Merge tag 'timers-core-2024-05-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timers and timekeeping updates from Thomas Gleixner:
 "Core code:

   - Make timekeeping and VDSO time readouts resilent against math
     overflow:

     In guest context the kernel is prone to math overflow when the host
     defers the timer interrupt due to overload, malfunction or malice.

     This can be mitigated by checking the clocksource delta for the
     maximum deferrement which is readily available. If that value is
     exceeded then the code uses a slowpath function which can handle
     the multiplication overflow.

     This functionality is enabled unconditionally in the kernel, but
     made conditional in the VDSO code. The latter is conditional
     because it allows architectures to optimize the check so it is not
     causing performance regressions.

     On X86 this is achieved by reworking the existing check for
     negative TSC deltas as a negative delta obviously exceeds the
     maximum deferrement when it is evaluated as an unsigned value. That
     avoids two conditionals in the hotpath and allows to hide both the
     negative delta and the large delta handling in the same slow path.

   - Add an initial minimal ktime_t abstraction for Rust

   - The usual boring cleanups and enhancements

  Drivers:

   - Boring updates to device trees and trivial enhancements in various
     drivers"

* tag 'timers-core-2024-05-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
  clocksource/drivers/arm_arch_timer: Mark hisi_161010101_oem_info const
  clocksource/drivers/timer-ti-dm: Remove an unused field in struct dmtimer
  clocksource/drivers/renesas-ostm: Avoid reprobe after successful early probe
  clocksource/drivers/renesas-ostm: Allow OSTM driver to reprobe for RZ/V2H(P) SoC
  dt-bindings: timer: renesas: ostm: Document Renesas RZ/V2H(P) SoC
  rust: time: doc: Add missing C header links
  clocksource: Make the int help prompt unit readable in ncurses
  hrtimer: Rename __hrtimer_hres_active() to hrtimer_hres_active()
  timerqueue: Remove never used function timerqueue_node_expires()
  rust: time: Add Ktime
  vdso: Fix powerpc build U64_MAX undeclared error
  clockevents: Convert s[n]printf() to sysfs_emit()
  clocksource: Convert s[n]printf() to sysfs_emit()
  clocksource: Make watchdog and suspend-timing multiplication overflow safe
  timekeeping: Let timekeeping_cycles_to_ns() handle both under and overflow
  timekeeping: Make delta calculation overflow safe
  timekeeping: Prepare timekeeping_cycles_to_ns() for overflow safety
  timekeeping: Fold in timekeeping_delta_to_ns()
  timekeeping: Consolidate timekeeping helpers
  timekeeping: Refactor timekeeping helpers
  ...

4 files changed, 44 insertions, 11 deletions

diff --git a/include/linux/math64.h b/include/linux/math64.h
index bf74478926d4..d34def7f9a8c 100644
--- a/include/linux/math64.h
+++ b/include/linux/math64.h
@@ -4,8 +4,8 @@
 
 #include <linux/types.h>
 #include <linux/math.h>
-#include <vdso/math64.h>
 #include <asm/div64.h>
+#include <vdso/math64.h>
 
 #if BITS_PER_LONG == 64
 
@@ -179,16 +179,12 @@ static __always_inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift)
 #ifndef mul_u64_u32_shr
 static __always_inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift)
 {
-	u32 ah, al;
+	u32 ah = a >> 32, al = a;
 	u64 ret;
 
-	al = a;
-	ah = a >> 32;
-
 	ret = mul_u32_u32(al, mul) >> shift;
 	if (ah)
 		ret += mul_u32_u32(ah, mul) << (32 - shift);
-
 	return ret;
 }
 #endif /* mul_u64_u32_shr */
diff --git a/include/linux/timerqueue.h b/include/linux/timerqueue.h
index 62973f7d4610..d306d9dd2207 100644
--- a/include/linux/timerqueue.h
+++ b/include/linux/timerqueue.h
@@ -37,11 +37,6 @@ static inline bool timerqueue_node_queued(struct timerqueue_node *node)
 	return !RB_EMPTY_NODE(&node->node);
 }
 
-static inline bool timerqueue_node_expires(struct timerqueue_node *node)
-{
-	return node->expires;
-}
-
 static inline void timerqueue_init_head(struct timerqueue_head *head)
 {
 	head->rb_root = RB_ROOT_CACHED;
diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h
index c71ddb6d4691..d04d394db064 100644
--- a/include/vdso/datapage.h
+++ b/include/vdso/datapage.h
@@ -61,6 +61,7 @@ struct vdso_timestamp {
  * @seq:		timebase sequence counter
  * @clock_mode:		clock mode
  * @cycle_last:		timebase at clocksource init
+ * @max_cycles:		maximum cycles which won't overflow 64bit multiplication
  * @mask:		clocksource mask
  * @mult:		clocksource multiplier
  * @shift:		clocksource shift
@@ -92,6 +93,9 @@ struct vdso_data {
 
 	s32			clock_mode;
 	u64			cycle_last;
+#ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
+	u64			max_cycles;
+#endif
 	u64			mask;
 	u32			mult;
 	u32			shift;
diff --git a/include/vdso/math64.h b/include/vdso/math64.h
index 7da703ee5561..22ae212f8b28 100644
--- a/include/vdso/math64.h
+++ b/include/vdso/math64.h
@@ -21,4 +21,42 @@ __iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
 	return ret;
 }
 
+#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
+
+#ifndef mul_u64_u32_add_u64_shr
+static __always_inline u64 mul_u64_u32_add_u64_shr(u64 a, u32 mul, u64 b, unsigned int shift)
+{
+	return (u64)((((unsigned __int128)a * mul) + b) >> shift);
+}
+#endif /* mul_u64_u32_add_u64_shr */
+
+#else
+
+#ifndef mul_u64_u32_add_u64_shr
+#ifndef mul_u32_u32
+static inline u64 mul_u32_u32(u32 a, u32 b)
+{
+	return (u64)a * b;
+}
+#define mul_u32_u32 mul_u32_u32
+#endif
+static __always_inline u64 mul_u64_u32_add_u64_shr(u64 a, u32 mul, u64 b, unsigned int shift)
+{
+	u32 ah = a >> 32, al = a;
+	bool ovf;
+	u64 ret;
+
+	ovf = __builtin_add_overflow(mul_u32_u32(al, mul), b, &ret);
+	ret >>= shift;
+	if (ovf && shift)
+		ret += 1ULL << (64 - shift);
+	if (ah)
+		ret += mul_u32_u32(ah, mul) << (32 - shift);
+
+	return ret;
+}
+#endif /* mul_u64_u32_add_u64_shr */
+
+#endif
+
 #endif /* __VDSO_MATH64_H */