Linux-libre 4.4-gnupck-4.4-gnu

1 files changed, 123 insertions, 16 deletions

diff --git a/arch/mips/include/asm/vdso.h b/arch/mips/include/asm/vdso.h
index cca56aa40..8f4ca5dd9 100644
--- a/arch/mips/include/asm/vdso.h
+++ b/arch/mips/include/asm/vdso.h
@@ -1,29 +1,136 @@
 /*
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
+ * Copyright (C) 2015 Imagination Technologies
+ * Author: Alex Smith <alex.smith@imgtec.com>
  *
- * Copyright (C) 2009 Cavium Networks
+ * 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;  either version 2 of the  License, or (at your
+ * option) any later version.
  */
 
 #ifndef __ASM_VDSO_H
 #define __ASM_VDSO_H
 
-#include <linux/types.h>
+#include <linux/mm_types.h>
 
+#include <asm/barrier.h>
 
-#ifdef CONFIG_32BIT
-struct mips_vdso {
-	u32 signal_trampoline[2];
-	u32 rt_signal_trampoline[2];
+/**
+ * struct mips_vdso_image - Details of a VDSO image.
+ * @data: Pointer to VDSO image data (page-aligned).
+ * @size: Size of the VDSO image data (page-aligned).
+ * @off_sigreturn: Offset of the sigreturn() trampoline.
+ * @off_rt_sigreturn: Offset of the rt_sigreturn() trampoline.
+ * @mapping: Special mapping structure.
+ *
+ * This structure contains details of a VDSO image, including the image data
+ * and offsets of certain symbols required by the kernel. It is generated as
+ * part of the VDSO build process, aside from the mapping page array, which is
+ * populated at runtime.
+ */
+struct mips_vdso_image {
+	void *data;
+	unsigned long size;
+
+	unsigned long off_sigreturn;
+	unsigned long off_rt_sigreturn;
+
+	struct vm_special_mapping mapping;
 };
-#else  /* !CONFIG_32BIT */
-struct mips_vdso {
-	u32 o32_signal_trampoline[2];
-	u32 o32_rt_signal_trampoline[2];
-	u32 rt_signal_trampoline[2];
-	u32 n32_rt_signal_trampoline[2];
+
+/*
+ * The following structures are auto-generated as part of the build for each
+ * ABI by genvdso, see arch/mips/vdso/Makefile.
+ */
+
+extern struct mips_vdso_image vdso_image;
+
+#ifdef CONFIG_MIPS32_O32
+extern struct mips_vdso_image vdso_image_o32;
+#endif
+
+#ifdef CONFIG_MIPS32_N32
+extern struct mips_vdso_image vdso_image_n32;
+#endif
+
+/**
+ * union mips_vdso_data - Data provided by the kernel for the VDSO.
+ * @xtime_sec:		Current real time (seconds part).
+ * @xtime_nsec:		Current real time (nanoseconds part, shifted).
+ * @wall_to_mono_sec:	Wall-to-monotonic offset (seconds part).
+ * @wall_to_mono_nsec:	Wall-to-monotonic offset (nanoseconds part).
+ * @seq_count:		Counter to synchronise updates (odd = updating).
+ * @cs_shift:		Clocksource shift value.
+ * @clock_mode:		Clocksource to use for time functions.
+ * @cs_mult:		Clocksource multiplier value.
+ * @cs_cycle_last:	Clock cycle value at last update.
+ * @cs_mask:		Clocksource mask value.
+ * @tz_minuteswest:	Minutes west of Greenwich (from timezone).
+ * @tz_dsttime:		Type of DST correction (from timezone).
+ *
+ * This structure contains data needed by functions within the VDSO. It is
+ * populated by the kernel and mapped read-only into user memory. The time
+ * fields are mirrors of internal data from the timekeeping infrastructure.
+ *
+ * Note: Care should be taken when modifying as the layout must remain the same
+ * for both 64- and 32-bit (for 32-bit userland on 64-bit kernel).
+ */
+union mips_vdso_data {
+	struct {
+		u64 xtime_sec;
+		u64 xtime_nsec;
+		u32 wall_to_mono_sec;
+		u32 wall_to_mono_nsec;
+		u32 seq_count;
+		u32 cs_shift;
+		u8 clock_mode;
+		u32 cs_mult;
+		u64 cs_cycle_last;
+		u64 cs_mask;
+		s32 tz_minuteswest;
+		s32 tz_dsttime;
+	};
+
+	u8 page[PAGE_SIZE];
 };
-#endif /* CONFIG_32BIT */
+
+static inline u32 vdso_data_read_begin(const union mips_vdso_data *data)
+{
+	u32 seq;
+
+	while (true) {
+		seq = ACCESS_ONCE(data->seq_count);
+		if (likely(!(seq & 1))) {
+			/* Paired with smp_wmb() in vdso_data_write_*(). */
+			smp_rmb();
+			return seq;
+		}
+
+		cpu_relax();
+	}
+}
+
+static inline bool vdso_data_read_retry(const union mips_vdso_data *data,
+					u32 start_seq)
+{
+	/* Paired with smp_wmb() in vdso_data_write_*(). */
+	smp_rmb();
+	return unlikely(data->seq_count != start_seq);
+}
+
+static inline void vdso_data_write_begin(union mips_vdso_data *data)
+{
+	++data->seq_count;
+
+	/* Ensure sequence update is written before other data page values. */
+	smp_wmb();
+}
+
+static inline void vdso_data_write_end(union mips_vdso_data *data)
+{
+	/* Ensure data values are written before updating sequence again. */
+	smp_wmb();
+	++data->seq_count;
+}
 
 #endif /* __ASM_VDSO_H */