From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0C1AC48BE5 for ; Wed, 16 Jun 2021 15:03:14 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id A1C956115C for ; Wed, 16 Jun 2021 15:03:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A1C956115C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=fTC4LLObtjSOvx9Tm8T/+Bo73p77PzF34P0O+B6ZBfM=; b=nBgPO+JE8sJyVk C6hwsnDu1R2ajKASz31pApiMXxVXw3Y/k4prS6xM+g66yC/rcaym5JjGHhzASODdgA/KD2/FihQHv B3Fsn2/I5dhdyhN2Um7wAngGxsUTj5dqva35hMpc1tltPVWgZq+eqNSUbz0gPELe90nPWgZyqxEef lG4986R+vaeUpfiE0avW83E8n4/aBMnWpnV1gzEXmGoBiO35UICaKHetb0j1CQoZWZkM6J9nPqIP3 /6v4poKndNQTk/nuHUQSfCeZFQSvSnLbDtIAaUEHJ9a/4t6nn99aNgJdj9on3K8p4l/h1D4VYNHdM qRc1na94tPmmEMlF+c0g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ltX30-006ndc-Fa; Wed, 16 Jun 2021 15:01:42 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ltX2x-006nd4-Dz; Wed, 16 Jun 2021 15:01:39 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=I5DjI7oj7+RHnDV6cxwDeOoQ3n60YwGRMyOOSPM02Qk=; b=FdKzXZ9x5ATmodn0JioFshI/ht bdpS5+BCXFSEs+EM4u+wfgZ0T6OKJCP/WkbnVQi3YNxOcuedepjMeyiMX9264TX3MQJaKszqGFgbo 4uvKVdhXRRK8u5GgHORw45pFBRkzSAzZBfyjVsW/4AOY93ztSstnsy5dU8B00kSIry2/1CcUNlp7n FhUhDHRYOhfr4cA/CaaLW3XuaaC1lPhNNsasz/NDn8eMulp0Njdvf2m4DR5k8Q9zVeBHqJXk9R9Na NR+8ZKhGQZsDOMEDmNefJ6KCJVtznwT7/l8liFHleWZrSoSFeJBPFbAC2uf/qO/hXLkZ5t0bbJLyr yKnVWqnw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1ltX2W-008AIS-NX; Wed, 16 Jun 2021 15:01:19 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id DC5F8300269; Wed, 16 Jun 2021 17:01:10 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C11E42C516D3B; Wed, 16 Jun 2021 17:01:10 +0200 (CEST) Date: Wed, 16 Jun 2021 17:01:10 +0200 From: Peter Zijlstra To: Mark-PK Tsai Cc: rostedt@goodmis.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, matthias.bgg@gmail.com, mhelsley@vmware.com, samitolvanen@google.com, yj.chiang@mediatek.com Subject: Re: [PATCH v3] recordmcount: Correct st_shndx handling Message-ID: References: <20210615162313.26081-1-mark-pk.tsai@mediatek.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210615162313.26081-1-mark-pk.tsai@mediatek.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jun 16, 2021 at 12:23:13AM +0800, Mark-PK Tsai wrote: > From: Peter Zijlstra > > One should only use st_shndx when >SHN_UNDEF and SHN_XINDEX, then use .symtab_shndx. Otherwise use 0. > > This handles the case: st_shndx >= SHN_LORESERVE && st_shndx != SHN_XINDEX. > > Reported-by: Mark-PK Tsai > Signed-off-by: Peter Zijlstra (Intel) > Tested-by: Mark-PK Tsai > [handle endianness of sym->st_shndx] > Signed-off-by: Mark-PK Tsai > --- > scripts/recordmcount.h | 13 +++++++++---- > 1 file changed, 9 insertions(+), 4 deletions(-) > > diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h > index f9b19524da11..ef9c3425f86b 100644 > --- a/scripts/recordmcount.h > +++ b/scripts/recordmcount.h > @@ -194,13 +194,18 @@ static unsigned int get_symindex(Elf_Sym const *sym, Elf32_Word const *symtab, > unsigned long offset; > int index; > > + if (w2(sym->st_shndx) > SHN_UNDEF && > + w2(sym->st_shndx) < SHN_LORESERVE) > return w2(sym->st_shndx); > > + if (w2(sym->st_shndx) == SHN_XINDEX) { > + offset = (unsigned long)sym - (unsigned long)symtab; > + index = offset / sizeof(*sym); > > + return w(symtab_shndx[index]); > + } > + > + return 0; > } Thanks. However that leads to atrocious codegen because w2 is an indirect function, something like the below seems much better. 1d00: 41 0f b7 7f 0e movzwl 0xe(%r15),%edi 1d05: c0 eb 04 shr $0x4,%bl 1d08: ff 15 7a 54 00 00 callq *0x547a(%rip) # 7188 1d0e: 85 c0 test %eax,%eax 1d10: 74 16 je 1d28 1d12: 41 0f b7 7f 0e movzwl 0xe(%r15),%edi 1d17: ff 15 6b 54 00 00 callq *0x546b(%rip) # 7188 1d1d: 3d ff fe 00 00 cmp $0xfeff,%eax 1d22: 0f 86 00 03 00 00 jbe 2028 1d28: 41 0f b7 7f 0e movzwl 0xe(%r15),%edi 1d2d: ff 15 55 54 00 00 callq *0x5455(%rip) # 7188 vs 1d0c: 41 0f b7 7f 0e movzwl 0xe(%r15),%edi 1d11: ff 15 71 54 00 00 callq *0x5471(%rip) # 7188 --- diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h index f9b19524da11..b3e9d0563c03 100644 --- a/scripts/recordmcount.h +++ b/scripts/recordmcount.h @@ -192,15 +192,23 @@ static unsigned int get_symindex(Elf_Sym const *sym, Elf32_Word const *symtab, Elf32_Word const *symtab_shndx) { unsigned long offset; + unsigned short shndx; int index; - if (sym->st_shndx != SHN_XINDEX) - return w2(sym->st_shndx); + shndx = w2(sym->st_shndx); - offset = (unsigned long)sym - (unsigned long)symtab; - index = offset / sizeof(*sym); + if (shndx > SHN_UNDEF && + shndx < SHN_LORESERVE) + return shndx; - return w(symtab_shndx[index]); + if (shndx == SHN_XINDEX) { + offset = (unsigned long)sym - (unsigned long)symtab; + index = offset / sizeof(*sym); + + return w(symtab_shndx[index]); + } + + return 0; } static unsigned int get_shnum(Elf_Ehdr const *ehdr, Elf_Shdr const *shdr0) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel