165 lines
4.1 KiB
C
165 lines
4.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
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*
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* This file contains the lowest level x86-specific interrupt
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* entry, irq-stacks and irq statistics code. All the remaining
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* irq logic is done by the generic kernel/irq/ code and
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* by the x86-specific irq controller code. (e.g. i8259.c and
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* io_apic.c.)
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*/
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#include <linux/seq_file.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/kernel_stat.h>
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#include <linux/notifier.h>
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#include <linux/cpu.h>
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#include <linux/delay.h>
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#include <linux/uaccess.h>
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#include <linux/percpu.h>
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#include <linux/mm.h>
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#include <asm/apic.h>
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#include <asm/nospec-branch.h>
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#ifdef CONFIG_DEBUG_STACKOVERFLOW
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int sysctl_panic_on_stackoverflow __read_mostly;
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/* Debugging check for stack overflow: is there less than 1KB free? */
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static int check_stack_overflow(void)
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{
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long sp;
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__asm__ __volatile__("andl %%esp,%0" :
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"=r" (sp) : "0" (THREAD_SIZE - 1));
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return sp < (sizeof(struct thread_info) + STACK_WARN);
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}
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static void print_stack_overflow(void)
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{
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printk(KERN_WARNING "low stack detected by irq handler\n");
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dump_stack();
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if (sysctl_panic_on_stackoverflow)
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panic("low stack detected by irq handler - check messages\n");
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}
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#else
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static inline int check_stack_overflow(void) { return 0; }
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static inline void print_stack_overflow(void) { }
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#endif
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DEFINE_PER_CPU(struct irq_stack *, hardirq_stack);
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DEFINE_PER_CPU(struct irq_stack *, softirq_stack);
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static void call_on_stack(void *func, void *stack)
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{
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asm volatile("xchgl %%ebx,%%esp \n"
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CALL_NOSPEC
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"movl %%ebx,%%esp \n"
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: "=b" (stack)
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: "0" (stack),
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[thunk_target] "D"(func)
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: "memory", "cc", "edx", "ecx", "eax");
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}
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static inline void *current_stack(void)
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{
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return (void *)(current_stack_pointer & ~(THREAD_SIZE - 1));
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}
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static inline int execute_on_irq_stack(int overflow, struct irq_desc *desc)
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{
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struct irq_stack *curstk, *irqstk;
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u32 *isp, *prev_esp, arg1;
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curstk = (struct irq_stack *) current_stack();
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irqstk = __this_cpu_read(hardirq_stack);
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/*
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* this is where we switch to the IRQ stack. However, if we are
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* already using the IRQ stack (because we interrupted a hardirq
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* handler) we can't do that and just have to keep using the
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* current stack (which is the irq stack already after all)
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*/
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if (unlikely(curstk == irqstk))
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return 0;
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isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));
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/* Save the next esp at the bottom of the stack */
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prev_esp = (u32 *)irqstk;
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*prev_esp = current_stack_pointer;
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if (unlikely(overflow))
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call_on_stack(print_stack_overflow, isp);
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asm volatile("xchgl %%ebx,%%esp \n"
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CALL_NOSPEC
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"movl %%ebx,%%esp \n"
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: "=a" (arg1), "=b" (isp)
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: "0" (desc), "1" (isp),
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[thunk_target] "D" (desc->handle_irq)
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: "memory", "cc", "ecx");
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return 1;
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}
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/*
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* allocate per-cpu stacks for hardirq and for softirq processing
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*/
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void irq_ctx_init(int cpu)
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{
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struct irq_stack *irqstk;
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if (per_cpu(hardirq_stack, cpu))
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return;
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irqstk = page_address(alloc_pages_node(cpu_to_node(cpu),
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THREADINFO_GFP,
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THREAD_SIZE_ORDER));
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per_cpu(hardirq_stack, cpu) = irqstk;
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irqstk = page_address(alloc_pages_node(cpu_to_node(cpu),
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THREADINFO_GFP,
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THREAD_SIZE_ORDER));
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per_cpu(softirq_stack, cpu) = irqstk;
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printk(KERN_DEBUG "CPU %u irqstacks, hard=%p soft=%p\n",
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cpu, per_cpu(hardirq_stack, cpu), per_cpu(softirq_stack, cpu));
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}
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void do_softirq_own_stack(void)
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{
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struct irq_stack *irqstk;
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u32 *isp, *prev_esp;
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irqstk = __this_cpu_read(softirq_stack);
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/* build the stack frame on the softirq stack */
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isp = (u32 *) ((char *)irqstk + sizeof(*irqstk));
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/* Push the previous esp onto the stack */
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prev_esp = (u32 *)irqstk;
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*prev_esp = current_stack_pointer;
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call_on_stack(__do_softirq, isp);
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}
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bool handle_irq(struct irq_desc *desc, struct pt_regs *regs)
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{
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int overflow = check_stack_overflow();
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if (IS_ERR_OR_NULL(desc))
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return false;
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if (user_mode(regs) || !execute_on_irq_stack(overflow, desc)) {
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if (unlikely(overflow))
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print_stack_overflow();
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generic_handle_irq_desc(desc);
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}
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return true;
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}
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