Hi,
We are observing issue on A73 core where ERRATUM_858921 is broken.
On 5.15 kernel arch_timer_enable_workaround is set by reading
arm64_858921_read_cntpct_el0 and arm64_858921_read_cntvct_el0 during
timer register using following path.
arch_timer_enable_workaround->atomic_set(&timer_unstable_counter_workaround_in_use,
1);
[code snap]
564 static
565 void arch_timer_enable_workaround(const struct
arch_timer_erratum_workaround *wa,
566 bool local)
567 {
568 int i;
569
570 if (local) {
571 __this_cpu_write(timer_unstable_counter_workaround, wa);
572 } else {
573 for_each_possible_cpu(i)
574 per_cpu(timer_unstable_counter_workaround, i) = wa;
575 }
576
577 if (wa->read_cntvct_el0 || wa->read_cntpct_el0)
578 atomic_set(&timer_unstable_counter_workaround_in_use, 1);
and based on above workaround enablement , appropriate function to get
counter is used.
1008 static void __init arch_counter_register(unsigned type)
1009 {
1010 u64 start_count;
1011
1012 /* Register the CP15 based counter if we have one */
1013 if (type & ARCH_TIMER_TYPE_CP15) {
1014 u64 (*rd)(void);
1015
1016 if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) ||
1017 arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) {
1018 if (arch_timer_counter_has_wa())
1019 rd = arch_counter_get_cntvct_stable;
1020 else
1021 rd = arch_counter_get_cntvct;
1022 } else {
1023 if (arch_timer_counter_has_wa())
1024 rd = arch_counter_get_cntpct_stable;
1025 else
1026 rd = arch_counter_get_cntpct;
1027 }
[snap]
1043 /* 56 bits minimum, so we assume worst case rollover */
1044 sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);
As our boot cores are not impacted by errata sched_clock_register() will
register !arch_timer_counter_has_wa() callback.
Now when errata impacted core boots up and sched_clock_register already
register will !arch_timer_counter_has_wa() path.
As sched_clock_register is not per_cpu bases so arch_timer_read_counter
will always point to !arch_timer_counter_has_wa() function calls.
Looks like this bug is side effect of following patch:
commit 0ea415390cd345b7d09e8c9ebd4b68adfe873043
Author: Marc Zyngier <[email protected]>
Date: Mon Apr 8 16:49:07 2019 +0100
clocksource/arm_arch_timer: Use arch_timer_read_counter to access
stable counters
Instead of always going via arch_counter_get_cntvct_stable to
access the
counter workaround, let's have arch_timer_read_counter point to the
right method.
For that, we need to track whether any CPU in the system has a
workaround for the counter. This is done by having an atomic variable
tracking this.
Acked-by: Mark Rutland <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Signed-off-by: Will Deacon <[email protected]>
Thanks
Yogesh Lal
On Thu, Jan 05, 2023 at 07:03:48PM +0530, Yogesh Lal wrote:
> Hi,
>
> We are observing issue on A73 core where ERRATUM_858921 is broken.
Do you *only* see this issue on v5.15.y, or is mainline (e.g. v6.2-rc2) also
broken?
I don't see any fix that fits your exact description below, but I do see that
we've made a bunch of changes in this area since.
>
> On 5.15 kernel arch_timer_enable_workaround is set by reading
> arm64_858921_read_cntpct_el0 and arm64_858921_read_cntvct_el0 during timer
> register using following path.
>
> arch_timer_enable_workaround->atomic_set(&timer_unstable_counter_workaround_in_use,
> 1);
>
> [code snap]
> 564 static
> 565 void arch_timer_enable_workaround(const struct
> arch_timer_erratum_workaround *wa,
> 566 bool local)
> 567 {
> 568 int i;
> 569
> 570 if (local) {
> 571 __this_cpu_write(timer_unstable_counter_workaround, wa);
> 572 } else {
> 573 for_each_possible_cpu(i)
> 574 per_cpu(timer_unstable_counter_workaround, i) = wa;
> 575 }
> 576
> 577 if (wa->read_cntvct_el0 || wa->read_cntpct_el0)
> 578 atomic_set(&timer_unstable_counter_workaround_in_use, 1);
>
>
> and based on above workaround enablement , appropriate function to get
> counter is used.
