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=-11.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 DDC4DC433E6 for ; Thu, 11 Feb 2021 15:18:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD7BC64F51 for ; Thu, 11 Feb 2021 15:18:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230228AbhBKPSZ (ORCPT ); Thu, 11 Feb 2021 10:18:25 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:44382 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230198AbhBKPNk (ORCPT ); Thu, 11 Feb 2021 10:13:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1613056324; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=IJk4z6TuxNr4nNxcX9hDO3Ok0FW7l/jb6b2/xDt4SXU=; b=Gs2+atYUV7O0QB1GEygYPEDxe9Gqdautn2+ZmDMNxyz8pZWk827SThoiRKmW1XwgG2aJ8w mff2ivOMYh7VBqkRsWUVdKeM/UzRlcidkwj3jmKaTLAnj0LfN4P61W1kFsPVppTHNW809j ZscdAk7FJcfY6bbyT8irZS1zCUSAmNc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-546-18QqE7EhPyWamxk0Tq_6UA-1; Thu, 11 Feb 2021 10:08:18 -0500 X-MC-Unique: 18QqE7EhPyWamxk0Tq_6UA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 7B4B51005501; Thu, 11 Feb 2021 15:08:15 +0000 (UTC) Received: from krava (unknown [10.40.192.105]) by smtp.corp.redhat.com (Postfix) with SMTP id 5AE1A60636; Thu, 11 Feb 2021 15:08:12 +0000 (UTC) Date: Thu, 11 Feb 2021 16:08:11 +0100 From: Jiri Olsa To: Andrii Nakryiko Cc: Nathan Chancellor , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Nick Desaulniers , Networking , bpf , clang-built-linux , Veronika Kabatova , Jiri Olsa Subject: Re: FAILED unresolved symbol vfs_truncate on arm64 with LLVM Message-ID: References: <20210209074904.GA286822@ubuntu-m3-large-x86> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, Feb 10, 2021 at 09:13:47PM +0100, Jiri Olsa wrote: > On Wed, Feb 10, 2021 at 10:20:20AM -0800, Andrii Nakryiko wrote: > > SNIP > > > > but below is change for checking that ftrace addrs are within elf functions > > > > > > seems to work in my tests, I'll run some more tests and send full patch > > > > It seems unnecessarily convoluted. I was thinking about something like > > this (the diff will totally be screwed up by gmail, and I haven't even > > compiled it): > > > > diff --git a/btf_encoder.c b/btf_encoder.c > > index b124ec20a689..8162b238bd43 100644 > > --- a/btf_encoder.c > > +++ b/btf_encoder.c > > @@ -236,6 +236,23 @@ get_kmod_addrs(struct btf_elf *btfe, __u64 > > **paddrs, __u64 *pcount) > > return 0; > > } > > > > +struct func_seg { __u64 start; __u64 end; }; > > + > > +static int func_exists(struct func_seg *segs, size_t len, __u64 addr) > > +{ > > + size_t l = 0, r = len - 1, m; > > + > > + while (l < r) { > > + m = l + (r - l + 1) / 2; > > + if (segs[m].start <= addr) > > + l = m; > > + else > > + r = m - 1; > > + } > > + > > + return segs[l].start <= addr && addr < segs[l].end; > > +} > > + > > static int setup_functions(struct btf_elf *btfe, struct funcs_layout *fl) > > { > > __u64 *addrs, count, i; > > @@ -286,7 +303,7 @@ static int setup_functions(struct btf_elf *btfe, > > struct funcs_layout *fl) > > __u64 addr = kmod ? func->addr + func->sh_addr : func->addr; > > > > /* Make sure function is within ftrace addresses. */ > > - if (bsearch(&addr, addrs, count, sizeof(addrs[0]), addrs_cmp)) { > > + if (func_exists(addrs, count, addr)) > > you pass addrs in here, but you mean func_seg array > filled with elf functions start/end values, right? > > > /* > > * We iterate over sorted array, so we can easily skip > > * not valid item and move following valid field into > > > > > > So the idea is to use address segments and check whether there is a > > segment that overlaps with a given address by first binary searching > > for a segment with the largest starting address that is <= addr. And > > then just confirming that segment does overlap with the requested > > address. > > > > WDYT? heya, with your approach I ended up with change below, it gives me same results as with the previous change I think I'll separate the kmod bool address computation later on, but I did not want to confuse this change for now jirka --- diff --git