From patchwork Wed Jun 7 07:23:35 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 690335 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 CF8C3C7EE29 for ; Wed, 7 Jun 2023 07:26:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239054AbjFGH0H (ORCPT ); Wed, 7 Jun 2023 03:26:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238984AbjFGHZn (ORCPT ); Wed, 7 Jun 2023 03:25:43 -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 BC82119BA; Wed, 7 Jun 2023 00:24:53 -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 1979663B59; Wed, 7 Jun 2023 07:24:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF8E5C4339E; Wed, 7 Jun 2023 07:24:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686122691; bh=VwNUPlSJTEZ1Nu/b8lVG8H0h0GBUJ6Yb+ifMNnx28Zw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fKDpVR5jLbnX8a+137NAPmMCbjLYBt9XjKgffVppjqYgpoYfrmjr501HOvXaGFHc1 VSqH/bjCdPadhGNU6QKGo/V/89F5bddoNMySymTCEEpQDLdVy+K/5PbwwtaV+7MHON Yiufyx3NcBlj0ku0Ni5OTl5qNUGRiqzq6utRBR++h5QGK/8/h2xgijyoktT6lwLBXl yBRMYYSyEOqX6fq5DsihyrD2gHJ7iCtMQjZv6uwILEzhp0NKXo0h+DDvNnY4qVAMyt 1zjJjm/oXBp7kLC/T7pnwF1G0U0ntGNUl3jJP9lcpnzPxrfAGH5MacREs6p2tmq/aW mPk+yb+PBvqJw== From: Ard Biesheuvel To: linux-efi@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel , Evgeniy Baskov , Borislav Petkov , Andy Lutomirski , Dave Hansen , Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Alexey Khoroshilov , Peter Jones , Gerd Hoffmann , Dave Young , Mario Limonciello , Kees Cook , Tom Lendacky , "Kirill A . Shutemov" , Linus Torvalds , Joerg Roedel Subject: [PATCH v5 13/20] x86/efistub: Perform 4/5 level paging switch from the stub Date: Wed, 7 Jun 2023 09:23:35 +0200 Message-Id: <20230607072342.4054036-14-ardb@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230607072342.4054036-1-ardb@kernel.org> References: <20230607072342.4054036-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=10131; i=ardb@kernel.org; h=from:subject; bh=VwNUPlSJTEZ1Nu/b8lVG8H0h0GBUJ6Yb+ifMNnx28Zw=; b=owGbwMvMwCFmkMcZplerG8N4Wi2JIaXBoOTteaUlqp+vs726cO3IwuMzTxwL2yBypuPzFqmQy 3u/fV+5saOUhUGMg0FWTJFFYPbfdztPT5SqdZ4lCzOHlQlkCAMXpwDcZDNGhil9z75HB2R0iSW0 y+R09/+NljUJign7cVg9yOLSfMO1yxkZtixSeJ/Es3cZh8Om/fn2V9+LTF5fGdY9XfzjlNp+1Y/ L2QA= X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org In preparation for updating the EFI stub boot flow to avoid the bare metal decompressor code altogether, implement the support code for switching between 4 and 5 levels of paging before jumping to the kernel proper. This reuses the newly refactored trampoline that the bare metal decompressor uses, but relies on EFI APIs to allocate 32-bit addressable memory and remap it with the appropriate permissions. Given that the bare metal decompressor will no longer call into the trampoline if the number of paging levels is already set correctly, it is no longer needed to remove NX restrictions from the memory range where this trampoline may end up. Acked-by: Kirill A. Shutemov Signed-off-by: Ard Biesheuvel --- drivers/firmware/efi/libstub/Makefile | 1 + drivers/firmware/efi/libstub/efi-stub-helper.c | 2 + drivers/firmware/efi/libstub/efistub.h | 1 + drivers/firmware/efi/libstub/x86-5lvl.c | 95 ++++++++++++++++++++ drivers/firmware/efi/libstub/x86-stub.c | 40 +++------ drivers/firmware/efi/libstub/x86-stub.h | 17 ++++ 6 files changed, 130 insertions(+), 26 deletions(-) diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index 16d64a34d1e19465..ae8874401a9f1490 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -88,6 +88,7 @@ lib-$(CONFIG_EFI_GENERIC_STUB) += efi-stub.o string.o intrinsics.o systable.o \ lib-$(CONFIG_ARM) += arm32-stub.o lib-$(CONFIG_ARM64) += arm64.o arm64-stub.o smbios.o lib-$(CONFIG_X86) += x86-stub.o +lib-$(CONFIG_X86_64) += x86-5lvl.o lib-$(CONFIG_RISCV) += riscv.o riscv-stub.o lib-$(CONFIG_LOONGARCH) += loongarch.o