From patchwork Wed Nov 7 01:00:25 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 10671695 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 42EF915E9 for ; Wed, 7 Nov 2018 01:04:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3127B2AD57 for ; Wed, 7 Nov 2018 01:04:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2273F2AFFE; Wed, 7 Nov 2018 01:04:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6003E2ADAE for ; Wed, 7 Nov 2018 01:04:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388680AbeKGKcQ (ORCPT ); Wed, 7 Nov 2018 05:32:16 -0500 Received: from mail-pl1-f195.google.com ([209.85.214.195]:34565 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388787AbeKGKcP (ORCPT ); Wed, 7 Nov 2018 05:32:15 -0500 Received: by mail-pl1-f195.google.com with SMTP id f12-v6so5863863plo.1 for ; Tue, 06 Nov 2018 17:04:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=9xfBRVzqB0Ls5pcWm0TbOgnmfv50OfmlPbrPGKqr5Q4=; b=RZdzMsfiVvb2DSFZ+LMXKG1CnlxvTVC3dYqrVtLBaFYtvXKjxblBWzgWVHTpKS7BqG so8JQ38uQTODgj93g6iP2Kj/jPndyZm9AEqslzClTTvG4lAmmkjS58A1JDhKt16gxSvr ukYQ90vb7t9N+Q1XdUVN5xi8nCiq1c2La7XQk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=9xfBRVzqB0Ls5pcWm0TbOgnmfv50OfmlPbrPGKqr5Q4=; b=YxpavHZ30M0+DAkVI7GVH7Y6LHqmZa6U/vpZ1oyv5G2PQJTwEp43U7iJj2MotblhTr G7bBoz/kbd+T316dQB9vLzKRPeXe1ae0FXzu0ruVSu04MRaE8qebpCACk5/AwTuSX1rt yQHE97j5PjPcBBIaZ1qjG98mP4JHg2ZNb8p7oMYx+uGF0y2g9LgKQEWLg3afnZ1QpPr+ JnwDcXU/SkbBUv9GsRdzyVUeFydUKKbHgajMbriJqh2Cnm4oiPb0iNJEbPcemoopedcH EHc40bZf5QGWI4eB0AnKOz/8KHaAO2+pwlYZBiwROXoEBWgA0vCi+SX0xusweIFpEkWI xErQ== X-Gm-Message-State: AGRZ1gKAhkZb3RunqPWpLQuYlson3Kh3H2ZHmLvW3H2ndcE6lVtYBeSj 3yv0rXL0foU+ktA84sBGwvzjIQ== X-Google-Smtp-Source: AJdET5cicUhIpSxBvTmLxr2xlyeIhgpeLbEqR7/5nFsCW/f0/Iq85LqnTKI08vM4CzNzoMpiJUb1rg== X-Received: by 2002:a17:902:8c89:: with SMTP id t9-v6mr9102632plo.336.1541552653824; Tue, 06 Nov 2018 17:04:13 -0800 (PST) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:1:c8e0:70d7:4be7:a36]) by smtp.gmail.com with ESMTPSA id v37sm30134695pgn.5.2018.11.06.17.04.12 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Nov 2018 17:04:13 -0800 (PST) From: Douglas Anderson To: Jason Wessel , Daniel Thompson Cc: kgdb-bugreport@lists.sourceforge.net, Peter Zijlstra , Douglas Anderson , linux-mips@linux-mips.org, linux-sh@vger.kernel.org, Borislav Petkov , linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, Catalin Marinas , James Hogan , linux-hexagon@vger.kernel.org, x86@kernel.org, Vineet Gupta , Thomas Gleixner , Michal Hocko , Ralf Baechle , linux-snps-arc@lists.infradead.org, Andrew Morton , "H. Peter Anvin" , Yoshinori Sato , Benjamin Herrenschmidt , Will Deacon , Paul Burton , Ingo Molnar , Russell King , linux-arm-kernel@lists.infradead.org, Christophe Leroy , Huang Ying , "David S. Miller" , Rich Felker , Michael Ellerman , Mike Rapoport , Paul Mackerras , Richard Kuo , linuxppc-dev@lists.ozlabs.org Subject: [PATCH v3 1/4] kgdb: Remove irq flags from roundup Date: Tue, 6 Nov 2018 17:00:25 -0800 Message-Id: <20181107010028.184543-2-dianders@chromium.org> X-Mailer: git-send-email 2.19.1.930.g4563a0d9d0-goog In-Reply-To: <20181107010028.184543-1-dianders@chromium.org> References: <20181107010028.184543-1-dianders@chromium.org> MIME-Version: 1.0 Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP The function kgdb_roundup_cpus() was passed a parameter that was documented as: > the flags that will be used when restoring the interrupts. There is > local_irq_save() call before kgdb_roundup_cpus(). Nobody used those flags. Anyone who wanted to temporarily turn on interrupts just did local_irq_enable() and local_irq_disable() without looking at them. So we can definitely remove the flags. Signed-off-by: Douglas Anderson --- Changes in v3: None Changes in v2: - Removing irq flags separated from fixing lockdep splat. arch/arc/kernel/kgdb.c | 2 +- arch/arm/kernel/kgdb.c | 2 +- arch/arm64/kernel/kgdb.c | 2 +- arch/hexagon/kernel/kgdb.c | 9 ++------- arch/mips/kernel/kgdb.c | 2 +- arch/powerpc/kernel/kgdb.c | 2 +- arch/sh/kernel/kgdb.c | 2 +- arch/sparc/kernel/smp_64.c | 2 +- arch/x86/kernel/kgdb.c | 9 ++------- include/linux/kgdb.h | 9 ++------- kernel/debug/debug_core.c | 2 +- 11 files changed, 14 insertions(+), 29 deletions(-) diff --git a/arch/arc/kernel/kgdb.c b/arch/arc/kernel/kgdb.c index 9a3c34af2ae8..0932851028e0 100644 --- a/arch/arc/kernel/kgdb.c +++ b/arch/arc/kernel/kgdb.c @@ -197,7 +197,7 @@ static void kgdb_call_nmi_hook(void *ignored) kgdb_nmicallback(raw_smp_processor_id(), NULL); } -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c index caa0dbe3dc61..f21077b077be 100644 --- a/arch/arm/kernel/kgdb.c +++ b/arch/arm/kernel/kgdb.c @@ -175,7 +175,7 @@ static void kgdb_call_nmi_hook(void *ignored) kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); } -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c index a20de58061a8..12c339ff6e75 100644 --- a/arch/arm64/kernel/kgdb.c +++ b/arch/arm64/kernel/kgdb.c @@ -289,7 +289,7 @@ static void kgdb_call_nmi_hook(void *ignored) kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); } -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); diff --git a/arch/hexagon/kernel/kgdb.c b/arch/hexagon/kernel/kgdb.c index 16c24b22d0b2..012e0e230ac2 100644 --- a/arch/hexagon/kernel/kgdb.c +++ b/arch/hexagon/kernel/kgdb.c @@ -119,17 +119,12 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) /** * kgdb_roundup_cpus - Get other CPUs into a holding pattern - * @flags: Current IRQ state * * On SMP systems, we need to get the attention of the other CPUs * and get them be in a known state. This should do what is needed * to get the other CPUs to call kgdb_wait(). Note that on some arches, * the NMI approach is not used for rounding up all the CPUs. For example, - * in case of MIPS, smp_call_function() is used to roundup CPUs. In - * this case, we have to make sure that interrupts are enabled before - * calling smp_call_function(). The argument to this function is - * the flags that will be used when restoring the interrupts. There is - * local_irq_save() call before kgdb_roundup_cpus(). + * in case of MIPS, smp_call_function() is used to roundup CPUs. * * On non-SMP systems, this is not called. */ @@ -139,7 +134,7 @@ static void hexagon_kgdb_nmi_hook(void *ignored) kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); } -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { local_irq_enable(); smp_call_function(hexagon_kgdb_nmi_hook, NULL, 0); diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c index eb6c0d582626..2b05effc17b4 100644 --- a/arch/mips/kernel/kgdb.c +++ b/arch/mips/kernel/kgdb.c @@ -219,7 +219,7 @@ static void kgdb_call_nmi_hook(void *ignored) set_fs(old_fs); } -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c index 59c578f865aa..b0e804844be0 100644 --- a/arch/powerpc/kernel/kgdb.c +++ b/arch/powerpc/kernel/kgdb.c @@ -124,7 +124,7 @@ static int kgdb_call_nmi_hook(struct pt_regs *regs) } #ifdef CONFIG_SMP -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { smp_send_debugger_break(); } diff --git a/arch/sh/kernel/kgdb.c b/arch/sh/kernel/kgdb.c index 4f04c6638a4d..cc57630f6bf2 100644 --- a/arch/sh/kernel/kgdb.c +++ b/arch/sh/kernel/kgdb.c @@ -319,7 +319,7 @@ static void kgdb_call_nmi_hook(void *ignored) kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); } -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c index 4792e08ad36b..f45d876983f1 100644 --- a/arch/sparc/kernel/smp_64.c +++ b/arch/sparc/kernel/smp_64.c @@ -1014,7 +1014,7 @@ void flush_dcache_page_all(struct mm_struct *mm, struct page *page) } #ifdef CONFIG_KGDB -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { smp_cross_call(&xcall_kgdb_capture, 0, 0, 0); } diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 8e36f249646e..ac6291a4178d 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -422,21 +422,16 @@ static void kgdb_disable_hw_debug(struct pt_regs *regs) #ifdef CONFIG_SMP /** * kgdb_roundup_cpus - Get other CPUs into a holding pattern - * @flags: Current IRQ state * * On SMP systems, we need to get the attention of the other CPUs * and get them be in a known state. This should do what is needed * to get the other CPUs to call kgdb_wait(). Note that on some arches, * the NMI approach is not used for rounding up all the CPUs. For example, - * in case of MIPS, smp_call_function() is used to roundup CPUs. In - * this case, we have to make sure that interrupts are enabled before - * calling smp_call_function(). The argument to this function is - * the flags that will be used when restoring the interrupts. There is - * local_irq_save() call before kgdb_roundup_cpus(). + * in case of MIPS, smp_call_function() is used to roundup CPUs. * * On non-SMP systems, this is not called. */ -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { apic->send_IPI_allbutself(APIC_DM_NMI); } diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index e465bb15912d..05e5b2eb0d32 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -178,21 +178,16 @@ kgdb_arch_handle_exception(int vector, int signo, int err_code, /** * kgdb_roundup_cpus - Get other CPUs into a holding pattern - * @flags: Current IRQ state * * On SMP systems, we need to get the attention of the other CPUs * and get them into a known state. This should do what is needed * to get the other CPUs to call kgdb_wait(). Note that on some arches, * the NMI approach is not used for rounding up all the CPUs. For example, - * in case of MIPS, smp_call_function() is used to roundup CPUs. In - * this case, we have to make sure that interrupts are enabled before - * calling smp_call_function(). The argument to this function is - * the flags that will be used when restoring the interrupts. There is - * local_irq_save() call before kgdb_roundup_cpus(). + * in case of MIPS, smp_call_function() is used to roundup CPUs. * * On non-SMP systems, this is not called. */ -extern void kgdb_roundup_cpus(unsigned long flags); +extern void kgdb_roundup_cpus(void); /** * kgdb_arch_set_pc - Generic call back to the program counter diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 65c0f1363788..f3cadda45f07 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -593,7 +593,7 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, /* Signal the other CPUs to enter kgdb_wait() */ else if ((!kgdb_single_step) && kgdb_do_roundup) - kgdb_roundup_cpus(flags); + kgdb_roundup_cpus(); #endif /* From patchwork Wed Nov 7 01:00:26 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 10671691 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4664113A4 for ; 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Tue, 06 Nov 2018 17:04:15 -0800 (PST) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:1:c8e0:70d7:4be7:a36]) by smtp.gmail.com with ESMTPSA id v37sm30134695pgn.5.2018.11.06.17.04.13 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Nov 2018 17:04:14 -0800 (PST) From: Douglas Anderson To: Jason Wessel , Daniel Thompson Cc: kgdb-bugreport@lists.sourceforge.net, Peter Zijlstra , Douglas Anderson , linux-mips@linux-mips.org, linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org, Catalin Marinas , James Hogan , linux-hexagon@vger.kernel.org, Vineet Gupta , Rich Felker , Ralf Baechle , linux-snps-arc@lists.infradead.org, Yoshinori Sato , Benjamin Herrenschmidt , Will Deacon , Paul Mackerras , Russell King , linux-arm-kernel@lists.infradead.org, Christophe Leroy , Michael Ellerman , Paul Burton , Richard Kuo , linuxppc-dev@lists.ozlabs.org Subject: [PATCH v3 2/4] kgdb: Fix kgdb_roundup_cpus() for arches who used smp_call_function() Date: Tue, 6 Nov 2018 17:00:26 -0800 Message-Id: <20181107010028.184543-3-dianders@chromium.org> X-Mailer: git-send-email 2.19.1.930.g4563a0d9d0-goog In-Reply-To: <20181107010028.184543-1-dianders@chromium.org> References: <20181107010028.184543-1-dianders@chromium.org> MIME-Version: 1.0 Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP When I had lockdep turned on and dropped into kgdb I got a nice splat on my system. Specifically it hit: DEBUG_LOCKS_WARN_ON(current->hardirq_context) Specifically it looked like this: sysrq: SysRq : DEBUG ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(current->hardirq_context) WARNING: CPU: 0 PID: 0 at .../kernel/locking/lockdep.c:2875 lockdep_hardirqs_on+0xf0/0x160 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0 #27 pstate: 604003c9 (nZCv DAIF +PAN -UAO) pc : lockdep_hardirqs_on+0xf0/0x160 ... Call trace: lockdep_hardirqs_on+0xf0/0x160 trace_hardirqs_on+0x188/0x1ac kgdb_roundup_cpus+0x14/0x3c kgdb_cpu_enter+0x53c/0x5cc kgdb_handle_exception+0x180/0x1d4 kgdb_compiled_brk_fn+0x30/0x3c brk_handler+0x134/0x178 do_debug_exception+0xfc/0x178 el1_dbg+0x18/0x78 kgdb_breakpoint+0x34/0x58 sysrq_handle_dbg+0x54/0x5c __handle_sysrq+0x114/0x21c handle_sysrq+0x30/0x3c qcom_geni_serial_isr+0x2dc/0x30c ... ... irq event stamp: ...45 hardirqs last enabled at (...44): [...] __do_softirq+0xd8/0x4e4 hardirqs last disabled at (...45): [...] el1_irq+0x74/0x130 softirqs last enabled at (...42): [...] _local_bh_enable+0x2c/0x34 softirqs last disabled at (...43): [...] irq_exit+0xa8/0x100 ---[ end trace adf21f830c46e638 ]--- Looking closely at it, it seems like a really bad idea to be calling local_irq_enable() in kgdb_roundup_cpus(). If nothing else that seems like it could violate spinlock semantics and cause a deadlock. Instead, let's use a private csd alongside smp_call_function_single_async() to round up the other CPUs. Using smp_call_function_single_async() doesn't require interrupts to be enabled so we can remove the offending bit of code. In order to avoid duplicating this across all the architectures that use the default kgdb_roundup_cpus(), we'll add a "weak" implementation to debug_core.c. Looking at all the people who previously had copies of this code, there were a few variants. I've attempted to keep the variants working like they used to. Specifically: * For arch/arc we passed NULL to kgdb_nmicallback() instead of get_irq_regs(). * For arch/mips there was a bit of extra code around kgdb_nmicallback() NOTE: In this patch we will still get into trouble if we try to round up a CPU that failed to round up before. We'll try to round it up again and potentially hang when we try to grab the csd lock. That's not new behavior but we'll still try to do better in a future patch. Suggested-by: Daniel Thompson Signed-off-by: Douglas Anderson --- Changes in v3: - No separate init call. - Don't round up the CPU that is doing the rounding up. - Add "#ifdef CONFIG_SMP" to match the rest of the file. - Updated desc saying we don't solve the "failed to roundup" case. - Document the ignored parameter. Changes in v2: - Removing irq flags separated from fixing lockdep splat. - Don't use smp_call_function (Daniel). arch/arc/kernel/kgdb.c | 10 ++-------- arch/arm/kernel/kgdb.c | 12 ------------ arch/arm64/kernel/kgdb.c | 12 ------------ arch/hexagon/kernel/kgdb.c | 27 --------------------------- arch/mips/kernel/kgdb.c | 9 +-------- arch/powerpc/kernel/kgdb.c | 4 ++-- arch/sh/kernel/kgdb.c | 12 ------------ include/linux/kgdb.h | 15 +++++++++++++-- kernel/debug/debug_core.c | 35 +++++++++++++++++++++++++++++++++++ 9 files changed, 53 insertions(+), 83 deletions(-) diff --git a/arch/arc/kernel/kgdb.c b/arch/arc/kernel/kgdb.c index 0932851028e0..68d9fe4b5aa7 100644 --- a/arch/arc/kernel/kgdb.c +++ b/arch/arc/kernel/kgdb.c @@ -192,18 +192,12 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) instruction_pointer(regs) = ip; } -static void kgdb_call_nmi_hook(void *ignored) +void kgdb_call_nmi_hook(void *ignored) { + /* Default implementation passes get_irq_regs() but we don't */ kgdb_nmicallback(raw_smp_processor_id(), NULL); } -void kgdb_roundup_cpus(void) -{ - local_irq_enable(); - smp_call_function(kgdb_call_nmi_hook, NULL, 0); - local_irq_disable(); -} - struct kgdb_arch arch_kgdb_ops = { /* breakpoint instruction: TRAP_S 0x3 */ #ifdef CONFIG_CPU_BIG_ENDIAN diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c index f21077b077be..d9a69e941463 100644 --- a/arch/arm/kernel/kgdb.c +++ b/arch/arm/kernel/kgdb.c @@ -170,18 +170,6 @@ static struct undef_hook kgdb_compiled_brkpt_hook = { .fn = kgdb_compiled_brk_fn }; -static void kgdb_call_nmi_hook(void *ignored) -{ - kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); -} - -void kgdb_roundup_cpus(void) -{ - local_irq_enable(); - smp_call_function(kgdb_call_nmi_hook, NULL, 0); - local_irq_disable(); -} - static int __kgdb_notify(struct die_args *args, unsigned long cmd) { struct pt_regs *regs = args->regs; diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c index 12c339ff6e75..da880247c734 100644 --- a/arch/arm64/kernel/kgdb.c +++ b/arch/arm64/kernel/kgdb.c @@ -284,18 +284,6 @@ static struct step_hook kgdb_step_hook = { .fn = kgdb_step_brk_fn }; -static void kgdb_call_nmi_hook(void *ignored) -{ - kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); -} - -void kgdb_roundup_cpus(void) -{ - local_irq_enable(); - smp_call_function(kgdb_call_nmi_hook, NULL, 0); - local_irq_disable(); -} - static int __kgdb_notify(struct die_args *args, unsigned long cmd) { struct pt_regs *regs = args->regs; diff --git a/arch/hexagon/kernel/kgdb.c b/arch/hexagon/kernel/kgdb.c index 012e0e230ac2..b95d12038a4e 100644 --- a/arch/hexagon/kernel/kgdb.c +++ b/arch/hexagon/kernel/kgdb.c @@ -115,33 +115,6 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) instruction_pointer(regs) = pc; } -#ifdef CONFIG_SMP - -/** - * kgdb_roundup_cpus - Get other CPUs into a holding pattern - * - * On SMP systems, we need to get the attention of the other CPUs - * and get them be in a known state. This should do what is needed - * to get the other CPUs to call kgdb_wait(). Note that on some arches, - * the NMI approach is not used for rounding up all the CPUs. For example, - * in case of MIPS, smp_call_function() is used to roundup CPUs. - * - * On non-SMP systems, this is not called. - */ - -static void hexagon_kgdb_nmi_hook(void *ignored) -{ - kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); -} - -void kgdb_roundup_cpus(void) -{ - local_irq_enable(); - smp_call_function(hexagon_kgdb_nmi_hook, NULL, 0); - local_irq_disable(); -} -#endif - /* Not yet working */ void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c index 2b05effc17b4..42f057a6c215 100644 --- a/arch/mips/kernel/kgdb.c +++ b/arch/mips/kernel/kgdb.c @@ -207,7 +207,7 @@ void arch_kgdb_breakpoint(void) ".set\treorder"); } -static void kgdb_call_nmi_hook(void *ignored) +void kgdb_call_nmi_hook(void *ignored) { mm_segment_t old_fs; @@ -219,13 +219,6 @@ static void kgdb_call_nmi_hook(void *ignored) set_fs(old_fs); } -void kgdb_roundup_cpus(void) -{ - local_irq_enable(); - smp_call_function(kgdb_call_nmi_hook, NULL, 