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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/*
2 * Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
3 *
4 * This file contains the lowest level x86-specific interrupt
5 * entry, irq-stacks and irq statistics code. All the remaining
6 * irq logic is done by the generic kernel/irq/ code and
7 * by the x86-specific irq controller code. (e.g. i8259.c and
8 * io_apic.c.)
9 */
10
11#include <linux/module.h>
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
24DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
25EXPORT_PER_CPU_SYMBOL(irq_stat);
26
27DEFINE_PER_CPU(struct pt_regs *, irq_regs);
28EXPORT_PER_CPU_SYMBOL(irq_regs);
29
30#ifdef CONFIG_DEBUG_STACKOVERFLOW
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}
47
48#else
49static inline int check_stack_overflow(void) { return 0; }
50static inline void print_stack_overflow(void) { }
51#endif
52
53/*
54 * per-CPU IRQ handling contexts (thread information and stack)
55 */
56union irq_ctx {
57 struct thread_info tinfo;
58 u32 stack[THREAD_SIZE/sizeof(u32)];
59} __attribute__((aligned(THREAD_SIZE)));
60
61static DEFINE_PER_CPU(union irq_ctx *, hardirq_ctx);
62static DEFINE_PER_CPU(union irq_ctx *, softirq_ctx);
63
64static void call_on_stack(void *func, void *stack)
65{
66 asm volatile("xchgl %%ebx,%%esp \n"
67 "call *%%edi \n"
68 "movl %%ebx,%%esp \n"
69 : "=b" (stack)
70 : "0" (stack),
71 "D"(func)
72 : "memory", "cc", "edx", "ecx", "eax");
73}
74
75static inline int
76execute_on_irq_stack(int overflow, struct irq_desc *desc, int irq)
77{
78 union irq_ctx *curctx, *irqctx;
79 u32 *isp, arg1, arg2;
80
81 curctx = (union irq_ctx *) current_thread_info();
82 irqctx = __this_cpu_read(hardirq_ctx);
83
84 /*
85 * this is where we switch to the IRQ stack. However, if we are
86 * already using the IRQ stack (because we interrupted a hardirq
87 * handler) we can't do that and just have to keep using the
88 * current stack (which is the irq stack already after all)
89 */
90 if (unlikely(curctx == irqctx))
91 return 0;
92
93 /* build the stack frame on the IRQ stack */
94 isp = (u32 *) ((char *)irqctx + sizeof(*irqctx));
95 irqctx->tinfo.task = curctx->tinfo.task;
96 irqctx->tinfo.previous_esp = current_stack_pointer;
97
98 /*
99 * Copy the softirq bits in preempt_count so that the
100 * softirq checks work in the hardirq context.
101 */
102 irqctx->tinfo.preempt_count =
103 (irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
104 (curctx->tinfo.preempt_count & SOFTIRQ_MASK);
105
106 if (unlikely(overflow))
107 call_on_stack(print_stack_overflow, isp);
108
109 asm volatile("xchgl %%ebx,%%esp \n"
110 "call *%%edi \n"
111 "movl %%ebx,%%esp \n"
112 : "=a" (arg1), "=d" (arg2), "=b" (isp)
113 : "0" (irq), "1" (desc), "2" (isp),
114 "D" (desc->handle_irq)
115 : "memory", "cc", "ecx");
116 return 1;
117}
118
119/*
120 * allocate per-cpu stacks for hardirq and for softirq processing
121 */
122void __cpuinit irq_ctx_init(int cpu)
123{
124 union irq_ctx *irqctx;
125
126 if (per_cpu(hardirq_ctx, cpu))
127 return;
128
129 irqctx = page_address(alloc_pages_node(cpu_to_node(cpu),
130 THREAD_FLAGS,
131 THREAD_ORDER));
132 memset(&irqctx->tinfo, 0, sizeof(struct thread_info));
133 irqctx->tinfo.cpu = cpu;
134 irqctx->tinfo.preempt_count = HARDIRQ_OFFSET;
135 irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
136
137 per_cpu(hardirq_ctx, cpu) = irqctx;
138
139 irqctx = page_address(alloc_pages_node(cpu_to_node(cpu),
140 THREAD_FLAGS,
141 THREAD_ORDER));
142 memset(&irqctx->tinfo, 0, sizeof(struct thread_info));
143 irqctx->tinfo.cpu = cpu;
144 irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
145
146 per_cpu(softirq_ctx, cpu) = irqctx;
147
148 printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",
149 cpu, per_cpu(hardirq_ctx, cpu), per_cpu(softirq_ctx, cpu));
150}
151
152asmlinkage void do_softirq(void)
153{
154 unsigned long flags;
155 struct thread_info *curctx;
156 union irq_ctx *irqctx;
157 u32 *isp;
158
159 if (in_interrupt())
160 return;
161
162 local_irq_save(flags);
163
164 if (local_softirq_pending()) {
165 curctx = current_thread_info();
166 irqctx = __this_cpu_read(softirq_ctx);
167 irqctx->tinfo.task = curctx->task;
168 irqctx->tinfo.previous_esp = current_stack_pointer;
169
170 /* build the stack frame on the softirq stack */
171 isp = (u32 *) ((char *)irqctx + sizeof(*irqctx));
172
173 call_on_stack(__do_softirq, isp);
174 /*
175 * Shouldn't happen, we returned above if in_interrupt():
176 */
177 WARN_ON_ONCE(softirq_count());
178 }
179
180 local_irq_restore(flags);
181}
182
183bool handle_irq(unsigned irq, struct pt_regs *regs)
184{
185 struct irq_desc *desc;
186 int overflow;
187
188 overflow = check_stack_overflow();
189
190 desc = irq_to_desc(irq);
191 if (unlikely(!desc))
192 return false;
193
194 if (!execute_on_irq_stack(overflow, desc, irq)) {
195 if (unlikely(overflow))
196 print_stack_overflow();
197 desc->handle_irq(irq, desc);
198 }
199
200 return true;
201}