From patchwork Wed May 14 15:58:41 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Thompson X-Patchwork-Id: 4176121 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id D7E94BFF02 for ; Wed, 14 May 2014 16:03:04 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id B6551201F5 for ; Wed, 14 May 2014 16:03:03 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8616D201C7 for ; Wed, 14 May 2014 16:03:02 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Wkbbl-0001dQ-91; Wed, 14 May 2014 16:00:41 +0000 Received: from mail-we0-f175.google.com ([74.125.82.175]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Wkbb0-0008Ss-LU for linux-arm-kernel@lists.infradead.org; Wed, 14 May 2014 15:59:55 +0000 Received: by mail-we0-f175.google.com with SMTP id t61so2116863wes.6 for ; Wed, 14 May 2014 08:59:32 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-type:content-transfer-encoding; bh=rYrZwZKHDrA6ikuWO+y+MwcC2GQ1CL0jLPLjXonwfWc=; b=J3QQBow7uxmAvE7zhewYVTu4dm1rerYhbZv2PgM6v/JyjZfFiG/KPoBYUJyoJrp6GF pCGGwEdqK+Pr9Dq4q4gxTi86dveI5n02XyQBu0xE8l3fQnAy/4SPbXl9eeeklDObLnTQ J15GfUZIiM4De7yuT5m4x+ANTEUZ2exIfusro9qDUXhSKYyrpRHzYuJmVAt6O8szsMdL i0YK6usuLTHYaR8QUBsuftAEmtgqX31Bf+CzUZ0B/h6mV0IpeOJ1jrvcZq8U/h+H5XYT 3uZ8LUrLZJKiKc6XUR95Z3W2FWpCyQaJFoaU8/4ikkxzlUXs30M2F8IUPYztm47k7vpA 0h7w== X-Gm-Message-State: ALoCoQndPHl6uiIkydEkzaKOHIHsO17lXOgXH3hO7XdEYKU+eTwYPE29GK6gcHc8L1TPaRsG+Erh X-Received: by 10.180.11.9 with SMTP id m9mr26658741wib.51.1400083172610; Wed, 14 May 2014 08:59:32 -0700 (PDT) Received: from sundance.lan (cpc4-aztw19-0-0-cust157.18-1.cable.virginm.net. [82.33.25.158]) by mx.google.com with ESMTPSA id dn4sm4687808wib.18.2014.05.14.08.59.30 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 14 May 2014 08:59:31 -0700 (PDT) From: Daniel Thompson To: Jason Wessel , kgdb-bugreport@lists.sourceforge.net Subject: [RFC 4/8] ARM: Add KGDB/KDB FIQ debugger generic code Date: Wed, 14 May 2014 16:58:41 +0100 Message-Id: <1400083125-1464-5-git-send-email-daniel.thompson@linaro.org> X-Mailer: git-send-email 1.9.0 In-Reply-To: <1400083125-1464-1-git-send-email-daniel.thompson@linaro.org> References: <1400083125-1464-1-git-send-email-daniel.thompson@linaro.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140514_085955_008668_2FA4A00E X-CRM114-Status: GOOD ( 23.45 ) X-Spam-Score: -0.7 (/) Cc: Mark Rutland , kernel@stlinux.com, Frederic Weisbecker , Linus Walleij , Jiri Slaby , Daniel Thompson , Dirk Behme , Russell King , Nicolas Pitre , Ian Campbell , Anton Vorontsov , "David A. Long" , linux-serial@vger.kernel.org, Catalin Marinas , kernel-team@android.com, devicetree@vger.kernel.org, linaro-kernel@lists.linaro.org, Pawel Moll , patches@linaro.org, Kumar Gala , Rob Herring , John Stultz , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Colin Cross , Christoffer Dall X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-2.5 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Anton Vorontsov The FIQ debugger may be used to debug situations when the kernel stuck in uninterruptable sections, e.g. the kernel infinitely loops or deadlocked in an interrupt or with interrupts disabled. By default KGDB FIQ is disabled in runtime, but can be enabled with kgdb_fiq.enable=1 kernel command line option. Signed-off-by: Anton Vorontsov Signed-off-by: John Stultz Signed-off-by: Daniel Thompson --- arch/arm/Kconfig | 2 + arch/arm/Kconfig.debug | 18 ++++++ arch/arm/include/asm/kgdb.h | 7 +++ arch/arm/kernel/Makefile | 1 + arch/arm/kernel/kgdb_fiq.c | 117 +++++++++++++++++++++++++++++++++++++++ arch/arm/kernel/kgdb_fiq_entry.S | 87 +++++++++++++++++++++++++++++ 6 files changed, 232 insertions(+) create mode 100644 arch/arm/kernel/kgdb_fiq.c create mode 100644 arch/arm/kernel/kgdb_fiq_entry.S diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index db3c541..419fd0a 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -307,6 +307,7 @@ choice config ARCH_MULTIPLATFORM bool "Allow multiple platforms to be selected" depends on MMU + select ARCH_MIGHT_HAVE_KGDB_FIQ select ARCH_WANT_OPTIONAL_GPIOLIB select ARM_HAS_SG_CHAIN select ARM_PATCH_PHYS_VIRT @@ -356,6 +357,7 @@ config ARCH_REALVIEW config ARCH_VERSATILE bool "ARM Ltd. Versatile family" + select ARCH_MIGHT_HAVE_KGDB_FIQ select ARCH_WANT_OPTIONAL_GPIOLIB select ARM_AMBA select ARM_TIMER_SP804 diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug index 6a2bcfd..1f1bec1 100644 --- a/arch/arm/Kconfig.debug +++ b/arch/arm/Kconfig.debug @@ -2,6 +2,24 @@ menu "Kernel hacking" source "lib/Kconfig.debug" +config ARCH_MIGHT_HAVE_KGDB_FIQ + bool + +config KGDB_FIQ + bool "KGDB FIQ support" + depends on KGDB_KDB && ARCH_MIGHT_HAVE_KGDB_FIQ && !THUMB2_KERNEL + select FIQ + help + The FIQ debugger may be used to debug situations when the + kernel stuck in uninterruptable sections, e.g. the kernel + infinitely loops or deadlocked in an interrupt or with + interrupts disabled. + + By default KGDB FIQ is disabled at runtime, but can be + enabled with kgdb_fiq.enable=1 kernel command line option. + + If unsure, say N. + config ARM_PTDUMP bool "Export kernel pagetable layout to userspace via debugfs" depends on DEBUG_KERNEL diff --git a/arch/arm/include/asm/kgdb.h b/arch/arm/include/asm/kgdb.h index 0a9d5dd..5de21f01 100644 --- a/arch/arm/include/asm/kgdb.h +++ b/arch/arm/include/asm/kgdb.h @@ -11,7 +11,9 @@ #define __ARM_KGDB_H__ #include +#include #include +#include /* * GDB assumes that we're a user process being debugged, so @@ -48,6 +50,11 @@ static inline void arch_kgdb_breakpoint(void) extern void kgdb_handle_bus_error(void); extern int kgdb_fault_expected; +extern char kgdb_fiq_handler; +extern char kgdb_fiq_handler_end; +asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs); +extern int kgdb_register_fiq(unsigned int fiq); + #endif /* !__ASSEMBLY__ */ /* diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile index 040619c..251f651 100644 --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -67,6 +67,7 @@ endif obj-$(CONFIG_OABI_COMPAT) += sys_oabi-compat.o obj-$(CONFIG_ARM_THUMBEE) += thumbee.o obj-$(CONFIG_KGDB) += kgdb.o +obj-$(CONFIG_KGDB_FIQ) += kgdb_fiq_entry.o kgdb_fiq.o obj-$(CONFIG_ARM_UNWIND) += unwind.o obj-$(CONFIG_HAVE_TCM) += tcm.o obj-$(CONFIG_OF) += devtree.o diff --git a/arch/arm/kernel/kgdb_fiq.c b/arch/arm/kernel/kgdb_fiq.c new file mode 100644 index 0000000..b236409 --- /dev/null +++ b/arch/arm/kernel/kgdb_fiq.c @@ -0,0 +1,117 @@ +/* + * KGDB FIQ + * + * Copyright 2010 Google, Inc. + * Arve Hjønnevåg + * Colin Cross + * Copyright 2012 Linaro Ltd. + * Anton Vorontsov + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static int kgdb_fiq_enabled; +module_param_named(enable, kgdb_fiq_enabled, int, 0600); +MODULE_PARM_DESC(enable, "set to 1 to enable FIQ KGDB"); + +static unsigned int kgdb_fiq; + +asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs) +{ + if (kgdb_nmi_poll_knock()) { + nmi_enter(); + kgdb_handle_exception(1, 0, 