'event->attr.type != event->pmu->type' has been done in
core.c::perf_init_event() ,core.c::perf_event_modify_attr(), etc.
This PMU is an uncore one. The core framework has disallowed
uncore-task events. So the judgement to event->cpu < 0 is no mean.
The two judgements have been done in kernel/events/core.c
Signed-off-by: JiaLong.Yang <[email protected]>
---
drivers/perf/arm_smmuv3_pmu.c | 8 --------
1 file changed, 8 deletions(-)
diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
index 6303b82566f9..8ea4a3227165 100644
--- a/drivers/perf/arm_smmuv3_pmu.c
+++ b/drivers/perf/arm_smmuv3_pmu.c
@@ -401,19 +401,11 @@ static int smmu_pmu_event_init(struct perf_event *event)
int group_num_events = 1;
u16 event_id;
- if (event->attr.type != event->pmu->type)
- return -ENOENT;
-
if (hwc->sample_period) {
dev_dbg(dev, "Sampling not supported\n");
return -EOPNOTSUPP;
}
- if (event->cpu < 0) {
- dev_dbg(dev, "Per-task mode not supported\n");
- return -EOPNOTSUPP;
- }
-
/* Verify specified event is supported on this PMU */
event_id = get_event(event);
if (event_id < SMMU_PMCG_ARCH_MAX_EVENTS &&
--
2.25.1
On Thu, Dec 21, 2023 at 05:38:01PM +0800, JiaLong.Yang wrote:
> 'event->attr.type != event->pmu->type' has been done in
> core.c::perf_init_event() ,core.c::perf_event_modify_attr(), etc.
>
> This PMU is an uncore one. The core framework has disallowed
> uncore-task events. So the judgement to event->cpu < 0 is no mean.
It would be great to refer to the changes which added those checks to
the perf core code. From reading the code myself, I can't convince myself
that perf_try_init_event() won't call into the driver.
>
> The two judgements have been done in kernel/events/core.c
>
> Signed-off-by: JiaLong.Yang <[email protected]>
> ---
> drivers/perf/arm_smmuv3_pmu.c | 8 --------
> 1 file changed, 8 deletions(-)
It looks like _many_ perf drivers have these checks, so if they really
aren't needed, we can clean this up bveyond SMMU. However, as I said
above, I'm not quite convinced we can drop them.
Will
On 2024-02-09 4:09 pm, Will Deacon wrote:
> On Thu, Dec 21, 2023 at 05:38:01PM +0800, JiaLong.Yang wrote:
>> 'event->attr.type != event->pmu->type' has been done in
>> core.c::perf_init_event() ,core.c::perf_event_modify_attr(), etc.
>>
>> This PMU is an uncore one. The core framework has disallowed
>> uncore-task events. So the judgement to event->cpu < 0 is no mean.
>
> It would be great to refer to the changes which added those checks to
> the perf core code. From reading the code myself, I can't convince myself
> that perf_try_init_event() won't call into the driver.
>
>>
>> The two judgements have been done in kernel/events/core.c
>>
>> Signed-off-by: JiaLong.Yang <[email protected]>
>> ---
>> drivers/perf/arm_smmuv3_pmu.c | 8 --------
>> 1 file changed, 8 deletions(-)
>
> It looks like _many_ perf drivers have these checks, so if they really
> aren't needed, we can clean this up bveyond SMMU. However, as I said
> above, I'm not quite convinced we can drop them.
Right, I think the logic prevents events with a specific PMU type being
offered to other PMUs, but as far as I'm aware doesn't apply the other
way round to stop generic events (PERF_TYPE_HARDWARE etc.) being offered
to all PMUs, so it's those that system PMUs need to reject.
It's been on my wishlist for a long time to have a capability flag to
say "I don't handle generic events, please only ever give me events of
my exact type" so we *can* truly factor this into the core.
Thanks,
Robin.
在 2024/2/10 0:32, Robin Murphy 写道:
> On 2024-02-09 4:09 pm, Will Deacon wrote:
>> On Thu, Dec 21, 2023 at 05:38:01PM +0800, JiaLong.Yang wrote:
>>> 'event->attr.type != event->pmu->type' has been done in
>>> core.c::perf_init_event() ,core.c::perf_event_modify_attr(), etc.
>>>
>>> This PMU is an uncore one. The core framework has disallowed
>>> uncore-task events. So the judgement to event->cpu < 0 is no mean.
>>
>> It would be great to refer to the changes which added those checks to
>> the perf core code. From reading the code myself, I can't convince myself
>> that perf_try_init_event() won't call into the driver.
>>
>>>
>>> The two judgements have been done in kernel/events/core.c
>>>
>>> Signed-off-by: JiaLong.Yang <[email protected]>
>>> ---
>>> drivers/perf/arm_smmuv3_pmu.c | 8 --------
>>> 1 file changed, 8 deletions(-)
>>
>> It looks like _many_ perf drivers have these checks, so if they really
>> aren't needed, we can clean this up bveyond SMMU. However, as I said
>> above, I'm not quite convinced we can drop them.
