[tip:x86/asm] x86/asm/entry/64: Use a define for an invalid segment selector

tip-bot for Borislav Petkov
2015-04-03T14:08:15Z

Commit-ID: 6b51311c976593fb7311322b1647a912cd456ec4
Gitweb: http://git.kernel.org/tip/6b51311c976593fb7311322b1647a912cd456ec4
Author: Borislav Petkov <bp@alien8.de>
AuthorDate: Fri, 3 Apr 2015 14:25:28 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 3 Apr 2015 15:29:13 +0200

x86/asm/entry/64: Use a define for an invalid segment selector

... instead of a naked number, for better readability.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1428054130-25847-1-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/segment.h | 2 ++
arch/x86/kernel/cpu/common.c | 2 +-
2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
index d394899..5a9856e 100644
--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -39,6 +39,8 @@
/* ... GDT has it cleared */
#define SEGMENT_GDT 0x0

+#define GDT_ENTRY_INVALID_SEG 0
+
#ifdef CONFIG_X86_32
/*
* The layout of the per-CPU GDT under Linux:
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index d56d307..3f70538 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1184,7 +1184,7 @@ void syscall_init(void)
wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (u64)ia32_sysenter_target);
#else
wrmsrl(MSR_CSTAR, ignore_sysret);
- wrmsrl_safe(MSR_IA32_SYSENTER_CS, 0ULL);
+ wrmsrl_safe(MSR_IA32_SYSENTER_CS, (u64)GDT_ENTRY_INVALID_SEG);