loongarch-stub.o diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c index 1e0203d74691ffcc..51779279fbff21b5 100644 --- a/drivers/firmware/efi/libstub/efi-stub-helper.c +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -73,6 +73,8 @@ efi_status_t efi_parse_options(char const *cmdline) efi_loglevel = CONSOLE_LOGLEVEL_QUIET; } else if (!strcmp(param, "noinitrd")) { efi_noinitrd = true; + } else if (IS_ENABLED(CONFIG_X86_64) && !strcmp(param, "no5lvl")) { + efi_no5lvl = true; } else if (!strcmp(param, "efi") && val) { efi_nochunk = parse_option_str(val, "nochunk"); efi_novamap |= parse_option_str(val, "novamap"); diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h index 6aa38a1bf1265d83..06b7abc92ced9e18 100644 --- a/drivers/firmware/efi/libstub/efistub.h +++ b/drivers/firmware/efi/libstub/efistub.h @@ -33,6 +33,7 @@ #define EFI_ALLOC_LIMIT ULONG_MAX #endif +extern bool efi_no5lvl; extern bool efi_nochunk; extern bool efi_nokaslr; extern int efi_loglevel; diff --git a/drivers/firmware/efi/libstub/x86-5lvl.c b/drivers/firmware/efi/libstub/x86-5lvl.c new file mode 100644 index 0000000000000000..2428578a3ae08be7 --- /dev/null +++ b/drivers/firmware/efi/libstub/x86-5lvl.c @@ -0,0 +1,95 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include + +#include +#include +#include + +#include "efistub.h" +#include "x86-stub.h" + +bool efi_no5lvl; + +static void (*la57_toggle)(void *trampoline, bool enable_5lvl); + +static const struct desc_struct gdt[] = { + [GDT_ENTRY_KERNEL32_CS] = GDT_ENTRY_INIT(0xc09b, 0, 0xfffff), + [GDT_ENTRY_KERNEL_CS] = GDT_ENTRY_INIT(0xa09b, 0, 0xfffff), +}; + +/* + * Enabling (or disabling) 5 level paging is tricky, because it can only be + * done from 32-bit mode with paging disabled. This means not only that the + * code itself must be running from 32-bit addressable physical memory, but + * also that the root page table must be 32-bit addressable, as programming + * a 64-bit value into CR3 when running in 32-bit mode is not supported. + */ +efi_status_t efi_setup_5level_paging(void) +{ + u8 tmpl_size = (u8 *)&trampoline_ljmp_imm_offset - (u8 *)&trampoline_32bit_src; + efi_status_t status; + u8 *la57_code; + + if (!efi_is_64bit()) + return EFI_SUCCESS; + + /* check for 5 level paging support */ + if (native_cpuid_eax(0) < 7 || + !(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31)))) + return EFI_SUCCESS; + + /* allocate some 32-bit addressable memory for code and a page table */ + status = efi_allocate_pages(2 * PAGE_SIZE, (unsigned long *)&la57_code, + U32_MAX); + if (status != EFI_SUCCESS) + return status; + + la57_toggle = memcpy(la57_code, trampoline_32bit_src, tmpl_size); + memset(la57_code + tmpl_size, 0x90, PAGE_SIZE - tmpl_size); + + /* + * To avoid the need to allocate a 32-bit addressable stack, the + * trampoline uses a LJMP instruction to switch back to long mode. + * LJMP takes an absolute destination address, which needs to be + * fixed up at runtime. + */ + *(u32 *)&la57_code[trampoline_ljmp_imm_offset] += (unsigned long)la57_code; + + efi_adjust_memory_range_protection((unsigned long)la57_toggle, PAGE_SIZE); + + return EFI_SUCCESS; +} + +void efi_5level_switch(void) +{ + bool want_la57 = IS_ENABLED(CONFIG_X86_5LEVEL) && !efi_no5lvl; + bool have_la57 = native_read_cr4() & X86_CR4_LA57; + bool need_toggle = want_la57 ^ have_la57; + u64 *pgt = (void *)la57_toggle + PAGE_SIZE; + u64 *cr3 = (u64 *)__native_read_cr3(); + u64 *new_cr3; + + if (!la57_toggle || !need_toggle) + return; + + if (!have_la57) { + /* + * 5 level paging will be enabled, so a root level page needs + * to be allocated from the 32-bit addressable physical region, + * with its first entry referring to the existing hierarchy. + */ + new_cr3 = memset(pgt, 0, PAGE_SIZE); + new_cr3[0] = (u64)cr3 | _PAGE_TABLE_NOENC; + } else { + /* take