From patchwork Thu Mar 12 13:39:20 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Thompson X-Patchwork-Id: 5995221 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 86F8B9F380 for ; Thu, 12 Mar 2015 13:46:49 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 85D942037C for ; Thu, 12 Mar 2015 13:46:48 +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 849D6202FF for ; Thu, 12 Mar 2015 13:46:47 +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 1YW3Oz-0003rc-I6; Thu, 12 Mar 2015 13:43:53 +0000 Received: from mail-wg0-f54.google.com ([74.125.82.54]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1YW3LP-0007YI-0W for linux-arm-kernel@lists.infradead.org; Thu, 12 Mar 2015 13:40:13 +0000 Received: by wggx13 with SMTP id x13so16448222wgg.4 for ; Thu, 12 Mar 2015 06:39:48 -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; bh=y3y/9hHlqZXfTVQNQ0hwE0lGkOn/6EE3tgGa3qJM+lY=; b=Ww5T71KqFmkc8H3myd42Is28lLjEKj2ZLcStiZGOncuUh9pL4Yzcae/GdVuOM9+xyl tGN/ExLpVH3+cvUTtcW0+xAud4sOiokMa9+xSUmCgSTTgMNXZTuIvTIRYGjjeAisLXFP WUpRNuNZnsuNxilzp9NANNSqZ7w+aymhanSc89z0rf0JAO4rsnslIUYBAC+E54tgr1mj 6oVemFVHYy3J2iaF+koLC5ozbKMgFaFGhm+PpDGOLaOcrJ38tPbzwDpn90q0maJr923s +IvrSKR6yAUyqwZt3V7WbK6inOpjAOyBM5OEcQUTys7aQVfkwEm6W8x23zCDy8ZhVSG2 oI3A== X-Gm-Message-State: ALoCoQlvIkkezAhh7q1jCnLQfyPrUdksnv6vueJ8+tWehLHUD1H6J+631VIuaPXSozJUaY0R9jVF X-Received: by 10.180.84.166 with SMTP id a6mr86622603wiz.4.1426167588778; Thu, 12 Mar 2015 06:39:48 -0700 (PDT) Received: from wychelm.lan (cpc4-aztw19-0-0-cust71.18-1.cable.virginm.net. [82.33.25.72]) by mx.google.com with ESMTPSA id xy2sm10116530wjc.14.2015.03.12.06.39.47 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 12 Mar 2015 06:39:48 -0700 (PDT) From: Daniel Thompson To: Thomas Gleixner , Jason Cooper Subject: [PATCH 4.0-rc2 v18 5/6] x86/nmi: Use common printk functions Date: Thu, 12 Mar 2015 13:39:20 +0000 Message-Id: <1426167561-25963-6-git-send-email-daniel.thompson@linaro.org> X-Mailer: git-send-email 2.1.0 In-Reply-To: <1426167561-25963-1-git-send-email-daniel.thompson@linaro.org> References: <1422022952-31552-1-git-send-email-daniel.thompson@linaro.org> <1426167561-25963-1-git-send-email-daniel.thompson@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150312_064011_253250_287F30FC X-CRM114-Status: GOOD ( 21.42 ) X-Spam-Score: -0.7 (/) Cc: x86@kernel.org, Daniel Thompson , linaro-kernel@lists.linaro.org, Russell King , patches@linaro.org, Marc Zyngier , Stephen Boyd , "H. Peter Anvin" , Will Deacon , linux-kernel@vger.kernel.org, Steven Rostedt , Daniel Drake , Dmitry Pervushin , Dirk Behme , John Stultz , Tim Sander , Catalin Marinas , Sumit Semwal , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_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 Much of the code sitting in arch/x86/kernel/apic/hw_nmi.c to support safe all-cpu backtracing from NMI has been copied to printk.c to make it accessible to other architectures. Port the x86 NMI backtrace to the generic code. Signed-off-by: Daniel Thompson Cc: Steven Rostedt Cc: Thomas Gleixner Acked-by: Ingo Molnar Cc: "H. Peter Anvin" Cc: x86@kernel.org --- arch/x86/Kconfig | 1 + arch/x86/kernel/apic/hw_nmi.c | 101 +++--------------------------------------- 2 files changed, 8 insertions(+), 94 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index c2fb8a87dccb..15278140833b 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -141,6 +141,7 @@ config X86 select ACPI_LEGACY_TABLES_LOOKUP if ACPI select X86_FEATURE_NAMES if PROC_FS select SRCU + select PRINTK_NMI_BACKTRACE if X86_LOCAL_APIC config INSTRUCTION_DECODER def_bool y diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c index 6873ab925d00..db934f9461ed 100644 --- a/arch/x86/kernel/apic/hw_nmi.c +++ b/arch/x86/kernel/apic/hw_nmi.c @@ -30,40 +30,16 @@ u64 hw_nmi_get_sample_period(int watchdog_thresh) #ifdef arch_trigger_all_cpu_backtrace /* For reliability, we're prepared to waste bits here. */ static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly; -static cpumask_t printtrace_mask; - -#define NMI_BUF_SIZE 4096 - -struct nmi_seq_buf { - unsigned char buffer[NMI_BUF_SIZE]; - struct seq_buf seq; -}; - -/* Safe printing in NMI context */ -static DEFINE_PER_CPU(struct nmi_seq_buf, nmi_print_seq); - -/* "in progress" flag of arch_trigger_all_cpu_backtrace */ -static unsigned long backtrace_flag; - -static void print_seq_line(struct nmi_seq_buf *s, int start, int end) -{ - const char *buf = s->buffer + start; - - printk("%.