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[23.128.96.18]) by mx.google.com with ESMTP id a17si10255027edx.507.2020.06.08.23.45.33; Mon, 08 Jun 2020 23:45:57 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=ibm.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727788AbgFIGml (ORCPT + 99 others); Tue, 9 Jun 2020 02:42:41 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:9058 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726917AbgFIGmk (ORCPT ); Tue, 9 Jun 2020 02:42:40 -0400 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 0596VgAf025432; Tue, 9 Jun 2020 02:42:04 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 31hys6qy1v-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 09 Jun 2020 02:42:04 -0400 Received: from m0098396.ppops.net (m0098396.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.36/8.16.0.36) with SMTP id 0596VnnL025968; Tue, 9 Jun 2020 02:42:03 -0400 Received: from ppma05fra.de.ibm.com (6c.4a.5195.ip4.static.sl-reverse.com [149.81.74.108]) by mx0a-001b2d01.pphosted.com with ESMTP id 31hys6qy10-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 09 Jun 2020 02:42:03 -0400 Received: from pps.filterd (ppma05fra.de.ibm.com [127.0.0.1]) by ppma05fra.de.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 0596aGra023961; Tue, 9 Jun 2020 06:42:01 GMT Received: from b06cxnps3075.portsmouth.uk.ibm.com (d06relay10.portsmouth.uk.ibm.com [9.149.109.195]) by ppma05fra.de.ibm.com with ESMTP id 31g2s7t68k-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 09 Jun 2020 06:42:01 +0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 0596fwsm37093540 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 9 Jun 2020 06:41:58 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D3E8DA4054; Tue, 9 Jun 2020 06:41:58 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1DCC3A4060; Tue, 9 Jun 2020 06:41:57 +0000 (GMT) Received: from JAVRIS.in.ibm.com (unknown [9.199.50.138]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Tue, 9 Jun 2020 06:41:56 +0000 (GMT) From: Kamalesh Babulal Subject: Re: [RFC][PATCH v4 27/32] objtool: mcount: Generic location and relocation table types To: Matt Helsley Cc: linux-kernel@vger.kernel.org, Josh Poimboeuf , Peter Zijlstra , Steven Rostedt , Sami Tolvanen , Julien Thierry References: <311ccd169cec877d0c1993772818f0e5cdf11dc4.1591125127.git.mhelsley@vmware.com> Message-ID: <79552506-b994-63ce-d3d9-8053dcbc02db@linux.vnet.ibm.com> Date: Tue, 9 Jun 2020 12:11:55 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <311ccd169cec877d0c1993772818f0e5cdf11dc4.1591125127.git.mhelsley@vmware.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.687 definitions=2020-06-09_01:2020-06-08,2020-06-09 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 spamscore=0 phishscore=0 mlxlogscore=999 malwarescore=0 priorityscore=1501 adultscore=0 impostorscore=0 lowpriorityscore=0 clxscore=1015 cotscore=-2147483648 bulkscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006090046 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/3/20 1:20 AM, Matt Helsley wrote: > Rather than building the exact ELF section data we need and > avoiding libelf's conversion step, use more GElf types > and then libelf's elfxx_xlatetof() functions to convert > the mcount locations (GElf_Addr) and associated relocations. > > This converts sift_rel_mcount() so that it doesn't use the > recordmcount wrapper. The next patch will move it out of the > wrapper. > > Signed-off-by: Matt Helsley > --- > tools/objtool/recordmcount.c | 44 +++---------- > tools/objtool/recordmcount.h | 120 ++++++++++++++--------------------- > 2 files changed, 59 insertions(+), 105 deletions(-) > > diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c > index 06a8f8ddefa7..ef3c360a3db9 100644 > --- a/tools/objtool/recordmcount.c > +++ b/tools/objtool/recordmcount.c [...] > -static uint_t *sift_rel_mcount(uint_t *mlocp, > - unsigned const offbase, > - Elf_Rel **const mrelpp, > +static void sift_rel_mcount(GElf_Addr **mlocpp, > + GElf_Sxword *r_offsetp, > + void **const mrelpp, > const struct section * const rels, > unsigned const recsym_index, > unsigned long const recval, > - unsigned const reltype) > + unsigned const reltype, > + bool is_rela) > { > - uint_t *const mloc0 = mlocp; > - Elf_Rel *mrelp = *mrelpp; > - unsigned int rel_entsize = rels->sh.sh_entsize; > - unsigned mcountsym = 