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Subject[PATCH v8 02/28] x86/boot: Relocate definition of the initial state of CR0
Date
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@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.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
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