Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933085AbbHIK0r (ORCPT ); Sun, 9 Aug 2015 06:26:47 -0400 Received: from terminus.zytor.com ([198.137.202.10]:36138 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932925AbbHIK0m (ORCPT ); Sun, 9 Aug 2015 06:26:42 -0400 Date: Sun, 9 Aug 2015 03:25:21 -0700 From: tip-bot for Andy Lutomirski Message-ID: Cc: bp@alien8.de, dvlasenk@redhat.com, nathan_lynch@mentor.com, brgerst@gmail.com, mingo@kernel.org, musl@lists.openwall.com, peterz@infradead.org, dalias@libc.org, ibid.ag@gmail.com, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, luto@amacapital.net, tglx@linutronix.de, hpa@zytor.com Reply-To: peterz@infradead.org, ibid.ag@gmail.com, dalias@libc.org, luto@amacapital.net, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, hpa@zytor.com, tglx@linutronix.de, bp@alien8.de, nathan_lynch@mentor.com, dvlasenk@redhat.com, mingo@kernel.org, brgerst@gmail.com, musl@lists.openwall.com In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/asm] x86/vdso: Emit a GNU hash Git-Commit-ID: 6b7e26547fad7ace3dcb27a5babd2317fb9d1e12 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2567 Lines: 60 Commit-ID: 6b7e26547fad7ace3dcb27a5babd2317fb9d1e12 Gitweb: http://git.kernel.org/tip/6b7e26547fad7ace3dcb27a5babd2317fb9d1e12 Author: Andy Lutomirski AuthorDate: Thu, 6 Aug 2015 14:45:45 -0700 Committer: Ingo Molnar CommitDate: Sat, 8 Aug 2015 10:42:07 +0200 x86/vdso: Emit a GNU hash Some dynamic loaders may be slightly faster if a GNU hash is available. Strangely, this seems to have no effect at all on the vdso size. This is unlikely to have any measurable effect on the time it takes to resolve vdso symbols (since there are so few of them). In some contexts, it can be a win for a different reason: if every DSO has a GNU hash section, then libc can avoid calculating SysV hashes at all. Both musl and glibc appear to have this optimization. It's plausible that this breaks some ancient glibc version. If so, then, depending on what glibc versions break, we could either require COMPAT_VDSO for them or consider reverting. Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Isaac Dunham Cc: Linus Torvalds Cc: Nathan Lynch Cc: Peter Zijlstra Cc: Rich Felker Cc: Thomas Gleixner Cc: musl@lists.openwall.com Link: http://lkml.kernel.org/r/fd56cc057a2d62ab31c56a48d04fccb435b3fd4f.1438897382.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/entry/vdso/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index 96c0617..a3d0767 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile @@ -175,7 +175,7 @@ quiet_cmd_vdso = VDSO $@ -Wl,-T,$(filter %.lds,$^) $(filter %.o,$^) && \ sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@' -VDSO_LDFLAGS = -fPIC -shared $(call cc-ldoption, -Wl$(comma)--hash-style=sysv) \ +VDSO_LDFLAGS = -fPIC -shared $(call cc-ldoption, -Wl$(comma)--hash-style=both) \ $(call cc-ldoption, -Wl$(comma)--build-id) -Wl,-Bsymbolic $(LTO_CFLAGS) GCOV_PROFILE := n -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/