x86_64,vsyscall: Make vsyscall emulation configurable
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>
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- arch/x86/Kconfig 18 additions, 0 deletionsarch/x86/Kconfig
- arch/x86/include/asm/fixmap.h 2 additions, 0 deletionsarch/x86/include/asm/fixmap.h
- arch/x86/include/asm/page_64.h 3 additions, 1 deletionarch/x86/include/asm/page_64.h
- arch/x86/include/asm/vsyscall.h 8 additions, 0 deletionsarch/x86/include/asm/vsyscall.h
- arch/x86/kernel/Makefile 1 addition, 2 deletionsarch/x86/kernel/Makefile
- arch/x86/kernel/setup.c 0 additions, 2 deletionsarch/x86/kernel/setup.c
- arch/x86/xen/mmu.c 4 additions, 2 deletionsarch/x86/xen/mmu.c
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