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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4712FC433F5 for ; Fri, 3 Dec 2021 10:13:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=uHMaNAsq9kzfEwRDe/Yrbe/iU+VzRcbPhTsph7WOxuA=; b=rPjR8FFelIORNx F0aqa/mUt/TgLXNg261mjvGNINsAB3csQ86IKkIlC7u7MHeGIPZ4EfGhapAZSMWDLenGnxNTMEvk4 8rnBfKMcJnLyfrWF5UA4eY+01b3ZlOnJG9QKG40cv+KIM5JqfdCdyWXE0U+ths+jCrb3SBrKyX/qL dxkbOqEfgMXS5jB6/dd9mVwk7c78Zr9141QNbn5sV15yhqd6wUInfu9jVRojZSB+fhqM9O9g5w+eZ gMkj+pdeE7+pM1nQk/lFbYZ2Fv18Z0DePCZmOZneUegQbglDIzYDx64pQBabs9Og9IQJp2SWSRsVH 8GhSPeDyFuMu5BH7WYZQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mt5XN-00F5YH-Qk; Fri, 03 Dec 2021 10:11:30 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mt5VY-00F4iy-EL for linux-arm-kernel@lists.infradead.org; Fri, 03 Dec 2021 10:09:37 +0000 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 0A10D629F5; Fri, 3 Dec 2021 10:09:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CC2A3C53FD2; Fri, 3 Dec 2021 10:09:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1638526175; bh=mRnWxuQK52Olb+7hhJ6kKIM30pjz6tbMig/TeGXgAPo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RDje2/uaf4KFK7f/GV4pKpztKR+cV5OoS989crJ2zvpRglO4DFixLDkeWKRvoQGLt buKK19787q5N3koRcYXpgY8KBPgBoks/Prwmmvl04QplKXiTqZ/Q16LNvVaX3aSHpM q1sH6OEyOFtVagsqXOEoRMwaLkOALQ/7YI3csYpiA234SxYdov7L5tNivpuXK/Rzff j/j/t8xxcOs0P52+aUPUBGoq++bxQmhDMChOQIVM104TQB1zkxGS1tEpwD6hWWrXJ4 yO00YM2yAqq/pAI53X7thtbCO+/JYSazKHBf13gwlNYvqd1Afk71evhgBT8khhXdNi 6efwJk24i2aTg== From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org, linux@armlinux.org.uk Cc: Ard Biesheuvel , Nicolas Pitre , Arnd Bergmann , Kees Cook , Keith Packard , Linus Walleij , Nick Desaulniers , Tony Lindgren , Marc Zyngier , Vladimir Murzin , Jesse Taube Subject: [PATCH v3 08/14] ARM: module: implement support for PC-relative group relocations Date: Fri, 3 Dec 2021 11:08:57 +0100 Message-Id: <20211203100903.334206-9-ardb@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20211203100903.334206-1-ardb@kernel.org> References: <20211203100903.334206-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3679; h=from:subject; bh=mRnWxuQK52Olb+7hhJ6kKIM30pjz6tbMig/TeGXgAPo=; b=owEB7QES/pANAwAKAcNPIjmS2Y8kAcsmYgBhqeywX2kmVUaf0U9LZopvXRi07t73EKv48xfhw7Ac mnJZvwqJAbMEAAEKAB0WIQT72WJ8QGnJQhU3VynDTyI5ktmPJAUCYanssAAKCRDDTyI5ktmPJLSnC/ 4k8uqQwNNEy78iDuY97KCszNcy2u2IDfY5wqZOp7bpkKRTmOtSgVH4oQSaTORn9m67j76xNyyZ5mjv x3VE4eH6SOBwRvxNBIwr127rh9lYzwkuHxa7MMe0pkJnvHIxDycLpWkJHK0a5TuBD0reLWK/2XyBCX dllUS07m3Y1ztHPg/LFu6m2reJq6DtzNbuIBN2CmLvX4oxVioU8SvYtpdSI/vmy1iWaBbr8qeCrwm7 fPyxp0dvUgfWUI77/1u3jI+PlQgG2bMDZuJxr1Bw4v4TxKD696dFJMcP+VD22/bispj1/KgJzBiaN9 V+XPvAK3E9KIAWuHlb3Bh9u/9vR4NcUxoYLz4+Vl34LZjRyFYQ8tTHgPCwkB8NNBxCO0DE1VvdFDTo njyOiCi+BJ257LxcWic7e5IvfdfAVQ6VPIXBLkTlyqN3JSg6HBwzaxxVxqbZG7GmPnwoECbhJLcZ7r 4OcXqGuYtOp+4Tn2htduA+SedaPd36oZ5o2vuRss+12a0= X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211203_020936_583027_BE50064E X-CRM114-Status: GOOD ( 18.96 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Add support for the R_ARM_ALU_PC_Gn_NC and R_ARM_LDR_PC_G2 group relocations so we can