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(nid: node, THREADINFO_GFP, THREAD_SIZE_ORDER); |
119 | if (!ph) |
120 | return -ENOMEM; |
121 | ps = alloc_pages_node(nid: node, THREADINFO_GFP, THREAD_SIZE_ORDER); |
122 | if (!ps) { |
123 | __free_pages(page: 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 | |