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>
diff --git a/arch/tile/include/asm/processor.h b/arch/tile/include/asm/processor.h
index fed1c04..461322b 100644
--- a/arch/tile/include/asm/processor.h
+++ b/arch/tile/include/asm/processor.h
@@ -180,10 +180,10 @@
#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