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 90BC2C4332F for ; Mon, 23 May 2022 20:33:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233104AbiEWUdN (ORCPT ); Mon, 23 May 2022 16:33:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233079AbiEWUdM (ORCPT ); Mon, 23 May 2022 16:33:12 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F1D9D3888; Mon, 23 May 2022 13:33:11 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8A846614C5; Mon, 23 May 2022 20:33:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 76106C385AA; Mon, 23 May 2022 20:33:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1653337991; bh=VNVQzR9kS5xu6l5roSausKAujCRxQKGSD7vdR797KGE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hIJVMVPO4q0ZiGjXpeP/mp4WoS7qMOycauFqdeUAuUGM43xRdfvgUY8U5T6wMqW1L zMPwuEAUOEXE75o6b8ynAoLKUQhYAvGJ0ymtZ1WAwPxNpjZO0V49qzIyyFprsl1zAP 8s3OG0kh5AngMWZjGcnxwNJOMNzDrPepOl+1DPt7XkAqz8gfKLlqQg516vupKzVIL/ TxUEMRRj8+CXre1EU5IRDttOTfc7nBok6vfvfW8mHhpuDbK2eizWsbWMngOCKATCwz Z7SOdDnPK8DfSpFWHOsq5M8fXFUT+49SGHKfi6/C6UAT0Y+OZE+EuW5lBjz53bDXLM LW3NXhYYO/qPA== Date: Mon, 23 May 2022 23:31:29 +0300 From: Jarkko Sakkinen To: Miguel Ojeda Cc: Linus Torvalds , Greg Kroah-Hartman , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Kees Cook , Petr Mladek , Alex Gaynor , Wedson Almeida Filho , Gary Guo , Boqun Feng , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Joe Lawrence , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , live-patching@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: Re: [PATCH v7 03/25] kallsyms: increase maximum kernel symbol length to 512 Message-ID: References: <20220523020209.11810-1-ojeda@kernel.org> <20220523020209.11810-4-ojeda@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220523020209.11810-4-ojeda@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On Mon, May 23, 2022 at 04:01:16AM +0200, Miguel Ojeda wrote: > Rust symbols can become quite long due to namespacing introduced > by modules, types, traits, generics, etc. For instance, > the following code: > > 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. There's no description what the patch does. > > Reviewed-by: Kees Cook > Reviewed-by: Petr Mladek > Co-developed-by: Alex Gaynor > Signed-off-by: Alex Gaynor > Co-developed-by: Wedson Almeida Filho > Signed-off-by: Wedson Almeida Filho > Co-developed-by: Gary Guo > Signed-off-by: Gary Guo > Co-developed-by: Boqun Feng > Signed-off-by: Boqun Feng > Signed-off-by: Miguel Ojeda > --- > This is a prerequisite patch, independently submitted at: > > https://lore.kernel.org/lkml/20220506203443.24721-4-ojeda@kernel.org/ > > include/linux/kallsyms.h | 2 +- > kernel/livepatch/core.c | 4 ++-- > scripts/kallsyms.c | 4 ++-- > tools/include/linux/kallsyms.h | 2 +- > tools/lib/perf/include/perf/event.h | 2 +- > tools/lib/symbol/kallsyms.h | 2 +- > 6 files changed, 8 insertions(+), 8 deletions(-) > > diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h > index ce1bd2fbf23e..e5ad6e31697d 100644 > --- a/include/linux/kallsyms.h > +++ b/include/linux/kallsyms.h > @@ -15,7 +15,7 @@ > > #include > > -#define KSYM_NAME_LEN 128 > +#define KSYM_NAME_LEN 512 > #define KSYM_SYMBOL_LEN (sizeof("%s+%#lx/%#lx [%s %s]") + \ > (KSYM_NAME_LEN - 1) + \ > 2*(BITS_PER_LONG*3/10) + (MODULE_NAME_LEN - 1) + \ > diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c > index bc475e62279d..ec06ce59d728 100644 > --- a/kernel/livepatch/core.c > +++ b/kernel/livepatch/core.c > @@ -213,7 +213,7 @@ static int klp_resolve_symbols(Elf_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(Elf_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 7e99799aa7b9..275044b840dc 100644 > --- a/scripts/kallsyms.c > +++ b/scripts/kallsyms.c > @@ -30,10 +30,10 @@ > #define _stringify_1(x) #x > #define _stringify(x) _stringify_1(x) > > -#define KSYM_NAME_LEN 128 > +#define KSYM_NAME_LEN 512 > > /* A substantially bigger size than the current maximum. */ > -#define KSYM_NAME_LEN_BUFFER 512 > +#define KSYM_NAME_LEN_BUFFER 2048 > _Static_assert( > KSYM_NAME_LEN_BUFFER == KSYM_NAME_LEN * 4, > "Please keep KSYM_NAME_LEN_BUFFER in sync with KSYM_NAME_LEN" > 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/lib/perf/include/perf/event.h b/tools/lib/perf/include/perf/event.h > index e7758707cadd..116a80c31675 100644 > --- a/tools/lib/perf/include/perf/event.h > +++ b/tools/lib/perf/include/perf/event.h > @@ -95,7 +95,7 @@ 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) > -- > 2.36.1 > BR, Jarkko