the new root table pointer from the current entry #0 */ + new_cr3 = (u64 *)(cr3[0] & PAGE_MASK); + + /* copy the new root table if it is not 32-bit addressable */ + if ((u64)new_cr3 > U32_MAX) + new_cr3 = memcpy(pgt, new_cr3, PAGE_SIZE); + } + + native_load_gdt(&(struct desc_ptr){ sizeof(gdt) - 1, (u64)gdt }); + + la57_toggle(new_cr3, want_la57); +} diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index 517cd68ea86cb7f4..f48a2e795d885af8 100644 --- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -17,6 +17,7 @@ #include #include "efistub.h" +#include "x86-stub.h" /* Maximum physical address for 64-bit kernel with 4-level paging */ #define MAXMEM_X86_64_4LEVEL (1ull << 46) @@ -223,8 +224,8 @@ static void retrieve_apple_device_properties(struct boot_params *boot_params) } } -static void -adjust_memory_range_protection(unsigned long start, unsigned long size) +void efi_adjust_memory_range_protection(unsigned long start, + unsigned long size) { efi_status_t status; efi_gcd_memory_space_desc_t desc; @@ -278,35 +279,14 @@ adjust_memory_range_protection(unsigned long start, unsigned long size) } } -/* - * Trampoline takes 2 pages and can be loaded in first megabyte of memory - * with its end placed between 128k and 640k where BIOS might start. - * (see arch/x86/boot/compressed/pgtable_64.c) - * - * We cannot find exact trampoline placement since memory map - * can be modified by UEFI, and it can alter the computed address. - */ - -#define TRAMPOLINE_PLACEMENT_BASE ((128 - 8)*1024) -#define TRAMPOLINE_PLACEMENT_SIZE (640*1024 - (128 - 8)*1024) - void startup_32(struct boot_params *boot_params); static void setup_memory_protection(unsigned long image_base, unsigned long image_size) { - /* - * Allow execution of possible trampoline used - * for switching between 4- and 5-level page tables - * and relocated kernel image. - */ - - adjust_memory_range_protection(TRAMPOLINE_PLACEMENT_BASE, - TRAMPOLINE_PLACEMENT_SIZE); - #ifdef CONFIG_64BIT if (image_base != (unsigned long)startup_32) - adjust_memory_range_protection(image_base, image_size); + efi_adjust_memory_range_protection(image_base, image_size); #else /* * Clear protection flags on a whole range of possible @@ -316,8 +296,8 @@ setup_memory_protection(unsigned long image_base, unsigned long image_size) * need to remove possible protection on relocated image * itself disregarding further relocations. */ - adjust_memory_range_protection(LOAD_PHYSICAL_ADDR, - KERNEL_IMAGE_SIZE - LOAD_PHYSICAL_ADDR); + efi_adjust_memory_range_protection(LOAD_PHYSICAL_ADDR, + KERNEL_IMAGE_SIZE - LOAD_PHYSICAL_ADDR); #endif } @@ -839,6 +819,12 @@ void __noreturn efi_stub_entry(efi_handle_t handle, efi_dxe_table = NULL; } + status = efi_setup_5level_paging(); + if (status != EFI_SUCCESS) { + efi_err("efi_setup_5level_paging() failed!\n"); + goto fail; + } + /* * If the kernel isn't already loaded at a suitable address, * relocate it. @@ -959,6 +945,8 @@ void __noreturn efi_stub_entry(efi_handle_t handle, goto fail; } + efi_5level_switch(); + if (IS_ENABLED(CONFIG_X86_64)) /* add offset of startup_64() */ bzimage_addr += 0x200; diff --git a/drivers/firmware/efi/libstub/x86-stub.h b/drivers/firmware/efi/libstub/x86-stub.h new file mode 100644 index 0000000000000000..37c5a36b9d8cf9b2 --- /dev/null +++ b/drivers/firmware/efi/libstub/x86-stub.h @@ -0,0 +1,17 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +#include + +extern void trampoline_32bit_src(void *, bool); +extern const u16 trampoline_ljmp_imm_offset; + +void efi_adjust_memory_range_protection(unsigned long start, + unsigned long size); + +#ifdef CONFIG_X86_64 +efi_status_t efi_setup_5level_paging(void); +void efi_5level_switch(void); +#else +static inline efi_status_t efi_setup_5level_paging(void) { return EFI_SUCCESS; } +static inline void efi_5level_switch(void) {} +#endif