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 91E08EB64D9 for ; Fri, 7 Jul 2023 15:08:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233335AbjGGPIa (ORCPT ); Fri, 7 Jul 2023 11:08:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229663AbjGGPI2 (ORCPT ); Fri, 7 Jul 2023 11:08:28 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F1711124 for ; Fri, 7 Jul 2023 08:08:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Sender:Reply-To:Content-ID:Content-Description; bh=ngymcJKfzUdLyl4Mlcar1YzSoF6nj3bJ0BiZlGdA5fU=; b=OLu3rDIaK4YQsYiz+caXIw/WiX W8J+Wa9Osj/y2FOMTD5aXMnjiiHIFujD8xnHa/NaKqDyjORPxCh8s9EMW5CnUCEA51vfYgIsStHBb 56y6iGv7BU7Meh8GOmlDGloyFD4mQgJytER7IjyDWr1JXYwR65moN6g1pKW7gYoGFPcRr2jOI8t1P cAVuUmy51YRwpUHZh9bHN9VpOKOcudpLTYl2+KIV/4L5sje5oxdBa2rpq3XS4A8Qz3Pl2tbsGWkVq Cq5+1GUnfbiCHFbVjxpANX9hStYpvNqZKImSDm4axVJV9eZNXG/ZYcDTX0lEh6/i+I/LKsYiQg5mp fZ4+zw/A==; Received: from [2601:1c2:980:9ec0::2764] by bombadil.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qHn48-004ynX-38; Fri, 07 Jul 2023 15:08:13 +0000 Message-ID: <437ac153-620c-2012-7ce3-66442b505972@infradead.org> Date: Fri, 7 Jul 2023 08:08:12 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH] module: Ignore RISC-V mapping symbols too Content-Language: en-US To: Palmer Dabbelt , mcgrof@kernel.org Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org References: <20230707054007.32591-1-palmer@rivosinc.com> From: Randy Dunlap In-Reply-To: <20230707054007.32591-1-palmer@rivosinc.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/6/23 22:40, Palmer Dabbelt wrote: > RISC-V has an extended form of mapping symbols that we use to encode > the ISA when it changes in the middle of an ELF. This trips up modpost > as a build failure, I haven't yet verified it yet but I believe the > kallsyms difference should result in stacks looking sane again. > > Reported-by: Randy Dunlap > Link: https://lore.kernel.org/all/9d9e2902-5489-4bf0-d9cb-556c8e5d71c2@infradead.org/ > Signed-off-by: Palmer Dabbelt Reviewed-by: Randy Dunlap Tested-by: Randy Dunlap # build-tested Thanks. > --- > I'm not sure about a fixes here, the breakage comes from a binutils change > that's pretty much independent from the kernel. > > Plumbing in through the RISC-V-specific switch is also a bit ugly, but I'm not > sure just dropping everyone's "$"-prefixed symbols is a good idea -- the rest > of this is sort of half-way arch-specific, though, so maybe that's the way to > go? I figure it's easier to delete stuff than add it, though. > --- > include/linux/module_symbol.h | 12 +++++++++++- > kernel/module/kallsyms.c | 8 +++++++- > scripts/mod/modpost.c | 2 +- > 3 files changed, 19 insertions(+), 3 deletions(-) > > diff --git a/include/linux/module_symbol.h b/include/linux/module_symbol.h > index 7ace7ba30203..5b799942b243 100644 > --- a/include/linux/module_symbol.h > +++ b/include/linux/module_symbol.h > @@ -3,12 +3,22 @@ > #define _LINUX_MODULE_SYMBOL_H > > /* This ignores the intensely annoying "mapping symbols" found in ELF files. */ > -static inline int is_mapping_symbol(const char *str) > +static inline int is_mapping_symbol(const char *str, int is_riscv) > { > if (str[0] == '.' && str[1] == 'L') > return true; > if (str[0] == 'L' && str[1] == '0') > return true; > + /* > + * RISC-V defines various special symbols that start with "$". The > + * mapping symbols, which exist to differentiate between incompatible > + * instruction encodings when disassembling, show up all over the place > + * and are generally not meant to be treated like other symbols. So > + * just ignore any of the special symbols. > + */ > + if (is_riscv) > + return str[0] == '$'; > + > return str[0] == '$' && > (str[1] == 'a' || str[1] == 'd' || str[1] == 't' || str[1] == 'x') > && (str[2] == '\0' || str[2] == '.'); > diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c > index ef73ae7c8909..1e988e542c5d 100644 > --- a/kernel/module/kallsyms.c > +++ b/kernel/module/kallsyms.c > @@ -12,6 +12,12 @@ > #include > #include "internal.h" > > +#ifdef CONFIG_RISCV > +#define IS_RISCV 1 > +#else > +#define IS_RISCV 0 > +#endif > + > /* Lookup exported symbol in given range of kernel_symbols */ > static const struct kernel_symbol *lookup_exported_symbol(const char *name, > const struct kernel_symbol *start, > @@ -289,7 +295,7 @@ static const char *find_kallsyms_symbol(struct module *mod, > * and inserted at a whim. > */ > if (*kallsyms_symbol_name(kallsyms, i) == '\0' || > - is_mapping_symbol(kallsyms_symbol_name(kallsyms, i))) > + is_mapping_symbol(kallsyms_symbol_name(kallsyms, i), IS_RISCV)) > continue; > > if (thisval <= addr && thisval > bestval) { > diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c > index b29b29707f10..7c71429d6502 100644 > --- a/scripts/mod/modpost.c > +++ b/scripts/mod/modpost.c > @@ -1052,7 +1052,7 @@ static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym) > > if (!name || !strlen(name)) > return 0; > - return !is_mapping_symbol(name); > + return !is_mapping_symbol(name, elf->hdr->e_machine == EM_RISCV); > } > > /* Look up the nearest symbol based on the section and the address */ -- ~Randy