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