0); - local_irq_disable(); -} - static int compute_signal(int tt) { struct hard_trap_info *ht; diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c index b0e804844be0..b4ce54d73337 100644 --- a/arch/powerpc/kernel/kgdb.c +++ b/arch/powerpc/kernel/kgdb.c @@ -117,7 +117,7 @@ int kgdb_skipexception(int exception, struct pt_regs *regs) return kgdb_isremovedbreak(regs->nip); } -static int kgdb_call_nmi_hook(struct pt_regs *regs) +static int kgdb_debugger_ipi(struct pt_regs *regs) { kgdb_nmicallback(raw_smp_processor_id(), regs); return 0; @@ -502,7 +502,7 @@ int kgdb_arch_init(void) old__debugger_break_match = __debugger_break_match; old__debugger_fault_handler = __debugger_fault_handler; - __debugger_ipi = kgdb_call_nmi_hook; + __debugger_ipi = kgdb_debugger_ipi; __debugger = kgdb_debugger; __debugger_bpt = kgdb_handle_breakpoint; __debugger_sstep = kgdb_singlestep; diff --git a/arch/sh/kernel/kgdb.c b/arch/sh/kernel/kgdb.c index cc57630f6bf2..14e012ad7c57 100644 --- a/arch/sh/kernel/kgdb.c +++ b/arch/sh/kernel/kgdb.c @@ -314,18 +314,6 @@ BUILD_TRAP_HANDLER(singlestep) local_irq_restore(flags); } -static void kgdb_call_nmi_hook(void *ignored) -{ - kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); -} - -void kgdb_roundup_cpus(void) -{ - local_irq_enable(); - smp_call_function(kgdb_call_nmi_hook, NULL, 0); - local_irq_disable(); -} - static int __kgdb_notify(struct die_args *args, unsigned long cmd) { int ret; diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index 05e5b2eb0d32..24422865cd18 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -176,14 +176,25 @@ kgdb_arch_handle_exception(int vector, int signo, int err_code, char *remcom_out_buffer, struct pt_regs *regs); +/** + * kgdb_call_nmi_hook - Call kgdb_nmicallback() on the current CPU + * @ignored: This parameter is only here to match the prototype. + * + * If you're using the default implementation of kgdb_roundup_cpus() + * this function will be called per CPU. If you don't implement + * kgdb_call_nmi_hook() a default will be used. + */ + +extern void kgdb_call_nmi_hook(void *ignored); + /** * kgdb_roundup_cpus - Get other CPUs into a holding pattern * * On SMP systems, we need to get the attention of the other CPUs * and get them into a known state. This should do what is needed * to get the other CPUs to call kgdb_wait(). Note that on some arches, - * the NMI approach is not used for rounding up all the CPUs. For example, - * in case of MIPS, smp_call_function() is used to roundup CPUs. + * the NMI approach is not used for rounding up all the CPUs. Normally + * those architectures can just not implement this and get the default. * * On non-SMP systems, this is not called. */ diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index f3cadda45f07..23f2b5613afa 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -55,6 +55,7 @@ #include #include #include +#include #include #include @@ -220,6 +221,40 @@ int __weak kgdb_skipexception(int exception, struct pt_regs *regs) return 0; } +#ifdef CONFIG_SMP + +/* + * Default (weak) implementation for kgdb_roundup_cpus + */ + +static DEFINE_PER_CPU(call_single_data_t, kgdb_roundup_csd); + +void __weak kgdb_call_nmi_hook(void *ignored) +{ + kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); +} + +void __weak kgdb_roundup_cpus(void) +{ + call_single_data_t *csd; + int this_cpu = get_cpu(); + int cpu; + + for_each_cpu(cpu, cpu_online_mask) { + /* No need to roundup ourselves */ + if (cpu == this_cpu) + continue; + + csd = &per_cpu(kgdb_roundup_csd, cpu); + csd->func = kgdb_call_nmi_hook; + smp_call_function_single_async(cpu, csd); + } + + put_cpu(); +} + +#endif + /* * Some architectures need cache flushes when we set/clear a * breakpoint: