From patchwork Tue Mar 7 14:04:38 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 13163716 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 87ACAC678D4 for ; Tue, 7 Mar 2023 14:26:00 +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=eKAq0TLgim2tQOEOem7I2HqCqlk9GwO6bXqIUkr16hY=; b=sF79M0rGyqiXxM rIytMI1EerYF3tRMWho5UZZX+G7EFfXBOQKBf7yQ2quEmFqlqYszALAtnlxK+GTFI3Mom1O97/jEP gPrXkvAkyytyrcUVm+QyrXs3FP/i3fygUQ4N0khFfqW+Gajhs4c4tR9EeTKSLhlWZMW8GafuhfGak IoU4vEV9kGfvSdNVm+oHads8Z37CK8CP1M6O7JkYsG0rjTub+tR+vvENn4Dh59lRTlNJGKETLacLi 7Xzkemk9aRv4utV21aKssYKuNl53Ip6j4DK+58mENVoqkBKin9KTkL3T/X3aJnei0jbV/+FHOID+4 FIlGneWOaI3AJcOD5SrA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1pZYF7-000leA-Db; Tue, 07 Mar 2023 14:24:41 +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 1pZXyI-000e8X-BV for linux-arm-kernel@lists.infradead.org; Tue, 07 Mar 2023 14:07:21 +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 5BA6261458; Tue, 7 Mar 2023 14:07:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CAD4DC4339C; Tue, 7 Mar 2023 14:07:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1678198036; bh=XnTvDw4ttdVCcfAeL2dMDAGtCMBFr94CQLQQmSGCFiY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iioG0f+xikmcLwqqv55zuuJUYG85WwLmOHchnc+kJlH7ULC9s3GK6OaXARyL2o6S/ qsDiDHjm9S9ectzT2lStvTr3IjA0jmFl0ZfJu5U/tcNVCy0uNA6w5qSCUcYI6sZQTN luBE6dOrPzni/K4wPVCg54bQ4KxRhVnUM9XeSAlvtxXk1YRRp4lYqMp/2TrQvJxlAd bZlAMiPUy4WKwTNCjMAfKAGowQOJLSYCjk24URoe97yQfEPQ3AEoGkhevB9f8caHAi Nu6fB9sIC4ZC1xa38Tq/+l1hHv2WC9VkENVmh9AlzhrM9ArsozwL9/LubPKgMzNcLN UsjyXIJ1KnzbQ== From: Ard Biesheuvel To: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, Ard Biesheuvel , Catalin Marinas , Will Deacon , Marc Zyngier , Mark Rutland , Ryan Roberts , Anshuman Khandual , Kees Cook Subject: [PATCH v3 16/60] arm64: head: move relocation handling to C code Date: Tue, 7 Mar 2023 15:04:38 +0100 Message-Id: <20230307140522.2311461-17-ardb@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230307140522.2311461-1-ardb@kernel.org> References: <20230307140522.2311461-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=10151; i=ardb@kernel.org; h=from:subject; bh=XnTvDw4ttdVCcfAeL2dMDAGtCMBFr94CQLQQmSGCFiY=; b=owGbwMvMwCFmkMcZplerG8N4Wi2JIYXdReXu2uPdS+6/s5VVaPtz8/m7KVvcSoOO+aQ+dN2Y9 jv561aFjlIWBjEOBlkxRRaB2X/f7Tw9UarWeZYszBxWJpAhDFycAjARU2GG/ynPPnA/CTiuyLvc ZWG4oG6RVE2454H7CrfPbwjgkiz/9oLhf1aNmxv3C8d5OZKnrTadUN9jLm5qcn9zqBHjqYjq0sg ULgA= 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-20230307_060718_580158_9A360679 X-CRM114-Status: GOOD ( 29.10 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Now that we have a mini C runtime before the kernel mapping is up, we can move the non-trivial relocation processing code out of head.S and reimplement it in C. Signed-off-by: Ard Biesheuvel --- arch/arm64/kernel/Makefile | 3 +- arch/arm64/kernel/head.S | 104 ++------------------ arch/arm64/kernel/pi/Makefile | 5 +- arch/arm64/kernel/pi/relocate.c | 62 ++++++++++++ arch/arm64/kernel/vmlinux.lds.S | 12 ++- 5 files changed, 82 insertions(+), 104 deletions(-) diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index ceba6792f5b3c473..e27168d6ed2050b9 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -58,7 +58,8 @@ obj-$(CONFIG_ACPI) += acpi.o obj-$(CONFIG_ACPI_NUMA) += acpi_numa.o obj-$(CONFIG_ARM64_ACPI_PARKING_PROTOCOL) += acpi_parking_protocol.o obj-$(CONFIG_PARAVIRT) += paravirt.o -obj-$(CONFIG_RANDOMIZE_BASE) += kaslr.o pi/ +obj-$(CONFIG_RELOCATABLE) += pi/ +obj-$(CONFIG_RANDOMIZE_BASE) += kaslr.o obj-$(CONFIG_HIBERNATION) += hibernate.o hibernate-asm.o obj-$(CONFIG_ELF_CORE) += elfcore.o obj-$(CONFIG_KEXEC_CORE) += machine_kexec.o relocate_kernel.o \ diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 65cdaaa2c859418f..5047a2952ec273f9 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -81,7 +81,7 @@ * x20 primary_entry() .. __primary_switch() CPU boot mode * x21 primary_entry() .. start_kernel() FDT pointer passed at boot in x0 * x22 create_idmap() .. start_kernel() ID map VA of the DT blob - * x23 primary_entry() .. start_kernel() physical misalignment/KASLR offset + * x23 __primary_switch() physical misalignment/KASLR offset * x24 __primary_switch() linear map KASLR seed * x25 primary_entry() .. start_kernel() supported VA size * x28 create_idmap() callee preserved temp register @@ -389,7 +389,7 @@ SYM_FUNC_START_LOCAL(create_idmap) /* Remap the kernel page tables r/w in the ID map */ adrp x1, _text adrp x2, init_pg_dir - adrp x3, init_pg_end + adrp x3, _end bic x4, x2, #SWAPPER_BLOCK_SIZE - 1 mov x5, SWAPPER_RW_MMUFLAGS mov x6, #SWAPPER_BLOCK_SHIFT @@ -777,97 +777,6 @@ SYM_FUNC_START_LOCAL(__no_granule_support) b 1b SYM_FUNC_END(__no_granule_support) -#ifdef CONFIG_RELOCATABLE -SYM_FUNC_START_LOCAL(__relocate_kernel) - /* - * Iterate over each entry in the relocation table, and apply the - * relocations in place. - */ - adr_l x9, __rela_start - adr_l x10, __rela_end - mov_q x11, KIMAGE_VADDR // default virtual offset - add x11, x11, x23 // actual virtual offset - -0: cmp x9, x10 - b.hs 1f - ldp x12, x13, [x9], #24 - ldr x14, [x9, #-8] - cmp w13, #R_AARCH64_RELATIVE - b.ne 0b - add x14, x14, x23 // relocate - str x14, [x12, x23] - b 0b - -1: -#ifdef CONFIG_RELR - /* - * Apply RELR relocations. - * - * RELR is a compressed format for storing relative relocations. The - * encoded sequence of entries looks like: - * [ AAAAAAAA BBBBBBB1 BBBBBBB1 ... AAAAAAAA BBBBBB1 ... ] - * - * i.e. start with an address, followed by any number of bitmaps. The - * address entry encodes 1 relocation. The subsequent bitmap entries - * encode up to 63 relocations each, at subsequent offsets following - * the last address entry. - * - * The bitmap entries must have 1 in the least significant bit. The - * assumption here is that an address cannot have 1 in lsb. Odd - * addresses are not supported. Any odd addresses are stored in the RELA - * section, which is handled above. - * - * Excluding the least significant bit in the bitmap, each non-zero - * bit in the bitmap represents a relocation to be applied to - * a corresponding machine word that follows the base address - * word. The second least significant bit represents the machine - * word immediately following the initial address, and each bit - * that follows represents the next word, in linear order. As such, - * a single bitmap can encode up to 63 relocations in a 64-bit object. - * - * In this implementation we store the address of the next RELR table - * entry in x9, the address being relocated by the current address or - * bitmap entry in x13 and the address being relocated by the current - * bit in x14. - */ - adr_l x9, __relr_start - adr_l x10, __relr_end - -2: cmp x9, x10 - b.hs 7f - ldr x11, [x9], #8 - tbnz x11, #0, 3f // branch to handle bitmaps - add x13, x11, x23 - ldr x12, [x13] // relocate address entry - add x12, x12, x23 - str x12, [x13], #8 // adjust to start of bitmap - b 2b - -3: mov x14, x13 -4: lsr x11, x11, #1 - cbz x11, 6f - tbz x11, #0, 5f // skip bit if not set - ldr x12, [x14] // relocate bit - add x12, x12, x23 - str x12, [x14] - -5: add x14, x14, #8 // move to next bit's address - b 4b - -6: /* - * Move to the next bitmap's address. 8 is the word size, and 63 is the - * number of significant bits in a bitmap entry. - */ - add x13, x13, #(8 * 63) - b 2b - -7: -#endif - ret - -SYM_FUNC_END(__relocate_kernel) -#endif - SYM_FUNC_START_LOCAL(__primary_switch) adrp x1, reserved_pg_dir adrp x2, init_idmap_pg_dir @@ -875,11 +784,11 @@ SYM_FUNC_START_LOCAL(__primary_switch) #ifdef CONFIG_RELOCATABLE adrp x23, KERNEL_START and x23, x23, MIN_KIMG_ALIGN - 1 -#ifdef CONFIG_RANDOMIZE_BASE - mov x0, x22 - adrp x1, init_pg_end + adrp x1, early_init_stack mov sp, x1 mov x29, xzr +#ifdef CONFIG_RANDOMIZE_BASE + mov x0, x22 bl __pi_kaslr_early_init and x24, x0, #SZ_2M - 1 // capture memstart