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-rw-r--r--include/vdso/datapage.h142
1 files changed, 142 insertions, 0 deletions
diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
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+++ b/include/vdso/datapage.h
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+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __VDSO_DATAPAGE_H
+#define __VDSO_DATAPAGE_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/compiler.h>
+#include <uapi/linux/time.h>
+#include <uapi/linux/types.h>
+#include <uapi/asm-generic/errno-base.h>
+
+#include <vdso/bits.h>
+#include <vdso/clocksource.h>
+#include <vdso/ktime.h>
+#include <vdso/limits.h>
+#include <vdso/math64.h>
+#include <vdso/processor.h>
+#include <vdso/time.h>
+#include <vdso/time32.h>
+#include <vdso/time64.h>
+
+#ifdef CONFIG_ARCH_HAS_VDSO_DATA
+#include <asm/vdso/data.h>
+#else
+struct arch_vdso_data {};
+#endif
+
+#define VDSO_BASES (CLOCK_TAI + 1)
+#define VDSO_HRES (BIT(CLOCK_REALTIME) | \
+ BIT(CLOCK_MONOTONIC) | \
+ BIT(CLOCK_BOOTTIME) | \
+ BIT(CLOCK_TAI))
+#define VDSO_COARSE (BIT(CLOCK_REALTIME_COARSE) | \
+ BIT(CLOCK_MONOTONIC_COARSE))
+#define VDSO_RAW (BIT(CLOCK_MONOTONIC_RAW))
+
+#define CS_HRES_COARSE 0
+#define CS_RAW 1
+#define CS_BASES (CS_RAW + 1)
+
+/**
+ * struct vdso_timestamp - basetime per clock_id
+ * @sec: seconds
+ * @nsec: nanoseconds
+ *
+ * There is one vdso_timestamp object in vvar for each vDSO-accelerated
+ * clock_id. For high-resolution clocks, this encodes the time
+ * corresponding to vdso_data.cycle_last. For coarse clocks this encodes
+ * the actual time.
+ *
+ * To be noticed that for highres clocks nsec is left-shifted by
+ * vdso_data.cs[x].shift.
+ */
+struct vdso_timestamp {
+ u64 sec;
+ u64 nsec;
+};
+
+/**
+ * struct vdso_data - vdso datapage representation
+ * @seq: timebase sequence counter
+ * @clock_mode: clock mode
+ * @cycle_last: timebase at clocksource init
+ * @mask: clocksource mask
+ * @mult: clocksource multiplier
+ * @shift: clocksource shift
+ * @basetime[clock_id]: basetime per clock_id
+ * @offset[clock_id]: time namespace offset per clock_id
+ * @tz_minuteswest: minutes west of Greenwich
+ * @tz_dsttime: type of DST correction
+ * @hrtimer_res: hrtimer resolution
+ * @__unused: unused
+ * @arch_data: architecture specific data (optional, defaults
+ * to an empty struct)
+ *
+ * vdso_data will be accessed by 64 bit and compat code at the same time
+ * so we should be careful before modifying this structure.
+ *
+ * @basetime is used to store the base time for the system wide time getter
+ * VVAR page.
+ *
+ * @offset is used by the special time namespace VVAR pages which are
+ * installed instead of the real VVAR page. These namespace pages must set
+ * @seq to 1 and @clock_mode to VDSO_CLOCKMODE_TIMENS to force the code into
+ * the time namespace slow path. The namespace aware functions retrieve the
+ * real system wide VVAR page, read host time and add the per clock offset.
+ * For clocks which are not affected by time namespace adjustment the
+ * offset must be zero.
+ */
+struct vdso_data {
+ u32 seq;
+
+ s32 clock_mode;
+ u64 cycle_last;
+ u64 mask;
+ u32 mult;
+ u32 shift;
+
+ union {
+ struct vdso_timestamp basetime[VDSO_BASES];
+ struct timens_offset offset[VDSO_BASES];
+ };
+
+ s32 tz_minuteswest;
+ s32 tz_dsttime;
+ u32 hrtimer_res;
+ u32 __unused;
+
+ struct arch_vdso_data arch_data;
+};
+
+/*
+ * We use the hidden visibility to prevent the compiler from generating a GOT
+ * relocation. Not only is going through a GOT useless (the entry couldn't and
+ * must not be overridden by another library), it does not even work: the linker
+ * cannot generate an absolute address to the data page.
+ *
+ * With the hidden visibility, the compiler simply generates a PC-relative
+ * relocation, and this is what we need.
+ */
+extern struct vdso_data _vdso_data[CS_BASES] __attribute__((visibility("hidden")));
+extern struct vdso_data _timens_data[CS_BASES] __attribute__((visibility("hidden")));
+
+/*
+ * The generic vDSO implementation requires that gettimeofday.h
+ * provides:
+ * - __arch_get_vdso_data(): to get the vdso datapage.
+ * - __arch_get_hw_counter(): to get the hw counter based on the
+ * clock_mode.
+ * - gettimeofday_fallback(): fallback for gettimeofday.
+ * - clock_gettime_fallback(): fallback for clock_gettime.
+ * - clock_getres_fallback(): fallback for clock_getres.
+ */
+#ifdef ENABLE_COMPAT_VDSO
+#include <asm/vdso/compat_gettimeofday.h>
+#else
+#include <asm/vdso/gettimeofday.h>
+#endif /* ENABLE_COMPAT_VDSO */
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __VDSO_DATAPAGE_H */