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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 | 2 | /* |
1da177e4 LT |
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 | ||
1da177e4 LT |
12 | #include <linux/seq_file.h> |
13 | #include <linux/interrupt.h> | |
14 | #include <linux/kernel_stat.h> | |
f3705136 ZM |
15 | #include <linux/notifier.h> |
16 | #include <linux/cpu.h> | |
17 | #include <linux/delay.h> | |
72ade5f9 | 18 | #include <linux/uaccess.h> |
42f8faec | 19 | #include <linux/percpu.h> |
5c1eb089 | 20 | #include <linux/mm.h> |
1da177e4 | 21 | |
e05d723f | 22 | #include <asm/apic.h> |
7614e913 | 23 | #include <asm/nospec-branch.h> |
e05d723f | 24 | |
de9b10af | 25 | #ifdef CONFIG_DEBUG_STACKOVERFLOW |
53b56502 IM |
26 | |
27 | int sysctl_panic_on_stackoverflow __read_mostly; | |
28 | ||
de9b10af TG |
29 | /* Debugging check for stack overflow: is there less than 1KB free? */ |
30 | static int check_stack_overflow(void) | |
31 | { | |
32 | long sp; | |
33 | ||
34 | __asm__ __volatile__("andl %%esp,%0" : | |
35 | "=r" (sp) : "0" (THREAD_SIZE - 1)); | |
36 | ||
37 | return sp < (sizeof(struct thread_info) + STACK_WARN); | |
38 | } | |
39 | ||
40 | static void print_stack_overflow(void) | |
41 | { | |
42 | printk(KERN_WARNING "low stack detected by irq handler\n"); | |
43 | dump_stack(); | |
55af7796 MH |
44 | if (sysctl_panic_on_stackoverflow) |
45 | panic("low stack detected by irq handler - check messages\n"); | |
de9b10af TG |
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 | ||
198d208d SR |
53 | DEFINE_PER_CPU(struct irq_stack *, hardirq_stack); |
54 | DEFINE_PER_CPU(struct irq_stack *, softirq_stack); | |
1da177e4 | 55 | |
403d8efc | 56 | static void call_on_stack(void *func, void *stack) |
04b361ab | 57 | { |
403d8efc | 58 | asm volatile("xchgl %%ebx,%%esp \n" |
7614e913 | 59 | CALL_NOSPEC |
403d8efc TG |
60 | "movl %%ebx,%%esp \n" |
61 | : "=b" (stack) | |
62 | : "0" (stack), | |
7614e913 | 63 | [thunk_target] "D"(func) |
403d8efc | 64 | : "memory", "cc", "edx", "ecx", "eax"); |
04b361ab | 65 | } |
1da177e4 | 66 | |
198d208d SR |
67 | static inline void *current_stack(void) |
68 | { | |
196bd485 | 69 | return (void *)(current_stack_pointer & ~(THREAD_SIZE - 1)); |
198d208d SR |
70 | } |
71 | ||
bd0b9ac4 | 72 | static inline int execute_on_irq_stack(int overflow, struct irq_desc *desc) |
de9b10af | 73 | { |
198d208d | 74 | struct irq_stack *curstk, *irqstk; |
bd0b9ac4 | 75 | u32 *isp, *prev_esp, arg1; |
1da177e4 | 76 | |
198d208d SR |
77 | curstk = (struct irq_stack *) current_stack(); |
78 | irqstk = __this_cpu_read(hardirq_stack); | |
1da177e4 LT |
79 | |
80 | /* | |
81 | * this is where we switch to the IRQ stack. However, if we are | |
82 | * already using the IRQ stack (because we interrupted a hardirq | |
83 | * handler) we can't do that and just have to keep using the | |
84 | * current stack (which is the irq stack already after all) | |
85 | */ | |
198d208d | 86 | if (unlikely(curstk == irqstk)) |
de9b10af | 87 | return 0; |
1da177e4 | 88 | |
198d208d SR |
89 | isp = (u32 *) ((char *)irqstk + sizeof(*irqstk)); |
90 | ||
91 | /* Save the next esp at the bottom of the stack */ | |
92 | prev_esp = (u32 *)irqstk; | |
196bd485 | 93 | *prev_esp = current_stack_pointer; |
1da177e4 | 94 | |
de9b10af | 95 | if (unlikely(overflow)) |
403d8efc TG |
96 | call_on_stack(print_stack_overflow, isp); |
97 | ||
98 | asm volatile("xchgl %%ebx,%%esp \n" | |
7614e913 | 99 | CALL_NOSPEC |
403d8efc | 100 | "movl %%ebx,%%esp \n" |
bd0b9ac4 TG |
101 | : "=a" (arg1), "=b" (isp) |
102 | : "0" (desc), "1" (isp), | |
7614e913 | 103 | [thunk_target] "D" (desc->handle_irq) |
403d8efc | 104 | : "memory", "cc", "ecx"); |
1da177e4 LT |
105 | return 1; |
106 | } | |
107 | ||
1da177e4 LT |
108 | /* |
109 | * allocate per-cpu stacks for hardirq and for softirq processing | |
110 | */ | |
148f9bb8 | 111 | void irq_ctx_init(int cpu) |
1da177e4 | 112 | { |
198d208d | 113 | struct irq_stack *irqstk; |
1da177e4 | 114 | |
198d208d | 115 | if (per_cpu(hardirq_stack, cpu)) |
1da177e4 LT |
116 | return; |
117 | ||
198d208d | 118 | irqstk = page_address(alloc_pages_node(cpu_to_node(cpu), |
38e7c572 TG |
119 | THREADINFO_GFP, |
120 | THREAD_SIZE_ORDER)); | |
198d208d | 121 | per_cpu(hardirq_stack, cpu) = irqstk; |
1da177e4 | 122 | |
198d208d | 123 | irqstk = page_address(alloc_pages_node(cpu_to_node(cpu), |
38e7c572 TG |
124 | THREADINFO_GFP, |
125 | THREAD_SIZE_ORDER)); | |
198d208d | 126 | per_cpu(softirq_stack, cpu) = irqstk; |
1da177e4 | 127 | |
403d8efc | 128 | printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n", |
198d208d | 129 | cpu, per_cpu(hardirq_stack, cpu), per_cpu(softirq_stack, cpu)); |
1da177e4 LT |
130 | } |
131 | ||
7d65f4a6 | 132 | void do_softirq_own_stack(void) |
1da177e4 | 133 | { |
198d208d | 134 | struct irq_stack *irqstk; |
0788aa6a | 135 | u32 *isp, *prev_esp; |
1da177e4 | 136 | |
198d208d | 137 | irqstk = __this_cpu_read(softirq_stack); |
1da177e4 | 138 | |
7d65f4a6 | 139 | /* build the stack frame on the softirq stack */ |
198d208d | 140 | isp = (u32 *) ((char *)irqstk + sizeof(*irqstk)); |
1da177e4 | 141 | |
0788aa6a | 142 | /* Push the previous esp onto the stack */ |
198d208d | 143 | prev_esp = (u32 *)irqstk; |
196bd485 | 144 | *prev_esp = current_stack_pointer; |
0788aa6a | 145 | |
7d65f4a6 | 146 | call_on_stack(__do_softirq, isp); |
1da177e4 | 147 | } |
403d8efc | 148 | |
a782a7e4 | 149 | bool handle_irq(struct irq_desc *desc, struct pt_regs *regs) |
9b2b76a3 | 150 | { |
bd0b9ac4 | 151 | int overflow = check_stack_overflow(); |
9b2b76a3 | 152 | |
a782a7e4 | 153 | if (IS_ERR_OR_NULL(desc)) |
9b2b76a3 JF |
154 | return false; |
155 | ||
bd0b9ac4 | 156 | if (user_mode(regs) || !execute_on_irq_stack(overflow, desc)) { |
9b2b76a3 JF |
157 | if (unlikely(overflow)) |
158 | print_stack_overflow(); | |
bd0b9ac4 | 159 | generic_handle_irq_desc(desc); |
9b2b76a3 JF |
160 | } |
161 | ||
162 | return true; | |
163 | } |