Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756429Ab2HWCSI (ORCPT ); Wed, 22 Aug 2012 22:18:08 -0400 Received: from mail.windriver.com ([147.11.1.11]:35291 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754754Ab2HWCRi (ORCPT ); Wed, 22 Aug 2012 22:17:38 -0400 From: Tiejun Chen To: CC: , , Subject: [v2][PATCH 3/3] powerpc/kgdb: restore current_thread_info properly Date: Thu, 23 Aug 2012 10:10:20 +0800 Message-ID: <1345687820-5248-3-git-send-email-tiejun.chen@windriver.com> X-Mailer: git-send-email 1.5.6 In-Reply-To: <1345687820-5248-1-git-send-email-tiejun.chen@windriver.com> References: <1345687820-5248-1-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 Content-Length: 2388 Lines: 65 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 properly. We should backup current_thread_info then restore that when exit. Signed-off-by: Tiejun Chen --- v2: fix a typo in patch head description. 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 05adb69..c470a40 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 @@ -153,6 +154,8 @@ 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; @@ -170,13 +173,17 @@ 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 -- 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/