From 1ad83c858c7d4ea210429142c99a1548e6715a35 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Wed, 29 Oct 2014 14:33:47 -0700 Subject: 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 Reviewed-by: Josh Triplett Cc: Konrad Rzeszutek Wilk Link: http://lkml.kernel.org/r/406db88b8dd5f0cbbf38216d11be34bbb43c7eae.1414618407.git.luto@amacapital.net Signed-off-by: Thomas Gleixner --- arch/x86/include/asm/vsyscall.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'arch/x86/include/asm/vsyscall.h') diff --git a/arch/x86/include/asm/vsyscall.h b/arch/x86/include/asm/vsyscall.h index 34f7d8857542..6ba66ee79710 100644 --- a/arch/x86/include/asm/vsyscall.h +++ b/arch/x86/include/asm/vsyscall.h @@ -4,6 +4,7 @@ #include #include +#ifdef CONFIG_X86_VSYSCALL_EMULATION extern void map_vsyscall(void); /* @@ -11,5 +12,12 @@ extern void map_vsyscall(void); * Returns true if handled. */ extern bool emulate_vsyscall(struct pt_regs *regs, unsigned long address); +#else +static inline void map_vsyscall(void) {} +static inline bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) +{ + return false; +} +#endif #endif /* _ASM_X86_VSYSCALL_H */ -- cgit v1.2.3