From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936020AbcHJTxe (ORCPT ); Wed, 10 Aug 2016 15:53:34 -0400 Received: from mailx.hitachi.co.jp ([133.145.228.49]:51870 "EHLO mailx.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934106AbcHJSgy (ORCPT ); Wed, 10 Aug 2016 14:36:54 -0400 Subject: [V4 PATCH 2/2] mips/panic: Replace smp_send_stop() with kdump friendly version in panic path From: Hidehiro Kawai To: Andrew Morton , Dave Young , "Eric W. Biederman" , Baoquan He , Ralf Baechle Cc: Corey Minyard , x86@kernel.org, David Daney , Xunlei Pang , Aaro Koskinen , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, HATAYAMA Daisuke , linux-mips@linux-mips.org, Masami Hiramatsu , "Steven J. Hill" , xen-devel@lists.xenproject.org, Daniel Walker , Vivek Goyal Date: Wed, 10 Aug 2016 17:09:50 +0900 Message-ID: <20160810080950.11028.28000.stgit@sysi4-13.yrl.intra.hitachi.co.jp> In-Reply-To: <20160810080946.11028.97686.stgit@sysi4-13.yrl.intra.hitachi.co.jp> References: <20160810080946.11028.97686.stgit@sysi4-13.yrl.intra.hitachi.co.jp> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Daniel Walker reported problems which happens when crash_kexec_post_notifiers kernel option is enabled (https://lkml.org/lkml/2015/6/24/44). In that case, smp_send_stop() is called before entering kdump routines which assume other CPUs are still online. As the result, kdump routines fail to save other CPUs' registers. Additionally for MIPS OCTEON, it misses to stop the watchdog timer. To fix this problem, call a new kdump friendly function, crash_smp_send_stop(), instead of the smp_send_stop() when crash_kexec_post_notifiers is enabled. crash_smp_send_stop() is a weak function, and it just call smp_send_stop(). Architecture codes should override it so that kdump can work appropriately. This patch provides MIPS version. Reported-by: Daniel Walker Fixes: f06e5153f4ae (kernel/panic.c: add "crash_kexec_post_notifiers" option) Signed-off-by: Hidehiro Kawai Cc: Ralf Baechle Cc: David Daney Cc: Aaro Koskinen Cc: "Steven J. Hill" Cc: Corey Minyard --- I'm not familiar with MIPS, and I don't have a test environment and just did build tests only. Please don't apply this patch until someone does enough tests, otherwise simply drop this patch. --- arch/mips/cavium-octeon/setup.c | 14 ++++++++++++++ arch/mips/include/asm/kexec.h | 1 + arch/mips/kernel/crash.c | 18 +++++++++++++++++- arch/mips/kernel/machine_kexec.c | 1 + 4 files changed, 33 insertions(+), 1 deletion(-) diff --git a/arch/mips/cavium-octeon/setup.c b/arch/mips/cavium-octeon/setup.c index cb16fcc..5537f95 100644 --- a/arch/mips/cavium-octeon/setup.c +++ b/arch/mips/cavium-octeon/setup.c @@ -267,6 +267,17 @@ static void octeon_crash_shutdown(struct pt_regs *regs) default_machine_crash_shutdown(regs); } +#ifdef CONFIG_SMP +void octeon_crash_smp_send_stop(void) +{ + int cpu; + + /* disable watchdogs */ + for_each_online_cpu(cpu) + cvmx_write_csr(CVMX_CIU_WDOGX(cpu_logical_map(cpu)), 0); +} +#endif + #endif /* CONFIG_KEXEC */ #ifdef CONFIG_CAVIUM_RESERVE32 @@ -911,6 +922,9 @@ void __init prom_init(void) _machine_kexec_shutdown = octeon_shutdown; _machine_crash_shutdown = octeon_crash_shutdown; _machine_kexec_prepare = octeon_kexec_prepare; +#ifdef CONFIG_SMP + _crash_smp_send_stop = octeon_crash_smp_send_stop; +#endif #endif octeon_user_io_init(); diff --git a/arch/mips/include/asm/kexec.h b/arch/mips/include/asm/kexec.h index ee25ebb..493a3cc 100644 --- a/arch/mips/include/asm/kexec.h +++ b/arch/mips/include/asm/kexec.h @@ -45,6 +45,7 @@ extern const unsigned char kexec_smp_wait[]; extern unsigned long secondary_kexec_args[4]; extern void (*relocated_kexec_smp_wait) (void *); extern atomic_t kexec_ready_to_reboot; +extern void (*_crash_smp_send_stop)(void); #endif #endif diff --git a/arch/mips/kernel/crash.c b/arch/mips/kernel/crash.c index 610f0f3..1723b17 100644 --- a/arch/mips/kernel/crash.c +++ b/arch/mips/kernel/crash.c @@ -47,9 +47,14 @@ static void crash_shutdown_secondary(void *passed_regs) static void crash_kexec_prepare_cpus(void) { + static int cpus_stopped; unsigned int msecs; + unsigned int ncpus; - unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */ + if (cpus_stopped) + return; + + ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */ dump_send_ipi(crash_shutdown_secondary); smp_wmb(); @@ -64,6 +69,17 @@ static void crash_kexec_prepare_cpus(void) cpu_relax(); mdelay(1); } + + cpus_stopped = 1; +} + +/* Override the weak function in kernel/panic.c */ +void crash_smp_send_stop(void) +{ + if (_crash_smp_send_stop) + _crash_smp_send_stop(); + + crash_kexec_prepare_cpus(); } #else /* !defined(CONFIG_SMP) */ diff --git a/arch/mips/kernel/machine_kexec.c b/arch/mips/kernel/machine_kexec.c index 50980bf3..5972520 100644 --- a/arch/mips/kernel/machine_kexec.c +++ b/arch/mips/kernel/machine_kexec.c @@ -25,6 +25,7 @@ void (*_machine_crash_shutdown)(struct pt_regs *regs) = NULL; #ifdef CONFIG_SMP void (*relocated_kexec_smp_wait) (void *); atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0); +void (*_crash_smp_send_stop)(void) = NULL; #endif int