From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Ricardo Neri Date: Fri, 27 Oct 2017 13:25:29 -0700 Subject: [PATCH] x86/boot: Relocate definition of the initial state of CR0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit CVE-2017-5754 Both head_32.S and head_64.S utilize the same value to initialize the control register CR0. Also, other parts of the kernel might want to access this initial definition (e.g., emulation code for User-Mode Instruction Prevention uses this state to provide a sane dummy value for CR0 when emulating the smsw instruction). Thus, relocate this definition to a header file from which it can be conveniently accessed. Suggested-by: Borislav Petkov Signed-off-by: Ricardo Neri Signed-off-by: Thomas Gleixner Reviewed-by: Borislav Petkov Reviewed-by: Andy Lutomirski Cc: "Michael S. Tsirkin" Cc: Peter Zijlstra Cc: Dave Hansen Cc: ricardo.neri@intel.com Cc: linux-mm@kvack.org Cc: Paul Gortmaker Cc: Huang Rui Cc: Shuah Khan Cc: linux-arch@vger.kernel.org Cc: Jonathan Corbet Cc: Jiri Slaby Cc: "Ravi V. Shankar" Cc: Denys Vlasenko Cc: Chris Metcalf Cc: Brian Gerst Cc: Josh Poimboeuf Cc: Chen Yucong Cc: Vlastimil Babka Cc: Dave Hansen Cc: Andy Lutomirski Cc: Masami Hiramatsu Cc: Paolo Bonzini Cc: Andrew Morton Cc: Linus Torvalds Link: https://lkml.kernel.org/r/1509135945-13762-3-git-send-email-ricardo.neri-calderon@linux.intel.com (cherry picked from commit b0ce5b8c95c83a7b98c679b117e3d6ae6f97154b) Signed-off-by: Andy Whitcroft Signed-off-by: Kleber Sacilotto de Souza (cherry picked from commit 27c31a88c22edab269abe17c0ac7db0351d26c5f) Signed-off-by: Fabian Grünbichler --- arch/x86/include/uapi/asm/processor-flags.h | 3 +++ arch/x86/kernel/head_32.S | 3 --- arch/x86/kernel/head_64.S | 3 --- 3 files changed, 3 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/uapi/asm/processor-flags.h b/arch/x86/include/uapi/asm/processor-flags.h index 185f3d10c194..39946d0a1d41 100644 --- a/arch/x86/include/uapi/asm/processor-flags.h +++ b/arch/x86/include/uapi/asm/processor-flags.h @@ -151,5 +151,8 @@ #define CX86_ARR_BASE 0xc4 #define CX86_RCR_BASE 0xdc +#define CR0_STATE (X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \ + X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \ + X86_CR0_PG) #endif /* _UAPI_ASM_X86_PROCESSOR_FLAGS_H */ diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 337a65377baf..7bbcdb1ea31a 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -213,9 +213,6 @@ ENTRY(startup_32_smp) #endif .Ldefault_entry: -#define CR0_STATE (X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \ - X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \ - X86_CR0_PG) movl $(CR0_STATE & ~X86_CR0_PG),%eax movl %eax,%cr0 diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index a2d8541b1da4..4117c1e0b3d2 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -137,9 +137,6 @@ ENTRY(secondary_startup_64) 1: wrmsr /* Make changes effective */ /* Setup cr0 */ -#define CR0_STATE (X86_CR0_PE | X86_CR0_MP | X86_CR0_ET | \ - X86_CR0_NE | X86_CR0_WP | X86_CR0_AM | \ - X86_CR0_PG) movl $CR0_STATE, %eax /* Make changes effective */ movq %rax, %cr0 -- 2.14.2