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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/kernel_stat.h>
15#include <linux/notifier.h>
16#include <linux/cpu.h>
17#include <linux/delay.h>
18#include <linux/uaccess.h>
19#include <linux/percpu.h>
20#include <linux/mm.h>
21
22#include <asm/apic.h>
23#include <asm/nospec-branch.h>
24
25#ifdef CONFIG_DEBUG_STACKOVERFLOW
26
27int sysctl_panic_on_stackoverflow __read_mostly;
28
29/* Debugging check for stack overflow: is there less than 1KB free? */
30static 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
40static void print_stack_overflow(void)
41{
42 printk(KERN_WARNING "low stack detected by irq handler\n");
43 dump_stack();
44 if (sysctl_panic_on_stackoverflow)
45 panic("low stack detected by irq handler - check messages\n");
46}
47
48#else
49static inline int check_stack_overflow(void) { return 0; }
50static inline void print_stack_overflow(void) { }
51#endif
52
53DEFINE_PER_CPU(struct irq_stack *, hardirq_stack);
54DEFINE_PER_CPU(struct irq_stack *, softirq_stack);
55
56static void call_on_stack(void *func, void *stack)
57{
58 asm volatile("xchgl %%ebx,%%esp \n"
59 CALL_NOSPEC
60 "movl %%ebx,%%esp \n"
61 : "=b" (stack)
62 : "0" (stack),
63 [thunk_target] "D"(func)
64 : "memory", "cc", "edx", "ecx", "eax");
65}
66
67static inline void *current_stack(void)
68{
69 return (void *)(current_stack_pointer & ~(THREAD_SIZE - 1));
70}
71
72static inline int execute_on_irq_stack(int overflow, struct irq_desc *desc)
73{
74 struct irq_stack *curstk, *irqstk;
75 u32 *isp, *prev_esp, arg1;
76
77 curstk = (struct irq_stack *) current_stack();
78 irqstk = __this_cpu_read(hardirq_stack);
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 */
86 if (unlikely(curstk == irqstk))
87 return 0;
88
89 isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));
90
91 /* Save the next esp at the bottom of the stack */
92 prev_esp = (u32 *)irqstk;
93 *prev_esp = current_stack_pointer;
94
95 if (unlikely(overflow))
96 call_on_stack(print_stack_overflow, isp);
97
98 asm volatile("xchgl %%ebx,%%esp \n"
99 CALL_NOSPEC
100 "movl %%ebx,%%esp \n"
101 : "=a" (arg1), "=b" (isp)
102 : "0" (desc), "1" (isp),
103 [thunk_target] "D" (desc->handle_irq)
104 : "memory", "cc", "ecx");
105 return 1;
106}
107
108/*
109 * allocate per-cpu stacks for hardirq and for softirq processing
110 */
111void irq_ctx_init(int cpu)
112{
113 struct irq_stack *irqstk;
114
115 if (per_cpu(hardirq_stack, cpu))
116 return;
117
118 irqstk = page_address(alloc_pages_node(cpu_to_node(cpu),
119 THREADINFO_GFP,
120 THREAD_SIZE_ORDER));
121 per_cpu(hardirq_stack, cpu) = irqstk;
122
123 irqstk = page_address(alloc_pages_node(cpu_to_node(cpu),
124 THREADINFO_GFP,
125 THREAD_SIZE_ORDER));
126 per_cpu(softirq_stack, cpu) = irqstk;
127
128 printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",
129 cpu, per_cpu(hardirq_stack, cpu), per_cpu(softirq_stack, cpu));
130}
131
132void do_softirq_own_stack(void)
133{
134 struct irq_stack *irqstk;
135 u32 *isp, *prev_esp;
136
137 irqstk = __this_cpu_read(softirq_stack);
138
139 /* build the stack frame on the softirq stack */
140 isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));
141
142 /* Push the previous esp onto the stack */
143 prev_esp = (u32 *)irqstk;
144 *prev_esp = current_stack_pointer;
145
146 call_on_stack(__do_softirq, isp);
147}
148
149bool handle_irq(struct irq_desc *desc, struct pt_regs *regs)
150{
151 int overflow = check_stack_overflow();
152
153 if (IS_ERR_OR_NULL(desc))
154 return false;
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 return true;
163}
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}