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 static void call_on_stack(void *func, void *stack) 56 { 57 asm volatile("xchgl %%ebx,%%esp \n" 58 CALL_NOSPEC 59 "movl %%ebx,%%esp \n" 60 : "=b" (stack) 61 : "0" (stack), 62 [thunk_target] "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(pcpu_hot.hardirq_stack_ptr); 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_NOSPEC 99 "movl %%ebx,%%esp \n" 100 : "=a" (arg1), "=b" (isp) 101 : "0" (desc), "1" (isp), 102 [thunk_target] "D" (desc->handle_irq) 103 : "memory", "cc", "ecx"); 104 return 1; 105 } 106 107 /* 108 * Allocate per-cpu stacks for hardirq and softirq processing 109 */ 110 int irq_init_percpu_irqstack(unsigned int cpu) 111 { 112 int node = cpu_to_node(cpu); 113 struct page *ph, *ps; 114 115 if (per_cpu(pcpu_hot.hardirq_stack_ptr, cpu)) 116 return 0; 117 118 ph = alloc_pages_node(node, THREADINFO_GFP, THREAD_SIZE_ORDER); 119 if (!ph) 120 return -ENOMEM; 121 ps = alloc_pages_node(node, THREADINFO_GFP, THREAD_SIZE_ORDER); 122 if (!ps) { 123 __free_pages(ph, THREAD_SIZE_ORDER); 124 return -ENOMEM; 125 } 126 127 per_cpu(pcpu_hot.hardirq_stack_ptr, cpu) = page_address(ph); 128 per_cpu(pcpu_hot.softirq_stack_ptr, cpu) = page_address(ps); 129 return 0; 130 } 131 132 #ifdef CONFIG_SOFTIRQ_ON_OWN_STACK 133 void do_softirq_own_stack(void) 134 { 135 struct irq_stack *irqstk; 136 u32 *isp, *prev_esp; 137 138 irqstk = __this_cpu_read(pcpu_hot.softirq_stack_ptr); 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 #endif 150 151 void __handle_irq(struct irq_desc *desc, struct pt_regs *regs) 152 { 153 int overflow = check_stack_overflow(); 154 155 if (user_mode(regs) || !execute_on_irq_stack(overflow, desc)) { 156 if (unlikely(overflow)) 157 print_stack_overflow(); 158 generic_handle_irq_desc(desc); 159 } 160 } 161