From patchwork Tue Jan 19 17:10:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 366436 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=-19.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 64298C169C3 for ; Tue, 19 Jan 2021 18:30:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3848522CAD for ; Tue, 19 Jan 2021 18:30:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731837AbhASS2s (ORCPT ); Tue, 19 Jan 2021 13:28:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:49886 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729334AbhASS2m (ORCPT ); Tue, 19 Jan 2021 13:28:42 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id AB15E233FE; Tue, 19 Jan 2021 17:10:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1611076235; bh=G5kPiaR5o5vrIDp4FM0/mzJ4oL5jJxHJ37HrBP1VCL8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fsdSg4jO5mzRX/szmu7JswpNYKWdpXntAt2/V3pfNCqt6B07zUTZUjbLruMgQgc0d oExMwInoylDuJPmI2ngb8NMtewWuwVWxIMy3EHDfGelbX+Giy96UewJwcL9ryjiMH0 1xbq9ElpjH1qwItZQCsJ9cWP1QGg08forWPbLzali4Uwpo0z1Gtjfq2pGDGggDNm/i QzVKgmt/MgiSBa2fyl9Q1UG+MF+3dncWaSqMsjDjRDn2yepDcoyenO6khbV6A18JPk jMPKFp6DCyM+vCH3qgQ2pslERJM7BHRHG16QhHhS3inQGDtcp1FRFfJeBrU0SBr2nX eFIJgcWwBzeuQ== From: Ard Biesheuvel To: linux-efi@vger.kernel.org Cc: Ard Biesheuvel Subject: [PATCH 2/2] efi: x86: clean up previous struct mm switching Date: Tue, 19 Jan 2021 18:10:21 +0100 Message-Id: <20210119171021.27974-2-ardb@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210119171021.27974-1-ardb@kernel.org> References: <20210119171021.27974-1-ardb@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org EFI on x86_64 keeps track of the process's MM pointer by storing it in a global struct called 'efi_scratch', which also used to contain the mixed mode stack pointer. Let's clean this up a little bit, by getting rid of the struct, and pushing the mm handling into the callees entirely. Signed-off-by: Ard Biesheuvel --- arch/x86/include/asm/efi.h | 17 +++++------------ arch/x86/platform/efi/efi_64.c | 27 +++++++++++++++------------ 2 files changed, 20 insertions(+), 24 deletions(-) diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h index 5e37e6d63c63..1328b7959b72 100644 --- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -95,20 +95,12 @@ extern asmlinkage u64 __efi_call(void *fp, ...); __efi_call(__VA_ARGS__); \ }) -/* - * struct efi_scratch - Scratch space used while switching to/from efi_mm - * @prev_mm: store/restore stolen mm_struct while switching to/from efi_mm - */ -struct efi_scratch { - struct mm_struct *prev_mm; -} __packed; - #define arch_efi_call_virt_setup() \ ({ \ efi_sync_low_kernel_mappings(); \ kernel_fpu_begin(); \ firmware_restrict_branch_speculation_start(); \ - efi_switch_mm(&efi_mm); \ + efi_enter_mm(); \ }) #define arch_efi_call_virt(p, f, args...) \ @@ -116,7 +108,7 @@ struct efi_scratch { #define arch_efi_call_virt_teardown() \ ({ \ - efi_switch_mm(efi_scratch.prev_mm); \ + efi_leave_mm(); \ firmware_restrict_branch_speculation_end(); \ kernel_fpu_end(); \ }) @@ -135,7 +127,6 @@ struct efi_scratch { #endif /* CONFIG_X86_32 */ -extern struct efi_scratch efi_scratch; extern int __init efi_memblock_x86_reserve_range(void); extern void __init efi_print_memmap(void); extern void __init efi_map_region(efi_memory_desc_t *md); @@ -148,10 +139,12 @@ extern void __init efi_dump_pagetable(void); extern void __init efi_apply_memmap_quirks(void); extern int __init efi_reuse_config(u64 tables, int nr_tables); extern void efi_delete_dummy_variable(void); -extern void efi_switch_mm(struct mm_struct *mm); extern void efi_recover_from_page_fault(unsigned long phys_addr); extern void efi_free_boot_services(void); +void efi_enter_mm(void); +void efi_leave_mm(void); + /* kexec external ABI */ struct efi_setup_data { u64 fw_vendor; diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index 1d904181e6a1..62a6c8650773 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -54,10 +54,7 @@ * 0xffff_ffff_0000_0000 and limit EFI VA mapping space to 64G. */ static u64 efi_va = EFI_VA_START; - -struct efi_scratch efi_scratch; - -EXPORT_SYMBOL_GPL(efi_mm); +static struct mm_struct *efi_prev_mm; /* * We need our own copy of the higher levels of the page tables @@ -481,11 +478,17 @@ void __init efi_dump_pagetable(void) * can not change under us. * It should be ensured that there are no concurent calls to this function. */ -void efi_switch_mm(struct mm_struct *mm) +void efi_enter_mm(void) +{ + efi_prev_mm = current->active_mm; + current->active_mm = &efi_mm; + switch_mm(efi_prev_mm, &efi_mm, NULL); +} + +void efi_leave_mm(void) { - efi_scratch.prev_mm = current->active_mm; - current->active_mm = mm; - switch_mm(efi_scratch.prev_mm, mm, NULL); + current->active_mm = efi_prev_mm; + switch_mm(&efi_mm, efi_prev_mm, NULL); } static DEFINE_SPINLOCK(efi_runtime_lock); @@ -549,12 +552,12 @@ efi_thunk_set_virtual_address_map(unsigned long memory_map_size, efi_sync_low_kernel_mappings(); local_irq_save(flags); - efi_switch_mm(&efi_mm); + efi_enter_mm(); status = __efi_thunk(set_virtual_address_map, memory_map_size, descriptor_size, descriptor_version, virtual_map); - efi_switch_mm(efi_scratch.prev_mm); + efi_leave_mm(); local_irq_restore(flags); return status; @@ -848,7 +851,7 @@ efi_set_virtual_address_map(unsigned long memory_map_size, descriptor_size, descriptor_version, virtual_map); - efi_switch_mm(&efi_mm); + efi_enter_mm(); kernel_fpu_begin(); @@ -864,7 +867,7 @@ efi_set_virtual_address_map(unsigned long memory_map_size, /* grab the virtually remapped EFI runtime services table pointer */ efi.runtime = READ_ONCE(systab->runtime); - efi_switch_mm(efi_scratch.prev_mm); + efi_leave_mm(); return status; }