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1ad83c858c
This adds CONFIG_X86_VSYSCALL_EMULATION, guarded by CONFIG_EXPERT. Turning it off completely disables vsyscall emulation, saving ~3.5k for vsyscall_64.c, 4k for vsyscall_emu_64.S (the fake vsyscall page), some tiny amount of core mm code that supports a gate area, and possibly 4k for a wasted pagetable. The latter is because the vsyscall addresses are misaligned and fit poorly in the fixmap. Signed-off-by: Andy Lutomirski <luto@amacapital.net> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Link: http://lkml.kernel.org/r/406db88b8dd5f0cbbf38216d11be34bbb43c7eae.1414618407.git.luto@amacapital.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
24 lines
539 B
C
24 lines
539 B
C
#ifndef _ASM_X86_VSYSCALL_H
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#define _ASM_X86_VSYSCALL_H
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#include <linux/seqlock.h>
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#include <uapi/asm/vsyscall.h>
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#ifdef CONFIG_X86_VSYSCALL_EMULATION
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extern void map_vsyscall(void);
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/*
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* Called on instruction fetch fault in vsyscall page.
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* Returns true if handled.
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*/
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extern bool emulate_vsyscall(struct pt_regs *regs, unsigned long address);
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#else
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static inline void map_vsyscall(void) {}
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static inline bool emulate_vsyscall(struct pt_regs *regs, unsigned long address)
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{
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return false;
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}
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#endif
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#endif /* _ASM_X86_VSYSCALL_H */
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