From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id 285716B02E9 for ; Wed, 8 Nov 2017 14:47:12 -0500 (EST) Received: by mail-pg0-f70.google.com with SMTP id q126so3392138pgq.7 for ; Wed, 08 Nov 2017 11:47:12 -0800 (PST) Received: from mga05.intel.com (mga05.intel.com. [192.55.52.43]) by mx.google.com with ESMTPS id 92si4510761plw.6.2017.11.08.11.47.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 08 Nov 2017 11:47:10 -0800 (PST) Subject: [PATCH 07/30] x86, kaiser: mark percpu data structures required for entry/exit From: Dave Hansen Date: Wed, 08 Nov 2017 11:46:59 -0800 References: <20171108194646.907A1942@viggo.jf.intel.com> In-Reply-To: <20171108194646.907A1942@viggo.jf.intel.com> Message-Id: <20171108194659.71951AEE@viggo.jf.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, dave.hansen@linux.intel.com, moritz.lipp@iaik.tugraz.at, daniel.gruss@iaik.tugraz.at, michael.schwarz@iaik.tugraz.at, richard.fellner@student.tugraz.at, luto@kernel.org, torvalds@linux-foundation.org, keescook@google.com, hughd@google.com, x86@kernel.org These patches are based on work from a team at Graz University of Technology posted here: https://github.com/IAIK/KAISER The KAISER approach keeps two copies of the page tables: one for running in the kernel and one for running userspace. But, there are a few structures that are needed for switching in and out of the kernel and a good subset of *those* are per-cpu data. Here's a short summary of the things we map to userspace: * The gdt_page's virtual address is pointed to by the LGDT instruction. It is needed to define the segments. Deeply required by CPU to run. * cpu_tss tells the CPU, among other things, where the new stacks are after user<->kernel transitions. Needed by the CPU to make ring transitions. * exception_stacks are needed at interrupt and exception entry so that we have a place to store data to, among other things, get a free register to load the kernel CR3. Signed-off-by: Dave Hansen Cc: Moritz Lipp Cc: Daniel Gruss Cc: Michael Schwarz Cc: Richard Fellner Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Kees Cook Cc: Hugh Dickins Cc: x86@kernel.org --- b/arch/x86/include/asm/desc.h | 2 +- b/arch/x86/include/asm/processor.h | 2 +- b/arch/x86/kernel/cpu/common.c | 4 ++-- b/arch/x86/kernel/process.c | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-) diff -puN arch/x86/include/asm/desc.h~kaiser-prep-x86-percpu-user-mapped arch/x86/include/asm/desc.h --- a/arch/x86/include/asm/desc.h~kaiser-prep-x86-percpu-user-mapped 2017-11-08 10:45:29.252681395 -0800 +++ b/arch/x86/include/asm/desc.h 2017-11-08 10:45:29.261681395 -0800 @@ -45,7 +45,7 @@ struct gdt_page { struct desc_struct gdt[GDT_ENTRIES]; } __attribute__((aligned(PAGE_SIZE))); -DECLARE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page); +DECLARE_PER_CPU_PAGE_ALIGNED_USER_MAPPED(struct gdt_page, gdt_page); /* Provide the original GDT */ static inline struct desc_struct *get_cpu_gdt_rw(unsigned int cpu) diff -puN arch/x86/include/asm/processor.h~kaiser-prep-x86-percpu-user-mapped arch/x86/include/asm/processor.h --- a/arch/x86/include/asm/processor.h~kaiser-prep-x86-percpu-user-mapped 2017-11-08 10:45:29.254681395 -0800 +++ b/arch/x86/include/asm/processor.h 2017-11-08 10:45:29.261681395 -0800 @@ -346,7 +346,7 @@ struct tss_struct { unsigned long SYSENTER_stack[64]; } ____cacheline_aligned; -DECLARE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss); +DECLARE_PER_CPU_SHARED_ALIGNED_USER_MAPPED(struct tss_struct, cpu_tss); /* * sizeof(unsigned long) coming from an extra "long" at the end diff -puN arch/x86/kernel/cpu/common.c~kaiser-prep-x86-percpu-user-mapped arch/x86/kernel/cpu/common.c --- a/arch/x86/kernel/cpu/common.c~kaiser-prep-x86-percpu-user-mapped 2017-11-08 10:45:29.256681395 -0800 +++ b/arch/x86/kernel/cpu/common.c 2017-11-08 10:45:29.262681395 -0800 @@ -98,7 +98,7 @@ static const struct cpu_dev default_cpu static const struct cpu_dev *this_cpu = &default_cpu; -DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = { +DEFINE_PER_CPU_PAGE_ALIGNED_USER_MAPPED(struct gdt_page, gdt_page) = { .gdt = { #ifdef CONFIG_X86_64 /* * We need valid kernel segments for data and code in long mode too @@ -1343,7 +1343,7 @@ static const unsigned int exception_stac [DEBUG_STACK - 1] = DEBUG_STKSZ }; -static DEFINE_PER_CPU_PAGE_ALIGNED(char, exception_stacks +DEFINE_PER_CPU_PAGE_ALIGNED_USER_MAPPED(char, exception_stacks [(N_EXCEPTION_STACKS - 1) * EXCEPTION_STKSZ + DEBUG_STKSZ]); /* May not be marked __init: used by software suspend */ diff -puN arch/x86/kernel/process.c~kaiser-prep-x86-percpu-user-mapped arch/x86/kernel/process.c --- a/arch/x86/kernel/process.c~kaiser-prep-x86-percpu-user-mapped 2017-11-08 10:45:29.257681395 -0800 +++ b/arch/x86/kernel/process.c 2017-11-08 10:45:29.262681395 -0800 @@ -46,7 +46,7 @@ * section. Since TSS's are completely CPU-local, we want them * on exact cacheline boundaries, to eliminate cacheline ping-pong. */ -__visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = { +__visible DEFINE_PER_CPU_SHARED_ALIGNED_USER_MAPPED(struct tss_struct, cpu_tss) = { .x86_tss = { /* * .sp0 is only used when entering ring 0 from a lower _ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org