1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar 4 * 5 * This file contains the lowest level x86-specific interrupt 6 * entry, irq-stacks and irq statistics code. All the remaining 7 * irq logic is done by the generic kernel/irq/ code and 8 * by the x86-specific irq controller code. (e.g. i8259.c and 9 * io_apic.c.) 10 */ 11 12 #include <linux/seq_file.h> 13 #include <linux/interrupt.h> 14 #include <linux/irq.h> 15 #include <linux/kernel_stat.h> 16 #include <linux/notifier.h> 17 #include <linux/cpu.h> 18 #include <linux/delay.h> 19 #include <linux/uaccess.h> 20 #include <linux/percpu.h> 21 #include <linux/mm.h> 22 23 #include <asm/apic.h> 24 #include <asm/nospec-branch.h> 25 #include <asm/softirq_stack.h> 26 27 #ifdef CONFIG_DEBUG_STACKOVERFLOW 28 29 int sysctl_panic_on_stackoverflow __read_mostly; 30 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 if (sysctl_panic_on_stackoverflow) 47 panic("low stack detected by irq handler - check messages\n"); 48 } 49 50 #else 51 static inline int check_stack_overflow(void) { return 0; } 52 static inline void print_stack_overflow(void) { } 53 #endif 54 55 DEFINE_PER_CPU(struct irq_stack *, hardirq_stack_ptr); 56 DEFINE_PER_CPU(struct irq_stack *, softirq_stack_ptr); 57 58 static void call_on_stack(void *func, void *stack) 59 { 60 asm volatile("xchgl %%ebx,%%esp \n" 61 CALL_NOSPEC 62 "movl %%ebx,%%esp \n" 63 : "=b" (stack) 64 : "0" (stack), 65 [thunk_target] "D"(func) 66 : "memory", "cc", "edx", "ecx", "eax"); 67 } 68 69 static inline void *current_stack(void) 70 { 71 return (void *)(current_stack_pointer & ~(THREAD_SIZE - 1)); 72 } 73 74 static inline int execute_on_irq_stack(int overflow, struct irq_desc *desc) 75 { 76 struct irq_stack *curstk, *irqstk; 77 u32 *isp, *prev_esp, arg1; 78 79 curstk = (struct irq_stack *) current_stack(); 80 irqstk = __this_cpu_read(hardirq_stack_ptr); 81 82 /* 83 * this is where we switch to the IRQ stack. However, if we are 84 * already using the IRQ stack (because we interrupted a hardirq 85 * handler) we can't do that and just have to keep using the 86 * current stack (which is the irq stack already after all) 87 */ 88 if (unlikely(curstk == irqstk)) 89 return 0; 90 91 isp = (u32 *) ((char *)irqstk + sizeof(*irqstk)); 92 93 /* Save the next esp at the bottom of the stack */ 94 prev_esp = (u32 *)irqstk; 95 *prev_esp = current_stack_pointer; 96 97 if (unlikely(overflow)) 98 call_on_stack(print_stack_overflow, isp); 99 100 asm volatile("xchgl %%ebx,%%esp \n" 101 CALL_NOSPEC 102 "movl %%ebx,%%esp \n" 103 : "=a" (arg1), "=b" (isp) 104 : "0" (desc), "1" (isp), 105 [thunk_target] "D" (desc->handle_irq) 106 : "memory", "cc", "ecx"); 107 return 1; 108 } 109 110 /* 111 * Allocate per-cpu stacks for hardirq and softirq processing 112 */ 113 int irq_init_percpu_irqstack(unsigned int cpu) 114 { 115 int node = cpu_to_node(cpu); 116 struct page *ph, *ps; 117 118 if (per_cpu(hardirq_stack_ptr, cpu)) 119 return 0; 120 121 ph = alloc_pages_node(node, THREADINFO_GFP, THREAD_SIZE_ORDER); 122 if (!ph) 123 return -ENOMEM; 124 ps = alloc_pages_node(node, THREADINFO_GFP, THREAD_SIZE_ORDER); 125 if (!ps) { 126 __free_pages(ph, THREAD_SIZE_ORDER); 127 return -ENOMEM; 128 } 129 130 per_cpu(hardirq_stack_ptr, cpu) = page_address(ph); 131 per_cpu(softirq_stack_ptr, cpu) = page_address(ps); 132 return 0; 133 } 134 135 void do_softirq_own_stack(void) 136 { 137 struct irq_stack *irqstk; 138 u32 *isp, *prev_esp; 139 140 irqstk = __this_cpu_read(softirq_stack_ptr); 141 142 /* build the stack frame on the softirq stack */ 143 isp = (u32 *) ((char *)irqstk + sizeof(*irqstk)); 144 145 /* Push the previous esp onto the stack */ 146 prev_esp = (u32 *)irqstk; 147 *prev_esp = current_stack_pointer; 148 149 call_on_stack(__do_softirq, isp); 150 } 151 152 void __handle_irq(struct irq_desc *desc, struct pt_regs *regs) 153 { 154 int overflow = check_stack_overflow(); 155 156 if (user_mode(regs) || !execute_on_irq_stack(overflow, desc)) { 157 if (unlikely(overflow)) 158 print_stack_overflow(); 159 generic_handle_irq_desc(desc); 160 } 161 } 162