>
> 1008 static void __init arch_counter_register(unsigned type)
> 1009 {
> 1010 u64 start_count;
> 1011
> 1012 /* Register the CP15 based counter if we have one */
> 1013 if (type & ARCH_TIMER_TYPE_CP15) {
> 1014 u64 (*rd)(void);
> 1015
> 1016 if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) ||
> 1017 arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) {
> 1018 if (arch_timer_counter_has_wa())
> 1019 rd = arch_counter_get_cntvct_stable;
> 1020 else
> 1021 rd = arch_counter_get_cntvct;
> 1022 } else {
> 1023 if (arch_timer_counter_has_wa())
> 1024 rd = arch_counter_get_cntpct_stable;
> 1025 else
> 1026 rd = arch_counter_get_cntpct;
> 1027 }
> [snap]
> 1043 /* 56 bits minimum, so we assume worst case rollover */
> 1044 sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);
>
>
> As our boot cores are not impacted by errata sched_clock_register() will
> register !arch_timer_counter_has_wa() callback.
It would be helpful to mention this fact (that the system is big.LITTLE, and
the boot cores are not Cortex-A73) earlier in the report.
> Now when errata impacted core boots up and sched_clock_register already
> register will !arch_timer_counter_has_wa() path.
> As sched_clock_register is not per_cpu bases so arch_timer_read_counter will
> always point to !arch_timer_counter_has_wa() function calls.
Hmm... yes, AFAICT this cannot work unless the affected CPUs are up before we
probe, and it doesn't make much sense for arch_counter_register() to look at
arch_timer_counter_has_wa() since it can be called before all CPUs are up.
> Looks like this bug is side effect of following patch:
>
> commit 0ea415390cd345b7d09e8c9ebd4b68adfe873043
> Author: Marc Zyngier <[email protected]>
> Date: Mon Apr 8 16:49:07 2019 +0100
>
> clocksource/arm_arch_timer: Use arch_timer_read_counter to access stable
> counters
>
> Instead of always going via arch_counter_get_cntvct_stable to access the
> counter workaround, let's have arch_timer_read_counter point to the
> right method.
>
> For that, we need to track whether any CPU in the system has a
> workaround for the counter. This is done by having an atomic variable
> tracking this.
>
> Acked-by: Mark Rutland <[email protected]>
> Signed-off-by: Marc Zyngier <[email protected]>
> Signed-off-by: Will Deacon <[email protected]>
>
Yeah, that does look to be broken, but I think there are futher issues anyway
(e.g. late onlining).
AFAICT we need to detect this *stupidly early* in the CPU bringup path in order
to handle this safely, which is quite painful.
What a great.
Thanks,
Mark.
On Thu, 05 Jan 2023 13:33:48 +0000,
Yogesh Lal <[email protected]> wrote:
>
> Hi,
>
> We are observing issue on A73 core where ERRATUM_858921 is broken.
>
> On 5.15 kernel arch_timer_enable_workaround is set by reading
> arm64_858921_read_cntpct_el0 and arm64_858921_read_cntvct_el0 during
> timer register using following path.
Have you checked whether the issue is still present on 6.1?
