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 D3F74C433EF for ; Fri, 26 Nov 2021 10:12:44 +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=KxCO9LKnV4mpaN2yyA145O8j5dl7k4VmALdouqhNxFo=; b=y7kJkjrbRCSDhq DIe3JjqPIcLbzfPmA/y24X2McDvNAacjHsgXnA9H2yY4ZwKNJrjAIMq/ivvFEDp9Iv7eSX5u2CkNl MN7HCllOnM429AZkNUFGyC5M6f3JjjzygEoHcsz9y/G8lcoevpAro5E32+mbUiyx72pCgALFaKkTu nF6NgWhjQ+ysSt4k4z6z0BdfgaCywhpZ4QLUbnH2Yzwo5vp0RjmN5ZXlVpJ33gKRKY0R2VxCng5JD b1OUuoeHAzmz6U/m326+zLsLxQ7IECewPb3/pRoE7Izib5ouNg9VXpXjkDVuXxkcEkl/Nc8cASB8o bgp5Y2rfKVaF9e6r626A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mqYCF-009txf-EZ; Fri, 26 Nov 2021 10:11:11 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mqYBR-009tgw-UA for linux-arm-kernel@lists.infradead.org; Fri, 26 Nov 2021 10:10:23 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6E83F6112F; Fri, 26 Nov 2021 10:10:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1637921421; bh=6FclMaOvFZwaz3+lzkTC9RF4aZp5uvK9Yk/wmXaMg0M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o7NjQtAfo9LQS/7qK3x4gLuztp8Ycw0zrb3UHYCXK8iTySMPh24XALcsw+WVe37v1 lx4uixncrjAa1EYKMTBmPy188p5o2iGukl8QoF/yEQJrYynCqc8VgkPCAPDtizy21B toEqR6BvSCpXszgkE5A9nZtxETMO4GcfnN9US2ALyU+gNlTiIEL8l+R8lM5AL1SAv0 Mjxu5MRNlebOpUOSn4wnT6KIB6ym7IYbFsfJtc/NqNt1nb592pUHDNSe/t0VkjmygL +h4149KOtngxvj0QCgN9ZXz0u8oqAeljHjOau91K0FmdqmST88jEen7yx1W27xs56h +CdDWUyiFfHHw== From: Ard Biesheuvel To: linux-arm-kernel@lists.infradead.org Cc: Ard Biesheuvel , Russell King , Nicolas Pitre , Arnd Bergmann , Kees Cook , Keith Packard , Linus Walleij , Nick Desaulniers , Tony Lindgren Subject: [RFC PATCH 2/6] ARM: module: implement support for PC-relative group relocations Date: Fri, 26 Nov 2021 11:10:02 +0100 Message-Id: <20211126101006.3410322-3-ardb@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20211126101006.3410322-1-ardb@kernel.org> References: <20211126101006.3410322-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3583; h=from:subject; bh=6FclMaOvFZwaz3+lzkTC9RF4aZp5uvK9Yk/wmXaMg0M=; b=owEB7QES/pANAwAKAcNPIjmS2Y8kAcsmYgBhoLJ5MZ39HBnPJiDpcTVdQ2qECN9lZ5H3lY4mZW4E Hr7YXnGJAbMEAAEKAB0WIQT72WJ8QGnJQhU3VynDTyI5ktmPJAUCYaCyeQAKCRDDTyI5ktmPJMLBDA C5Jh9i0fZbZB4U+CoyvCORha2D2Q0tdluZxyCJ+xLcch9JOUSg27rNyiexG/DrFqA0Sawj3dd/8EPz MlJyAMMiKZZNOidKRT8ffWEVX4vYqQkuME7WxQCoMmtlwrmlPR2uLWuRBe6Jn/v3b7JnhTaevixUaP RTmSw+U0NE25p9VUi5n0D+kuP9DIMkzJgo387ChzwetEJZLJr+q7cz+TgHUADgIhWjJbMwqt/2bqQv ckKGvt0EberU8tTRwdElx+bvWpU8K4TI5elpKMbV+240AmBaUCiqly8n1nCbdHb+HhlI1gIGSWRDgc C2ZjDJW6ii3lXK8xbCP9+UKDwkLtV/5yKMPIe5jVCiiyHBPwkUGLhtmIgVQ2/1susCI4QsjtOse85G u8bFHvnBbOXZ9LF2m/QD5SYaEMNRGHtGT/mC3FVANb4u82eKq+Z7rFTOEWB0E2lQWeV9eSRob6lC8J X/D3UL4q5k403gYemMsejLoXJZ7rddvB5HdBuAlzHXg5A= 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-20211126_021022_074838_089581C0 X-CRM114-Status: GOOD ( 16.54 ) 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. 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 c2354990290b..0c7f218f9012 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