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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4AB7AEE14D0 for ; Wed, 6 Sep 2023 20:54:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244569AbjIFUyY (ORCPT ); Wed, 6 Sep 2023 16:54:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42454 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244557AbjIFUyX (ORCPT ); Wed, 6 Sep 2023 16:54:23 -0400 Received: from mail-wr1-x430.google.com (mail-wr1-x430.google.com [IPv6:2a00:1450:4864:20::430]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DD28519BB; Wed, 6 Sep 2023 13:54:17 -0700 (PDT) Received: by mail-wr1-x430.google.com with SMTP id ffacd0b85a97d-31c3df710bdso281842f8f.1; Wed, 06 Sep 2023 13:54:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1694033656; x=1694638456; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date:message-id:reply-to; bh=6kVCXHAEjEM8goSFYvxXt/gFxYeO8nmrzpZAICgJpDE=; b=WRg50l3e054AP/FJdPcq5EkqENfuhzGraycFkPkkaIWsc68bbq69C99KHh1tp37ao0 Ii9NJ5vFq4mjeykZwiUHPPBVTbU+tMT/YHJQuV/KxowP7+zIqDdYL9h+04MYcA5Vy7S+ 2rBV3+K4uAjtRtc6QwJmD5qDO46q4oQENpqrDQB7EFqG9FIiyvh55ah+Vg3S2lrEfhGI O7VXINFDPCCk6n35kkahnRGqhW9NNUHejhUM4VQzGjj2ahupUb4ZhGDHFxN+u7iI7z1n pOYb4tvqrWmNDspaZ97z68Y1mm6CFKKCIvmvEJbhaCz3Im7uJ2SpQoXoZaCKG0aPyPjL ViMQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1694033656; x=1694638456; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=6kVCXHAEjEM8goSFYvxXt/gFxYeO8nmrzpZAICgJpDE=; b=PxFHxbyarRPsr6hjMH6p7opvQyEXF+MtEuIV9ATQzo8Zi3dx85sEHVtWixm1goYXLG I8bjLOATPzVPQg2a1/2LHud4AnCMn+s0VLNpDpWneuL870hqTPD2J3fUZ4hkb1E5n8PK VS9L1y6WX2ArE+w2mwsY1jwI4zlPo3mqt0Aq/uSUuswTY1SfXmA74q835aC6JyF1x2qQ 5AFziXkUwg9xiMiz63JJZ337EPMA6GRwsmfZaDhPU8erZBp04jT9+OUFOYOJ62wFEStX y3MLSXocszzGkMDFiqes8y9JKKruG4+N8eBXvLL7jw27EZDxG56WhE1RG+4TtxoQnZFo oRFA== X-Gm-Message-State: AOJu0YyOtUdgoMK7qPCHRHOSr5/FaxfN//DC+S2fe7Riz16KIIVfk4UK P1VoBjEUaB/CTn0CruhzGgU= X-Google-Smtp-Source: AGHT+IG4ooluzmxwcYlqOgvX4/v7UF1oQSyZHST17ujusbKy/cUFYsvzWSMQkJmILJfYgGTJTfe45Q== X-Received: by 2002:a5d:6582:0:b0:31a:d4a9:bdac with SMTP id q2-20020a5d6582000000b0031ad4a9bdacmr3038816wru.11.1694033655894; Wed, 06 Sep 2023 13:54:15 -0700 (PDT) Received: from krava ([83.240.60.62]) by smtp.gmail.com with ESMTPSA id j9-20020a170906410900b009926928d486sm9420794ejk.35.2023.09.06.13.54.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Sep 2023 13:54:15 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Wed, 6 Sep 2023 22:54:13 +0200 To: Rong Tao Cc: olsajiri@gmail.com, andrii@kernel.org, daniel@iogearbox.net, sdf@google.com, Rong Tao , Alexei Starovoitov , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Hao Luo , Mykola Lysenko , Shuah Khan , Maxime Coquelin , Alexandre Torgue , Yafang Shao , "open list:BPF [GENERAL] (Safe Dynamic Programs and Tools)" , open list , "open list:KERNEL SELFTEST FRAMEWORK" , "moderated list:ARM/STM32 ARCHITECTURE" , "moderated list:ARM/STM32 ARCHITECTURE" Subject: Re: [PATCH bpf-next v11 1/2] selftests/bpf: trace_helpers.c: optimize kallsyms cache Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 05, 2023 at 10:04:18PM +0800, Rong Tao wrote: > From: Rong