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-rw-r--r--include/vdso/vsyscall.h3
-rw-r--r--kernel/time/timekeeping.c2
-rw-r--r--kernel/time/timekeeping_internal.h11
-rw-r--r--kernel/time/vsyscall.c41
4 files changed, 53 insertions, 4 deletions
diff --git a/include/vdso/vsyscall.h b/include/vdso/vsyscall.h
index 2c6134e0c23d..b0fdc9c6bf43 100644
--- a/include/vdso/vsyscall.h
+++ b/include/vdso/vsyscall.h
@@ -6,6 +6,9 @@
#include <asm/vdso/vsyscall.h>
+unsigned long vdso_update_begin(void);
+void vdso_update_end(unsigned long flags);
+
#endif /* !__ASSEMBLY__ */
#endif /* __VDSO_VSYSCALL_H */
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 63a632f9896c..4c7212f3c603 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -50,7 +50,7 @@ static struct {
.seq = SEQCNT_ZERO(tk_core.seq),
};
-static DEFINE_RAW_SPINLOCK(timekeeper_lock);
+DEFINE_RAW_SPINLOCK(timekeeper_lock);
static struct timekeeper shadow_timekeeper;
/**
diff --git a/kernel/time/timekeeping_internal.h b/kernel/time/timekeeping_internal.h
index bcbb52db2256..4ca2787d1642 100644
--- a/kernel/time/timekeeping_internal.h
+++ b/kernel/time/timekeeping_internal.h
@@ -1,12 +1,14 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _TIMEKEEPING_INTERNAL_H
#define _TIMEKEEPING_INTERNAL_H
-/*
- * timekeeping debug functions
- */
+
#include <linux/clocksource.h>
+#include <linux/spinlock.h>
#include <linux/time.h>
+/*
+ * timekeeping debug functions
+ */
#ifdef CONFIG_DEBUG_FS
extern void tk_debug_account_sleep_time(const struct timespec64 *t);
#else
@@ -31,4 +33,7 @@ static inline u64 clocksource_delta(u64 now, u64 last, u64 mask)
}
#endif
+/* Semi public for serialization of non timekeeper VDSO updates. */
+extern raw_spinlock_t timekeeper_lock;
+
#endif /* _TIMEKEEPING_INTERNAL_H */
diff --git a/kernel/time/vsyscall.c b/kernel/time/vsyscall.c
index 54ce6eb2ca36..88e6b8ed6ca5 100644
--- a/kernel/time/vsyscall.c
+++ b/kernel/time/vsyscall.c
@@ -13,6 +13,8 @@
#include <vdso/helpers.h>
#include <vdso/vsyscall.h>
+#include "timekeeping_internal.h"
+
static inline void update_vdso_data(struct vdso_data *vdata,
struct timekeeper *tk)
{
@@ -127,3 +129,42 @@ void update_vsyscall_tz(void)
__arch_sync_vdso_data(vdata);
}
+
+/**
+ * vdso_update_begin - Start of a VDSO update section
+ *
+ * Allows architecture code to safely update the architecture specific VDSO
+ * data. Disables interrupts, acquires timekeeper lock to serialize against
+ * concurrent updates from timekeeping and invalidates the VDSO data
+ * sequence counter to prevent concurrent readers from accessing
+ * inconsistent data.
+ *
+ * Returns: Saved interrupt flags which need to be handed in to
+ * vdso_update_end().
+ */
+unsigned long vdso_update_begin(void)
+{
+ struct vdso_data *vdata = __arch_get_k_vdso_data();
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
+ vdso_write_begin(vdata);
+ return flags;
+}
+
+/**
+ * vdso_update_end - End of a VDSO update section
+ * @flags: Interrupt flags as returned from vdso_update_begin()
+ *
+ * Pairs with vdso_update_begin(). Marks vdso data consistent, invokes data
+ * synchronization if the architecture requires it, drops timekeeper lock
+ * and restores interrupt flags.
+ */
+void vdso_update_end(unsigned long flags)
+{
+ struct vdso_data *vdata = __arch_get_k_vdso_data();
+
+ vdso_write_end(vdata);
+ __arch_sync_vdso_data(vdata);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
+}

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