• Andy Lutomirski's avatar
    x86-64: Clean up vdso/kernel shared variables · 8c49d9a7
    Andy Lutomirski authored
    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: default avatarAndy 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%3ESigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    8c49d9a7
vgtod.h 590 Bytes