tile: implement gettimeofday() via vDSO

This change creates the framework for vDSO calls, makes the existing
rt_sigreturn() mechanism use it, and adds a fast gettimeofday().
Now that we need to expose the vDSO address to userspace, we add
AT_SYSINFO_EHDR to the set of aux entries provided to userspace.
(You can disable any extra vDSO support by booting with vdso=0,
but the rt_sigreturn vDSO page will still be provided.)

Note that glibc has supported the tile vDSO since release 2.17.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/tile/include/asm/processor.h b/arch/tile/include/asm/processor.h
index fed1c044fec8..461322b473b5 100644
--- a/arch/tile/include/asm/processor.h
+++ b/arch/tile/include/asm/processor.h
@@ -180,10 +180,10 @@ struct thread_struct {
 #define TASK_SIZE               TASK_SIZE_MAX
 #endif
 
-/* We provide a minimal "vdso" a la x86; just the sigreturn code for now. */
-#define VDSO_BASE               (TASK_SIZE - PAGE_SIZE)
+#define VDSO_BASE       ((unsigned long)current->active_mm->context.vdso_base)
+#define VDSO_SYM(x)     (VDSO_BASE + (unsigned long)(x))
 
-#define STACK_TOP               VDSO_BASE
+#define STACK_TOP               TASK_SIZE
 
 /* STACK_TOP_MAX is used temporarily in execve and should not check COMPAT. */
 #define STACK_TOP_MAX           TASK_SIZE_MAX