Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759115AbdCVLON (ORCPT ); Wed, 22 Mar 2017 07:14:13 -0400 Received: from ozlabs.org ([103.22.144.67]:37817 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758855AbdCVLOF (ORCPT ); Wed, 22 Mar 2017 07:14:05 -0400 From: Michael Ellerman To: Thadeu Lima de Souza Cascardo , linuxppc-dev@lists.ozlabs.org Cc: linux-kernel@vger.kernel.org, Paul Mackerras , Benjamin Herrenschmidt Subject: Re: [PATCH] powerpc: fix /proc/self/stack In-Reply-To: <20170317155921.24369-1-cascardo@canonical.com> References: <20170317155921.24369-1-cascardo@canonical.com> User-Agent: Notmuch/0.21 (https://notmuchmail.org) Date: Wed, 22 Mar 2017 22:03:53 +1100 Message-ID: <87inn1d146.fsf@concordia.ellerman.id.au> 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: 1109 Lines: 40 Thadeu Lima de Souza Cascardo writes: > For the current task, the kernel stack would only tell the last time the > process was rescheduled, if ever. Use the current stack pointer for the > current task. You say "fix" in the subject, but is it a bug, or just an enhancement? > This is also consistent with some other architectures. Such as .. arm64 and x86 (though it's buried in the unwind code). > diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c > index 6671195..2446066 100644 > --- a/arch/powerpc/kernel/stacktrace.c > +++ b/arch/powerpc/kernel/stacktrace.c > @@ -59,7 +59,12 @@ EXPORT_SYMBOL_GPL(save_stack_trace); > > void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace) > { > - save_context_stack(trace, tsk->thread.ksp, tsk, 0); > + unsigned long sp = tsk->thread.ksp; > + > + if (tsk == current) > + sp = current_stack_pointer(); else sp = tsk->thread.ksp; Would be clearer IMHO. > + > + save_context_stack(trace, sp, tsk, 0); > } > EXPORT_SYMBOL_GPL(save_stack_trace_tsk); > > -- > 2.9.3 cheers