From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763904AbZEHV1n (ORCPT ); Fri, 8 May 2009 17:27:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763585AbZEHVXu (ORCPT ); Fri, 8 May 2009 17:23:50 -0400 Received: from mail.windriver.com ([147.11.1.11]:44766 "EHLO mail.wrs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755446AbZEHVXg (ORCPT ); Fri, 8 May 2009 17:23:36 -0400 From: Jason Wessel To: linux-kernel@vger.kernel.org Cc: kgdb-bugreport@lists.sourceforge.net, kdb@oss.sgi.com, Jason Wessel Subject: [PATCH 10/13] RFC ONLY - mips,kgdb: kdb low level trap catch and stack trace Date: Fri, 8 May 2009 16:23:17 -0500 Message-Id: <1241817800-9320-11-git-send-email-jason.wessel@windriver.com> X-Mailer: git-send-email 1.6.3.rc0.1.gf800 In-Reply-To: <1241817800-9320-10-git-send-email-jason.wessel@windriver.com> References: <1241817800-9320-1-git-send-email-jason.wessel@windriver.com> <1241817800-9320-2-git-send-email-jason.wessel@windriver.com> <1241817800-9320-3-git-send-email-jason.wessel@windriver.com> <1241817800-9320-4-git-send-email-jason.wessel@windriver.com> <1241817800-9320-5-git-send-email-jason.wessel@windriver.com> <1241817800-9320-6-git-send-email-jason.wessel@windriver.com> <1241817800-9320-7-git-send-email-jason.wessel@windriver.com> <1241817800-9320-8-git-send-email-jason.wessel@windriver.com> <1241817800-9320-9-git-send-email-jason.wessel@windriver.com> <1241817800-9320-10-git-send-email-jason.wessel@windriver.com> X-OriginalArrivalTime: 08 May 2009 21:23:31.0856 (UTC) FILETIME=[3CC22900:01C9D023] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a RFC patch. The work to possibly merge kdb and kgdb is being evaluated and this patch is considered only a proof of concept or prototype. The only way the debugger can handle a trap in inside rcu_lock, notify_die, or atomic_notifier_call_chain without a recursive fault is to have a low level "first opportunity handler" do_trap_or_bp() handler. Generally this will be something the vast majority of folks will not need, but for those who need it, it is added as a kernel .config option called KGDB_LOW_LEVEL_TRAP. Also added was a die notification for oops such that kdb can catch an oops for analysis. There appeared no obvious way to pass the struct pt_regs from the original exception back to the stack back tracer, so a special case was added to show_stack() for when kdb is active because you generally desire to generally look at the back trace of the original exception. Signed-off-by: Jason Wessel --- arch/mips/include/asm/kgdb.h | 2 ++ arch/mips/kernel/kgdb.c | 22 +++++++++++++++++++++- arch/mips/kernel/traps.c | 14 ++++++++++++++ lib/Kconfig.kgdb | 2 +- 4 files changed, 38 insertions(+), 2 deletions(-) diff --git a/arch/mips/include/asm/kgdb.h b/arch/mips/include/asm/kgdb.h index 48223b0..19002d6 100644 --- a/arch/mips/include/asm/kgdb.h +++ b/arch/mips/include/asm/kgdb.h @@ -38,6 +38,8 @@ extern int kgdb_early_setup; extern void *saved_vectors[32]; extern void handle_exception(struct pt_regs *regs); extern void breakinst(void); +extern int kgdb_ll_trap(int cmd, const char *str, + struct pt_regs *regs, long err, int trap, int sig); #endif /* __KERNEL__ */ diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c index 54f2d40..a4e546a 100644 --- a/arch/mips/kernel/kgdb.c +++ b/arch/mips/kernel/kgdb.c @@ -202,7 +202,7 @@ static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd, if (atomic_read(&kgdb_active) != -1) kgdb_nmicallback(smp_processor_id(), regs); - if (kgdb_handle_exception(trap, compute_signal(trap), 0, regs)) + if (kgdb_handle_exception(trap, compute_signal(trap), cmd, regs)) return NOTIFY_DONE; if (atomic_read(&kgdb_setting_breakpoint)) @@ -216,6 +216,26 @@ static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd, return NOTIFY_STOP; } +#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP +int kgdb_ll_trap(int cmd, const char *str, + struct pt_regs *regs, long err, int trap, int sig) +{ + struct die_args args = { + .regs = regs, + .str = str, + .err = err, + .trapnr = trap, + .signr = sig, + + }; + + if (!kgdb_io_module_registered) + return NOTIFY_DONE; + + return kgdb_mips_notify(NULL, cmd, &args); +} +#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */ + static struct notifier_block kgdb_notifier = { .notifier_call = kgdb_mips_notify, }; diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index e83da17..fbf427e 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -24,6 +24,8 @@ #include #include #include +#include +#include #include #include @@ -186,6 +188,11 @@ void show_stack(struct task_struct *task, unsigned long *sp) regs.regs[29] = task->thread.reg29; regs.regs[31] = 0; regs.cp0_epc = task->thread.reg31; +#ifdef CONFIG_KGDB_KDB + } else if (atomic_read(&kgdb_active) != -1 && + kdb_current_regs) { + memcpy(®s, kdb_current_regs, sizeof(regs)); +#endif /* CONFIG_KGDB_KDB */ } else { prepare_frametrace(®s); } @@ -360,6 +367,8 @@ void __noreturn die(const char * str, const struct pt_regs * regs) unsigned long dvpret = dvpe(); #endif /* CONFIG_MIPS_MT_SMTC */ + notify_die(DIE_OOPS, str, (struct pt_regs *)regs, SIGSEGV, 0, 0); + console_verbose(); spin_lock_irq(&die_lock); bust_spinlocks(1); @@ -701,6 +710,11 @@ static void do_trap_or_bp(struct pt_regs *regs, unsigned int code, siginfo_t info; char b[40]; +#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP + if (kgdb_ll_trap(DIE_TRAP, str, regs, code, 0, 0) == NOTIFY_STOP) + return; +#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */ + if (notify_die(DIE_TRAP, str, regs, code, 0, 0) == NOTIFY_STOP) return; diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb index a2f63be..b5d3637 100644 --- a/lib/Kconfig.kgdb +++ b/lib/Kconfig.kgdb @@ -59,7 +59,7 @@ config KGDB_TESTS_BOOT_STRING config KGDB_LOW_LEVEL_TRAP bool "KGDB: Allow debugging with traps in notifiers" - depends on X86 || PPC + depends on X86 || PPC || MIPS default n help This will add an extra call back to kgdb for the breakpoint -- 1.6.3.rc0.1.gf800