>
> Right, I think the logic prevents events with a specific PMU type being
> offered to other PMUs, but as far as I'm aware doesn't apply the other
> way round to stop generic events (PERF_TYPE_HARDWARE etc.) being offered
> to all PMUs, so it's those that system PMUs need to reject. >
> It's been on my wishlist for a long time to have a capability flag to
> say "I don't handle generic events, please only ever give me events of
> my exact type" so we *can* truly factor this into the core.
It's core framework's responsible to differ generic events and others,
or uncore pmu and core pmu.
Here we have flag PERF_TYPE_HARDWARE, PERF_TYPE_HW_CACHE,
PERF_PMU_CAP_EXTENDED_HW_TYPE doing this.
again:
rcu_read_lock();
pmu = idr_find(&pmu_idr, type);
rcu_read_unlock();
if (pmu) {
if (event->attr.type != type && type != PERF_TYPE_RAW &&
!(pmu->capabilities & PERF_PMU_CAP_EXTENDED_HW_TYPE))
goto fail; /* generic event with no ability pmu */
This can avoid driver code (event->attr.type != event->pmu->type).
And, code:
if (pmu->task_ctx_nr == perf_invalid_context && (task || cgroup_fd != -1)) {
err = -EINVAL;
goto err_pmu;
}
can promise not uncore-task event.
We should confirm that uncore event should be cpu >= 0.
>
> Thanks,
> Robin.
>
On 19/02/2024 6:37 am, Yang Jialong 杨佳龙 wrote:
>
>
> 在 2024/2/10 0:32, Robin Murphy 写道:
>> On 2024-02-09 4:09 pm, Will Deacon wrote:
>>> On Thu, Dec 21, 2023 at 05:38:01PM +0800, JiaLong.Yang wrote:
>>>> 'event->attr.type != event->pmu->type' has been done in
>>>> core.c::perf_init_event() ,core.c::perf_event_modify_attr(), etc.
>>>>
>>>> This PMU is an uncore one. The core framework has disallowed
>>>> uncore-task events. So the judgement to event->cpu < 0 is no mean.
>>>
>>> It would be great to refer to the changes which added those checks to
>>> the perf core code. From reading the code myself, I can't convince
>>> myself
>>> that perf_try_init_event() won't call into the driver.
>>>
>>>>
>>>> The two judgements have been done in kernel/events/core.c
>>>>
>>>> Signed-off-by: JiaLong.Yang <[email protected]>
>>>> ---
>>>> drivers/perf/arm_smmuv3_pmu.c | 8 --------
>>>> 1 file changed, 8 deletions(-)
>>>
>>> It looks like _many_ perf drivers have these checks, so if they really
>>> aren't needed, we can clean this up bveyond SMMU. However, as I said
>>> above, I'm not quite convinced we can drop them.
>>
>> Right, I think the logic prevents events with a specific PMU type
>> being offered to other PMUs, but as far as I'm aware doesn't apply the
>> other way round to stop generic events (PERF_TYPE_HARDWARE etc.) being
>> offered to all PMUs, so it's those that system PMUs need to reject. >
>> It's been on my wishlist for a long time to have a capability flag to
>> say "I don't handle generic events, please only ever give me events of
>> my exact type" so we *can* truly factor this into the core.
>
>
> It's core framework's responsible to differ generic events and others,
> or uncore pmu and core pmu.
> Here we have flag PERF_TYPE_HARDWARE, PERF_TYPE_HW_CACHE,
> PERF_PMU_CAP_EXTENDED_HW_TYPE doing this.
>
> again:
> rcu_read_lock();
> pmu = idr_find(&pmu_idr, type);
> rcu_read_unlock();
> if (pmu) {
> if (event->attr.type != type && type != PERF_TYPE_RAW &&
> !(pmu->capabilities & PERF_PMU_CAP_EXTENDED_HW_TYPE))
> goto fail; /* generic event with no ability pmu */
> This can avoid driver code (event->attr.type != event->pmu->type).
Now consider the other case below that, where "type" has not matched
anything registered, so "pmu" is NULL, and the event is then offered to
*every* registered PMU to see if anyone accepts it. Note that even CPU
PMUs don't always register as PERF_TYPE_RAW, and in particular arm_pmu
doesn't.
Thanks,
Robin.
在 2024/2/27 2:57, Robin Murphy 写道:
> On 19/02/2024 6:37 am, Yang Jialong 杨佳龙 wrote:
>>
>>
>> 在 2024/2/10 0:32, Robin Murphy 写道:
>>> On 2024-02-09 4:09 pm, Will Deacon wrote:
>>>> On Thu, Dec 21, 2023 at 05:38:01PM +0800, JiaLong.Yang wrote:
>>>>> 'event->attr.type != event->pmu->type' has been done in
>>>>> core.c::perf_init_event() ,core.c::perf_event_modify_attr(), etc.
