From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934104Ab0BYVYB (ORCPT ); Thu, 25 Feb 2010 16:24:01 -0500 Received: from mail.windriver.com ([147.11.1.11]:63891 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934022Ab0BYVXt (ORCPT ); Thu, 25 Feb 2010 16:23:49 -0500 From: Jason Wessel To: torvalds@linux-foundation.org Cc: linux-kernel@vger.kernel.org, kgdb-bugreport@lists.sourceforge.net, Jason Wessel , Frederic Weisbecker , Ingo Molnar Subject: [PATCH 3/8] x86,kgdb: Implement early hardware breakpoint debugging Date: Thu, 25 Feb 2010 15:22:01 -0600 Message-Id: <1267132926-23685-4-git-send-email-jason.wessel@windriver.com> X-Mailer: git-send-email 1.6.4.rc1 In-Reply-To: <1267132926-23685-1-git-send-email-jason.wessel@windriver.com> References: <1267132926-23685-1-git-send-email-jason.wessel@windriver.com> X-OriginalArrivalTime: 25 Feb 2010 21:22:47.0382 (UTC) FILETIME=[AD48B760:01CAB660] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It is not possible to use the hw_breakpoint.c API prior to mm_init(), but it is possible to use hardware breakpoints with the kernel debugger. Prior to smp_init() it is possible to simply write to the dr registers of the boot cpu directly. This can be used up until the kgdb_arch_late() is invoked, at which point the standard hw_breakpoint.c API will get used. CC: Frederic Weisbecker CC: Ingo Molnar Signed-off-by: Jason Wessel --- arch/x86/kernel/kgdb.c | 30 ++++++++++++++++++++++++++++-- 1 files changed, 28 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 896874a..8e79fea 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -199,6 +199,8 @@ static struct hw_breakpoint { struct perf_event **pev; } breakinfo[4]; +static unsigned long early_dr7; + static void kgdb_correct_hw_break(void) { int breakno; @@ -210,6 +212,14 @@ static void kgdb_correct_hw_break(void) int cpu = raw_smp_processor_id(); if (!breakinfo[breakno].enabled) continue; + if (dbg_is_early) { + set_debugreg(breakinfo[breakno].addr, breakno); + early_dr7 |= encode_dr7(breakno, + breakinfo[breakno].len, + breakinfo[breakno].type); + set_debugreg(early_dr7, 7); + continue; + } bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu); info = counter_arch_bp(bp); if (bp->attr.disabled != 1) @@ -224,7 +234,8 @@ static void kgdb_correct_hw_break(void) if (!val) bp->attr.disabled = 0; } - hw_breakpoint_restore(); + if (!dbg_is_early) + hw_breakpoint_restore(); } static int hw_break_reserve_slot(int breakno) @@ -233,6 +244,9 @@ static int hw_break_reserve_slot(int breakno) int cnt = 0; struct perf_event **pevent; + if (dbg_is_early) + return 0; + for_each_online_cpu(cpu) { cnt++; pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); @@ -258,6 +272,9 @@ static int hw_break_release_slot(int breakno) struct perf_event **pevent; int cpu; + if (dbg_is_early) + return 0; + for_each_online_cpu(cpu) { pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu); if (dbg_release_bp_slot(*pevent)) @@ -302,7 +319,11 @@ static void kgdb_remove_all_hw_break(void) bp = *per_cpu_ptr(breakinfo[i].pev, cpu); if (bp->attr.disabled == 1) continue; - arch_uninstall_hw_breakpoint(bp); + if (dbg_is_early) + early_dr7 &= ~encode_dr7(i, breakinfo[i].len, + breakinfo[i].type); + else + arch_uninstall_hw_breakpoint(bp); bp->attr.disabled = 1; } } @@ -379,6 +400,11 @@ void kgdb_disable_hw_debug(struct pt_regs *regs) for (i = 0; i < 4; i++) { if (!breakinfo[i].enabled) continue; + if (dbg_is_early) { + early_dr7 &= ~encode_dr7(i, breakinfo[i].len, + breakinfo[i].type); + continue; + } bp = *per_cpu_ptr(breakinfo[i].pev, cpu); if (bp->attr.disabled == 1) continue; -- 1.6.4.rc1