offset seed bic x0, x0, #SZ_2M - 1 @@ -892,7 +801,8 @@ SYM_FUNC_START_LOCAL(__primary_switch) adrp x1, init_pg_dir load_ttbr1 x1, x1, x2 #ifdef CONFIG_RELOCATABLE - bl __relocate_kernel + mov x0, x23 + bl __pi_relocate_kernel #endif ldr x8, =__primary_switched adrp x0, KERNEL_START // __pa(KERNEL_START) diff --git a/arch/arm64/kernel/pi/Makefile b/arch/arm64/kernel/pi/Makefile index 2bbe866417d453ff..d084c1dcf4165420 100644 --- a/arch/arm64/kernel/pi/Makefile +++ b/arch/arm64/kernel/pi/Makefile @@ -38,5 +38,6 @@ $(obj)/lib-%.pi.o: OBJCOPYFLAGS += --prefix-alloc-sections=.init $(obj)/lib-%.o: $(srctree)/lib/%.c FORCE $(call if_changed_rule,cc_o_c) -obj-y := kaslr_early.pi.o lib-fdt.pi.o lib-fdt_ro.pi.o -extra-y := $(patsubst %.pi.o,%.o,$(obj-y)) +obj-y := relocate.pi.o +obj-$(CONFIG_RANDOMIZE_BASE) += kaslr_early.pi.o lib-fdt.pi.o lib-fdt_ro.pi.o +extra-y := $(patsubst %.pi.o,%.o,$(obj-y)) diff --git a/arch/arm64/kernel/pi/relocate.c b/arch/arm64/kernel/pi/relocate.c new file mode 100644 index 0000000000000000..1853408ea76b0e5d --- /dev/null +++ b/arch/arm64/kernel/pi/relocate.c @@ -0,0 +1,62 @@ +// SPDX-License-Identifier: GPL-2.0-only +// Copyright 2023 Google LLC +// Authors: Ard Biesheuvel +// Peter Collingbourne + +#include +#include +#include + +extern const Elf64_Rela rela_start[], rela_end[]; +extern const u64 relr_start[], relr_end[]; + +void __init relocate_kernel(u64 offset) +{ + u64 *place = NULL; + + for (const Elf64_Rela *rela = rela_start; rela < rela_end; rela++) { + if (ELF64_R_TYPE(rela->r_info) != R_AARCH64_RELATIVE) + continue; + *(u64 *)(rela->r_offset + offset) = rela->r_addend + offset; + } + + if (!IS_ENABLED(CONFIG_RELR) || !offset) + return; + + /* + * Apply RELR relocations. + * + * RELR is a compressed format for storing relative relocations. The + * encoded sequence of entries looks like: + * [ AAAAAAAA BBBBBBB1 BBBBBBB1 ... AAAAAAAA BBBBBB1 ... ] + * + * i.e. start with an address, followed by any number of bitmaps. The + * address entry encodes 1 relocation. The subsequent bitmap entries + * encode up to 63 relocations each, at subsequent offsets following + * the last address entry. + * + * The bitmap entries must have 1 in the least significant bit. The + * assumption here is that an address cannot have 1 in lsb. Odd + * addresses are not supported. Any odd addresses are stored in the + * RELA section, which is handled above. + * + * With the exception of the least significant bit, each bit in the + * bitmap corresponds with a machine word that follows the base address + * word, and the bit value indicates whether or not a relocation needs + * to be applied to it. The second least significant bit represents the + * machine word immediately following the initial address, and each bit + * that follows represents the next word, in linear order. As such, a + * single bitmap can encode up to 63 relocations in a 64-bit object. + */ + for (const u64 *relr = relr_start; relr < relr_end; relr++) { + if ((*relr & 1) == 0) { + place = (u64 *)(*relr + offset); + *place++ += offset; + } else { + for (u64 *p = place, r = *relr >> 1; r; p++, r >>= 1) + if (r & 1) + *p += offset; + place += 63; + } + } +} diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index b9202c2ee18e02d8..ec24b1e70d606ec8 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -271,15 +271,15 @@ SECTIONS HYPERVISOR_RELOC_SECTION .rela.dyn : ALIGN(8) { - __rela_start = .; + __pi_rela_start = .; *(.rela .rela*) - __rela_end = .; + __pi_rela_end = .; } .relr.dyn : ALIGN(8) { - __relr_start = .; + __pi_relr_start = .; *(.relr.dyn) - __relr_end = .; + __pi_relr_end = .; } . = ALIGN(SEGMENT_ALIGN); @@ -318,6 +318,10 @@ SECTIONS init_pg_dir = .; . += INIT_DIR_SIZE; init_pg_end = .; +#ifdef CONFIG_RELOCATABLE + . += SZ_4K; /* stack for the early relocation code */ + early_init_stack = .; +#endif . = ALIGN(SEGMENT_ALIGN); __pecoff_data_size = ABSOLUTE(. - __initdata_begin);