>>>>>
>>>>> This PMU is an uncore one. The core framework has disallowed
>>>>> uncore-task events. So the judgement to event->cpu < 0 is no mean.
>>>>
>>>> It would be great to refer to the changes which added those checks to
>>>> the perf core code. From reading the code myself, I can't convince
>>>> myself
>>>> that perf_try_init_event() won't call into the driver.
>>>>
>>>>>
>>>>> The two judgements have been done in kernel/events/core.c
>>>>>
>>>>> Signed-off-by: JiaLong.Yang <[email protected]>
>>>>> ---
>>>>> drivers/perf/arm_smmuv3_pmu.c | 8 --------
>>>>> 1 file changed, 8 deletions(-)
>>>>
>>>> It looks like _many_ perf drivers have these checks, so if they really
>>>> aren't needed, we can clean this up bveyond SMMU. However, as I said
>>>> above, I'm not quite convinced we can drop them.
>>>
>>> Right, I think the logic prevents events with a specific PMU type
>>> being offered to other PMUs, but as far as I'm aware doesn't apply
>>> the other way round to stop generic events (PERF_TYPE_HARDWARE etc.)
>>> being offered to all PMUs, so it's those that system PMUs need to
>>> reject. >
>>> It's been on my wishlist for a long time to have a capability flag to
>>> say "I don't handle generic events, please only ever give me events
>>> of my exact type" so we *can* truly factor this into the core.
>>
>>
>> It's core framework's responsible to differ generic events and others,
>> or uncore pmu and core pmu.
>> Here we have flag PERF_TYPE_HARDWARE, PERF_TYPE_HW_CACHE,
>> PERF_PMU_CAP_EXTENDED_HW_TYPE doing this.
>>
>> again:
>> rcu_read_lock();
>> pmu = idr_find(&pmu_idr, type);
>> rcu_read_unlock();
>> if (pmu) {
>> if (event->attr.type != type && type != PERF_TYPE_RAW &&
>> !(pmu->capabilities &
>> PERF_PMU_CAP_EXTENDED_HW_TYPE))
>> goto fail; /* generic event with no ability
>> pmu */
>> This can avoid driver code (event->attr.type != event->pmu->type).
>
> Now consider the other case below that, where "type" has not matched
> anything registered, so "pmu" is NULL, and the event is then offered to
> *every* registered PMU to see if anyone accepts it. Note that even CPU
> PMUs don't always register as PERF_TYPE_RAW, and in particular arm_pmu
> doesn't.
>
arm_pmu has flag PERF_PMU_CAP_EXTENDED_HW_TYPE.
From below command, we can say that generic events is related to the
pmus with type PERF_TYPE_RAW.
~/real_kernel $ grep -nr "PERF_TYPE_HARDWARE" arch/ drivers/ |cut -d:
-f1|xargs egrep -c "perf_pmu_register.*PERF_TYPE_RAW"
arch/alpha/kernel/perf_event.c:1
arch/alpha/kernel/perf_event.c:1
arch/arc/kernel/perf_event.c:1
arch/csky/kernel/perf_event.c:1
arch/loongarch/kernel/perf_event.c:1
arch/loongarch/kernel/perf_event.c:1
arch/mips/kernel/perf_event_mipsxx.c:1
arch/mips/kernel/perf_event_mipsxx.c:1
arch/powerpc/perf/8xx-pmu.c:1
arch/powerpc/perf/core-fsl-emb.c:1
arch/powerpc/perf/core-book3s.c:1
arch/riscv/kvm/vcpu_pmu.c:0
arch/s390/kernel/perf_cpum_sf.c:1
arch/s390/kernel/perf_cpum_cf.c:0
arch/s390/kernel/perf_cpum_cf.c:0
arch/s390/kernel/perf_cpum_cf.c:0
arch/s390/kernel/perf_cpum_cf.c:0
arch/sh/kernel/perf_event.c:1
arch/sh/kernel/perf_event.c:1
arch/sparc/kernel/perf_event.c:1
arch/x86/events/amd/ibs.c:0
arch/x86/events/intel/core.c:0
arch/x86/events/core.c:1
arch/xtensa/kernel/perf_event.c:1
drivers/perf/arm_pmu.c:0
drivers/perf/arm_pmu.c:0
drivers/perf/riscv_pmu.c:0
drivers/perf/riscv_pmu_legacy.c:1
drivers/perf/arm_pmuv3.c:0
drivers/perf/riscv_pmu_sbi.c:1
From this, we can say that generic events is related to the pmus with
capability PERF_PMU_CAP_EXTENDED_HW_TYPE.