use them in modules. These will be used to load the current task pointer from a global variable without having to rely on a literal pool entry to carry the address of this variable, which would be slightly less efficient. Acked-by: Linus Walleij Acked-by: Nicolas Pitre Signed-off-by: Ard Biesheuvel --- arch/arm/include/asm/elf.h | 3 + arch/arm/kernel/module.c | 63 ++++++++++++++++++++ 2 files changed, 66 insertions(+) diff --git a/arch/arm/include/asm/elf.h b/arch/arm/include/asm/elf.h index b8102a6ddf16..d68101655b74 100644 --- a/arch/arm/include/asm/elf.h +++ b/arch/arm/include/asm/elf.h @@ -61,6 +61,9 @@ typedef struct user_fp elf_fpregset_t; #define R_ARM_MOVT_ABS 44 #define R_ARM_MOVW_PREL_NC 45 #define R_ARM_MOVT_PREL 46 +#define R_ARM_ALU_PC_G0_NC 57 +#define R_ARM_ALU_PC_G1_NC 59 +#define R_ARM_LDR_PC_G2 63 #define R_ARM_THM_CALL 10 #define R_ARM_THM_JUMP24 30 diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c index beac45e89ba6..22bdce7a7f95 100644 --- a/arch/arm/kernel/module.c +++ b/arch/arm/kernel/module.c @@ -68,6 +68,20 @@ bool module_exit_section(const char *name) strstarts(name, ".ARM.exidx.exit"); } +static u32 get_group_rem(u32 group, u32 *offset) +{ + u32 val = *offset; + u32 shift; + do { + shift = val ? (31 - __fls(val)) & ~1 : 32; + *offset = val; + if (!val) + break; + val &= 0xffffff >> shift; + } while (group--); + return shift; +} + int apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned int relindex, struct module *module) @@ -82,6 +96,7 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned long loc; Elf32_Sym *sym; const char *symname; + u32 shift, group = 1; s32 offset; u32 tmp; #ifdef CONFIG_THUMB2_KERNEL @@ -212,6 +227,54 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex, *(u32 *)loc = __opcode_to_mem_arm(tmp); break; + case R_ARM_ALU_PC_G0_NC: + group = 0; + fallthrough; + case R_ARM_ALU_PC_G1_NC: + tmp = __mem_to_opcode_arm(*(u32 *)loc); + offset = ror32(tmp & 0xff, (tmp & 0xf00) >> 7); + if (tmp & BIT(22)) + offset = -offset; + offset += sym->st_value - loc; + if (offset < 0) { + offset = -offset; + tmp = (tmp & ~BIT(23)) | BIT(22); // SUB opcode + } else { + tmp = (tmp & ~BIT(22)) | BIT(23); // ADD opcode + } + + shift = get_group_rem(group, &offset); + if (shift < 24) { + offset >>= 24 - shift; + offset |= (shift + 8) << 7; + } + *(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset); + break; + + case R_ARM_LDR_PC_G2: + tmp = __mem_to_opcode_arm(*(u32 *)loc); + offset = tmp & 0xfff; + if (~tmp & BIT(23)) // U bit cleared? + offset = -offset; + offset += sym->st_value - loc; + if (offset < 0) { + offset = -offset; + tmp &= ~BIT(23); // clear U bit + } else { + tmp |= BIT(23); // set U bit + } + get_group_rem(2, &offset); + + if (offset > 0xfff) { + pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n", + module->name, relindex, i, symname, + ELF32_R_TYPE(rel->r_info), loc, + sym->st_value); + return -ENOEXEC; + } + *(u32 *)loc = __opcode_to_mem_arm((tmp & ~0xfff) | offset); + break; + #ifdef CONFIG_THUMB2_KERNEL case R_ARM_THM_CALL: case R_ARM_THM_JUMP24: -- 2.30.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel