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x86/irq/64: Remove stack overflow debug code

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All stack types on x86 64-bit have guard pages now.

So there is no point in executing probabilistic overflow checks as the
guard pages are a accurate and reliable overflow prevention.

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/20190414160146.466354762@linutronix.de
This commit is contained in:
Thomas Gleixner 2019-04-14 18:00:08 +02:00 committed by Borislav Petkov
parent 18b7a6bef6
commit 117ed45485
2 changed files with 1 additions and 57 deletions
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2
arch/x86/Kconfig
View File

@ -14,6 +14,7 @@ config X86_32
select ARCH_WANT_IPC_PARSE_VERSION
select CLKSRC_I8253
select CLONE_BACKWARDS
select HAVE_DEBUG_STACKOVERFLOW
select MODULES_USE_ELF_REL
select OLD_SIGACTION
@ -138,7 +139,6 @@ config X86
select HAVE_COPY_THREAD_TLS
select HAVE_C_RECORDMCOUNT
select HAVE_DEBUG_KMEMLEAK
select HAVE_DEBUG_STACKOVERFLOW
select HAVE_DMA_CONTIGUOUS
select HAVE_DYNAMIC_FTRACE
select HAVE_DYNAMIC_FTRACE_WITH_REGS

56
arch/x86/kernel/irq_64.c
View File

@ -26,64 +26,8 @@
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;