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8c49d9a74b
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>
37 lines
779 B
C
37 lines
779 B
C
#ifndef _ASM_X86_VSYSCALL_H
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#define _ASM_X86_VSYSCALL_H
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enum vsyscall_num {
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__NR_vgettimeofday,
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__NR_vtime,
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__NR_vgetcpu,
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};
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#define VSYSCALL_START (-10UL << 20)
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#define VSYSCALL_SIZE 1024
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#define VSYSCALL_END (-2UL << 20)
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#define VSYSCALL_MAPPED_PAGES 1
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#define VSYSCALL_ADDR(vsyscall_nr) (VSYSCALL_START+VSYSCALL_SIZE*(vsyscall_nr))
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#ifdef __KERNEL__
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#include <linux/seqlock.h>
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/* Definitions for CONFIG_GENERIC_TIME definitions */
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#define __vsyscall_fn \
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__attribute__ ((unused, __section__(".vsyscall_fn"))) notrace
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#define VGETCPU_RDTSCP 1
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#define VGETCPU_LSL 2
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/* kernel space (writeable) */
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extern int vgetcpu_mode;
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extern struct timezone sys_tz;
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#include <asm/vvar.h>
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extern void map_vsyscall(void);
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#endif /* __KERNEL__ */
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#endif /* _ASM_X86_VSYSCALL_H */
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