| 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 | #ifdef CONFIG_DEBUG_STACKOVERFLOW |
| 25 | |
| 26 | int sysctl_panic_on_stackoverflow __read_mostly; |
| 27 | |
| 28 | /* Debugging check for stack overflow: is there less than 1KB free? */ |
| 29 | static int check_stack_overflow(void) |
| 30 | { |
| 31 | long sp; |
| 32 | |
| 33 | __asm__ __volatile__("andl %%esp,%0" : |
| 34 | "=r" (sp) : "0" (THREAD_SIZE - 1)); |
| 35 | |
| 36 | return sp < (sizeof(struct thread_info) + STACK_WARN); |
| 37 | } |
| 38 | |
| 39 | static void print_stack_overflow(void) |
| 40 | { |
| 41 | printk(KERN_WARNING "low stack detected by irq handler\n"); |
| 42 | dump_stack(); |
| 43 | if (sysctl_panic_on_stackoverflow) |
| 44 | panic("low stack detected by irq handler - check messages\n"); |
| 45 | } |
| 46 | |
| 47 | #else |
| 48 | static inline int check_stack_overflow(void) { return 0; } |
| 49 | static inline void print_stack_overflow(void) { } |
| 50 | #endif |
| 51 | |
| 52 | DEFINE_PER_CPU(struct irq_stack *, hardirq_stack); |
| 53 | DEFINE_PER_CPU(struct irq_stack *, softirq_stack); |
| 54 | |
| 55 | static void call_on_stack(void *func, void *stack) |
| 56 | { |
| 57 | asm volatile("xchgl %%ebx,%%esp \n" |
| 58 | "call *%%edi \n" |
| 59 | "movl %%ebx,%%esp \n" |
| 60 | : "=b" (stack) |
| 61 | : "0" (stack), |
| 62 | "D"(func) |
| 63 | : "memory", "cc", "edx", "ecx", "eax"); |
| 64 | } |
| 65 | |
| 66 | static inline void *current_stack(void) |
| 67 | { |
| 68 | return (void *)(current_stack_pointer() & ~(THREAD_SIZE - 1)); |
| 69 | } |
| 70 | |
| 71 | static inline int execute_on_irq_stack(int overflow, struct irq_desc *desc) |
| 72 | { |
| 73 | struct irq_stack *curstk, *irqstk; |
| 74 | u32 *isp, *prev_esp, arg1; |
| 75 | |
| 76 | curstk = (struct irq_stack *) current_stack(); |
| 77 | irqstk = __this_cpu_read(hardirq_stack); |
| 78 | |
| 79 | /* |
| 80 | * this is where we switch to the IRQ stack. However, if we are |
| 81 | * already using the IRQ stack (because we interrupted a hardirq |
| 82 | * handler) we can't do that and just have to keep using the |
| 83 | * current stack (which is the irq stack already after all) |
| 84 | */ |
| 85 | if (unlikely(curstk == irqstk)) |
| 86 | return 0; |
| 87 | |
| 88 | isp = (u32 *) ((char *)irqstk + sizeof(*irqstk)); |
| 89 | |
| 90 | /* Save the next esp at the bottom of the stack */ |
| 91 | prev_esp = (u32 *)irqstk; |
| 92 | *prev_esp = current_stack_pointer(); |
| 93 | |
| 94 | if (unlikely(overflow)) |
| 95 | call_on_stack(print_stack_overflow, isp); |
| 96 | |
| 97 | asm volatile("xchgl %%ebx,%%esp \n" |
| 98 | "call *%%edi \n" |
| 99 | "movl %%ebx,%%esp \n" |
| 100 | : "=a" (arg1), "=b" (isp) |
| 101 | : "0" (desc), "1" (isp), |
| 102 | "D" (desc->handle_irq) |
| 103 | : "memory", "cc", "ecx"); |
| 104 | return 1; |
| 105 | } |
| 106 | |
| 107 | /* |
| 108 | * allocate per-cpu stacks for hardirq and for softirq processing |
| 109 | */ |
| 110 | void irq_ctx_init(int cpu) |
| 111 | { |
| 112 | struct irq_stack *irqstk; |
| 113 | |
| 114 | if (per_cpu(hardirq_stack, cpu)) |
| 115 | return; |
| 116 | |
| 117 | irqstk = page_address(alloc_pages_node(cpu_to_node(cpu), |
| 118 | THREADINFO_GFP, |
| 119 | THREAD_SIZE_ORDER)); |
| 120 | per_cpu(hardirq_stack, cpu) = irqstk; |
| 121 | |
| 122 | irqstk = page_address(alloc_pages_node(cpu_to_node(cpu), |
| 123 | THREADINFO_GFP, |
| 124 | THREAD_SIZE_ORDER)); |
| 125 | per_cpu(softirq_stack, cpu) = irqstk; |
| 126 | |
| 127 | printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n", |
| 128 | cpu, per_cpu(hardirq_stack, cpu), per_cpu(softirq_stack, cpu)); |
| 129 | } |
| 130 | |
| 131 | void do_softirq_own_stack(void) |
| 132 | { |
| 133 | struct thread_info *curstk; |
| 134 | struct irq_stack *irqstk; |
| 135 | u32 *isp, *prev_esp; |
| 136 | |
| 137 | curstk = current_stack(); |
| 138 | irqstk = __this_cpu_read(softirq_stack); |
| 139 | |
| 140 | /* build the stack frame on the softirq stack */ |
| 141 | isp = (u32 *) ((char *)irqstk + sizeof(*irqstk)); |
| 142 | |
| 143 | /* Push the previous esp onto the stack */ |
| 144 | prev_esp = (u32 *)irqstk; |
| 145 | *prev_esp = current_stack_pointer(); |
| 146 | |
| 147 | call_on_stack(__do_softirq, isp); |
| 148 | } |
| 149 | |
| 150 | bool handle_irq(struct irq_desc *desc, struct pt_regs *regs) |
| 151 | { |
| 152 | int overflow = check_stack_overflow(); |
| 153 | |
| 154 | if (IS_ERR_OR_NULL(desc)) |
| 155 | return false; |
| 156 | |
| 157 | if (user_mode(regs) || !execute_on_irq_stack(overflow, desc)) { |
| 158 | if (unlikely(overflow)) |
| 159 | print_stack_overflow(); |
| 160 | generic_handle_irq_desc(desc); |
| 161 | } |
| 162 | |
| 163 | return true; |
| 164 | } |