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=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 A181DC433E6 for ; Wed, 10 Feb 2021 20:15:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 708F964EDA for ; Wed, 10 Feb 2021 20:15:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232894AbhBJUPh (ORCPT ); Wed, 10 Feb 2021 15:15:37 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:60228 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232633AbhBJUPe (ORCPT ); Wed, 10 Feb 2021 15:15:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1612988034; 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=F8qPD5DmBym140GmfNF1grPRmnSGg7P4Xsc0eTmldHE=; b=D5qiBQ48RuO/+Skve4raz4q60NeMfmUluX2UlNyF/5SmbWicPe0pladhAHRoniY+sEU+Xi wIun3JX57dO7X9usAdGzdWQBrMfPlOiwQckIIikFqNJ4eO/5mdehWTkAOfiDcsLqzdj6dq KbenCDLG4VHEJYttushYnkhKpn5g7tU= 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-575-iC_hdPsLNaufqMXmbgQzow-1; Wed, 10 Feb 2021 15:13:50 -0500 X-MC-Unique: iC_hdPsLNaufqMXmbgQzow-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D622384E240; Wed, 10 Feb 2021 20:13:47 +0000 (UTC) Received: from krava (unknown [10.40.195.206]) by smtp.corp.redhat.com (Postfix) with SMTP id 5E5C119D7C; Wed, 10 Feb 2021 20:13:44 +0000 (UTC) Date: Wed, 10 Feb 2021 21:13:43 +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 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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? I liked the approach below because it got rid of that bsearch ;-) but yea, yours seems to be less code chage and staighforward jirka > > > > > jirka > > > > > > --- > > diff --git a/btf_encoder.c b/btf_encoder.c > > index b124ec20a689..548a12847f99 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++; > > @@ -236,9 +248,25 @@ get_kmod_addrs(struct btf_elf *btfe, __u64 **paddrs, __u64 *pcount) > > return 0; > > } > > > > +static bool is_addr_in_func(__u64 addr, struct elf_function *func, 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; > > + > > + return start <= addr && addr < end; > > +} > > + > > static int setup_functions(struct btf_elf *btfe, struct funcs_layout *fl) > > { > > - __u64 *addrs, count, i; > > + __u64 *addrs, count, i_func, i_addr; > > int functions_valid = 0; > > bool kmod = false; > > > > @@ -266,43 +294,62 @@ static int setup_functions(struct btf_elf *btfe, struct funcs_layout *fl) > > return 0; > > } > > > > - qsort(addrs, count, sizeof(addrs[0]), addrs_cmp); > > - qsort(functions, functions_cnt, sizeof(functions[0]), functions_cmp); > > - > > /* > > - * Let's got through all collected functions and filter > > - * out those that are not in ftrace. > > + * Sort both functions and addrs so we can iterate > > + * both of them simultaneously and found matching > > + * func/addr pairs. > > */ > > - 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; > > + qsort(addrs, count, sizeof(addrs[0]), addrs_cmp); > > + qsort(functions, functions_cnt, sizeof(functions[0]), functions_cmp_addr); > > + > > + for (i_func = 0, i_addr = 0; i_func < functions_cnt; i_func++) { > > + struct elf_function *func = &functions[i_func]; > > + > > + if (i_func + 1 < functions_cnt) > > + func->end = functions[i_func + 1].addr; > > + > > + for (; i_addr < count; i_addr++) { > > + __u64 addr = addrs[i_addr]; > > + > > + /* Functions are ahead, catch up with addrs. */ > > + if (addr < func->addr) > > + continue; > > + > > + /* Addr is within function - mark function as valid. */ > > + if (is_addr_in_func(addr, func, kmod)) { > > + /* > > + * We iterate over sorted array, so we can easily skip > > + * not valid item and move following valid field into > > + * its place, and still keep the 'new' array sorted. > > + */ > > + if (i_func != functions_valid) > > + functions[functions_valid] = functions[i_func]; > > + functions_valid++; > > + i_addr++; > > + } > > > > - /* Make sure function is within ftrace addresses. */ > > - if (bsearch(&addr, addrs, count, sizeof(addrs[0]), addrs_cmp)) { > > /* > > - * We iterate over sorted array, so we can easily skip > > - * not valid item and move following valid field into > > - * its place, and still keep the 'new' array sorted. > > + * Addrs are ahead, catch up with functions, or we just > > + * found valid function and want to move to another. > > */ > > - if (i != functions_valid) > > - functions[functions_valid] = functions[i]; > > - functions_valid++; > > + break; > > } > > } > > > > + if (btf_elf__verbose) { > > + printf("Found %d functions out of %d symbols and %llu ftrace addresses.\n", > > + functions_valid, functions_cnt, count); > > + } > > + > > functions_cnt = functions_valid; > > free(addrs); > > > > - if (btf_elf__verbose) > > - printf("Found %d functions!\n", functions_cnt); > > + /* > > + * And finaly sort 'valid' functions by name, > > + * so find_function can be used. > > + */ > > + qsort(functions, functions_cnt, sizeof(functions[0]), functions_cmp_name); > > + > > return 0; > > } > > > > @@ -312,7 +359,7 @@ 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) > > >