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s390/time: Provide sched_clock_noinstr()

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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: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>  # Hyper-V
Link: https://lore.kernel.org/r/20230519102715.570170436@infradead.org
This commit is contained in:
Peter Zijlstra
2023-05-19 12:21:04 +02:00
parent 6b10fef09f
commit 91b41a2375
2 changed files with 14 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
arch/s390/include/asm/timex.h
View File

@@ -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);
}

5
arch/s390/kernel/time.c
View File

@@ -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.
*/