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