>
> arch_timer_enable_workaround->atomic_set(&timer_unstable_counter_workaround_in_use,
> 1);
>
> [code snap]
> 564 static
> 565 void arch_timer_enable_workaround(const struct
> arch_timer_erratum_workaround *wa,
> 566 bool local)
> 567 {
> 568 int i;
> 569
> 570 if (local) {
> 571 __this_cpu_write(timer_unstable_counter_workaround, wa);
> 572 } else {
> 573 for_each_possible_cpu(i)
> 574 per_cpu(timer_unstable_counter_workaround, i) = wa;
> 575 }
> 576
> 577 if (wa->read_cntvct_el0 || wa->read_cntpct_el0)
> 578 atomic_set(&timer_unstable_counter_workaround_in_use, 1);
>
>
> and based on above workaround enablement , appropriate function to get
> counter is used.
>
> 1008 static void __init arch_counter_register(unsigned type)
> 1009 {
> 1010 u64 start_count;
> 1011
> 1012 /* Register the CP15 based counter if we have one */
> 1013 if (type & ARCH_TIMER_TYPE_CP15) {
> 1014 u64 (*rd)(void);
> 1015
> 1016 if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) ||
> 1017 arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) {
> 1018 if (arch_timer_counter_has_wa())
> 1019 rd = arch_counter_get_cntvct_stable;
> 1020 else
> 1021 rd = arch_counter_get_cntvct;
> 1022 } else {
> 1023 if (arch_timer_counter_has_wa())
> 1024 rd = arch_counter_get_cntpct_stable;
> 1025 else
> 1026 rd = arch_counter_get_cntpct;
> 1027 }
> [snap]
> 1043 /* 56 bits minimum, so we assume worst case rollover */
> 1044 sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);
>
>
> As our boot cores are not impacted by errata sched_clock_register()
> will register !arch_timer_counter_has_wa() callback.
>
> Now when errata impacted core boots up and sched_clock_register
> already register will !arch_timer_counter_has_wa() path.
> As sched_clock_register is not per_cpu bases so
> arch_timer_read_counter will always point to
> !arch_timer_counter_has_wa() function calls.
Please try the following hack, only compile tested as I do not have
access to any affected HW, and report whether this solves your issue
or not. Note that this is based on 6.2-rc2.
Thanks,
M.
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index e09d4427f604..a7cf0a2c86d3 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -230,6 +230,28 @@ static u64 arch_counter_read_cc(const struct cyclecounter *cc)
return arch_timer_read_counter();
}
+static bool arch_timer_counter_has_wa(void);
+
+static u64 (*arch_counter_get_read_fn(void))(void)
+{
+ u64 (*rd)(void);
+
+ if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) ||
+ arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) {
+ if (arch_timer_counter_has_wa())
+ rd = arch_counter_get_cntvct_stable;
+ else
+ rd = arch_counter_get_cntvct;
+ } else {
+ if (arch_timer_counter_has_wa())
+ rd = arch_counter_get_cntpct_stable;
+ else
+ rd = arch_counter_get_cntpct;
+ }
+
+ return rd;
+}
+
static struct clocksource clocksource_counter = {
.name = "arch_sys_counter",
.id = CSID_ARM_ARCH_COUNTER,
@@ -571,8 +593,10 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa
per_cpu(timer_unstable_counter_workaround, i) = wa;
}
- if (wa->read_cntvct_el0 || wa->read_cntpct_el0)
+ 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();
+ }
/*
* Don't use the vdso fastpath if errata require using the
@@ -641,7 +665,7 @@ static bool arch_timer_counter_has_wa(void)
#else
#define arch_timer_check_ool_workaround(t,a) do { } while(0)
#define arch_timer_this_cpu_has_cntvct_wa() ({false;})
-#define arch_timer_counter_has_wa() ({false;})
+static bool arch_timer_counter_has_wa(void) { return false; }
#endif /* CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND */
static __always_inline irqreturn_t timer_handler(const int access,
@@ -1079,22 +1103,7 @@ static void __init arch_counter_register(unsigned type)
/* Register the CP15 based counter if we have one */
if (type & ARCH_TIMER_TYPE_CP15) {
- u64 (*rd)(void);
-
- if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) ||
- arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) {
- if (arch_timer_counter_has_wa())
- rd = arch_counter_get_cntvct_stable;
- else
- rd = arch_counter_get_cntvct;
- } else {
- if (arch_timer_counter_has_wa())
- rd = arch_counter_get_cntpct_stable;
- else
- rd = arch_counter_get_cntpct;
- }
-
- arch_timer_read_counter = rd;
+ 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;
--
Without deviation from the norm, progress is not possible.
