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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL 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 30AB8C433B4 for ; Wed, 14 Apr 2021 23:48:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1315E61220 for ; Wed, 14 Apr 2021 23:48:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230056AbhDNXtM (ORCPT ); Wed, 14 Apr 2021 19:49:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229994AbhDNXtJ (ORCPT ); Wed, 14 Apr 2021 19:49:09 -0400 Received: from mail-lj1-x234.google.com (mail-lj1-x234.google.com [IPv6:2a00:1450:4864:20::234]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F58AC061760 for ; Wed, 14 Apr 2021 16:48:45 -0700 (PDT) Received: by mail-lj1-x234.google.com with SMTP id l14so22224387ljb.1 for ; Wed, 14 Apr 2021 16:48:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=sYrhQ+L0KHq4tveN5clEASWcQ37/wtC32tCYh0nBGLo=; b=oVcontEvK+/+8MA7Pe0KxzkdxdTY9uAw/triIXdClbgN0AqR9y8J3vDKWQGZQognij Dv00nHR4pwZKbHwSELVW5MrGADWTow2YAHFxLyIaZMUVnYn+HgFQ8m6I4nxQIIa6oaxR vZ1zOvsFHhQpoJofcGiYwlm0N3C7yvAyenfpmab9wAukwMa/kcYewOhykPReLODnnHdD B/UdliM0FMyAu1rYPLtGw/OMmDtd0yatWxtt6mS1EiYKE4B+p79g4b6MjsuD0Gv3Y+C0 z7Zo437En5Rw8m6Tf0iCuERtCSm0c+tBNu9xHU8I+jVxM5wFKHnusyAReqAdFalPdrTB RNWQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=sYrhQ+L0KHq4tveN5clEASWcQ37/wtC32tCYh0nBGLo=; b=VKxWV1HkI2RKuZe46K9og5WyRmo7jE1uuNaoouQs5DJmbHS04JJfk390MH3+v9L1q/ qd4CWinGD5r4a2hbYrFqk2TwwaKSEPnGSmtziV5tQ0FLH94/0jf1ElmoRRAtUg4L74HQ d9QNDClfnf8MV6oS2uvo66raLkwHumFKYgIaVMOPbj4D0Sx6aIdKLsOJN1SIQp6gpd8i WLRXgZezEFt2zDxwSRsLsC4XF85IwGVxLuotr7GsrGjhNIYkwJGE8qPkx8nlxQ9YszYD 0yprwRkBAKzw3pZkI2arZ8O8/IR9h4oz0HCXULxdxOcmKdqIziZt/xpjgFRQepR0zUkG 1NyQ== X-Gm-Message-State: AOAM533GnQ46ugLSnzPiU0Jcx6kgxSg2bSC8iCyuesrnYFcfv61D5Ml9 xPtJbleYgbvaHMzq29YTb1GRHwZfjHkBWcUD/GHNbA== X-Google-Smtp-Source: ABdhPJxDm6QXae66Kp5wtL/ye/7TEOwYZKMxEQuOI5NmLFtK+zp9XBWYUFbSmyJLar215o9dcq4wZWgDF/OjIY+UAhA= X-Received: by 2002:a2e:5716:: with SMTP id l22mr239987ljb.244.1618444123676; Wed, 14 Apr 2021 16:48:43 -0700 (PDT) MIME-Version: 1.0 References: <20210414184604.23473-1-ojeda@kernel.org> <20210414184604.23473-3-ojeda@kernel.org> In-Reply-To: <20210414184604.23473-3-ojeda@kernel.org> From: Nick Desaulniers Date: Wed, 14 Apr 2021 16:48:31 -0700 Message-ID: Subject: Re: [PATCH 02/13] kallsyms: Increase maximum kernel symbol length to 512 To: Miguel Ojeda Cc: Linus Torvalds , Greg Kroah-Hartman , rust-for-linux@vger.kernel.org, Linux Kbuild mailing list , Linux Doc Mailing List , LKML , Alex Gaynor , Geoffrey Thomas , Finn Behrens , Adam Bratschi-Kaye , Wedson Almeida Filho Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: rust-for-linux@vger.kernel.org On Wed, Apr 14, 2021 at 11:48 AM wrote: > > From: Miguel Ojeda > > Rust symbols can become quite long due to namespacing introduced > by modules, types, traits, generics, etc. For instance, for: > > pub mod my_module { > pub struct MyType; > pub struct MyGenericType(T); > > pub trait MyTrait { > fn my_method() -> u32; > } > > impl MyTrait for MyGenericType { > fn my_method() -> u32 { > 42 > } > } > } > > generates a symbol of length 96 when using the upcoming v0 mangling scheme: > > _RNvXNtCshGpAVYOtgW1_7example9my_moduleINtB2_13MyGenericTypeNtB2_6MyTypeENtB2_7MyTrait9my_method > > At the moment, Rust symbols may reach up to 300 in length. > Setting 512 as the maximum seems like a reasonable choice to > keep some headroom. What are the implications of this change for someone not using Rust? Does it change the binary size of vmlinux for a defconfig build, for example? > > Co-developed-by: Alex Gaynor > Signed-off-by: Alex Gaynor > Co-developed-by: Geoffrey Thomas > Signed-off-by: Geoffrey Thomas > Co-developed-by: Finn Behrens > Signed-off-by: Finn Behrens > Co-developed-by: Adam Bratschi-Kaye > Signed-off-by: Adam Bratschi-Kaye > Co-developed-by: Wedson Almeida Filho > Signed-off-by: Wedson Almeida Filho > Signed-off-by: Miguel Ojeda > --- > include/linux/kallsyms.h | 2 +- > kernel/livepatch/core.c | 4 ++-- > scripts/kallsyms.c | 2 +- > tools/include/linux/kallsyms.h | 2 +- > tools/include/linux/lockdep.h | 2 +- > tools/lib/perf/include/perf/event.h | 2 +- > tools/lib/symbol/kallsyms.h | 2 +- > 7 files changed, 8 insertions(+), 8 deletions(-) > > diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h > index 465060acc981..5cdc6903abca 100644 > --- a/include/linux/kallsyms.h > +++ b/include/linux/kallsyms.h > @@ -14,7 +14,7 @@ > > #include > > -#define KSYM_NAME_LEN 128 > +#define KSYM_NAME_LEN 512 > #define KSYM_SYMBOL_LEN (sizeof("%s+%#lx/%#lx [%s]") + (KSYM_NAME_LEN - 1) + \ > 2*(BITS_PER_LONG*3/10) + (MODULE_NAME_LEN - 1) + 1) > > diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c > index 335d988bd811..73874e5edfda 100644 > --- a/kernel/livepatch/core.c > +++ b/kernel/livepatch/core.c > @@ -213,7 +213,7 @@ static int klp_resolve_symbols(Elf64_Shdr *sechdrs, const char *strtab, > * we use the smallest/strictest upper bound possible (56, based on > * the current definition of MODULE_NAME_LEN) to prevent overflows. > */ > - BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 128); > + BUILD_BUG_ON(MODULE_NAME_LEN < 56 || KSYM_NAME_LEN != 512); > > relas = (Elf_Rela *) relasec->sh_addr; > /* For each rela in this klp relocation section */ > @@ -227,7 +227,7 @@ static int klp_resolve_symbols(Elf64_Shdr *sechdrs, const char *strtab, > > /* Format: .klp.sym.sym_objname.sym_name,sympos */ > cnt = sscanf(strtab + sym->st_name, > - ".klp.sym.%55[^.].%127[^,],%lu", > + ".klp.sym.%55[^.].%511[^,],%lu", > sym_objname, sym_name, &sympos); > if (cnt != 3) { > pr_err("symbol %s has an incorrectly formatted name\n", > diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c > index bcdabee13aab..9bab5f55ade3 100644 > --- a/scripts/kallsyms.c > +++ b/scripts/kallsyms.c > @@ -27,7 +27,7 @@ > > #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0])) > > -#define KSYM_NAME_LEN 128 > +#define KSYM_NAME_LEN 512 > > struct sym_entry { > unsigned long long addr; > diff --git a/tools/include/linux/kallsyms.h b/tools/include/linux/kallsyms.h > index efb6c3f5f2a9..5a37ccbec54f 100644 > --- a/tools/include/linux/kallsyms.h > +++ b/tools/include/linux/kallsyms.h > @@ -6,7 +6,7 @@ > #include > #include > > -#define KSYM_NAME_LEN 128 > +#define KSYM_NAME_LEN 512 > > struct module; > > diff --git a/tools/include/linux/lockdep.h b/tools/include/linux/lockdep.h > index e56997288f2b..d9c163f3ab24 100644 > --- a/tools/include/linux/lockdep.h > +++ b/tools/include/linux/lockdep.h > @@ -47,7 +47,7 @@ static inline int debug_locks_off(void) > > #define task_pid_nr(tsk) ((tsk)->pid) > > -#define KSYM_NAME_LEN 128 > +#define KSYM_NAME_LEN 512 > #define printk(...) dprintf(STDOUT_FILENO, __VA_ARGS__) > #define pr_err(format, ...) fprintf (stderr, format, ## __VA_ARGS__) > #define pr_warn pr_err > diff --git a/tools/lib/perf/include/perf/event.h b/tools/lib/perf/include/perf/event.h > index d82054225fcc..f5c40325b441 100644 > --- a/tools/lib/perf/include/perf/event.h > +++ b/tools/lib/perf/include/perf/event.h > @@ -93,7 +93,7 @@ struct perf_record_throttle { > }; > > #ifndef KSYM_NAME_LEN > -#define KSYM_NAME_LEN 256 > +#define KSYM_NAME_LEN 512 > #endif > > struct perf_record_ksymbol { > diff --git a/tools/lib/symbol/kallsyms.h b/tools/lib/symbol/kallsyms.h > index 72ab9870454b..542f9b059c3b 100644 > --- a/tools/lib/symbol/kallsyms.h > +++ b/tools/lib/symbol/kallsyms.h > @@ -7,7 +7,7 @@ > #include > > #ifndef KSYM_NAME_LEN > -#define KSYM_NAME_LEN 256 > +#define KSYM_NAME_LEN 512 > #endif > > static inline u8 kallsyms2elf_binding(char type) > -- > 2.17.1 > -- Thanks, ~Nick Desaulniers