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| author |   Andy Lutomirski <luto@amacapital.net> | 2014-10-29 14:33:47 -0700 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2014-11-03 21:44:57 +0100 |
| commit | 1ad83c858c7d4ea210429142c99a1548e6715a35 (patch) | |
| tree | 9c40dd5e49b646ae68e252c9a3e8afbd01a6a588 /arch/x86/xen | |
| parent | x86_64, vsyscall: Rewrite comment and clean up headers in vsyscall code (diff) | |
| download | linux-dev-1ad83c858c7d4ea210429142c99a1548e6715a35.tar.xz linux-dev-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/xen')
| -rw-r--r-- | arch/x86/xen/mmu.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index a8a1a3d08d4d..8906cf0e536f 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -1457,8 +1457,10 @@ static int xen_pgd_alloc(struct mm_struct *mm) page->private = (unsigned long)user_pgd; if (user_pgd != NULL) { +#ifdef CONFIG_X86_VSYSCALL_EMULATION user_pgd[pgd_index(VSYSCALL_ADDR)] = __pgd(__pa(level3_user_vsyscall) | _PAGE_TABLE); +#endif ret = 0; } @@ -2021,7 +2023,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot) # ifdef CONFIG_HIGHMEM case FIX_KMAP_BEGIN ... FIX_KMAP_END: # endif -#else +#elif defined(CONFIG_X86_VSYSCALL_EMULATION) case VSYSCALL_PAGE: #endif case FIX_TEXT_POKE0: @@ -2060,7 +2062,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot) __native_set_fixmap(idx, pte); -#ifdef CONFIG_X86_64 +#ifdef CONFIG_X86_VSYSCALL_EMULATION /* Replicate changes to map the vsyscall page into the user pagetable vsyscall mapping. */ if (idx == VSYSCALL_PAGE) { |