From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 33C0FC10F13 for ; Sun, 14 Apr 2019 16:03:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0CE1B2084E for ; Sun, 14 Apr 2019 16:03:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727881AbfDNQDY (ORCPT ); Sun, 14 Apr 2019 12:03:24 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:43370 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727812AbfDNQDV (ORCPT ); Sun, 14 Apr 2019 12:03:21 -0400 Received: from localhost ([127.0.0.1] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1hFhbC-0002lV-D2; Sun, 14 Apr 2019 18:03:18 +0200 Message-Id: <20190414160146.466354762@linutronix.de> User-Agent: quilt/0.65 Date: Sun, 14 Apr 2019 18:00:08 +0200 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Andy Lutomirski , Josh Poimboeuf , Sean Christopherson Subject: [patch V3 32/32] x86/irq/64: Remove stack overflow debug code References: <20190414155936.679808307@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- arch/x86/Kconfig | 2 - arch/x86/kernel/irq_64.c | 56 ----------------------------------------------- 2 files changed, 1 insertion(+), 57 deletions(-) --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -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 --- a/arch/x86/kernel/irq_64.c +++ b/arch/x86/kernel/irq_64.c @@ -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;