[PATCH] Fix x86-64 vsyscall32 mapping

The x86-64 kernel incorrectly marks the 32-bit vsyscall page mapping at
virtual address 0xffffe000 as a global one, even though that mapping
does not exist globally.  As such, task switches do not correctly
invalidate the mapping, and strange behaviour ensues if a 64-bit program
happens to use that same virtual address for something else.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/ia32/syscall32.c

@@ -55,7 +55,7 @@ int __map_syscall32(struct mm_struct *mm, unsigned long address)
  			if (pte_none(*pte)) {
  				set_pte(pte,
  					mk_pte(virt_to_page(syscall32_page),
- 					       PAGE_KERNEL_VSYSCALL));
+ 					       PAGE_KERNEL_VSYSCALL32));
  			}
  			/* Flush only the local CPU. Other CPUs taking a fault
  			   will just end up here again

include/asm-x86_64/pgtable.h

@@ -182,6 +182,7 @@ extern inline void pgd_clear (pgd_t * pgd)
 #define PAGE_KERNEL_EXEC MAKE_GLOBAL(__PAGE_KERNEL_EXEC)
 #define PAGE_KERNEL_RO MAKE_GLOBAL(__PAGE_KERNEL_RO)
 #define PAGE_KERNEL_NOCACHE MAKE_GLOBAL(__PAGE_KERNEL_NOCACHE)
+#define PAGE_KERNEL_VSYSCALL32 __pgprot(__PAGE_KERNEL_VSYSCALL)
 #define PAGE_KERNEL_VSYSCALL MAKE_GLOBAL(__PAGE_KERNEL_VSYSCALL)
 #define PAGE_KERNEL_LARGE MAKE_GLOBAL(__PAGE_KERNEL_LARGE)
 #define PAGE_KERNEL_VSYSCALL_NOCACHE MAKE_GLOBAL(__PAGE_KERNEL_VSYSCALL_NOCACHE)