x86-64: Clean up vdso/kernel shared variables
Variables that are shared between the vdso and the kernel are
currently a bit of a mess. They are each defined with their own
magic, they are accessed differently in the kernel, the vsyscall page,
and the vdso, and one of them (vsyscall_clock) doesn't even really
exist.
This changes them all to use a common mechanism. All of them are
delcared in vvar.h with a fixed address (validated by the linker
script). In the kernel (as before), they look like ordinary
read-write variables. In the vsyscall page and the vdso, they are
accessed through a new macro VVAR, which gives read-only access.
The vdso is now loaded verbatim into memory without any fixups. As a
side bonus, access from the vdso is faster because a level of
indirection is removed.
While we're at it, pack jiffies and vgetcpu_mode into the same
cacheline.
Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3C7357882fbb51fa30491636a7b6528747301b7ee9.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/include/asm/vsyscall.h b/arch/x86/include/asm/vsyscall.h
index d0983d2..d555973 100644
--- a/arch/x86/include/asm/vsyscall.h
+++ b/arch/x86/include/asm/vsyscall.h
@@ -16,27 +16,19 @@
#ifdef __KERNEL__
#include <linux/seqlock.h>
-#define __section_vgetcpu_mode __attribute__ ((unused, __section__ (".vgetcpu_mode"), aligned(16)))
-#define __section_jiffies __attribute__ ((unused, __section__ (".jiffies"), aligned(16)))
-
/* Definitions for CONFIG_GENERIC_TIME definitions */
-#define __section_vsyscall_gtod_data __attribute__ \
- ((unused, __section__ (".vsyscall_gtod_data"),aligned(16)))
-#define __section_vsyscall_clock __attribute__ \
- ((unused, __section__ (".vsyscall_clock"),aligned(16)))
#define __vsyscall_fn \
__attribute__ ((unused, __section__(".vsyscall_fn"))) notrace
#define VGETCPU_RDTSCP 1
#define VGETCPU_LSL 2
-extern int __vgetcpu_mode;
-extern volatile unsigned long __jiffies;
-
/* kernel space (writeable) */
extern int vgetcpu_mode;
extern struct timezone sys_tz;
+#include <asm/vvar.h>
+
extern void map_vsyscall(void);
#endif /* __KERNEL__ */