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/fixmap.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/include/asm/fixmap.h') diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h index ffb1733ac91f2..d8d5bcb2a0b51 100644 --- a/arch/x86/include/asm/fixmap.h +++ b/arch/x86/include/asm/fixmap.h @@ -69,7 +69,9 @@ enum fixed_addresses { #ifdef CONFIG_X86_32 FIX_HOLE, #else +#ifdef CONFIG_X86_VSYSCALL_EMULATION VSYSCALL_PAGE = (FIXADDR_TOP - VSYSCALL_ADDR) >> PAGE_SHIFT, +#endif #ifdef CONFIG_PARAVIRT_CLOCK PVCLOCK_FIXMAP_BEGIN, PVCLOCK_FIXMAP_END = PVCLOCK_FIXMAP_BEGIN+PVCLOCK_VSYSCALL_NR_PAGES-1, -- cgit v1.2.3