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authorAndy Lutomirski <luto@amacapital.net>2014-10-29 14:33:47 -0700
committerThomas Gleixner <tglx@linutronix.de>2014-11-03 21:44:57 +0100
commit1ad83c858c7d4ea210429142c99a1548e6715a35 (patch)
tree9c40dd5e49b646ae68e252c9a3e8afbd01a6a588 /arch/x86/xen/mmu.c
parent95c46b56922409ed8838b3b420b11cfebb8c6c88 (diff)
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/mmu.c')
-rw-r--r--arch/x86/xen/mmu.c6
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) {