On 1/5/2023 7:42 PM, Mark Rutland wrote:
> On Thu, Jan 05, 2023 at 07:03:48PM +0530, Yogesh Lal wrote:
>> Hi,
>>
>> We are observing issue on A73 core where ERRATUM_858921 is broken.
> Do you *only* see this issue on v5.15.y, or is mainline (e.g. v6.2-rc2) also
> broken?
Checked the code path and looks like its broken on mainline also.
> I don't see any fix that fits your exact description below, but I do see that
> we've made a bunch of changes in this area since.
>
>> On 5.15 kernel arch_timer_enable_workaround is set by reading
>> arm64_858921_read_cntpct_el0 and arm64_858921_read_cntvct_el0 during timer
>> register using following path.
>>
>> arch_timer_enable_workaround->atomic_set(&timer_unstable_counter_workaround_in_use,
>> 1);
>>
>> [code snap]
>> 564 static
>> 565 void arch_timer_enable_workaround(const struct
>> arch_timer_erratum_workaround *wa,
>> 566 bool local)
>> 567 {
>> 568 int i;
>> 569
>> 570 if (local) {
>> 571 __this_cpu_write(timer_unstable_counter_workaround, wa);
>> 572 } else {
>> 573 for_each_possible_cpu(i)
>> 574 per_cpu(timer_unstable_counter_workaround, i) = wa;
>> 575 }
>> 576
>> 577 if (wa->read_cntvct_el0 || wa->read_cntpct_el0)
>> 578 atomic_set(&timer_unstable_counter_workaround_in_use, 1);
>>
>>
>> and based on above workaround enablement , appropriate function to get
>> counter is used.
>>
>> 1008 static void __init arch_counter_register(unsigned type)
>> 1009 {
>> 1010 u64 start_count;
>> 1011
>> 1012 /* Register the CP15 based counter if we have one */
>> 1013 if (type & ARCH_TIMER_TYPE_CP15) {
>> 1014 u64 (*rd)(void);
>> 1015
>> 1016 if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) ||
>> 1017 arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) {
>> 1018 if (arch_timer_counter_has_wa())
>> 1019 rd = arch_counter_get_cntvct_stable;
>> 1020 else
>> 1021 rd = arch_counter_get_cntvct;
>> 1022 } else {
>> 1023 if (arch_timer_counter_has_wa())
>> 1024 rd = arch_counter_get_cntpct_stable;
>> 1025 else
>> 1026 rd = arch_counter_get_cntpct;
>> 1027 }
>> [snap]
>> 1043 /* 56 bits minimum, so we assume worst case rollover */
>> 1044 sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);
>>
>>
>> As our boot cores are not impacted by errata sched_clock_register() will
>> register !arch_timer_counter_has_wa() callback.
> It would be helpful to mention this fact (that the system is big.LITTLE, and
> the boot cores are not Cortex-A73) earlier in the report.
will take care
>
>> Now when errata impacted core boots up and sched_clock_register already
>> register will !arch_timer_counter_has_wa() path.
>> As sched_clock_register is not per_cpu bases so arch_timer_read_counter will
>> always point to !arch_timer_counter_has_wa() function calls.
> Hmm... yes, AFAICT this cannot work unless the affected CPUs are up before we
> probe, and it doesn't make much sense for arch_counter_register() to look at
> arch_timer_counter_has_wa() since it can be called before all CPUs are up.
