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 X-Spam-Level: X-Spam-Status: No, score=-12.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DF35C282C4 for ; Mon, 4 Feb 2019 08:46:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE50020820 for ; Mon, 4 Feb 2019 08:46:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728393AbfBDIqJ (ORCPT ); Mon, 4 Feb 2019 03:46:09 -0500 Received: from terminus.zytor.com ([198.137.202.136]:50215 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726242AbfBDIqI (ORCPT ); Mon, 4 Feb 2019 03:46:08 -0500 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id x148jY7L356500 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Mon, 4 Feb 2019 00:45:34 -0800 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id x148jYhK356497; Mon, 4 Feb 2019 00:45:34 -0800 Date: Mon, 4 Feb 2019 00:45:34 -0800 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Ard Biesheuvel Message-ID: Cc: hpa@zytor.com, ard.biesheuvel@linaro.org, matt@codeblueprint.co.uk, peterz@infradead.org, sai.praneeth.prakhya@intel.com, bjorn.andersson@linaro.org, leif.lindholm@linaro.org, xypron.glpk@gmx.de, tglx@linutronix.de, bp@alien8.de, pjones@redhat.com, mingo@kernel.org, lee.jones@linaro.org, agraf@suse.de, takahiro.akashi@linaro.org, linux-kernel@vger.kernel.org, jhugo@codeaurora.org, torvalds@linux-foundation.org Reply-To: tglx@linutronix.de, leif.lindholm@linaro.org, xypron.glpk@gmx.de, bp@alien8.de, bjorn.andersson@linaro.org, matt@codeblueprint.co.uk, sai.praneeth.prakhya@intel.com, peterz@infradead.org, hpa@zytor.com, ard.biesheuvel@linaro.org, torvalds@linux-foundation.org, jhugo@codeaurora.org, agraf@suse.de, takahiro.akashi@linaro.org, linux-kernel@vger.kernel.org, mingo@kernel.org, lee.jones@linaro.org, pjones@redhat.com In-Reply-To: <20190202094119.13230-8-ard.biesheuvel@linaro.org> References: <20190202094119.13230-8-ard.biesheuvel@linaro.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:efi/core] efi/arm/arm64: Allow SetVirtualAddressMap() to be omitted Git-Commit-ID: 4e46c2a956215482418d7b315749fb1b6c6bc224 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 4e46c2a956215482418d7b315749fb1b6c6bc224 Gitweb: https://git.kernel.org/tip/4e46c2a956215482418d7b315749fb1b6c6bc224 Author: Ard Biesheuvel AuthorDate: Sat, 2 Feb 2019 10:41:16 +0100 Committer: Ingo Molnar CommitDate: Mon, 4 Feb 2019 08:27:26 +0100 efi/arm/arm64: Allow SetVirtualAddressMap() to be omitted The UEFI spec revision 2.7 errata A section 8.4 has the following to say about the virtual memory runtime services: "This section contains function definitions for the virtual memory support that may be optionally used by an operating system at runtime. If an operating system chooses to make EFI runtime service calls in a virtual addressing mode instead of the flat physical mode, then the operating system must use the services in this section to switch the EFI runtime services from flat physical addressing to virtual addressing." So it is pretty clear that calling SetVirtualAddressMap() is entirely optional, and so there is no point in doing so unless it achieves anything useful for us. This is not the case for 64-bit ARM. The identity mapping used by the firmware is arbitrarily converted into another permutation of userland addresses (i.e., bits [63:48] cleared), and the runtime code could easily deal with the original layout in exactly the same way as it deals with the converted layout. However, due to constraints related to page size differences if the OS is not running with 4k pages, and related to systems that may expose the individual sections of PE/COFF runtime modules as different memory regions, creating the virtual layout is a bit fiddly, and requires us to sort the memory map and reason about adjacent regions with identical