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/vdso.h b/arch/tile/include/asm/vdso.h
new file mode 100644
index 0000000..9f6a78d
--- /dev/null
+++ b/arch/tile/include/asm/vdso.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2012 Tilera Corporation. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT. See the GNU General Public License for
+ * more details.
+ */
+
+#ifndef __TILE_VDSO_H__
+#define __TILE_VDSO_H__
+
+#include <linux/types.h>
+
+/*
+ * Note about the vdso_data structure:
+ *
+ * NEVER USE THEM IN USERSPACE CODE DIRECTLY. The layout of the
+ * structure is supposed to be known only to the function in the vdso
+ * itself and may change without notice.
+ */
+
+struct vdso_data {
+ __u64 tz_update_count; /* Timezone atomicity ctr */
+ __u64 tb_update_count; /* Timebase atomicity ctr */
+ __u64 xtime_tod_stamp; /* TOD clock for xtime */
+ __u64 xtime_clock_sec; /* Kernel time second */
+ __u64 xtime_clock_nsec; /* Kernel time nanosecond */
+ __u64 wtom_clock_sec; /* Wall to monotonic clock second */
+ __u64 wtom_clock_nsec; /* Wall to monotonic clock nanosecond */
+ __u32 mult; /* Cycle to nanosecond multiplier */
+ __u32 shift; /* Cycle to nanosecond divisor (power of two) */
+ __u32 tz_minuteswest; /* Minutes west of Greenwich */
+ __u32 tz_dsttime; /* Type of dst correction */
+};
+
+extern struct vdso_data *vdso_data;
+
+/* __vdso_rt_sigreturn is defined with the addresses in the vdso page. */
+extern void __vdso_rt_sigreturn(void);
+
+extern int setup_vdso_pages(void);
+
+#endif /* __TILE_VDSO_H__ */