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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
*
* This file contains the lowest level x86_64-specific interrupt
* entry and irq statistics code. All the remaining irq logic is
* done by the generic kernel/irq/ code and in the
* x86_64-specific irq controller code. (e.g. i8259.c and
* io_apic.c.)
*/
#include <linux/kernel_stat.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/seq_file.h>
#include <linux/delay.h>
#include <linux/ftrace.h>
#include <linux/uaccess.h>
#include <linux/smp.h>
#include <linux/sched/task_stack.h>
#include <asm/cpu_entry_area.h>
#include <asm/io_apic.h>
#include <asm/apic.h>
DEFINE_PER_CPU_PAGE_ALIGNED(struct irq_stack, irq_stack_backing_store) __visible;
DECLARE_INIT_PER_CPU(irq_stack_backing_store);
int sysctl_panic_on_stackoverflow;
/*
* Probabilistic stack overflow check:
*
* Regular device interrupts can enter on the following stacks:
*
* - User stack
*
* - Kernel task stack
*
* - Interrupt stack if a device driver reenables interrupts
* which should only happen in really old drivers.
*
* - Debug IST stack
*
* All other contexts are invalid.
*/
static inline void stack_overflow_check(struct pt_regs *regs)
{
#ifdef CONFIG_DEBUG_STACKOVERFLOW
#define STACK_MARGIN 128
u64 irq_stack_top, irq_stack_bottom, estack_top, estack_bottom;
u64 curbase = (u64)task_stack_page(current);
struct cea_exception_stacks *estacks;
if (user_mode(regs))
return;
if (regs->sp >= curbase + sizeof(struct pt_regs) + STACK_MARGIN &&
regs->sp <= curbase + THREAD_SIZE)
return;
irq_stack_top = (u64)__this_cpu_read(hardirq_stack_ptr);
irq_stack_bottom = irq_stack_top - IRQ_STACK_SIZE + STACK_MARGIN;
if (regs->sp >= irq_stack_bottom && regs->sp <= irq_stack_top)
return;
estacks = __this_cpu_read(cea_exception_stacks);
estack_top = CEA_ESTACK_TOP(estacks, DB);
estack_bottom = CEA_ESTACK_BOT(estacks, DB) + STACK_MARGIN;
if (regs->sp >= estack_bottom && regs->sp <= estack_top)
return;
WARN_ONCE(1, "do_IRQ(): %s has overflown the kernel stack (cur:%Lx,sp:%lx, irq stack:%Lx-%Lx, exception stack: %Lx-%Lx, ip:%pF)\n",
current->comm, curbase, regs->sp,
irq_stack_bottom, irq_stack_top,
estack_bottom, estack_top, (void *)regs->ip);
if (sysctl_panic_on_stackoverflow)
panic("low stack detected by irq handler - check messages\n");
#endif
}
bool handle_irq(struct irq_desc *desc, struct pt_regs *regs)
{
stack_overflow_check(regs);
if (IS_ERR_OR_NULL(desc))
return false;
generic_handle_irq_desc(desc);
return true;
}
#ifdef CONFIG_VMAP_STACK
/*
* VMAP the backing store with guard pages
*/
static int map_irq_stack(unsigned int cpu)
{
char *stack = (char *)per_cpu_ptr(&irq_stack_backing_store, cpu);
struct page *pages[IRQ_STACK_SIZE / PAGE_SIZE];
void *va;
int i;
for (i = 0; i < IRQ_STACK_SIZE / PAGE_SIZE; i++) {
phys_addr_t pa = per_cpu_ptr_to_phys(stack + (i << PAGE_SHIFT));
pages[i] = pfn_to_page(pa >> PAGE_SHIFT);
}
va = vmap(pages, IRQ_STACK_SIZE / PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
if (!va)
return -ENOMEM;
per_cpu(hardirq_stack_ptr, cpu) = va + IRQ_STACK_SIZE;
return 0;
}
#else
/*
* If VMAP stacks are disabled due to KASAN, just use the per cpu
* backing store without guard pages.
*/
static int map_irq_stack(unsigned int cpu)
{
void *va = per_cpu_ptr(&irq_stack_backing_store, cpu);
per_cpu(hardirq_stack_ptr, cpu) = va + IRQ_STACK_SIZE;
return 0;
}
#endif
int irq_init_percpu_irqstack(unsigned int cpu)
{
if (per_cpu(hardirq_stack_ptr, cpu))
return 0;
return map_irq_stack(cpu);
}
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