From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755321AbZDNJkO (ORCPT ); Tue, 14 Apr 2009 05:40:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753855AbZDNJjn (ORCPT ); Tue, 14 Apr 2009 05:39:43 -0400 Received: from mx1.emlix.com ([193.175.82.87]:50643 "EHLO mx1.emlix.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751330AbZDNJjm (ORCPT ); Tue, 14 Apr 2009 05:39:42 -0400 From: Johannes Weiner To: Andrew Morton Cc: Chris Zankel , linux-kernel@vger.kernel.org Subject: [patch 01/12] xtensa: always use correct stack pointer for stack traces Date: Tue, 14 Apr 2009 11:41:09 +0200 Message-Id: <1239702080-14355-2-git-send-email-jw@emlix.com> In-Reply-To: <1239702080-14355-1-git-send-email-jw@emlix.com> References: <1239702080-14355-1-git-send-email-jw@emlix.com> Organization: emlix gmbh, Goettingen, Germany Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit '28a0ce7 xtensa: use correct stack pointer for stack traces' changed the stack tracer from always reading the stack pointer register to always using the saved value in the task descriptor. The author was too dense to consider the fact that the saved stack value is stale for a running process und thus unusable for 'current'. What we do now is to use the stack pointer register (a1) for when the task is unknown - we can't help it then - or when the task is 'current'. For everything else use the saved stack pointer value contained in the task descriptor. Signed-off-by: Johannes Weiner --- arch/xtensa/kernel/traps.c | 16 ++++++++++++++-- 1 files changed, 14 insertions(+), 2 deletions(-) diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c index 9f0b711..ba9ab93 100644 --- a/arch/xtensa/kernel/traps.c +++ b/arch/xtensa/kernel/traps.c @@ -369,6 +369,18 @@ void show_regs(struct pt_regs * regs) regs->syscall); } +static __always_inline unsigned long *stack_pointer(struct task_struct *task) +{ + unsigned long *sp; + + if (!task || task == current) + __asm__ __volatile__ ("mov %0, a1\n" : "=a"(sp)); + else + sp = (unsigned long *)task->thread.sp; + + return sp; +} + void show_trace(struct task_struct *task, unsigned long *sp) { unsigned long a0, a1, pc; @@ -377,7 +389,7 @@ void show_trace(struct task_struct *task, unsigned long *sp) if (sp) a1 = (unsigned long)sp; else - a1 = task->thread.sp; + a1 = (unsigned long)stack_pointer(task); sp_start = a1 & ~(THREAD_SIZE-1); sp_end = sp_start + THREAD_SIZE; @@ -420,7 +432,7 @@ void show_stack(struct task_struct *task, unsigned long *sp) unsigned long *stack; if (!sp) - sp = (unsigned long *)task->thread.sp; + sp = stack_pointer(task); stack = sp; printk("\nStack: "); -- 1.6.2.107.ge47ee