From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753456Ab0C2UJc (ORCPT ); Mon, 29 Mar 2010 16:09:32 -0400 Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:48990 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752272Ab0C2UJa (ORCPT ); Mon, 29 Mar 2010 16:09:30 -0400 Date: Mon, 29 Mar 2010 13:09:31 -0700 (PDT) Message-Id: <20100329.130931.149161813.davem@davemloft.net> To: fweisbec@gmail.com Cc: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org Subject: Re: [BUG] fault while using perf callchains in sparc64 From: David Miller In-Reply-To: <20100328043446.GA11748@nowhere> References: <20100328043446.GA11748@nowhere> X-Mailer: Mew version 6.3 on Emacs 23.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Frederic Weisbecker Date: Sun, 28 Mar 2010 06:34:49 +0200 > I get kernel crashes each time I use perf with callchains > on sparc 64. > > It triggers with a simple: > > perf record -a -f -g sleep 1 This should fix it, thanks again. sparc64: Properly truncate pt_regs framepointer in perf callback. For 32-bit processes, we save the full 64-bits of the regs in pt_regs. But unlike when the userspace actually does load and store instructions, the top 32-bits don't get automatically truncated by the cpu in kernel mode (because the kernel doesn't execute with PSTATE_AM address masking enabled). So we have to do it by hand. Reported-by: Frederic Weisbecker Signed-off-by: David S. Miller --- arch/sparc/kernel/perf_event.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/arch/sparc/kernel/perf_event.c b/arch/sparc/kernel/perf_event.c index 9f2b2ba..610112e 100644 --- a/arch/sparc/kernel/perf_event.c +++ b/arch/sparc/kernel/perf_event.c @@ -1337,7 +1337,7 @@ static void perf_callchain_user_32(struct pt_regs *regs, callchain_store(entry, PERF_CONTEXT_USER); callchain_store(entry, regs->tpc); - ufp = regs->u_regs[UREG_I6]; + ufp = regs->u_regs[UREG_I6] & 0xffffffffUL; do { struct sparc_stackf32 *usf, sf; unsigned long pc; -- 1.7.0.3