x86-64: Clean up vdso/kernel shared variables
authorAndy Lutomirski <luto@MIT.EDU>
Mon, 23 May 2011 13:31:24 +0000 (09:31 -0400)
committerThomas Gleixner <tglx@linutronix.de>
Tue, 24 May 2011 12:51:28 +0000 (14:51 +0200)
commit8c49d9a74bac5ea3f18480307057241b808fcc0c
treea9d2d8160ca37e9292e605cf3cdd85b29646c4b7
parentd762f4383100c2a87b1a3f2d678cd3b5425655b4
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>
15 files changed:
arch/x86/include/asm/vdso.h
arch/x86/include/asm/vgtod.h
arch/x86/include/asm/vsyscall.h
arch/x86/include/asm/vvar.h [new file with mode: 0644]
arch/x86/kernel/time.c
arch/x86/kernel/tsc.c
arch/x86/kernel/vmlinux.lds.S
arch/x86/kernel/vsyscall_64.c
arch/x86/vdso/Makefile
arch/x86/vdso/vclock_gettime.c
arch/x86/vdso/vdso.lds.S
arch/x86/vdso/vextern.h [deleted file]
arch/x86/vdso/vgetcpu.c
arch/x86/vdso/vma.c
arch/x86/vdso/vvar.c [deleted file]