From patchwork Sun May 21 16:04:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Masahiro Yamada X-Patchwork-Id: 13249436 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 39974C77B7C for ; Sun, 21 May 2023 16:05:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229901AbjEUQFY (ORCPT ); Sun, 21 May 2023 12:05:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55132 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230153AbjEUQFV (ORCPT ); Sun, 21 May 2023 12:05:21 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5206ECD; Sun, 21 May 2023 09:05:20 -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 D7A6F60FA7; Sun, 21 May 2023 16:05:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D86ECC433D2; Sun, 21 May 2023 16:05:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1684685119; bh=WHBV7iLszGwzqmoBiBCGvksDMYSMzg3ZUVZdErHe9Yg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jSg/z3aGOvkuyn5c5Urq2Q/TCkD0gnjBzHJ/S1qxaUK6+Fl/neoCMcMq5PMDX2t3U x9DBmCetn/NGYRUL1voVIqs4beFG+xlcjSGp79Lz+hdx+0uO+1mC+PYjv6jYLQkfnW EAOnq0H7IpKBFNsauz47zEInl1/v0r2Ng3o5w+2/USxCuOt9JCXpCWnYxMlDJlLAVn OudINlJvQf4Zpe7uXDiCMXBYD++Farbf5mi1SC7h7kBCmQJxecGbt4NuY4yAk1zoGN jHeFGEqZwxWAWyrbtkdvBXTvCiew1GQqsHcSYC2Buwx0HvDtVtXzUS0ZP9cE4Appn5 jbpzCkZPaVyzA== From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Nathan Chancellor , Nick Desaulniers , Nicolas Schier , Masahiro Yamada Subject: [PATCH v6 03/20] modpost: detect section mismatch for R_ARM_MOVW_ABS_NC and R_ARM_MOVT_ABS Date: Mon, 22 May 2023 01:04:08 +0900 Message-Id: <20230521160426.1881124-4-masahiroy@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230521160426.1881124-1-masahiroy@kernel.org> References: <20230521160426.1881124-1-masahiroy@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org ARM defconfig misses to detect some section mismatches. [test code] #include int __initdata foo; int get_foo(int x) { return foo; } It is apparently a bad reference, but modpost does not report anything for ARM defconfig (i.e. multi_v7_defconfig). The test code above produces the following relocations. Relocation section '.rel.text' at offset 0x200 contains 2 entries: Offset Info Type Sym.Value Sym. Name 00000000 0000062b R_ARM_MOVW_ABS_NC 00000000 .LANCHOR0 00000004 0000062c R_ARM_MOVT_ABS 00000000 .LANCHOR0 Relocation section '.rel.ARM.exidx' at offset 0x210 contains 2 entries: Offset Info Type Sym.Value Sym. Name 00000000 0000022a R_ARM_PREL31 00000000 .text 00000000 00001000 R_ARM_NONE 00000000 __aeabi_unwind_cpp_pr0 Currently, R_ARM_MOVW_ABS_NC and R_ARM_MOVT_ABS are just skipped. Add code to handle them. I checked arch/arm/kernel/module.c to learn how the offset is encoded in the instruction. The referenced symbol in relocation might be a local anchor. If is_valid_name() returns false, let's search for a better symbol name. Signed-off-by: Masahiro Yamada --- scripts/mod/modpost.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 34fbbd85bfde..ed2301e951a9 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1108,7 +1108,7 @@ static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym) /** * Find symbol based on relocation record info. * In some cases the symbol supplied is a valid symbol so - * return refsym. If st_name != 0 we assume this is a valid symbol. + * return refsym. If is_valid_name() == true, we assume this is a valid symbol. * In other cases the symbol needs to be looked up in the symbol table * based on section and address. * **/ @@ -1121,7 +1121,7 @@ static Elf_Sym *find_tosym(struct elf_info *elf, Elf64_Sword addr, Elf64_Sword d; unsigned int relsym_secindex; - if (relsym->st_name != 0) + if (is_valid_name(elf, relsym)) return relsym; /* @@ -1312,11 +1312,19 @@ static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r) unsigned int r_typ = ELF_R_TYPE(r->r_info); Elf_Sym *sym = elf->symtab_start + ELF_R_SYM(r->r_info); unsigned int inst = TO_NATIVE(*reloc_location(elf, sechdr, r)); + int offset; switch (r_typ) { case R_ARM_ABS32: r->r_addend = inst + sym->st_value; break; + case R_ARM_MOVW_ABS_NC: + case R_ARM_MOVT_ABS: + offset = ((inst & 0xf0000) >> 4) | (inst & 0xfff); + offset = (offset ^ 0x8000) - 0x8000; + offset += sym->st_value; + r->r_addend = offset; + break; case R_ARM_PC24: case R_ARM_CALL: case R_ARM_JUMP24: