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| author | Andy Lutomirski <luto@amacapital.net> | 2014-10-29 22:33:47 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2014-11-03 21:44:57 +0100 |
| commit | 1ad83c858c7d4ea210429142c99a1548e6715a35 (patch) | |
| tree | 9c40dd5e49b646ae68e252c9a3e8afbd01a6a588 /arch/x86/include/asm | |
| parent | x86_64, vsyscall: Rewrite comment and clean up headers in vsyscall code (diff) | |
| download | linux-1ad83c858c7d4ea210429142c99a1548e6715a35.tar.xz linux-1ad83c858c7d4ea210429142c99a1548e6715a35.zip | |
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>
Diffstat (limited to 'arch/x86/include/asm')
| -rw-r--r-- | arch/x86/include/asm/fixmap.h | 2 | ||||
| -rw-r--r-- | arch/x86/include/asm/page_64.h | 4 | ||||
| -rw-r--r-- | arch/x86/include/asm/vsyscall.h | 8 |
3 files changed, 13 insertions, 1 deletions
diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h index ffb1733ac91f..d8d5bcb2a0b5 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, diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h index f408caf73430..b3bebf9e5746 100644 --- a/arch/x86/include/asm/page_64.h +++ b/arch/x86/include/asm/page_64.h @@ -39,6 +39,8 @@ void copy_page(void *to, void *from); #endif /* !__ASSEMBLY__ */ -#define __HAVE_ARCH_GATE_AREA 1 +#ifdef CONFIG_X86_VSYSCALL_EMULATION +# define __HAVE_ARCH_GATE_AREA 1 +#endif #endif /* _ASM_X86_PAGE_64_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 <linux/seqlock.h> #include <uapi/asm/vsyscall.h> +#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 */ |