irq_32.c

  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 bool check_stack_overflow(void)
 33{
 34	unsigned long sp = current_stack_pointer & (THREAD_SIZE - 1);
 35
 36	return sp < (sizeof(struct thread_info) + STACK_WARN);
 37}
 38
 39static void print_stack_overflow(void)
 40{
 41	printk(KERN_WARNING "low stack detected by irq handler\n");
 42	dump_stack();
 43	if (sysctl_panic_on_stackoverflow)
 44		panic("low stack detected by irq handler - check messages\n");
 45}
 46
 47#else
 48static inline bool check_stack_overflow(void) { return false; }
 49static inline void print_stack_overflow(void) { }
 50#endif
 51
 52DEFINE_PER_CPU_CACHE_HOT(struct irq_stack *, softirq_stack_ptr);
 53
 54static void call_on_stack(void *func, void *stack)
 55{
 56	asm volatile("xchgl %[sp], %%esp\n"
 57		     CALL_NOSPEC
 58		     "movl %[sp], %%esp"
 59		     : [sp] "+b" (stack)
 60		     : [thunk_target] "D" (func)
 61		     : "memory", "cc", "edx", "ecx", "eax");
 62}
 63
 64static inline void *current_stack(void)
 65{
 66	return (void *)(current_stack_pointer & ~(THREAD_SIZE - 1));
 67}
 68
 69static inline bool execute_on_irq_stack(bool overflow, struct irq_desc *desc)
 70{
 71	struct irq_stack *curstk, *irqstk;
 72	u32 *isp, *prev_esp;
 73
 74	curstk = (struct irq_stack *) current_stack();
 75	irqstk = __this_cpu_read(hardirq_stack_ptr);
 76
 77	/*
 78	 * this is where we switch to the IRQ stack. However, if we are
 79	 * already using the IRQ stack (because we interrupted a hardirq
 80	 * handler) we can't do that and just have to keep using the
 81	 * current stack (which is the irq stack already after all)
 82	 */
 83	if (unlikely(curstk == irqstk))
 84		return false;
 85
 86	isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));
 87
 88	/* Save the next esp at the bottom of the stack */
 89	prev_esp = (u32 *)irqstk;
 90	*prev_esp = current_stack_pointer;
 91
 92	if (unlikely(overflow))
 93		call_on_stack(print_stack_overflow, isp);
 94
 95	asm volatile("xchgl %[sp], %%esp\n"
 96		     CALL_NOSPEC
 97		     "movl %[sp], %%esp"
 98		     : "+a" (desc), [sp] "+b" (isp)
 99		     : [thunk_target] "D" (desc->handle_irq)
100		     : "memory", "cc", "edx", "ecx");
101	return true;
102}
103
104/*
105 * Allocate per-cpu stacks for hardirq and softirq processing
106 */
107int irq_init_percpu_irqstack(unsigned int cpu)
108{
109	int node = cpu_to_node(cpu);
110	struct page *ph, *ps;
111
112	if (per_cpu(hardirq_stack_ptr, cpu))
113		return 0;
114
115	ph = alloc_pages_node(node, THREADINFO_GFP, THREAD_SIZE_ORDER);
116	if (!ph)
117		return -ENOMEM;
118	ps = alloc_pages_node(node, THREADINFO_GFP, THREAD_SIZE_ORDER);
119	if (!ps) {
120		__free_pages(ph, THREAD_SIZE_ORDER);
121		return -ENOMEM;
122	}
123
124	per_cpu(hardirq_stack_ptr, cpu) = page_address(ph);
125	per_cpu(softirq_stack_ptr, cpu) = page_address(ps);
126	return 0;
127}
128
129#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
130void do_softirq_own_stack(void)
131{
132	struct irq_stack *irqstk;
133	u32 *isp, *prev_esp;
134
135	irqstk = __this_cpu_read(softirq_stack_ptr);
136
137	/* build the stack frame on the softirq stack */
138	isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));
139
140	/* Push the previous esp onto the stack */
141	prev_esp = (u32 *)irqstk;
142	*prev_esp = current_stack_pointer;
143
144	call_on_stack(__do_softirq, isp);
145}
146#endif
147
148void __handle_irq(struct irq_desc *desc, struct pt_regs *regs)
149{
150	bool overflow = check_stack_overflow();
151
152	if (user_mode(regs) || !execute_on_irq_stack(overflow, desc)) {
153		if (unlikely(overflow))
154			print_stack_overflow();
155		generic_handle_irq_desc(desc);
156	}
157}