0; > + GElf_Rel *mrelp = *mrelpp; > + GElf_Rela *mrelap = *mrelpp; > + unsigned int mcount_sym_info = 0; > struct reloc *reloc; > > list_for_each_entry(reloc, &rels->reloc_list, list) { > - if (!mcountsym) > - mcountsym = get_mcountsym(reloc); > - > - if (mcountsym == GELF_R_INFO(reloc->sym->idx, reloc->type) && !is_fake_mcount(reloc)) { > - uint_t const addend = > - _w(reloc->offset - recval + mcount_adjust); > - mrelp->r_offset = _w(offbase > - + ((void *)mlocp - (void *)mloc0)); > - Elf_r_info(mrelp, recsym_index, reltype); > - if (rel_entsize == sizeof(Elf_Rela)) { > - ((Elf_Rela *)mrelp)->r_addend = addend; > - *mlocp++ = 0; > - } else > - *mlocp++ = addend; > - > - mrelp = (Elf_Rel *)(rel_entsize + (void *)mrelp); > + unsigned long addend; > + > + if (!mcount_sym_info) > + mcount_sym_info = get_mcount_sym_info(reloc); > + > + if (mcount_sym_info != GELF_R_INFO(reloc->sym->idx, reloc->type) || is_fake_mcount(reloc)) > + continue; Hi Matt, I was trying out the patch series on ppc64le and found that __mcount_loc and .rela__mcount_loc section pairs do not get generated. # readelf -S fs/proc/cmdline.o|grep mcount # Debugged the cause to get_mcountsym()'s return type. It returns reloc type from GELF_R_INFO() and expects Elf64_Xword a.k.a unsigned long to be the return type but get_mcountsym() returns unsigned int on 64-bit. On power the _mcount is of relocation type R_PPC64_REL24 (info 0x170000000a), using unsigned int truncates the value to 0xa and fails the above check. Using below fix, that converts mcount_sym_info to use unsigned long, generates the __mcount_loc section pairs. --- a/tools/objtool/mcount.c +++ b/tools/objtool/mcount.c @@ -163,7 +163,7 @@ static int is_mcounted_section_name(char const *const txtname) strcmp(".cpuidle.text", txtname) == 0; } -static unsigned int get_mcount_sym_info(struct reloc *reloc) +static unsigned long get_mcount_sym_info(struct reloc *reloc) { struct symbol *sym = reloc->sym; char const *symname = sym->name; @@ -274,7 +274,7 @@ static int nop_mcount(struct section * const rels, { struct reloc *reloc; struct section *txts = find_section_by_index(lf, rels->sh.sh_info); - unsigned int mcount_sym_info = 0; + unsigned long mcount_sym_info = 0; int once = 0; list_for_each_entry(reloc, &rels->reloc_list, list) { @@ -363,7 +363,7 @@ static void sift_rel_mcount(GElf_Addr **mlocpp, { GElf_Rel *mrelp = *mrelpp; GElf_Rela *mrelap = *mrelpp; - unsigned int mcount_sym_info = 0; + unsigned long mcount_sym_info = 0; struct reloc *reloc; list_for_each_entry(reloc, &rels->reloc_list, list) { # readelf -S fs/proc/cmdline.o|grep mcount [31] __mcount_loc PROGBITS 0000000000000000 00022f10 [32] .rela__mcount_loc RELA 0000000000000000 00022f20 > + > + addend = reloc->offset - recval + mcount_adjust; > + if (is_rela) { > + mrelap->r_offset = *r_offsetp; > + mrelap->r_info = GELF_R_INFO(recsym_index, reltype); > + mrelap->r_addend = addend; > + mrelap++; > + **mlocpp = 0; > + } else { > + mrelp->r_offset = *r_offsetp; > + mrelp->r_info = GELF_R_INFO(recsym_index, reltype); > + mrelp++; > + **mlocpp = addend; > } > + (*mlocpp)++; > + r_offsetp += loc_size; the offsets generated for rela__mcount_loc section are incorrect: # readelf -rW fs/proc/meminfo.o [...] Relocation section '.rela__mcount_loc' at offset 0x59a48 contains 4 entries: Offset Info Type Symbol's Value Symbol's Name + Addend 0000000000000000 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + c 00000a059c401f38 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + 64 0000000000000000 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + 7c 0000000000000000 0000000600000026 R_PPC64_ADDR64 0000000000000000 .init.text + c changing the above line to *r_offsetp += loc_size and initializing r_offset=0 in do_mcount() generates the correct offset: # readelf -rW fs/proc/meminfo.o [...] Relocation section '.rela__mcount_loc' at offset 0x59a48 contains 4 entries: Offset Info Type Symbol's Value Symbol's Name + Addend 0000000000000000 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + c 0000000000000008 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + 64 0000000000000010 0000000200000026 R_PPC64_ADDR64 0000000000000000 .text + 7c 0000000000000018 0000000600000026 R_PPC64_ADDR64 0000000000000000 .init.text + c > } > - *mrelpp = mrelp; > - return mlocp; > + *mrelpp = is_rela ? (void *)mrelap : (void *)mrelp; > } > > -- Kamalesh