Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756733AbZLWVVk (ORCPT ); Wed, 23 Dec 2009 16:21:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756559AbZLWVV3 (ORCPT ); Wed, 23 Dec 2009 16:21:29 -0500 Received: from mail.windriver.com ([147.11.1.11]:45138 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756345AbZLWVUs (ORCPT ); Wed, 23 Dec 2009 16:20:48 -0500 From: Jason Wessel To: linux-kernel@vger.kernel.org Cc: kgdb-bugreport@lists.sourceforge.net, kdb@oss.sgi.com, mingo@elte.hu, Jason Wessel , Benjamin Herrenschmidt , Paul Mackerras Subject: [PATCH 21/37] powerpc,kgdb: Introduce low level trap catching Date: Wed, 23 Dec 2009 15:19:34 -0600 Message-Id: <1261603190-5036-22-git-send-email-jason.wessel@windriver.com> X-Mailer: git-send-email 1.6.4.rc1 In-Reply-To: <1261603190-5036-21-git-send-email-jason.wessel@windriver.com> References: <1261603190-5036-1-git-send-email-jason.wessel@windriver.com> <1261603190-5036-2-git-send-email-jason.wessel@windriver.com> <1261603190-5036-3-git-send-email-jason.wessel@windriver.com> <1261603190-5036-4-git-send-email-jason.wessel@windriver.com> <1261603190-5036-5-git-send-email-jason.wessel@windriver.com> <1261603190-5036-6-git-send-email-jason.wessel@windriver.com> <1261603190-5036-7-git-send-email-jason.wessel@windriver.com> <1261603190-5036-8-git-send-email-jason.wessel@windriver.com> <1261603190-5036-9-git-send-email-jason.wessel@windriver.com> <1261603190-5036-10-git-send-email-jason.wessel@windriver.com> <1261603190-5036-11-git-send-email-jason.wessel@windriver.com> <1261603190-5036-12-git-send-email-jason.wessel@windriver.com> <1261603190-5036-13-git-send-email-jason.wessel@windriver.com> <1261603190-5036-14-git-send-email-jason.wessel@windriver.com> <1261603190-5036-15-git-send-email-jason.wessel@windriver.com> <1261603190-5036-16-git-send-email-jason.wessel@windriver.com> <1261603190-5036-17-git-send-email-jason.wessel@windriver.com> <1261603190-5036-18-git-send-email-jason.wessel@windriver.com> <1261603190-5036-19-git-send-email-jason.wessel@windriver.com> <1261603190-5036-20-git-send-email-jason.wessel@windriver.com> <1261603190-5036-21-git-send-email-jason.wessel@windriver.com> X-OriginalArrivalTime: 23 Dec 2009 21:20:21.0395 (UTC) FILETIME=[BBD4DE30:01CA8415] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3301 Lines: 96 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" low level program_check_exception() handler. The other change here is to make sure that kgdb_handle_exception() is called with correct parameters when catching an oops, because kdb needs to know if the entry was an oops, single step, or breakpoint exception. CC: Benjamin Herrenschmidt CC: Paul Mackerras Signed-off-by: Jason Wessel --- arch/powerpc/kernel/kgdb.c | 7 +++++-- arch/powerpc/kernel/traps.c | 7 +++++++ lib/Kconfig.kgdb | 2 +- 3 files changed, 13 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c index 7aafcc5..c06fe55 100644 --- a/arch/powerpc/kernel/kgdb.c +++ b/arch/powerpc/kernel/kgdb.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -115,7 +116,9 @@ void kgdb_roundup_cpus(unsigned long flags) /* KGDB functions to use existing PowerPC64 hooks. */ static int kgdb_debugger(struct pt_regs *regs) { - return kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs); + if (kgdb_handle_exception(1, computeSignal(TRAP(regs)), DIE_OOPS, regs)) + return 0; + return 1; } static int kgdb_handle_breakpoint(struct pt_regs *regs) @@ -123,7 +126,7 @@ static int kgdb_handle_breakpoint(struct pt_regs *regs) if (user_mode(regs)) return 0; - if (kgdb_handle_exception(0, SIGTRAP, 0, regs) != 0) + if (kgdb_handle_exception(1, SIGTRAP, 0, regs) != 0) return 0; if (*(u32 *) (regs->nip) == *(u32 *) (&arch_kgdb_ops.gdb_bpt_instr)) diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index d069ff8..379104a 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -809,12 +809,19 @@ void __kprobes program_check_exception(struct pt_regs *regs) return; } if (reason & REASON_TRAP) { + +#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP + if (debugger_bpt(regs)) + return; +#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */ /* trap exception */ if (notify_die(DIE_BPT, "breakpoint", regs, 5, 5, SIGTRAP) == NOTIFY_STOP) return; +#ifndef CONFIG_KGDB_LOW_LEVEL_TRAP if (debugger_bpt(regs)) return; +#endif /* ! CONFIG_KGDB_LOW_LEVEL_TRAP */ if (!(regs->msr & MSR_PR) && /* not user-mode */ report_bug(regs->nip, regs) == BUG_TRAP_TYPE_WARN) { diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb index 2172c69..64cc65d 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 + depends on X86 || PPC default n help This will add an extra call back to kgdb for the breakpoint -- 1.6.4.rc1 -- 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/