From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932390Ab2HVKuq (ORCPT ); Wed, 22 Aug 2012 06:50:46 -0400 Received: from mail1.windriver.com ([147.11.146.13]:49609 "EHLO mail1.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755363Ab2HVKuk (ORCPT ); Wed, 22 Aug 2012 06:50:40 -0400 From: Tiejun Chen To: CC: , , Subject: [PATCH 3/3] powerpc/kgdb: restore current_thread_info properly Date: Wed, 22 Aug 2012 18:43:12 +0800 Message-ID: <1345632192-19810-3-git-send-email-tiejun.chen@windriver.com> X-Mailer: git-send-email 1.5.6 In-Reply-To: <1345632192-19810-1-git-send-email-tiejun.chen@windriver.com> References: <1345632192-19810-1-git-send-email-tiejun.chen@windriver.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For powerpc BooKE and e200, singlestep is handled on the critical/dbg exception stack. This causes current_thread_info() to fail for kgdb internal, so previously We work around this issue by copying the thread_info from the kernel stack before calling kgdb_handle_exception, and copying it back afterwards. But actually we don't do this previously. We should backp current_thread_info then restore that when exit. CC: Jason Wessel Signed-off-by: Tiejun Chen --- arch/powerpc/kernel/kgdb.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c index e84252b..7dcdbe7 100644 --- a/arch/powerpc/kernel/kgdb.c +++ b/arch/powerpc/kernel/kgdb.c @@ -25,6 +25,7 @@ #include #include #include +#include /* * This table contains the mapping between PowerPC hardware trap types, and @@ -156,6 +157,8 @@ static int kgdb_handle_breakpoint(struct pt_regs *regs) static int kgdb_singlestep(struct pt_regs *regs) { struct thread_info *thread_info, *exception_thread_info; + struct thread_info *backup_current_thread_info = \ + (struct thread_info *)kmalloc(sizeof(struct thread_info), GFP_KERNEL); if (user_mode(regs)) return 0; @@ -173,13 +176,17 @@ static int kgdb_singlestep(struct pt_regs *regs) thread_info = (struct thread_info *)(regs->gpr[1] & ~(THREAD_SIZE-1)); exception_thread_info = current_thread_info(); - if (thread_info != exception_thread_info) + if (thread_info != exception_thread_info) { + /* Save the original current_thread_info. */ + memcpy(backup_current_thread_info, exception_thread_info, sizeof *thread_info); memcpy(exception_thread_info, thread_info, sizeof *thread_info); + } kgdb_handle_exception(0, SIGTRAP, 0, regs); if (thread_info != exception_thread_info) - memcpy(thread_info, exception_thread_info, sizeof *thread_info); + /* Restore current_thread_info lastly. */ + memcpy(exception_thread_info, backup_current_thread_info, sizeof *thread_info); return 1; } -- 1.5.6