From patchwork Mon Dec 19 11:15:22 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nix X-Patchwork-Id: 18565 Received: (qmail 121229 invoked by alias); 19 Dec 2016 11:25:54 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 121055 invoked by uid 89); 19 Dec 2016 11:25:52 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.6 required=5.0 tests=AWL, BAYES_00, KAM_LAZY_DOMAIN_SECURITY, RP_MATCHES_RCVD autolearn=ham version=3.3.2 spammy=Hx-languages-length:1614 X-HELO: mail.esperi.org.uk From: Nix To: libc-alpha@sourceware.org Cc: fweimer@redhat.com Subject: [PATCH 09/15] De-PLTize __stack_chk_fail internal calls within libc.so. Date: Mon, 19 Dec 2016 11:15:22 +0000 Message-Id: <20161219111528.14969-10-nix@esperi.org.uk> In-Reply-To: <20161219111528.14969-1-nix@esperi.org.uk> References: <20161219111528.14969-1-nix@esperi.org.uk> X-DCC--Metrics: spindle 1480; Body=2 Fuz1=2 Fuz2=2 From: Adhemerval Zanella We use the same assembler-macro trick we use to de-PLTize compiler-generated libcalls to memcpy and memset to redirect __stack_chk_fail to __stack_chk_fail_local. v5: New. v6: Only do it within the shared library: with __stack_chk_fail_local in libc_pic.a now we don't need to worry about calls from inside other routines in libc_nonshared.a any more. v8: Merge #ifdef blocks. v10: Use STACK_PROTECTOR_LEVEL to avoid renaming in files where stack-protection is suppressed. * sysdeps/generic/symbol-hacks.h [STACK_PROTECTOR_LEVEL && STACK_PROTECTOR_LEVEL > 0] (__stack_chk_fail): Add internal alias. --- sysdeps/generic/symbol-hacks.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/sysdeps/generic/symbol-hacks.h b/sysdeps/generic/symbol-hacks.h index ce576c9..d614c09 100644 --- a/sysdeps/generic/symbol-hacks.h +++ b/sysdeps/generic/symbol-hacks.h @@ -4,4 +4,16 @@ asm ("memmove = __GI_memmove"); asm ("memset = __GI_memset"); asm ("memcpy = __GI_memcpy"); + +/* Some targets do not use __stack_chk_fail_local. In libc.so, + redirect __stack_chk_fail to a hidden reference + __stack_chk_fail_local, to avoid the PLT reference. + __stack_chk_fail itself is a global symbol, exported from libc.so, + and cannot be made hidden. */ + +# if IS_IN (libc) && defined SHARED && \ + defined STACK_PROTECTOR_LEVEL && STACK_PROTECTOR_LEVEL > 0 +asm (".hidden __stack_chk_fail_local\n" + "__stack_chk_fail = __stack_chk_fail_local"); +# endif #endif