>
>> Looks like this bug is side effect of following patch:
>>
>> commit 0ea415390cd345b7d09e8c9ebd4b68adfe873043
>> Author: Marc Zyngier <[email protected]>
>> Date: Mon Apr 8 16:49:07 2019 +0100
>>
>> clocksource/arm_arch_timer: Use arch_timer_read_counter to access stable
>> counters
>>
>> Instead of always going via arch_counter_get_cntvct_stable to access the
>> counter workaround, let's have arch_timer_read_counter point to the
>> right method.
>>
>> For that, we need to track whether any CPU in the system has a
>> workaround for the counter. This is done by having an atomic variable
>> tracking this.
>>
>> Acked-by: Mark Rutland <[email protected]>
>> Signed-off-by: Marc Zyngier <[email protected]>
>> Signed-off-by: Will Deacon <[email protected]>
>>
> Yeah, that does look to be broken, but I think there are futher issues anyway
> (e.g. late onlining).
>
> AFAICT we need to detect this *stupidly early* in the CPU bringup path in order
> to handle this safely, which is quite painful.
>
> What a great.
>
> Thanks,
> Mark.
On 1/5/2023 7:52 PM, Marc Zyngier wrote:
> On Thu, 05 Jan 2023 13:33:48 +0000,
> Yogesh Lal <[email protected]> wrote:
>> Hi,
>>
>> We are observing issue on A73 core where ERRATUM_858921 is broken.
>>
>> On 5.15 kernel arch_timer_enable_workaround is set by reading
>> arm64_858921_read_cntpct_el0 and arm64_858921_read_cntvct_el0 during
>> timer register using following path.
> Have you checked whether the issue is still present on 6.1?
yes, its preset there as well.
>
>> arch_timer_enable_workaround->atomic_set(&timer_unstable_counter_workaround_in_use,
>> 1);
>>
>> [code snap]
>> 564 static
>> 565 void arch_timer_enable_workaround(const struct
>> arch_timer_erratum_workaround *wa,
>> 566 bool local)
>> 567 {
>> 568 int i;
>> 569
>> 570 if (local) {
>> 571 __this_cpu_write(timer_unstable_counter_workaround, wa);
>> 572 } else {
>> 573 for_each_possible_cpu(i)
>> 574 per_cpu(timer_unstable_counter_workaround, i) = wa;
>> 575 }
>> 576
>> 577 if (wa->read_cntvct_el0 || wa->read_cntpct_el0)
>> 578 atomic_set(&timer_unstable_counter_workaround_in_use, 1);
>>
>>
>> and based on above workaround enablement , appropriate function to get
>> counter is used.
>>
>> 1008 static void __init arch_counter_register(unsigned type)
>> 1009 {
>> 1010 u64 start_count;
>> 1011
>> 1012 /* Register the CP15 based counter if we have one */
>> 1013 if (type & ARCH_TIMER_TYPE_CP15) {
>> 1014 u64 (*rd)(void);
>> 1015
>> 1016 if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) ||
>> 1017 arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) {
>> 1018 if (arch_timer_counter_has_wa())
>> 1019 rd = arch_counter_get_cntvct_stable;
>> 1020 else
>> 1021 rd = arch_counter_get_cntvct;
>> 1022 } else {
>> 1023 if (arch_timer_counter_has_wa())
>> 1024 rd = arch_counter_get_cntpct_stable;
>> 1025 else
>> 1026 rd = arch_counter_get_cntpct;
>> 1027 }
>> [snap]
>> 1043 /* 56 bits minimum, so we assume worst case rollover */
>> 1044 sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);
>>
>>
>> As our boot cores are not impacted by errata sched_clock_register()
>> will register !arch_timer_counter_has_wa() callback.
>>
>> Now when errata impacted core boots up and sched_clock_register
>> already register will !arch_timer_counter_has_wa() path.
>> As sched_clock_register is not per_cpu bases so
>> arch_timer_read_counter will always point to
>> !arch_timer_counter_has_wa() function calls.
