "0" (irq), "1" (desc), "2" (isp), 111 "D" (desc->handle_irq) 112 : "memory", "cc", "ecx"); 113 return 1; 114 } 115 116 /* 117 * allocate per-cpu stacks for hardirq and for softirq processing 118 */ 119 void irq_ctx_init(int cpu) 120 { 121 union irq_ctx *irqctx; 122 123 if (per_cpu(hardirq_ctx, cpu)) 124 return; 125 126 irqctx = page_address(alloc_pages_node(cpu_to_node(cpu), 127 THREADINFO_GFP, 128 THREAD_SIZE_ORDER)); 129 memset(&irqctx->tinfo, 0, sizeof(struct thread_info)); 130 irqctx->tinfo.cpu = cpu; 131 irqctx->tinfo.addr_limit = MAKE_MM_SEG(0); 132 133 per_cpu(hardirq_ctx, cpu) = irqctx; 134 135 irqctx = page_address(alloc_pages_node(cpu_to_node(cpu), 136 THREADINFO_GFP, 137 THREAD_SIZE_ORDER)); 138 memset(&irqctx->tinfo, 0, sizeof(struct thread_info)); 139 irqctx->tinfo.cpu = cpu; 140 irqctx->tinfo.addr_limit = MAKE_MM_SEG(0); 141 142 per_cpu(softirq_ctx, cpu) = irqctx; 143 144 printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n", 145 cpu, per_cpu(hardirq_ctx, cpu), per_cpu(softirq_ctx, cpu)); 146 } 147 148 void do_softirq_own_stack(void) 149 { 150 struct thread_info *curctx; 151 union irq_ctx *irqctx; 152 u32 *isp; 153 154 curctx = current_thread_info(); 155 irqctx = __this_cpu_read(softirq_ctx); 156 irqctx->tinfo.task = curctx->task; 157 irqctx->tinfo.previous_esp = current_stack_pointer; 158 159 /* build the stack frame on the softirq stack */ 160 isp = (u32 *) ((char *)irqctx + sizeof(*irqctx)); 161 162 call_on_stack(__do_softirq, isp); 163 } 164 165 bool handle_irq(unsigned irq, struct pt_regs *regs) 166 { 167 struct irq_desc *desc; 168 int overflow; 169 170 overflow = check_stack_overflow(); 171 172 desc = irq_to_desc(irq); 173 if (unlikely(!desc)) 174 return false; 175 176 if (user_mode_vm(regs) || !execute_on_irq_stack(overflow, desc, irq)) { 177 if (unlikely(overflow)) 178 print_stack_overflow(); 179 desc->handle_irq(irq, desc); 180 } 181 182 return true; 183 } 184