Tao > > Static ksyms often have problems because the number of symbols exceeds the > MAX_SYMS limit. Like changing the MAX_SYMS from 300000 to 400000 in > commit e76a014334a6("selftests/bpf: Bump and validate MAX_SYMS") solves > the problem somewhat, but it's not the perfect way. > > This commit uses dynamic memory allocation, which completely solves the > problem caused by the limitation of the number of kallsyms. At the same > time, add APIs: > > load_kallsyms_local() > ksym_search_local() > ksym_get_addr_local() > free_kallsyms_local() > > There are used to solve the problem of selftests/bpf updating kallsyms > after attach new symbols during testmod testing. > > Acked-by: Stanislav Fomichev > Signed-off-by: Rong Tao looks good, I added few more coments, with them addressed you can add my Acked-by: Jiri Olsa thanks, jirka > --- > v11: Remove useless load_kallsyms_refresh() and modify code some format > v10: https://lore.kernel.org/lkml/tencent_0A73B402B1D440480838ABF7124CE5EA5505@qq.com/ > Keep the original load_kallsyms(). > v9: https://lore.kernel.org/lkml/tencent_254B7015EED7A5D112C45E033DA1822CF107@qq.com/ > Add load_kallsyms_local,ksym_search_local,ksym_get_addr_local functions. > v8: https://lore.kernel.org/lkml/tencent_6D23FE187408D965E95DFAA858BC7E8C760A@qq.com/ > Resolves inter-thread contention for ksyms global variables. > v7: https://lore.kernel.org/lkml/tencent_BD6E19C00BF565CD5C36A9A0BD828CFA210A@qq.com/ > Fix __must_check macro. > v6: https://lore.kernel.org/lkml/tencent_4A09A36F883A06EA428A593497642AF8AF08@qq.com/ > Apply libbpf_ensure_mem() > v5: https://lore.kernel.org/lkml/tencent_0E9E1A1C0981678D5E7EA9E4BDBA8EE2200A@qq.com/ > Release the allocated memory once the load_kallsyms_refresh() upon error > given it's dynamically allocated. > v4: https://lore.kernel.org/lkml/tencent_59C74613113F0C728524B2A82FE5540A5E09@qq.com/ > Make sure most cases we don't need the realloc() path to begin with, > and check strdup() return value. > v3: https://lore.kernel.org/lkml/tencent_50B4B2622FE7546A5FF9464310650C008509@qq.com/ > Do not use structs and judge ksyms__add_symbol function return value. > v2: https://lore.kernel.org/lkml/tencent_B655EE5E5D463110D70CD2846AB3262EED09@qq.com/ > Do the usual len/capacity scheme here to amortize the cost of realloc, and > don't free symbols. > v1: https://lore.kernel.org/lkml/tencent_AB461510B10CD484E0B2F62E3754165F2909@qq.com/ SNIP > +static int ksyms__add_symbol(struct ksyms *ksyms, const char *name, > + unsigned long addr) > +{ > + void *tmp; > + > + tmp = strdup(name); > + if (!tmp) > + return -ENOMEM; > + ksyms->syms[ksyms->sym_cnt].addr = addr; > + ksyms->syms[ksyms->sym_cnt].name = tmp; > + > + ksyms->sym_cnt++; > + > + return 0; nit, extra new lines above > +} > + > +void free_kallsyms_local(struct ksyms *ksyms) > +{ > + unsigned int i; > + > + if (!ksyms) > + return; > + > + if (!ksyms->syms) { > + free(ksyms); > + return; > + } > + > + for (i = 0; i < ksyms->sym_cnt; i++) > + free(ksyms->syms[i].name); > + free(ksyms->syms); > + free(ksyms); > +} > > static int ksym_cmp(const void *p1, const void *p2) > { > return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr; > } > > -int load_kallsyms_refresh(void) > +struct ksyms *load_kallsyms_local(struct ksyms *ksyms) > { > FILE *f; > char func[256], buf[256]; > char symbol; > void *addr; > - int i = 0; > + int ret; > > - sym_cnt = 0; > + /* flush kallsyms, free the previously allocated dynamic memory */ > + free_kallsyms_local(ksyms); with the removal of the refresh function (from last version) there's no need now for ksyms argument in load_kallsyms_local all the current users of load_kallsyms_local are passing NULL arg > > f = fopen("/proc/kallsyms", "r"); > if (!f) > - return -ENOENT; > + return NULL; > + > + ksyms = calloc(1, sizeof(struct ksyms)); > + if (!ksyms) missing fclose(f); > + return NULL; > > while (fgets(buf, sizeof(buf), f)) { > if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3) > break; > if (!addr) > continue; > - if (i >= MAX_SYMS) > - return -EFBIG; > > - syms[i].addr = (long) addr; > - syms[i].name = strdup(func); > - i++; > + ret = libbpf_ensure_mem((void **) &ksyms->syms, &ksyms->sym_cap, > + sizeof(struct ksym), ksyms->sym_cnt + 1); > + if (ret) > + goto error; > + ret = ksyms__add_symbol(ksyms, func, (unsigned long)addr); > + if (ret) > + goto error; > } > fclose(f); > - sym_cnt = i; > - qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp); > - return 0; > + qsort(ksyms->syms, ksyms->sym_cnt, sizeof(struct ksym), ksym_cmp); > + return ksyms; > + > +error: > + free_kallsyms_local(ksyms); missing fclose(f); > + return NULL; > } > > int load_kallsyms(void) > { > - /* > - * This is called/used from multiplace places, > - * load symbols just once. > - */ > - if (sym_cnt) > - return 0; > - return load_kallsyms_refresh(); > + if (!ksyms) > + ksyms = load_kallsyms_local(NULL); > + return ksyms ? 0 : 1; > } > > -struct ksym *ksym_search(long key) > +struct ksym *ksym_search_local(struct ksyms *ksyms, long key) > { > - int start = 0, end = sym_cnt; > + int start = 0, end = ksyms->sym_cnt; > int result; > > + if (!ksyms) > + return NULL; I don't think we need to check !ksyms in here, you don't do that check in ksym_get_addr_local and I think it's fine > + > /* kallsyms not loaded. return NULL */ > - if (sym_cnt <= 0) > + if (ksyms->sym_cnt <= 0) > return NULL; > > while (start < end) { SNIP > diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h > index 876f3e711df6..d6eeec85a5e4 100644 > --- a/tools/testing/selftests/bpf/trace_helpers.h > +++ b/tools/testing/selftests/bpf/trace_helpers.h > @@ -11,13 +11,18 @@ struct ksym { > long addr; > char *name; > }; > +struct ksyms; > > int load_kallsyms(void); > -int load_kallsyms_refresh(void); > - > struct ksym *ksym_search(long key); > long ksym_get_addr(const char *name); > > +struct ksyms *load_kallsyms_local(struct ksyms *ksyms); > +struct ksym *ksym_search_local(struct ksyms *ksyms, long key); > +long ksym_get_addr_local(struct ksyms *ksyms, const char *name); > + nit, extra newline > +void free_kallsyms_local(struct ksyms *ksyms); > + > /* open kallsyms and find addresses on the fly, faster than load + search. */ > int kallsyms_find(const char *sym, unsigned long long *addr); > > -- > 2.41.0 >