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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
29int sysctl_panic_on_stackoverflow __read_mostly;
30
31/* Debugging check for stack overflow: is there less than 1KB free? */
32static 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
42static 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
51static inline int check_stack_overflow(void) { return 0; }
52static inline void print_stack_overflow(void) { }
53#endif
54
55static 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
66static inline void *current_stack(void)
67{
68 return (void *)(current_stack_pointer & ~(THREAD_SIZE - 1));
69}
70
71static 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 */
110int 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
133void 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
151void __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}
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
29int sysctl_panic_on_stackoverflow __read_mostly;
30
31/* Debugging check for stack overflow: is there less than 1KB free? */
32static 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
42static 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
51static inline int check_stack_overflow(void) { return 0; }
52static inline void print_stack_overflow(void) { }
53#endif
54
55DEFINE_PER_CPU(struct irq_stack *, hardirq_stack_ptr);
56DEFINE_PER_CPU(struct irq_stack *, softirq_stack_ptr);
57
58static 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
69static inline void *current_stack(void)
70{
71 return (void *)(current_stack_pointer & ~(THREAD_SIZE - 1));
72}
73
74static 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 */
113int 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
135void 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
152void __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}