> Please try the following hack, only compile tested as I do not have
> access to any affected HW, and report whether this solves your issue
> or not. Note that this is based on 6.2-rc2.
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.
1007 static void __init arch_counter_register(unsigned type)
1008 {
[snap]
1043 /* 56 bits minimum, so we assume worst case rollover */
1044 sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);
Also update_clock_read_data will called with
!arch_timer_counter_has_wa() read function calls.
153 void sched_clock_register(u64 (*read)(void), int bits, unsigned long
rate)
[snap]
183 cd.actual_read_sched_clock = read;
184
185 rd.read_sched_clock = read;
186 rd.sched_clock_mask = new_mask;
187 rd.mult = new_mult;
188 rd.shift = new_shift;
189 rd.epoch_cyc = new_epoch;
190 rd.epoch_ns = ns;
191
192 update_clock_read_data(&rd);
> Thanks,
>
> M.
>
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index e09d4427f604..a7cf0a2c86d3 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -230,6 +230,28 @@ static u64 arch_counter_read_cc(const struct cyclecounter *cc)
> return arch_timer_read_counter();
> }
>
> +static bool arch_timer_counter_has_wa(void);
> +
> +static u64 (*arch_counter_get_read_fn(void))(void)
> +{
> + u64 (*rd)(void);
> +
> + if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) ||
> + arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) {
> + if (arch_timer_counter_has_wa())
> + rd = arch_counter_get_cntvct_stable;
> + else
> + rd = arch_counter_get_cntvct;
> + } else {
> + if (arch_timer_counter_has_wa())
> + rd = arch_counter_get_cntpct_stable;
> + else
> + rd = arch_counter_get_cntpct;
> + }
> +
> + return rd;
> +}
> +
> static struct clocksource clocksource_counter = {
> .name = "arch_sys_counter",
> .id = CSID_ARM_ARCH_COUNTER,
> @@ -571,8 +593,10 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa
> per_cpu(timer_unstable_counter_workaround, i) = wa;
> }
>
> - if (wa->read_cntvct_el0 || wa->read_cntpct_el0)
> + 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();
> + }
>
> /*
> * Don't use the vdso fastpath if errata require using the
> @@ -641,7 +665,7 @@ static bool arch_timer_counter_has_wa(void)
> #else
> #define arch_timer_check_ool_workaround(t,a) do { } while(0)
> #define arch_timer_this_cpu_has_cntvct_wa() ({false;})
> -#define arch_timer_counter_has_wa() ({false;})
> +static bool arch_timer_counter_has_wa(void) { return false; }
> #endif /* CONFIG_ARM_ARCH_TIMER_OOL_WORKAROUND */
>
> static __always_inline irqreturn_t timer_handler(const int access,
> @@ -1079,22 +1103,7 @@ static void __init arch_counter_register(unsigned type)
>
> /* Register the CP15 based counter if we have one */
> if (type & ARCH_TIMER_TYPE_CP15) {
> - u64 (*rd)(void);
> -
> - if ((IS_ENABLED(CONFIG_ARM64) && !is_hyp_mode_available()) ||
> - arch_timer_uses_ppi == ARCH_TIMER_VIRT_PPI) {
> - if (arch_timer_counter_has_wa())
> - rd = arch_counter_get_cntvct_stable;
> - else
> - rd = arch_counter_get_cntvct;
> - } else {
> - if (arch_timer_counter_has_wa())
> - rd = arch_counter_get_cntpct_stable;
> - else
> - rd = arch_counter_get_cntpct;
> - }
> -
> - arch_timer_read_counter = rd;
> + 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;
>
On Mon, 09 Jan 2023 06:52:20 +0000,
Yogesh Lal <[email protected]> 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.
On 1/9/2023 4:09 PM, Marc Zyngier wrote:
> On Mon, 09 Jan 2023 06:52:20 +0000,
> Yogesh Lal <[email protected]> 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 for the patch, its working fine now.
>
> 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);
>
>