From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp04.au.ibm.com (e23smtp04.au.ibm.com [202.81.31.146]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id B4AF51A028D for ; Wed, 13 Jan 2016 21:00:43 +1100 (AEDT) Received: from localhost by e23smtp04.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 13 Jan 2016 20:00:42 +1000 Received: from d23relay10.au.ibm.com (d23relay10.au.ibm.com [9.190.26.77]) by d23dlp03.au.ibm.com (Postfix) with ESMTP id BFB233578056 for ; Wed, 13 Jan 2016 21:00:39 +1100 (EST) Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay10.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u0DA0Vd253739562 for ; Wed, 13 Jan 2016 21:00:39 +1100 Received: from d23av01.au.ibm.com (localhost [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u0DA06gR006488 for ; Wed, 13 Jan 2016 21:00:07 +1100 Message-ID: <56962014.5040702@linux.vnet.ibm.com> Date: Wed, 13 Jan 2016 15:29:48 +0530 From: Hemant Kumar MIME-Version: 1.0 To: =?UTF-8?B?5bmz5p2+6ZuF5bezIC8gSElSQU1BVFXvvIxNQVNBTUk=?= , "linux-kernel@vger.kernel.org" CC: "mjw@redhat.com" , "sukadev@linux.vnet.ibm.com" , "linuxppc-dev@lists.ozlabs.org" , "srikar@linux.vnet.ibm.com" , "acme@kernel.org" Subject: Re: [PATCH v2] perf/probe: Search both .eh_frame and .debug_frame sections for probe location References: <1451900918-6710-1-git-send-email-hemant@linux.vnet.ibm.com> <50399556C9727B4D88A595C8584AAB37526926A9@GSjpTKYDCembx32.service.hitachi.net> In-Reply-To: <50399556C9727B4D88A595C8584AAB37526926A9@GSjpTKYDCembx32.service.hitachi.net> Content-Type: text/plain; charset=utf-8; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 01/12/2016 04:34 PM, 平松雅巳 / HIRAMATU，MASAMI wrote: > Hi Hemant, > >> From: Hemant Kumar [mailto:hemant@linux.vnet.ibm.com] >> >> perf probe through debuginfo__find_probes() in util/probe-finder.c >> checks for the functions' frame descriptions in either .eh_frame section >> of an ELF or the .debug_frame. The check is based on whether either one >> of these sections is present. Depending on distro, toolchain defaults, >> architetcutre, build flags, etc., CFI might be found in either .eh_frame >> and/or .debug_frame. Sometimes, it may happen that, .eh_frame, even if >> present, may not be complete and may miss some descriptions. Therefore, >> to be sure, to find the CFI covering an address we will always have to >> investigate both if available. > OK, so we'd better check both cfi's. > [...] >> +/* Find probe points from debuginfo */ >> +static int debuginfo__find_probes(struct debuginfo *dbg, >> + struct probe_finder *pf) >> +{ >> + int ret = 0; >> + >> +#if _ELFUTILS_PREREQ(0, 142) >> + Elf *elf; >> + GElf_Ehdr ehdr; >> + GElf_Shdr shdr; >> + >> + if (pf->cfi_eh || pf->cfi_dbg) >> + return debuginfo__find_probe_location(dbg, pf); >> + >> + /* Get the call frame information from this dwarf */ >> + elf = dwarf_getelf(dbg->dbg); >> + if (elf == NULL) >> + return -EINVAL; >> + >> + if (gelf_getehdr(elf, &ehdr) == NULL) >> + return -EINVAL; >> + >> + if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) && >> + shdr.sh_type == SHT_PROGBITS) { >> + pf->cfi_eh = dwarf_getcfi_elf(elf); >> + } else { >> + pf->cfi_dbg = dwarf_getcfi(dbg->dbg); >> + } > Hmm, if you want to check both of those cfi's, don't we have to do below? > > if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) && > shdr.sh_type == SHT_PROGBITS) > pf->cfi_eh = dwarf_getcfi_elf(elf); > > pf->cfi_dbg = dwarf_getcfi(dbg->dbg); > > Then, both of pf->cfi_* will be filled (if the elf has ".eh_frame"). > > Thanks! Ah, right. Fixed in v3. > > -- Thanks, Hemant Kumar