From owner-svn-src-head@freebsd.org Mon Jan 16 14:49:30 2017 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 7D2CACB2109; Mon, 16 Jan 2017 14:49:30 +0000 (UTC) (envelope-from emaste@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 3535A15E5; Mon, 16 Jan 2017 14:49:30 +0000 (UTC) (envelope-from emaste@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id v0GEnTmt093548; Mon, 16 Jan 2017 14:49:29 GMT (envelope-from emaste@FreeBSD.org) Received: (from emaste@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id v0GEnTTN093545; Mon, 16 Jan 2017 14:49:29 GMT (envelope-from emaste@FreeBSD.org) Message-Id: <201701161449.v0GEnTTN093545@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: emaste set sender to emaste@FreeBSD.org using -f From: Ed Maste Date: Mon, 16 Jan 2017 14:49:29 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r312288 - head/libexec/rtld-elf/amd64 X-SVN-Group: head MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 16 Jan 2017 14:49:30 -0000 Author: emaste Date: Mon Jan 16 14:49:29 2017 New Revision: 312288 URL: https://svnweb.freebsd.org/changeset/base/312288 Log: rtld: do not rely on a populated GOT on amd64 On rela architectures GNU BFD ld and gold store the relocation addend in GOT entries (in addition to the relocation's r_addend field). rtld previously relied on this to access its own _DYNAMIC symbol in order to apply its own relocations. However, recording addends in the GOT is not specified by the ABI, and some versions of LLVM's LLD linker leave the GOT uninitialized on rela architectures. BFD ld does not populate the GOT on sparc64, and sparc64 rtld has a machine-dependent rtld_dynamic_addr() function that returns the _DYNAMIC address. Use the same approach on amd64, obtaining the %rip- relative _DYNAMIC address following a suggestion from Rafael Espíndola. Architectures other than amd64 should be addressed in future work. PR: 214972 Reviewed by: kib MFC after: 2 weeks Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D9180 Modified: head/libexec/rtld-elf/amd64/rtld_machdep.h head/libexec/rtld-elf/amd64/rtld_start.S Modified: head/libexec/rtld-elf/amd64/rtld_machdep.h ============================================================================== --- head/libexec/rtld-elf/amd64/rtld_machdep.h Mon Jan 16 14:31:17 2017 (r312287) +++ head/libexec/rtld-elf/amd64/rtld_machdep.h Mon Jan 16 14:49:29 2017 (r312288) @@ -35,8 +35,8 @@ struct Struct_Obj_Entry; /* Return the address of the .dynamic section in the dynamic linker. */ -#define rtld_dynamic(obj) \ - ((const Elf_Dyn *)((obj)->relocbase + (Elf_Addr)&_DYNAMIC)) +Elf_Dyn *rtld_dynamic_addr(void); +#define rtld_dynamic(obj) rtld_dynamic_addr() /* Fixup the jump slot at "where" to transfer control to "target". */ static inline Elf_Addr Modified: head/libexec/rtld-elf/amd64/rtld_start.S ============================================================================== --- head/libexec/rtld-elf/amd64/rtld_start.S Mon Jan 16 14:31:17 2017 (r312287) +++ head/libexec/rtld-elf/amd64/rtld_start.S Mon Jan 16 14:49:29 2017 (r312288) @@ -156,4 +156,16 @@ _rtld_bind_start: .cfi_endproc .size _rtld_bind_start, . - _rtld_bind_start + .align 4 + .globl rtld_dynamic_addr + .type rtld_dynamic_addr,@function +rtld_dynamic_addr: + .cfi_startproc + .weak _DYNAMIC + .hidden _DYNAMIC + lea _DYNAMIC(%rip),%rax + ret + .cfi_endproc + .size rtld_dynamic_addr, . - rtld_dynamic_addr + .section .note.GNU-stack,"",%progbits