x86/vdso: Track each mm's loaded vDSO image as well as its base

As we start to do more intelligent things with the vDSO at
runtime (as opposed to just at mm initialization time), we'll
need to know which vDSO is in use.

In principle, we could guess based on the mm type, but that's
over-complicated and error-prone.  Instead, just track it in the
mmu context.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/c99ac48681bad709ca7ad5ee899d9042a3af6b00.1451446564.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index b8f69e264ac4148afbdaeedc69e24132980117a9..80b021067bd6ba4cb4d258cf5c3ba7b8e98b28f3 100644 (file)
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -121,6 +121,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
 
        text_start = addr - image->sym_vvar_start;
        current->mm->context.vdso = (void __user *)text_start;
+       current->mm->context.vdso_image = image;
 
        /*
         * MAYWRITE to allow gdb to COW and set breakpoints

diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h
index 55234d5e7160db83bd9854a40c87b8e70593b3c7..1ea0baef1175c407e9097e125a84b226be28266c 100644 (file)
--- a/arch/x86/include/asm/mmu.h
+++ b/arch/x86/include/asm/mmu.h
@@ -19,7 +19,8 @@ typedef struct {
 #endif
 
        struct mutex lock;
-       void __user *vdso;
+       void __user *vdso;                      /* vdso base address */
+       const struct vdso_image *vdso_image;    /* vdso image in use */
 
        atomic_t perf_rdpmc_allowed;    /* nonzero if rdpmc is allowed */
 } mm_context_t;