diff options
| -rw-r--r-- | include/vdso/vsyscall.h | 3 | ||||
| -rw-r--r-- | kernel/time/timekeeping.c | 2 | ||||
| -rw-r--r-- | kernel/time/timekeeping_internal.h | 11 | ||||
| -rw-r--r-- | kernel/time/vsyscall.c | 41 |
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); +} |