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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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