From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DAB4853B7 for ; Wed, 9 Aug 2023 11:14:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F710C433C8; Wed, 9 Aug 2023 11:14:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1691579682; bh=fIbIexN/PwieNz9wogcGqDRjx5VT9i5L/oCNbr7eD9o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IsbHYOOybrxjK9V42gY8jvYtffjbroFwo83XsP1Z1wb/2ApuD0lwZqh4MRgIELRzE IZaGVMqtC8cInkUGBdBnLIll4SHxWWnO2Kt6cMq3vYP63a5DYmFWi4Ay9fGKObx2SF iFeb3GKe1TFfn32kfxcNi1u4joYWJzCl/uRK7gkI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Masahiro Yamada , Sasha Levin Subject: [PATCH 4.19 079/323] modpost: fix section mismatch message for R_ARM_{PC24,CALL,JUMP24} Date: Wed, 9 Aug 2023 12:38:37 +0200 Message-ID: <20230809103701.764099575@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230809103658.104386911@linuxfoundation.org> References: <20230809103658.104386911@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Masahiro Yamada [ Upstream commit 56a24b8ce6a7f9c4a21b2276a8644f6f3d8fc14d ] addend_arm_rel() processes R_ARM_PC24, R_ARM_CALL, R_ARM_JUMP24 in a wrong way. Here, test code. [test code for R_ARM_JUMP24] .section .init.text,"ax" bar: bx lr .section .text,"ax" .globl foo foo: b bar [test code for R_ARM_CALL] .section .init.text,"ax" bar: bx lr .section .text,"ax" .globl foo foo: push {lr} bl bar pop {pc} If you compile it with ARM multi_v7_defconfig, modpost will show the symbol name, (unknown). WARNING: modpost: vmlinux.o: section mismatch in reference: foo (section: .text) -> (unknown) (section: .init.text) (You need to use GNU linker instead of LLD to reproduce it.) Fix the code to make modpost show the correct symbol name. I imported (with adjustment) sign_extend32() from include/linux/bitops.h. The '+8' is the compensation for pc-relative instruction. It is documented in "ELF for the Arm Architecture" [1]. "If the relocation is pc-relative then compensation for the PC bias (the PC value is 8 bytes ahead of the executing instruction in Arm state and 4 bytes in Thumb state) must be encoded in the relocation by the object producer." [1]: https://github.com/ARM-software/abi-aa/blob/main/aaelf32/aaelf32.rst Fixes: 56a974fa2d59 ("kbuild: make better section mismatch reports on arm") Fixes: 6e2e340b59d2 ("ARM: 7324/1: modpost: Fix section warnings for ARM for many compilers") Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin --- scripts/mod/modpost.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 41b1791a9463b..2060a3fe9691d 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1751,12 +1751,20 @@ static int addend_386_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r) #define R_ARM_THM_JUMP19 51 #endif +static int32_t sign_extend32(int32_t value, int index) +{ + uint8_t shift = 31 - index; + + return (int32_t)(value << shift) >> shift; +} + 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); void *loc = reloc_location(elf, sechdr, r); uint32_t inst; + int32_t offset; switch (r_typ) { case R_ARM_ABS32: @@ -1766,6 +1774,10 @@ static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r) case R_ARM_PC24: case R_ARM_CALL: case R_ARM_JUMP24: + inst = TO_NATIVE(*(uint32_t *)loc); + offset = sign_extend32((inst & 0x00ffffff) << 2, 25); + r->r_addend = offset + sym->st_value + 8; + break; case R_ARM_THM_CALL: case R_ARM_THM_JUMP24: case R_ARM_THM_JUMP19: -- 2.39.2