kernel-ark/arch/x86/include/asm/vdso.h
Andy Lutomirski 8c49d9a74b 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>
2011-05-24 14:51:28 +02:00

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C

#ifndef _ASM_X86_VDSO_H
#define _ASM_X86_VDSO_H
#if defined CONFIG_X86_32 || defined CONFIG_COMPAT
extern const char VDSO32_PRELINK[];
/*
* Given a pointer to the vDSO image, find the pointer to VDSO32_name
* as that symbol is defined in the vDSO sources or linker script.
*/
#define VDSO32_SYMBOL(base, name) \
({ \
extern const char VDSO32_##name[]; \
(void *)(VDSO32_##name - VDSO32_PRELINK + (unsigned long)(base)); \
})
#endif
/*
* These symbols are defined with the addresses in the vsyscall page.
* See vsyscall-sigreturn.S.
*/
extern void __user __kernel_sigreturn;
extern void __user __kernel_rt_sigreturn;
/*
* These symbols are defined by vdso32.S to mark the bounds
* of the ELF DSO images included therein.
*/
extern const char vdso32_int80_start, vdso32_int80_end;
extern const char vdso32_syscall_start, vdso32_syscall_end;
extern const char vdso32_sysenter_start, vdso32_sysenter_end;
#endif /* _ASM_X86_VDSO_H */