Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
new file mode 100644
index 0000000..2e302c0
--- /dev/null
+++ b/include/vdso/datapage.h
@@ -0,0 +1,89 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __VDSO_DATAPAGE_H
+#define __VDSO_DATAPAGE_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/bits.h>
+#include <linux/time.h>
+#include <linux/types.h>
+
+#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
+ * @tz_minuteswest: minutes west of Greenwich
+ * @tz_dsttime: type of DST correction
+ * @hrtimer_res: hrtimer resolution
+ * @__unused: unused
+ *
+ * vdso_data will be accessed by 64 bit and compat code at the same time
+ * so we should be careful before modifying this structure.
+ */
+struct vdso_data {
+ u32 seq;
+
+ s32 clock_mode;
+ u64 cycle_last;
+ u64 mask;
+ u32 mult;
+ u32 shift;
+
+ struct vdso_timestamp basetime[VDSO_BASES];
+
+ s32 tz_minuteswest;
+ s32 tz_dsttime;
+ u32 hrtimer_res;
+ u32 __unused;
+};
+
+/*
+ * 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")));
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __VDSO_DATAPAGE_H */
diff --git a/include/vdso/helpers.h b/include/vdso/helpers.h
new file mode 100644
index 0000000..01641db
--- /dev/null
+++ b/include/vdso/helpers.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __VDSO_HELPERS_H
+#define __VDSO_HELPERS_H
+
+#ifndef __ASSEMBLY__
+
+#include <vdso/datapage.h>
+
+static __always_inline u32 vdso_read_begin(const struct vdso_data *vd)
+{
+ u32 seq;
+
+ while ((seq = READ_ONCE(vd->seq)) & 1)
+ cpu_relax();
+
+ smp_rmb();
+ return seq;
+}
+
+static __always_inline u32 vdso_read_retry(const struct vdso_data *vd,
+ u32 start)
+{
+ u32 seq;
+
+ smp_rmb();
+ seq = READ_ONCE(vd->seq);
+ return seq != start;
+}
+
+static __always_inline void vdso_write_begin(struct vdso_data *vd)
+{
+ /*
+ * WRITE_ONCE it is required otherwise the compiler can validly tear
+ * updates to vd[x].seq and it is possible that the value seen by the
+ * reader it is inconsistent.
+ */
+ WRITE_ONCE(vd[CS_HRES_COARSE].seq, vd[CS_HRES_COARSE].seq + 1);
+ WRITE_ONCE(vd[CS_RAW].seq, vd[CS_RAW].seq + 1);
+ smp_wmb();
+}
+
+static __always_inline void vdso_write_end(struct vdso_data *vd)
+{
+ smp_wmb();
+ /*
+ * WRITE_ONCE it is required otherwise the compiler can validly tear
+ * updates to vd[x].seq and it is possible that the value seen by the
+ * reader it is inconsistent.
+ */
+ WRITE_ONCE(vd[CS_HRES_COARSE].seq, vd[CS_HRES_COARSE].seq + 1);
+ WRITE_ONCE(vd[CS_RAW].seq, vd[CS_RAW].seq + 1);
+}
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __VDSO_HELPERS_H */
diff --git a/include/vdso/vsyscall.h b/include/vdso/vsyscall.h
new file mode 100644
index 0000000..2c6134e
--- /dev/null
+++ b/include/vdso/vsyscall.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __VDSO_VSYSCALL_H
+#define __VDSO_VSYSCALL_H
+
+#ifndef __ASSEMBLY__
+
+#include <asm/vdso/vsyscall.h>
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __VDSO_VSYSCALL_H */