Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932732AbaJ1DrD (ORCPT ); Mon, 27 Oct 2014 23:47:03 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:45561 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932695AbaJ1Dq6 (ORCPT ); Mon, 27 Oct 2014 23:46:58 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Christopher Alexander Tobias Schulze , "David S. Miller" Subject: [PATCH 3.16 098/127] sparc64: Fix pcr_ops initialization and usage bugs. Date: Tue, 28 Oct 2014 11:35:33 +0800 Message-Id: <20141028033425.127052005@linuxfoundation.org> X-Mailer: git-send-email 2.1.2 In-Reply-To: <20141028033420.925922046@linuxfoundation.org> References: <20141028033420.925922046@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: "David S. Miller" [ Upstream commit 8bccf5b313180faefce38e0d1140f76e0f327d28 ] Christopher reports that perf_event_print_debug() can crash in uniprocessor builds. The crash is due to pcr_ops being NULL. This happens because pcr_arch_init() is only invoked by smp_cpus_done() which only executes in SMP builds. init_hw_perf_events() is closely intertwined with pcr_ops being setup properly, therefore: 1) Call pcr_arch_init() early on from init_hw_perf_events(), instead of from smp_cpus_done(). 2) Do not hook up a PMU type if pcr_ops is NULL after pcr_arch_init(). 3) Move init_hw_perf_events to a later initcall so that it we will be sure to invoke pcr_arch_init() after all cpus are brought up. Finally, guard the one naked sequence of pcr_ops dereferences in __global_pmu_self() with an appropriate NULL check. Reported-by: Christopher Alexander Tobias Schulze Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- arch/sparc/kernel/perf_event.c | 7 +++++-- arch/sparc/kernel/process_64.c | 3 +++ arch/sparc/kernel/smp_64.c | 1 - 3 files changed, 8 insertions(+), 3 deletions(-) --- a/arch/sparc/kernel/perf_event.c +++ b/arch/sparc/kernel/perf_event.c @@ -1671,9 +1671,12 @@ static bool __init supported_pmu(void) static int __init init_hw_perf_events(void) { + int err; + pr_info("Performance events: "); - if (!supported_pmu()) { + err = pcr_arch_init(); + if (err || !supported_pmu()) { pr_cont("No support for PMU type '%s'\n", sparc_pmu_type); return 0; } @@ -1685,7 +1688,7 @@ static int __init init_hw_perf_events(vo return 0; } -early_initcall(init_hw_perf_events); +pure_initcall(init_hw_perf_events); void perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs) --- a/arch/sparc/kernel/process_64.c +++ b/arch/sparc/kernel/process_64.c @@ -312,6 +312,9 @@ static void __global_pmu_self(int this_c struct global_pmu_snapshot *pp; int i, num; + if (!pcr_ops) + return; + pp = &global_cpu_snapshot[this_cpu].pmu; num = 1; --- a/arch/sparc/kernel/smp_64.c +++ b/arch/sparc/kernel/smp_64.c @@ -1383,7 +1383,6 @@ void __cpu_die(unsigned int cpu) void __init smp_cpus_done(unsigned int max_cpus) { - pcr_arch_init(); } void smp_send_reschedule(int cpu) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/