memory types etc etc. So the obvious fix is to stop calling SetVirtualAddressMap() altogether on arm64 systems. However, to avoid surprises, which are notoriously hard to diagnose when it comes to OS<->firmware interactions, let's start by making it an opt-out feature, and implement support for the 'efi=novamap' kernel command line parameter on ARM and arm64 systems. ( Note that 32-bit ARM generally does require SetVirtualAddressMap() to be used, given that the physical memory map and the kernel virtual address map are not guaranteed to be non-overlapping like on arm64. However, having support for efi=novamap,noruntime on 32-bit ARM, combined with the recently proposed support for earlycon=efifb, is likely to be useful to diagnose boot issues on such systems if they have no accessible serial port. ) Tested-by: Jeffrey Hugo Tested-by: Bjorn Andersson Tested-by: Lee Jones Signed-off-by: Ard Biesheuvel Cc: AKASHI Takahiro Cc: Alexander Graf Cc: Borislav Petkov Cc: Heinrich Schuchardt Cc: Leif Lindholm Cc: Linus Torvalds Cc: Matt Fleming Cc: Peter Jones Cc: Peter Zijlstra Cc: Sai Praneeth Prakhya Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20190202094119.13230-8-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar --- drivers/firmware/efi/libstub/arm-stub.c | 5 +++++ drivers/firmware/efi/libstub/efi-stub-helper.c | 10 ++++++++++ drivers/firmware/efi/libstub/efistub.h | 1 + drivers/firmware/efi/libstub/fdt.c | 3 +++ 4 files changed, 19 insertions(+) diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c index eee42d5e25ee..626ec4b4a664 100644 --- a/drivers/firmware/efi/libstub/arm-stub.c +++ b/drivers/firmware/efi/libstub/arm-stub.c @@ -370,6 +370,11 @@ void efi_get_virtmap(efi_memory_desc_t *memory_map, unsigned long map_size, paddr = in->phys_addr; size = in->num_pages * EFI_PAGE_SIZE; + if (novamap()) { + in->virt_addr = in->phys_addr; + continue; + } + /* * Make the mapping compatible with 64k pages: this allows * a 4k page size kernel to kexec a 64k page size kernel and diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c index 8f2d000bec75..e4610e72b78f 100644 --- a/drivers/firmware/efi/libstub/efi-stub-helper.c +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -31,6 +31,7 @@ static unsigned long __chunk_size = EFI_READ_CHUNK_SIZE; static int __section(.data) __nokaslr; static int __section(.data) __quiet; +static int __section(.data) __novamap; int __pure nokaslr(void) { @@ -40,6 +41,10 @@ int __pure is_quiet(void) { return __quiet; } +int __pure novamap(void) +{ + return __novamap; +} #define EFI_MMAP_NR_SLACK_SLOTS 8 @@ -479,6 +484,11 @@ efi_status_t efi_parse_options(char const *cmdline) __chunk_size = -1UL; } + if (!strncmp(str, "novamap", 7)) { + str += strlen("novamap"); + __novamap = 1; + } + /* Group words together, delimited by "," */ while (*str && *str != ' ' && *str != ',') str++; diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h index cefcf6ba3150..1b1dfcaa6fb9 100644 --- a/drivers/firmware/efi/libstub/efistub.h +++ b/drivers/firmware/efi/libstub/efistub.h @@ -27,6 +27,7 @@ extern int __pure nokaslr(void); extern int __pure is_quiet(void); +extern int __pure novamap(void); #define pr_efi(sys_table, msg) do { \ if (!is_quiet()) efi_printk(sys_table, "EFI stub: "msg); \ diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c index 7cfc51935c4b..5440ba17a1c5 100644 --- a/drivers/firmware/efi/libstub/fdt.c +++ b/drivers/firmware/efi/libstub/fdt.c @@ -318,6 +318,9 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table, if (status == EFI_SUCCESS) { efi_set_virtual_address_map_t *svam; + if (novamap()) + return EFI_SUCCESS; + /* Install the new virtual address map */ svam = sys_table->runtime->set_virtual_address_map; status = svam(runtime_entry_count * desc_size, desc_size,