Commit 91b41a23 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

s390/time: Provide sched_clock_noinstr() 



With the intent to provide local_clock_noinstr(), a variant of
local_clock() that's safe to be called from noinstr code (with the
assumption that any such code will already be non-preemptible),
prepare for things by providing a noinstr sched_clock_noinstr()
function.

Specifically, preempt_enable_*() calls out to schedule(), which upsets
noinstr validation efforts.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>  # Hyper-V
Link: https://lore.kernel.org/r/20230519102715.570170436@infradead.org
parent 6b10fef0

arch/s390/include/asm/timex.h

+9 −4
Original line number Diff line number Diff line
@@ -63,7 +63,7 @@ static inline int store_tod_clock_ext_cc(union tod_clock *clk) 
	return cc;

}



static inline void store_tod_clock_ext(union tod_clock *tod)

static __always_inline void store_tod_clock_ext(union tod_clock *tod)

{

	asm volatile("stcke %0" : "=Q" (*tod) : : "cc");

}
@@ -177,7 +177,7 @@ static inline void local_tick_enable(unsigned long comp) 


typedef unsigned long cycles_t;



static inline unsigned long get_tod_clock(void)

static __always_inline unsigned long get_tod_clock(void)

{

	union tod_clock clk;
@@ -204,6 +204,11 @@ void init_cpu_timer(void); 


extern union tod_clock tod_clock_base;



static __always_inline unsigned long __get_tod_clock_monotonic(void)

{

	return get_tod_clock() - tod_clock_base.tod;

}



/**

 * get_clock_monotonic - returns current time in clock rate units

 *
@@ -216,7 +221,7 @@ static inline unsigned long get_tod_clock_monotonic(void) 
	unsigned long tod;



	preempt_disable_notrace();

	tod = get_tod_clock() - tod_clock_base.tod;

	tod = __get_tod_clock_monotonic();

	preempt_enable_notrace();

	return tod;

}
@@ -240,7 +245,7 @@ static inline unsigned long get_tod_clock_monotonic(void) 
 * -> ns = (th * 125) + ((tl * 125) >> 9);

 *

 */

static inline unsigned long tod_to_ns(unsigned long todval)

static __always_inline unsigned long tod_to_ns(unsigned long todval)

{

	return ((todval >> 9) * 125) + (((todval & 0x1ff) * 125) >> 9);

}

arch/s390/kernel/time.c

+5 −0
Original line number Diff line number Diff line
@@ -102,6 +102,11 @@ void __init time_early_init(void) 
			((long) qui.old_leap * 4096000000L);

}



unsigned long long noinstr sched_clock_noinstr(void)

{

	return tod_to_ns(__get_tod_clock_monotonic());

}



/*

 * Scheduler clock - returns current time in nanosec units.

 */