linux-kernel - [PATCH v8 02/28] x86/boot: Relocate definition of the initial state of CR0

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Date:   Fri, 18 Aug 2017 17:27:43 -0700
From:   Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To:     Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...e.de>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Brian Gerst <brgerst@...il.com>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Liang Z Li <liang.z.li@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Huang Rui <ray.huang@....com>, Jiri Slaby <jslaby@...e.cz>,
        Jonathan Corbet <corbet@....net>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Chen Yucong <slaoub@...il.com>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Shuah Khan <shuah@...nel.org>, linux-kernel@...r.kernel.org,
        x86@...nel.org, ricardo.neri@...el.com,
        Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
        Andy Lutomirski <luto@...capital.net>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...el.com>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-arch@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH v8 02/28] x86/boot: Relocate definition of the initial state of CR0

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
to 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.

Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-arch@...r.kernel.org
Cc: linux-mm@...ck.org
Suggested-by: Borislav Petkov <bp@...en8.de>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
---
 arch/x86/include/uapi/asm/processor-flags.h | 6 ++++++
 arch/x86/kernel/head_32.S                   | 3 ---
 arch/x86/kernel/head_64.S                   | 3 ---
 3 files changed, 6 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..aae1f2aa7563 100644
--- a/arch/x86/include/uapi/asm/processor-flags.h
+++ b/arch/x86/include/uapi/asm/processor-flags.h
@@ -151,5 +151,11 @@
 #define CX86_ARR_BASE	0xc4
 #define CX86_RCR_BASE	0xdc
 
+/*
+ * Initial state of CR0 for head_32/64.S
+ */
+#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 0332664eb158..f64059835863 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 513cbb012ecc..5e1bfdd86b5b 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -149,9 +149,6 @@ 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
-- 
2.13.0