[PATCH 4.14 033/159] x86/boot: Relocate definition of the initial state of CR0

Greg Kroah-Hartman
2017-12-22T08:59:46Z

From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>

commit b0ce5b8c95c83a7b98c679b117e3d6ae6f97154b upstream.

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 <bp@alien8.de>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: ricardo.neri@intel.com
Cc: linux-mm@kvack.org
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: linux-arch@vger.kernel.org
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Chen Yucong <slaoub@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/1509135945-13762-3-git-send-email-ricardo.neri-calderon@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
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(-)

--- a/arch/x86/include/uapi/asm/processor-flags.h
+++ b/arch/x86/include/uapi/asm/processor-flags.h
@@ -152,5 +152,8 @@
#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 */
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -212,9 +212,6 @@ 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

--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -154,9 +154,6 @@ 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