~/real_kernel $ grep -nr "PERF_TYPE_HARDWARE" arch/ drivers/ |cut -d:
-f1|xargs grep -c "PERF_PMU_CAP_EXTENDED_HW_TYPE"
arch/alpha/kernel/perf_event.c:0
arch/alpha/kernel/perf_event.c:0
arch/arc/kernel/perf_event.c:0
arch/csky/kernel/perf_event.c:0
arch/loongarch/kernel/perf_event.c:0
arch/loongarch/kernel/perf_event.c:0
arch/mips/kernel/perf_event_mipsxx.c:0
arch/mips/kernel/perf_event_mipsxx.c:0
arch/powerpc/perf/8xx-pmu.c:0
arch/powerpc/perf/core-fsl-emb.c:0
arch/powerpc/perf/core-book3s.c:0
arch/riscv/kvm/vcpu_pmu.c:0
arch/s390/kernel/perf_cpum_sf.c:0
arch/s390/kernel/perf_cpum_cf.c:0
arch/s390/kernel/perf_cpum_cf.c:0
arch/s390/kernel/perf_cpum_cf.c:0
arch/s390/kernel/perf_cpum_cf.c:0
arch/sh/kernel/perf_event.c:0
arch/sh/kernel/perf_event.c:0
arch/sparc/kernel/perf_event.c:0
arch/x86/events/amd/ibs.c:0
arch/x86/events/intel/core.c:0
arch/x86/events/core.c:1
arch/xtensa/kernel/perf_event.c:0
drivers/perf/arm_pmu.c:2
drivers/perf/arm_pmu.c:2
drivers/perf/riscv_pmu.c:0
drivers/perf/riscv_pmu_legacy.c:0
drivers/perf/arm_pmuv3.c:0
drivers/perf/riscv_pmu_sbi.c:0
****************************
Something bad belows:
~/real_kernel $ grep -nr "PERF_TYPE_HARDWARE" arch/ drivers/ |cut -d:
-f1|xargs egrep -c "perf_pmu_register.*-1"
arch/alpha/kernel/perf_event.c:0
arch/alpha/kernel/perf_event.c:0
arch/arc/kernel/perf_event.c:0
arch/csky/kernel/perf_event.c:0
arch/loongarch/kernel/perf_event.c:0
arch/loongarch/kernel/perf_event.c:0
arch/mips/kernel/perf_event_mipsxx.c:0
arch/mips/kernel/perf_event_mipsxx.c:0
arch/powerpc/perf/8xx-pmu.c:0
arch/powerpc/perf/core-fsl-emb.c:0
arch/powerpc/perf/core-book3s.c:0
arch/riscv/kvm/vcpu_pmu.c:0
arch/s390/kernel/perf_cpum_sf.c:0
arch/s390/kernel/perf_cpum_cf.c:2
arch/s390/kernel/perf_cpum_cf.c:2
arch/s390/kernel/perf_cpum_cf.c:2
arch/s390/kernel/perf_cpum_cf.c:2
arch/sh/kernel/perf_event.c:0
arch/sh/kernel/perf_event.c:0
arch/sparc/kernel/perf_event.c:0
arch/x86/events/amd/ibs.c:1
arch/x86/events/intel/core.c:0
arch/x86/events/core.c:0
arch/xtensa/kernel/perf_event.c:0
drivers/perf/arm_pmu.c:1
drivers/perf/arm_pmu.c:1
drivers/perf/riscv_pmu.c:0
drivers/perf/riscv_pmu_legacy.c:0
drivers/perf/arm_pmuv3.c:0
drivers/perf/riscv_pmu_sbi.c:0
The pmus::event_init handled PERF_TYPE_HARDWARE, but they was registered
with perf_pmu_register(*, *, -1) without CAP_EXTENDED_HW_TPYE.
Can we unify them with PERF_TYPE_RAW or CAP_EXTENDED_HW_TYPE? Maybe the
latter is well. So we can assign idr PERF_TYPE_HARDWARE and
PERF_TYPE_HW_CACHE a known pmu in perf_pmu_register just like:
if(is_support_generic(pmu)) {
ret = idr_alloc(&pmu_idr, pmu, PERF_TYPE_HARDWAR, PERF_TYPE_HARDWARE +
1, GFP_KERNEL);
if(ret < 0)
goto free_pdc;
ret = idr_alloc(&pmu_idr, pmu, PERF_TYPE_HW_CACHE, PERF_TYPE_HW_CACHE +
1, GFP_KERNEL);
if(ret < 0)
goto free_pdc;
}
We will has a easy and rational way to write code in
core.c::perf_init_event and perf_try_init_event about generic events. We
can judge cpu < 0 in perf_try_init_event for uncore pmus.
> Thanks,
> Robin.
>