From patchwork Fri Feb 26 01:57:37 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Pluzhnikov X-Patchwork-Id: 588568 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 9BDCB140CC1 for ; Fri, 26 Feb 2016 12:58:18 +1100 (AEDT) Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; secure) header.d=sourceware.org header.i=@sourceware.org header.b=u0tVH3jB; dkim-atps=neutral DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:mime-version:in-reply-to:references:from:date :message-id:subject:to:content-type; q=dns; s=default; b=jAtZz9o yI3sfzVSC/RSY+8tJ4S3byaHm885OCgiraMNnF/xCv70obyl0lhe46DaEQS92Tl4 opPMBE/FEaaTXldn8EvbXwb16WcVWLjA2s+bGthnfOiaoOXVM1/rtpOnRs+e/wHa XlNJoQQ/SzsBLtPfZDJ6jqNY/CifJ00fpnzo= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:mime-version:in-reply-to:references:from:date :message-id:subject:to:content-type; s=default; bh=qFo9lKMSRXLvk CPjEZ0nXz837Po=; b=u0tVH3jBs+l+R8vvGKh5xLLDMkwpwF/WeW144dXoXGYMT BgKX3B2eKIfZ5Er4zhrQBldbVLflB8NJgWdNdU/yhiHMKQJRB21gSkDiyZw/XUtC vVKpcZsy1IK6cep3Pf1vM+BlVQmWGGeNTYe0E5bUoytOGtzTjw792AyWNPZPI4= Received: (qmail 39636 invoked by alias); 26 Feb 2016 01:58:12 -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 39510 invoked by uid 89); 26 Feb 2016 01:58:11 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-0.7 required=5.0 tests=AWL, BAYES_00, KAM_STOCKGEN, SPF_PASS autolearn=no version=3.3.2 spammy=20160226, 2016-02-26, Allocate, mmm X-HELO: mail-wm0-f51.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:content-type; bh=AR/AEdXUZM095Uy9cX4nCwWqclJ0kZbDW0H0VFLoOLM=; b=e/lZs8NIvnUWBr9gSeo3cX+gmjDHc7VyZtGUb5XVJpNJq5JwiffRsje1O0PJ9Q7uKo Sm2r7/TYdMqGckZvGn3/LJREdbudzi5iIEVfOIiVeYszBY6VI3u+0PcFiIP2dZrvMTGL sEt9uvjkSsuLypsN1p81rHtNEUU91Tcgs06ZvtyD2i5GESQcpbxDveObzoRDu5oz/syI 10DkblsrnIWU+U2HD9IqVUO2tK4RTZhtyqSvqGIhtVxmKDbwtAmO/UwuJGTg/u8L+1u4 l8/V3JUD6AlQZY+1c3P+h3ZhJt8N+qgo37lzQA9uon5v4Gyf4ZXW3AI26vI/64zdW0Jt mfzw== X-Gm-Message-State: AG10YORabzZLTk9uHDIcn7Pat4IbmrEoyoViEF1ghRR9/ngYVw5N8qWFJHJA666aa9PMDtPFM6GPef1C1PDJIDdz X-Received: by 10.194.123.131 with SMTP id ma3mr27604211wjb.107.1456451887134; Thu, 25 Feb 2016 17:58:07 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20160222091457.GJ19841@vapier.lan> References: <20160222091457.GJ19841@vapier.lan> From: Paul Pluzhnikov Date: Thu, 25 Feb 2016 17:57:37 -0800 Message-ID: Subject: Re: [PATCH][BZ #19490] Add unwind descriptors for x86_64 _mcount and __fentry__ To: Paul Pluzhnikov , GLIBC Devel On Mon, Feb 22, 2016 at 1:14 AM, Mike Frysinger wrote: > On 23 Jan 2016 14:52, Paul Pluzhnikov wrote: ... >> + cfi_rel_offset (rdi, 32) >> + cfi_rel_offset (r8, 40) >> + cfi_rel_offset (r9, 48) > > don't we usually interleave the insns & cfi calls so that it's harder > for them to get out of sync ? I don't believe we are very consistent here. E.g. in sysdeps/i386/submul_1.S: ENTRY (__mpn_submul_1) pushl %edi cfi_adjust_cfa_offset (4) pushl %esi cfi_adjust_cfa_offset (4) pushl %ebp cfi_adjust_cfa_offset (4) pushl %ebx cfi_adjust_cfa_offset (4) cfi_rel_offset (edi, 12) cfi_rel_offset (esi, 8) cfi_rel_offset (ebp, 4) cfi_rel_offset (ebx, 0) But x86_64 does seem to interleave, so I've updated the patch to do the same. >> .type C_SYMBOL_NAME(__fentry__), @function >> .align ALIGNARG(4) >> C_LABEL(__fentry__) >> - /* Allocate space for 7 registers. */ >> + cfi_startproc >> + /* Allocate space for 7 registers (+8 for proper stack alignment). */ >> subq $64,%rsp > > mmm, 56 is used above w/_mcount and is 8 byte aligned. are you saying > we need 16 byte alignment and thus _mcount should be fixed ? No: the difference between _mcount and __fentry__ is that the former is called after function prologue. That is, on entry into _mcount (%RSP & 0xF) == 8 (as is usual for x86_64), but on entry into __fentry__ (%RSP & 0xF) == 0 (which is special). Note that I am only changing comment here, not the actual alignment. Thanks, 2016-02-26 Paul Pluzhnikov [BZ #19490] * sysdeps/x86_64/_mcount.S (_mcount): Add unwind descriptor. (__fentry__): Likewise diff --git a/sysdeps/x86_64/_mcount.S b/sysdeps/x86_64/_mcount.S index 5d7edd2..a498a48 100644 --- a/sysdeps/x86_64/_mcount.S +++ b/sysdeps/x86_64/_mcount.S @@ -28,15 +28,24 @@ .type C_SYMBOL_NAME(_mcount), @function .align ALIGNARG(4) C_LABEL(_mcount) + cfi_startproc /* Allocate space for 7 registers. */ subq $56,%rsp + cfi_adjust_cfa_offset (56) movq %rax,(%rsp) + cfi_rel_offset (rax, 0) movq %rcx,8(%rsp) + cfi_rel_offset (rcx, 8) movq %rdx,16(%rsp) + cfi_rel_offset (rdx, 16) movq %rsi,24(%rsp) + cfi_rel_offset (rsi, 24) movq %rdi,32(%rsp) + cfi_rel_offset (rdi, 32) movq %r8,40(%rsp) + cfi_rel_offset (r8, 40) movq %r9,48(%rsp) + cfi_rel_offset (r9, 48) /* Setup parameter for __mcount_internal. */ /* selfpc is the return address on the stack. */ @@ -51,14 +60,23 @@ C_LABEL(_mcount) /* Pop the saved registers. Please note that `mcount' has no return value. */ movq 48(%rsp),%r9 + cfi_restore (r9) movq 40(%rsp),%r8 + cfi_restore (r8) movq 32(%rsp),%rdi + cfi_restore (rdi) movq 24(%rsp),%rsi + cfi_restore (rsi) movq 16(%rsp),%rdx + cfi_restore (rdx) movq 8(%rsp),%rcx + cfi_restore (rcx) movq (%rsp),%rax + cfi_restore (rax) addq $56,%rsp + cfi_adjust_cfa_offset (-56) ret + cfi_endproc ASM_SIZE_DIRECTIVE(C_SYMBOL_NAME(_mcount)) @@ -69,15 +87,25 @@ weak_alias (_mcount, mcount) .type C_SYMBOL_NAME(__fentry__), @function .align ALIGNARG(4) C_LABEL(__fentry__) - /* Allocate space for 7 registers. */ + cfi_startproc + /* Allocate space for 7 registers + (+8 bytes for proper stack alignment). */ subq $64,%rsp + cfi_adjust_cfa_offset (64) movq %rax,(%rsp) + cfi_rel_offset (rax, 0) movq %rcx,8(%rsp) + cfi_rel_offset (rcx, 8) movq %rdx,16(%rsp) + cfi_rel_offset (rdx, 16) movq %rsi,24(%rsp) + cfi_rel_offset (rsi, 24) movq %rdi,32(%rsp) + cfi_rel_offset (rdi, 32) movq %r8,40(%rsp) + cfi_rel_offset (r8, 40) movq %r9,48(%rsp) + cfi_rel_offset (r9, 48) /* Setup parameter for __mcount_internal. */ /* selfpc is the return address on the stack. */ @@ -92,13 +120,22 @@ C_LABEL(__fentry__) /* Pop the saved registers. Please note that `__fentry__' has no return value. */ movq 48(%rsp),%r9 + cfi_restore (r9) movq 40(%rsp),%r8 + cfi_restore (r8) movq 32(%rsp),%rdi + cfi_restore (rdi) movq 24(%rsp),%rsi + cfi_restore (rsi) movq 16(%rsp),%rdx + cfi_restore (rdx) movq 8(%rsp),%rcx + cfi_restore (rcx) movq (%rsp),%rax + cfi_restore (rax) addq $64,%rsp + cfi_adjust_cfa_offset (-64) ret + cfi_endproc ASM_SIZE_DIRECTIVE(C_SYMBOL_NAME(__fentry__))