*s", (end - start) + 1, buf); -} void arch_trigger_all_cpu_backtrace(bool include_self) { - struct nmi_seq_buf *s; - int len; - int cpu; int i; int this_cpu = get_cpu(); - if (test_and_set_bit(0, &backtrace_flag)) { + if (0 != printk_nmi_backtrace_prepare()) { /* - * If there is already a trigger_all_cpu_backtrace() in progress - * (backtrace_flag == 1), don't output double cpu dump infos. + * If there is already an nmi printk sequence in + * progress then just give up... */ put_cpu(); return; @@ -73,16 +49,6 @@ void arch_trigger_all_cpu_backtrace(bool include_self) if (!include_self) cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask)); - cpumask_copy(&printtrace_mask, to_cpumask(backtrace_mask)); - /* - * Set up per_cpu seq_buf buffers that the NMIs running on the other - * CPUs will write to. - */ - for_each_cpu(cpu, to_cpumask(backtrace_mask)) { - s = &per_cpu(nmi_print_seq, cpu); - seq_buf_init(&s->seq, s->buffer, NMI_BUF_SIZE); - } - if (!cpumask_empty(to_cpumask(backtrace_mask))) { pr_info("sending NMI to %s CPUs:\n", (include_self ? "all" : "other")); @@ -97,73 +63,20 @@ void arch_trigger_all_cpu_backtrace(bool include_self) touch_softlockup_watchdog(); } - /* - * Now that all the NMIs have triggered, we can dump out their - * back traces safely to the console. - */ - for_each_cpu(cpu, &printtrace_mask) { - int last_i = 0; - - s = &per_cpu(nmi_print_seq, cpu); - len = seq_buf_used(&s->seq); - if (!len) - continue; - - /* Print line by line. */ - for (i = 0; i < len; i++) { - if (s->buffer[i] == '\n') { - print_seq_line(s, last_i, i); - last_i = i + 1; - } - } - /* Check if there was a partial line. */ - if (last_i < len) { - print_seq_line(s, last_i, len - 1); - pr_cont("\n"); - } - } - - clear_bit(0, &backtrace_flag); - smp_mb__after_atomic(); + printk_nmi_backtrace_complete(); put_cpu(); } -/* - * It is not safe to call printk() directly from NMI handlers. - * It may be fine if the NMI detected a lock up and we have no choice - * but to do so, but doing a NMI on all other CPUs to get a back trace - * can be done with a sysrq-l. We don't want that to lock up, which - * can happen if the NMI interrupts a printk in progress. - * - * Instead, we redirect the vprintk() to this nmi_vprintk() that writes - * the content into a per cpu seq_buf buffer. Then when the NMIs are - * all done, we can safely dump the contents of the seq_buf to a printk() - * from a non NMI context. - */ -static int nmi_vprintk(const char *fmt, va_list args) -{ - struct nmi_seq_buf *s = this_cpu_ptr(&nmi_print_seq); - unsigned int len = seq_buf_used(&s->seq); - - seq_buf_vprintf(&s->seq, fmt, args); - return seq_buf_used(&s->seq) - len; -} - static int arch_trigger_all_cpu_backtrace_handler(unsigned int cmd, struct pt_regs *regs) { - int cpu; - - cpu = smp_processor_id(); + int cpu = smp_processor_id(); if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) { - printk_func_t printk_func_save = this_cpu_read(printk_func); - - /* Replace printk to write into the NMI seq */ - this_cpu_write(printk_func, nmi_vprintk); + printk_nmi_backtrace_this_cpu_begin(); printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu); show_regs(regs); - this_cpu_write(printk_func, printk_func_save); + printk_nmi_backtrace_this_cpu_end(); cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask)); return NMI_HANDLED;