Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753320Ab3JDRbw (ORCPT ); Fri, 4 Oct 2013 13:31:52 -0400 Received: from terminus.zytor.com ([198.137.202.10]:58665 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752231Ab3JDRbu (ORCPT ); Fri, 4 Oct 2013 13:31:50 -0400 Date: Fri, 4 Oct 2013 10:31:26 -0700 From: tip-bot for Mike Travis Message-ID: Cc: linux-kernel@vger.kernel.org, paulus@samba.org, hpa@zytor.com, mingo@kernel.org, jason.wessel@windriver.com, a.p.zijlstra@chello.nl, travis@sgi.com, acme@ghostprotocols.net, hedi@sgi.com, sivanich@sgi.com, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, paulus@samba.org, linux-kernel@vger.kernel.org, travis@sgi.com, a.p.zijlstra@chello.nl, jason.wessel@windriver.com, acme@ghostprotocols.net, hedi@sgi.com, sivanich@sgi.com, tglx@linutronix.de In-Reply-To: <20131002151418.089692683@asylum.americas.sgi.com> References: <20131002151418.089692683@asylum.americas.sgi.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/uv] x86/UV: Add call to KGDB/KDB from NMI handler Git-Commit-ID: e379ea82dd53a5cc8e3ac0b7899a8012006c712c X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Fri, 04 Oct 2013 10:31:33 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4656 Lines: 136 Commit-ID: e379ea82dd53a5cc8e3ac0b7899a8012006c712c Gitweb: http://git.kernel.org/tip/e379ea82dd53a5cc8e3ac0b7899a8012006c712c Author: Mike Travis AuthorDate: Wed, 2 Oct 2013 10:14:19 -0500 Committer: Ingo Molnar CommitDate: Thu, 3 Oct 2013 18:48:09 +0200 x86/UV: Add call to KGDB/KDB from NMI handler This patch restores the capability to enter KDB (and KGDB) from the UV NMI handler. This is needed because the UV system console is not capable of sending the 'break' signal to the serial console port. It is also useful when the kernel is hung in such a way that it isn't responding to normal external I/O, so sending 'g' to sysreq-trigger does not work either. Another benefit of the external NMI command is that all the cpus receive the NMI signal at roughly the same time so they are more closely aligned timewise. It utilizes the newly added kgdb_nmicallin function to gain entry to KGDB/KDB by the master. The slaves still enter via the standard kgdb_nmicallback function. It also uses the new 'send_ready' pointer to tell KGDB/KDB to signal the slaves when to proceed into the KGDB slave loop. It is enabled when the nmi action is set to "kdb" and the kernel is built with CONFIG_KDB enabled. Note that if kgdb is connected that interface will be used instead. Signed-off-by: Mike Travis Reviewed-by: Dimitri Sivanich Reviewed-by: Hedi Berriche Cc: Peter Zijlstra Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Cc: Jason Wessel Link: http://lkml.kernel.org/r/20131002151418.089692683@asylum.americas.sgi.com Signed-off-by: Ingo Molnar --- arch/x86/platform/uv/uv_nmi.c | 47 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 46 insertions(+), 1 deletion(-) diff --git a/arch/x86/platform/uv/uv_nmi.c b/arch/x86/platform/uv/uv_nmi.c index 9126dfb..9b8ac60 100644 --- a/arch/x86/platform/uv/uv_nmi.c +++ b/arch/x86/platform/uv/uv_nmi.c @@ -21,7 +21,9 @@ #include #include +#include #include +#include #include #include #include @@ -32,6 +34,7 @@ #include #include #include +#include #include #include #include @@ -153,8 +156,9 @@ module_param_named(retry_count, uv_nmi_retry_count, int, 0644); * "dump" - dump process stack for each cpu * "ips" - dump IP info for each cpu * "kdump" - do crash dump + * "kdb" - enter KDB/KGDB (default) */ -static char uv_nmi_action[8] = "dump"; +static char uv_nmi_action[8] = "kdb"; module_param_string(action, uv_nmi_action, sizeof(uv_nmi_action), 0644); static inline bool uv_nmi_action_is(const char *action) @@ -540,6 +544,43 @@ static inline void uv_nmi_kdump(int cpu, int master, struct pt_regs *regs) } #endif /* !CONFIG_KEXEC */ +#ifdef CONFIG_KGDB_KDB +/* Call KDB from NMI handler */ +static void uv_call_kdb(int cpu, struct pt_regs *regs, int master) +{ + int ret; + + if (master) { + /* call KGDB NMI handler as MASTER */ + ret = kgdb_nmicallin(cpu, X86_TRAP_NMI, regs, + &uv_nmi_slave_continue); + if (ret) { + pr_alert("KDB returned error, is kgdboc set?\n"); + atomic_set(&uv_nmi_slave_continue, SLAVE_EXIT); + } + } else { + /* wait for KGDB signal that it's ready for slaves to enter */ + int sig; + + do { + cpu_relax(); + sig = atomic_read(&uv_nmi_slave_continue); + } while (!sig); + + /* call KGDB as slave */ + if (sig == SLAVE_CONTINUE) + kgdb_nmicallback(cpu, regs); + } + uv_nmi_sync_exit(master); +} + +#else /* !CONFIG_KGDB_KDB */ +static inline void uv_call_kdb(int cpu, struct pt_regs *regs, int master) +{ + pr_err("UV: NMI error: KGDB/KDB is not enabled in this kernel\n"); +} +#endif /* !CONFIG_KGDB_KDB */ + /* * UV NMI handler */ @@ -576,6 +617,10 @@ int uv_handle_nmi(unsigned int reason, struct pt_regs *regs) if (uv_nmi_action_is("ips") || uv_nmi_action_is("dump")) uv_nmi_dump_state(cpu, regs, master); + /* Call KDB if enabled */ + else if (uv_nmi_action_is("kdb")) + uv_call_kdb(cpu, regs, master); + /* Clear per_cpu "in nmi" flag */ atomic_set(&uv_cpu_nmi.state, UV_NMI_STATE_OUT); -- 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/