0, regs); + nmi_exit(); + } + + eoi_fiq(kgdb_fiq); +} + +static struct fiq_handler kgdb_fiq_desc = { + .name = "kgdb", +}; + +static long kgdb_fiq_setup_stack(void *info) +{ + struct pt_regs regs; + + regs.ARM_sp = __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER) + + THREAD_START_SP; + WARN_ON(!regs.ARM_sp); + + set_fiq_regs(®s); + return 0; +} + +/** + * kgdb_fiq_enable_nmi - Manage NMI-triggered entry to KGDB + * @on: Flag to either enable or disable an NMI + * + * This function manages NMIs that usually cause KGDB to enter. That is, not + * all NMIs should be enabled or disabled, but only those that issue + * kgdb_handle_exception(). + * + * The call counts disable requests, and thus allows to nest disables. But + * trying to enable already enabled NMI is an error. + */ +static void kgdb_fiq_enable_nmi(bool on) +{ + static atomic_t cnt; + int ret; + + ret = atomic_add_return(on ? 1 : -1, &cnt); + if (ret > 1 && on) { + /* + * There should be only one instance that calls this function + * in "enable, disable" order. All other users must call + * disable first, then enable. If not, something is wrong. + */ + WARN_ON(1); + return; + } + + if (ret > 0) + enable_fiq(kgdb_fiq); + else + disable_fiq(kgdb_fiq); +} + +int kgdb_register_fiq(unsigned int fiq) +{ + int err; + int cpu; + + if (!kgdb_fiq_enabled) + return -ENODEV; + + kgdb_fiq = fiq; + + err = claim_fiq(&kgdb_fiq_desc); + if (err) { + pr_warn("%s: unable to claim fiq", __func__); + return err; + } + + for_each_possible_cpu(cpu) + work_on_cpu(cpu, kgdb_fiq_setup_stack, NULL); + + set_fiq_handler(&kgdb_fiq_handler, + &kgdb_fiq_handler_end - &kgdb_fiq_handler); + + arch_kgdb_ops.enable_nmi = kgdb_fiq_enable_nmi; + return 0; +} diff --git a/arch/arm/kernel/kgdb_fiq_entry.S b/arch/arm/kernel/kgdb_fiq_entry.S new file mode 100644 index 0000000..d6becca --- /dev/null +++ b/arch/arm/kernel/kgdb_fiq_entry.S @@ -0,0 +1,87 @@ +/* + * KGDB FIQ entry + * + * Copyright 1996,1997,1998 Russell King. + * Copyright 2012 Linaro Ltd. + * Anton Vorontsov + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation. + */ + +#include +#include +#include +#include +#include "entry-header.S" + + .text + +@ This is needed for usr_entry/alignment_trap +.LCcralign: + .long cr_alignment +.LCdohandle: + .long kgdb_fiq_do_handle + + .macro fiq_handler + ldr r1, =.LCdohandle + mov r0, sp + adr lr, BSYM(9997f) + ldr pc, [r1] +9997: + .endm + + .align 5 +__fiq_svc: + svc_entry + fiq_handler + mov r0, sp + ldmib r0, {r1 - r14} + msr cpsr_c, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT + add r8, r0, #S_PC + ldr r9, [r0, #S_PSR] + msr spsr_cxsf, r9 + ldr r0, [r0, #S_R0] + ldmia r8, {pc}^ + + UNWIND(.fnend ) +ENDPROC(__fiq_svc) + .ltorg + + .align 5 +__fiq_usr: + usr_entry + kuser_cmpxchg_check + fiq_handler + get_thread_info tsk + mov why, #0 + b ret_to_user_from_irq + UNWIND(.fnend ) +ENDPROC(__fiq_usr) + .ltorg + + .global kgdb_fiq_handler +kgdb_fiq_handler: + + vector_stub fiq, FIQ_MODE, 4 + + .long __fiq_usr @ 0 (USR_26 / USR_32) + .long __fiq_svc @ 1 (FIQ_26 / FIQ_32) + .long __fiq_svc @ 2 (IRQ_26 / IRQ_32) + .long __fiq_svc @ 3 (SVC_26 / SVC_32) + .long __fiq_svc @ 4 + .long __fiq_svc @ 5 + .long __fiq_svc @ 6 + .long __fiq_svc @ 7 + .long __fiq_svc @ 8 + .long __fiq_svc @ 9 + .long __fiq_svc @ a + .long __fiq_svc @ b + .long __fiq_svc @ c + .long __fiq_svc @ d + .long __fiq_svc @ e + .long __fiq_svc @ f + + .global kgdb_fiq_handler_end +kgdb_fiq_handler_end: