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The orig_ist[] array is a shadow copy of the IST array in the TSS. The reason why it exists is that older kernels used two TSS variants with different pointers into the debug stack. orig_ist[] contains the real starting points. There is no point anymore to do so because the same information can be retrieved using the base address of the cpu entry area mapping and the offsets of the various exception stacks. No functional change. Preparation for removing orig_ist. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Nicolai Stange <nstange@suse.de> Cc: Sean Christopherson <sean.j.christopherson@intel.com> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20190414160144.885741626@linutronix.de
90 lines
2.4 KiB
C
90 lines
2.4 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_64-specific interrupt
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* entry and irq statistics code. All the remaining irq logic is
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* done by the generic kernel/irq/ code and in the
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* x86_64-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/kernel_stat.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/seq_file.h>
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#include <linux/delay.h>
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#include <linux/ftrace.h>
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#include <linux/uaccess.h>
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#include <linux/smp.h>
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#include <linux/sched/task_stack.h>
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#include <asm/cpu_entry_area.h>
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#include <asm/io_apic.h>
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#include <asm/apic.h>
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int sysctl_panic_on_stackoverflow;
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/*
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* Probabilistic stack overflow check:
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*
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* Regular device interrupts can enter on the following stacks:
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*
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* - User stack
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*
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* - Kernel task stack
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*
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* - Interrupt stack if a device driver reenables interrupts
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* which should only happen in really old drivers.
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*
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* - Debug IST stack
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*
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* All other contexts are invalid.
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*/
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static inline void stack_overflow_check(struct pt_regs *regs)
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{
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#ifdef CONFIG_DEBUG_STACKOVERFLOW
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#define STACK_MARGIN 128
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u64 irq_stack_top, irq_stack_bottom, estack_top, estack_bottom;
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u64 curbase = (u64)task_stack_page(current);
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struct cea_exception_stacks *estacks;
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if (user_mode(regs))
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return;
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if (regs->sp >= curbase + sizeof(struct pt_regs) + STACK_MARGIN &&
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regs->sp <= curbase + THREAD_SIZE)
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return;
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irq_stack_top = (u64)__this_cpu_read(irq_stack_ptr);
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irq_stack_bottom = irq_stack_top - IRQ_STACK_SIZE + STACK_MARGIN;
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if (regs->sp >= irq_stack_bottom && regs->sp <= irq_stack_top)
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return;
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estacks = __this_cpu_read(cea_exception_stacks);
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estack_top = CEA_ESTACK_TOP(estacks, DB);
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estack_bottom = CEA_ESTACK_BOT(estacks, DB) + STACK_MARGIN;
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if (regs->sp >= estack_bottom && regs->sp <= estack_top)
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return;
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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",
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current->comm, curbase, regs->sp,
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irq_stack_bottom, irq_stack_top,
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estack_bottom, estack_top, (void *)regs->ip);
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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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#endif
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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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stack_overflow_check(regs);
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if (IS_ERR_OR_NULL(desc))
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return false;
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generic_handle_irq_desc(desc);
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return true;
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}
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