a/btf_encoder.c b/btf_encoder.c index b124ec20a689..34df08f2fb4e 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -36,6 +36,7 @@ struct funcs_layout { struct elf_function { const char *name; unsigned long addr; + unsigned long end; unsigned long sh_addr; bool generated; }; @@ -44,7 +45,7 @@ static struct elf_function *functions; static int functions_alloc; static int functions_cnt; -static int functions_cmp(const void *_a, const void *_b) +static int functions_cmp_name(const void *_a, const void *_b) { const struct elf_function *a = _a; const struct elf_function *b = _b; @@ -52,6 +53,16 @@ static int functions_cmp(const void *_a, const void *_b) return strcmp(a->name, b->name); } +static int functions_cmp_addr(const void *_a, const void *_b) +{ + const struct elf_function *a = _a; + const struct elf_function *b = _b; + + if (a->addr == b->addr) + return 0; + return a->addr < b->addr ? -1 : 1; +} + static void delete_functions(void) { free(functions); @@ -98,6 +109,7 @@ static int collect_function(struct btf_elf *btfe, GElf_Sym *sym, functions[functions_cnt].name = name; functions[functions_cnt].addr = elf_sym__value(sym); + functions[functions_cnt].end = (__u64) -1; functions[functions_cnt].sh_addr = sh.sh_addr; functions[functions_cnt].generated = false; functions_cnt++; @@ -236,6 +248,40 @@ get_kmod_addrs(struct btf_elf *btfe, __u64 **paddrs, __u64 *pcount) return 0; } +static int is_ftrace_func(struct elf_function *func, __u64 *addrs, + __u64 count, bool kmod) +{ + /* + * For vmlinux image both addrs[x] and functions[x]::addr + * values are final address and are comparable. + * + * For kernel module addrs[x] is final address, but + * functions[x]::addr is relative address within section + * and needs to be relocated by adding sh_addr. + */ + __u64 start = kmod ? func->addr + func->sh_addr : func->addr; + __u64 end = kmod ? func->end + func->sh_addr : func->end; + + size_t l = 0, r = count - 1, m; + __u64 addr = 0; + + while (l < r) { + m = l + (r - l + 1) / 2; + addr = addrs[m]; + + if (start <= addr && addr < end) + return true; + + if (start <= addr) + r = m - 1; + else + l = m; + } + + addr = addrs[l]; + return start <= addr && addr < end; +} + static int setup_functions(struct btf_elf *btfe, struct funcs_layout *fl) { __u64 *addrs, count, i; @@ -267,7 +313,7 @@ static int setup_functions(struct btf_elf *btfe, struct funcs_layout *fl) } qsort(addrs, count, sizeof(addrs[0]), addrs_cmp); - qsort(functions, functions_cnt, sizeof(functions[0]), functions_cmp); + qsort(functions, functions_cnt, sizeof(functions[0]), functions_cmp_addr); /* * Let's got through all collected functions and filter @@ -275,18 +321,12 @@ static int setup_functions(struct btf_elf *btfe, struct funcs_layout *fl) */ for (i = 0; i < functions_cnt; i++) { struct elf_function *func = &functions[i]; - /* - * For vmlinux image both addrs[x] and functions[x]::addr - * values are final address and are comparable. - * - * For kernel module addrs[x] is final address, but - * functions[x]::addr is relative address within section - * and needs to be relocated by adding sh_addr. - */ - __u64 addr = kmod ? func->addr + func->sh_addr : func->addr; + + if (i + 1 < functions_cnt) + func->end = functions[i + 1].addr; /* Make sure function is within ftrace addresses. */ - if (bsearch(&addr, addrs, count, sizeof(addrs[0]), addrs_cmp)) { + if (is_ftrace_func(func, addrs, count, kmod)) { /* * We iterate over sorted array, so we can easily skip * not valid item and move following valid field into @@ -303,6 +343,8 @@ static int setup_functions(struct btf_elf *btfe, struct funcs_layout *fl) if (btf_elf__verbose) printf("Found %d functions!\n", functions_cnt); + + qsort(functions, functions_cnt, sizeof(functions[0]), functions_cmp_name); return 0; } @@ -312,7 +354,7 @@ static struct elf_function *find_function(const struct btf_elf *btfe, struct elf_function key = { .name = name }; return bsearch(&key, functions, functions_cnt, sizeof(functions[0]), - functions_cmp); + functions_cmp_name); } static bool btf_name_char_ok(char c, bool first)