From patchwork Fri Oct 4 10:05:01 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vineet Gupta X-Patchwork-Id: 280573 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from silver.osuosl.org (silver.osuosl.org [140.211.166.136]) by ozlabs.org (Postfix) with ESMTP id 252022C00A7 for ; Fri, 4 Oct 2013 20:05:34 +1000 (EST) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 8598F25BA7; Fri, 4 Oct 2013 10:05:32 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id m3b4LvwgbTXT; Fri, 4 Oct 2013 10:05:30 +0000 (UTC) Received: from ash.osuosl.org (ash.osuosl.org [140.211.166.34]) by silver.osuosl.org (Postfix) with ESMTP id D15F9264AD; Fri, 4 Oct 2013 10:05:29 +0000 (UTC) X-Original-To: uclibc@lists.busybox.net Delivered-To: uclibc@osuosl.org Received: from hemlock.osuosl.org (hemlock.osuosl.org [140.211.166.133]) by ash.osuosl.org (Postfix) with ESMTP id 251B51C28BD for ; Fri, 4 Oct 2013 10:05:28 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 2187393B52 for ; Fri, 4 Oct 2013 10:05:28 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id YR6TenRWxGFz for ; Fri, 4 Oct 2013 10:05:25 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from alvesta.synopsys.com (us02smtp2.synopsys.com [198.182.60.77]) by hemlock.osuosl.org (Postfix) with ESMTP id 9BADC88B6A for ; Fri, 4 Oct 2013 10:05:25 +0000 (UTC) Received: from WBSNus02mta1 (us02secmta1.synopsys.com [10.12.235.96]) by alvesta.synopsys.com (Postfix) with ESMTP id 32AFBB5631; Fri, 4 Oct 2013 03:05:25 -0700 (PDT) Received: from us02secmta1.internal.synopsys.com (us02secmta1.internal.synopsys.com [127.0.0.1]) by us02secmta1.internal.synopsys.com (Service) with ESMTP id 24E274E214; Fri, 4 Oct 2013 03:05:25 -0700 (PDT) Received: from mailhost.synopsys.com (mailhost1.synopsys.com [10.12.238.239]) by us02secmta1.internal.synopsys.com (Service) with ESMTP id EB47D4E202; Fri, 4 Oct 2013 03:05:24 -0700 (PDT) Received: from mailhost.synopsys.com (localhost [127.0.0.1]) by mailhost.synopsys.com (Postfix) with ESMTP id D8639574; Fri, 4 Oct 2013 03:05:24 -0700 (PDT) Received: from us01wehtc1.internal.synopsys.com (us01wehtc1-vip.internal.synopsys.com [10.12.239.236]) by mailhost.synopsys.com (Postfix) with ESMTP id D1FA1573; Fri, 4 Oct 2013 03:05:24 -0700 (PDT) Received: from IN01WEHTCA.internal.synopsys.com (10.144.199.104) by us01wehtc1.internal.synopsys.com (10.12.239.235) with Microsoft SMTP Server (TLS) id 14.2.298.4; Fri, 4 Oct 2013 03:05:24 -0700 Received: from vineetg-E6520.internal.synopsys.com (10.12.197.243) by IN01WEHTCA.internal.synopsys.com (10.144.199.243) with Microsoft SMTP Server (TLS) id 14.2.298.4; Fri, 4 Oct 2013 15:35:19 +0530 From: Vineet Gupta To: Subject: [PATCH v2] Fix weak/strong attribute of __errno_location and it's __GI alias Date: Fri, 4 Oct 2013 15:35:01 +0530 Message-ID: <1380881101-8581-1-git-send-email-vgupta@synopsys.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <20131004083838.GP6918@tarshish> References: <20131004083838.GP6918@tarshish> MIME-Version: 1.0 X-Originating-IP: [10.12.197.243] Cc: Vineet Gupta X-BeenThere: uclibc@uclibc.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Discussion and development of uClibc \(the embedded C library\)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: uclibc-bounces@uclibc.org Sender: uclibc-bounces@uclibc.org A simple statically linked hello world program was segfaulting for ARC in linuxthreads.old configuration (although the root casue applies cross-arch for NPTL as well as linuxthreads.old as described) The crash was due to branch to NULL in _stdio_init 0001026c <_stdio_init>: 1026c: push_s blink 1026e: st.a r13,[sp,-8] 10272: bl.d 0 --> supposed call to __errno_location The call was NOT getting patched to libc internal only alias __GI___errno_location, because it was weak while it's exported cousin, __errno_location was strong/normal. arc-linux-uclibc-nm libc/misc/internals/__errno_location.os 00000000 W __GI___errno_location 00000000 T __errno_location This is exactly opposite to what is expected. Quoting Peter S. Mazinger, commit 87936cd013041 "errno and *_init cleanup" | The rule adopted: | for enabled threads we make in libc the __GI_x() variants strong, x() weak | and (should) provide another strong x() in libpthread. | If threads are disabled, even the __GI_x() variants are weak. With the fix, we see the right settings as below 00000000 T __GI___errno_location 00000000 W __errno_location Note that problem won't show up in a static busybox build as it references errno and that seems to elide the issue. I can confirm the same/more issues with latest ARM buildroot builds w/o my fix. (1). linuxthreads.old (broken just like ARC) arm-linux-nm uclibc-snapshot/libc/misc/internals/__errno_location.os 00000000 W __GI___errno_location 00000000 T __errno_location But presumably the issue there is NOT catestrophic because ARM linker is likely smarter and patches a NOP instead of NULL branch. 00008388 <_stdio_init>: 8388: e92d4038 push {r3, r4, r5, lr} 838c: e320f000 nop {0} (2) NPTL build (exported version is not weak) 00000000 T __GI___errno_location 00000000 T __errno_location This causes a static link with libpthread and test program referencing errno to fail to link. #include int main(void) { printf("%d\n", errno); } arm-linux-gcc -static -pthread -o tst tst.o arm-buildroot-linux-uclibcgnueabi/sysroot/usr/lib/libc.a(__errno_location.os): In function `__errno_location': __errno_location.c:(.text+0x0): multiple definition of `__errno_location' arm-buildroot-linux-uclibcgnueabi/sysroot/usr/lib/libpthread.a (errno_location.os):errno_location.c:(.text+0x0): first defined here Signed-off-by: Vineet Gupta Cc: Baruch Siach Tested-by: Baruch Siach --- include/netdb.h | 2 +- libc/misc/internals/__errno_location.c | 2 +- libc/misc/internals/__h_errno_location.c | 2 +- libc/sysdeps/linux/common/bits/errno.h | 2 +- 4 files changed, 4 insertions(+), 4 deletions(-) diff --git a/include/netdb.h b/include/netdb.h index 14cf3d24dae0..8fdfa0fccc7d 100644 --- a/include/netdb.h +++ b/include/netdb.h @@ -59,7 +59,7 @@ __BEGIN_DECLS /* Function to get address of global `h_errno' variable. */ extern int *__h_errno_location (void) __THROW __attribute__ ((__const__)); #ifdef _LIBC -# ifndef __UCLIBC_HAS_TLS__ +# if !defined(__UCLIBC_HAS_TLS__) && !defined(__UCLIBC_HAS_THREADS__) extern int weak_const_function *__h_errno_location(void); # endif #endif diff --git a/libc/misc/internals/__errno_location.c b/libc/misc/internals/__errno_location.c index dec913f3031d..be7a9093efa3 100644 --- a/libc/misc/internals/__errno_location.c +++ b/libc/misc/internals/__errno_location.c @@ -16,4 +16,4 @@ int *__errno_location(void) { return &errno; } -libc_hidden_def(__errno_location) +libc_hidden_weak(__errno_location) diff --git a/libc/misc/internals/__h_errno_location.c b/libc/misc/internals/__h_errno_location.c index 41353d74a648..6653681cbf09 100644 --- a/libc/misc/internals/__h_errno_location.c +++ b/libc/misc/internals/__h_errno_location.c @@ -16,4 +16,4 @@ int *__h_errno_location(void) { return &h_errno; } -libc_hidden_def(__h_errno_location) +libc_hidden_weak(__h_errno_location) diff --git a/libc/sysdeps/linux/common/bits/errno.h b/libc/sysdeps/linux/common/bits/errno.h index 7ef1b9440a34..777338fb1e0a 100644 --- a/libc/sysdeps/linux/common/bits/errno.h +++ b/libc/sysdeps/linux/common/bits/errno.h @@ -43,7 +43,7 @@ /* Function to get address of global `errno' variable. */ extern int *__errno_location (void) __THROW __attribute__ ((__const__)); # ifdef _LIBC -# ifndef __UCLIBC_HAS_TLS__ +# if !defined(__UCLIBC_HAS_TLS__) && !defined(__UCLIBC_HAS_THREADS__) extern int weak_const_function *__errno_location(void); # endif # endif