From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 29161 invoked by alias); 21 Dec 2012 20:14:15 -0000 Received: (qmail 29145 invoked by uid 22791); 21 Dec 2012 20:14:14 -0000 X-SWARE-Spam-Status: No, hits=-2.9 required=5.0 tests=AWL,BAYES_00,KHOP_THREADED,TW_EG,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from usmamail.tilera.com (HELO USMAMAIL.TILERA.COM) (12.216.194.151) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 21 Dec 2012 20:14:07 +0000 Received: from [10.7.0.95] (10.9.0.23) by USMAExch2.tad.internal.tilera.com (10.3.0.33) with Microsoft SMTP Server id 14.0.694.0; Fri, 21 Dec 2012 15:14:06 -0500 Message-ID: <50D4C30D.1020803@tilera.com> Date: Fri, 21 Dec 2012 20:14:00 -0000 From: Chris Metcalf User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: , "David S. Miller" Subject: Re: [PATCH] tile: fix DWARF bug in clone() for created thread References: <201212141551.qBEFpsJe000377@farm-0002.internal.tilera.com> In-Reply-To: <201212141551.qBEFpsJe000377@farm-0002.internal.tilera.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact libc-ports-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: libc-ports-owner@sourceware.org X-SW-Source: 2012-12/txt/msg00058.txt.bz2 On 12/14/2012 10:46 AM, Chris Metcalf wrote: > [David - this is pretty low risk (just adds one DWARF CFI directive), > but also fixes a pretty minor bug. So your call as to whether I should > wait for 2.18 to commit.] Ping? I like the idea of fixing this in 2.17 just because customers tend to go "WTF?" when they see this in the debugger output. > Previously, we would see a bad frame in the gdb backtrace output, e.g.: > > (gdb) bt > #0 foo () at foo.c:5 > #1 0x000000aaaab68ee8 in start_thread () from /lib/libpthread.so.0 > #2 0x000000aaaad01c88 in clone () from /lib/libc.so.6 > #3 0x0000000000000000 in ?? () > > With this change the bogus frame #3 is gone and we have the > same output as x86 does for the same program. > > 2012-12-14 Chris Metcalf > > * sysdeps/unix/sysv/linux/tile/nptl/clone.S: Fix DWARF info. > > diff --git a/ports/sysdeps/unix/sysv/linux/tile/nptl/clone.S b/ports/sysdeps/unix/sysv/linux/tile/nptl/clone.S > index de4fa13..27592cc 100644 > --- a/ports/sysdeps/unix/sysv/linux/tile/nptl/clone.S > +++ b/ports/sysdeps/unix/sysv/linux/tile/nptl/clone.S > @@ -160,6 +160,8 @@ ENTRY (__clone) > r32: the user function pointer */ > > .Lthread_start: > + cfi_def_cfa_offset (FRAME_SIZE) > + cfi_undefined (lr) > /* Check and see if we need to reset the PID, which we do if > CLONE_THREAD isn't set, i.e. we're not staying in the thread group. > If CLONE_VM is set, we're doing some kind of thread-like clone, > @@ -167,7 +169,6 @@ ENTRY (__clone) > in getpid(). Otherwise (if CLONE_VM isn't set), it's a > fork-like clone, and we go ahead and write the cached values > from the true system pid (retrieved via __NR_getpid syscall). */ > - cfi_def_cfa_offset (FRAME_SIZE) > #ifdef __tilegx__ > { > moveli r0, hw1_last(CLONE_VM) -- Chris Metcalf, Tilera Corp. http://www.tilera.com