[PATCH] x86-64: fix perms/range of vsyscall vma in /proc/*/maps

The final line of /proc/<pid>/maps on x86_64 for native 64-bit
tasks shows an incorrect ending address and incorrect permissions.  There
is only a single page mapped in this vsyscall region, and it is accessible
for both read and execute.

The patch below fixes this.  (Since 32-bit-compat tasks have a real vma
with correct perms/range, no change is necessary for that scenario.)

Before the patch, a "cat /proc/self/maps | tail -1" shows this:

        ffffffffff600000-ffffffffffe00000 ---p 00000000 [...]

After the patch, this is the output:

        ffffffffff600000-ffffffffff601000 r-xp 00000000 [...]

Signed-off-by: Ernie Petrides <petrides@redhat.com>
Signed-off-by: Andi Kleen <ak@suse.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/vsyscall.c b/arch/x86_64/kernel/vsyscall.c
index 92546c1526f1..c3de9a09cd9f 100644
--- a/arch/x86_64/kernel/vsyscall.c
+++ b/arch/x86_64/kernel/vsyscall.c
@@ -290,6 +290,7 @@ static void __init map_vsyscall(void)
 	extern char __vsyscall_0;
 	unsigned long physaddr_page0 = __pa_symbol(&__vsyscall_0);
 
+	/* Note that VSYSCALL_MAPPED_PAGES must agree with the code below. */
 	__set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_page0, PAGE_KERNEL_VSYSCALL);
 }