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SubjectRe: ERRATUM_858921 is broken on 5.15 kernel
On Mon, 09 Jan 2023 06:52:20 +0000,
Yogesh Lal <quic_ylal@quicinc.com> wrote:
>
> tested it on affected h/w but looks like sched_clock is still pointing
> to !arch_timer_counter_has_wa() function calls,
> may be due to sched_clock_register will register once during non
> errata impacted core booting.

Ah, of course. We register the function itself instead of an
indirection. Please try this on top of the previous patch.

Thanks,

M.

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index a7cf0a2c86d3..8232c86b9e7c 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -217,7 +217,12 @@ static notrace u64 arch_counter_get_cntvct(void)
* to exist on arm64. arm doesn't use this before DT is probed so even
* if we don't have the cp15 accessors we won't have a problem.
*/
-u64 (*arch_timer_read_counter)(void) __ro_after_init = arch_counter_get_cntvct;
+static u64 (*__arch_timer_read_counter)(void) __ro_after_init = arch_counter_get_cntvct;
+
+u64 arch_timer_read_counter(void)
+{
+ return __arch_timer_read_counter();
+}
EXPORT_SYMBOL_GPL(arch_timer_read_counter);

static u64 arch_counter_read(struct clocksource *cs)
@@ -595,7 +600,7 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa

if (wa->read_cntvct_el0 || wa->read_cntpct_el0) {
atomic_set(&timer_unstable_counter_workaround_in_use, 1);
- arch_timer_read_counter = arch_counter_get_read_fn();
+ __arch_timer_read_counter = arch_counter_get_read_fn();
}

/*
@@ -1103,10 +1108,10 @@ static void __init arch_counter_register(unsigned type)

/* Register the CP15 based counter if we have one */
if (type & ARCH_TIMER_TYPE_CP15) {
- arch_timer_read_counter = arch_counter_get_read_fn();
+ __arch_timer_read_counter = arch_counter_get_read_fn();
clocksource_counter.vdso_clock_mode = vdso_default;
} else {
- arch_timer_read_counter = arch_counter_get_cntvct_mem;
+ __arch_timer_read_counter = arch_counter_get_cntvct_mem;
}

width = arch_counter_get_width();
diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h
index e3c3816d19ba..3ac297a756e8 100644
--- a/include/clocksource/arm_arch_timer.h
+++ b/include/clocksource/arm_arch_timer.h
@@ -89,7 +89,7 @@ struct arch_timer_mem {
#ifdef CONFIG_ARM_ARCH_TIMER

extern u32 arch_timer_get_rate(void);
-extern u64 (*arch_timer_read_counter)(void);
+extern u64 arch_timer_read_counter(void);
extern struct arch_timer_kvm_info *arch_timer_get_kvm_info(void);
extern bool arch_timer_evtstrm_available(void);

--
Without deviation from the norm, progress is not possible.

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