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SubjectRe: [PATCH 06/13] perf/x86/amd: Support PERF_SAMPLE_PHY_ADDR using IBS_DC_PHYSADDR
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On 25-May-22 4:51 PM, Peter Zijlstra wrote:
> On Wed, May 25, 2022 at 03:09:31PM +0530, Ravi Bangoria wrote:
>> IBS_DC_PHYSADDR provides the physical data address for the tagged load/
>> store operation. Populate perf sample physical address using it.
>>
>> Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
>> ---
>> arch/x86/events/amd/ibs.c | 26 +++++++++++++++++++++++++-
>> 1 file changed, 25 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
>> index b57736357e25..c719020c0e83 100644
>> --- a/arch/x86/events/amd/ibs.c
>> +++ b/arch/x86/events/amd/ibs.c
>> @@ -986,13 +986,35 @@ static void perf_ibs_get_data_addr(struct perf_event *event,
>> data->addr = ibs_data->regs[ibs_op_msr_idx(MSR_AMD64_IBSDCLINAD)];
>> }
>>
>> +static void perf_ibs_get_phy_addr(struct perf_event *event,
>> + struct perf_ibs_data *ibs_data,
>> + struct perf_sample_data *data)
>> +{
>> + union perf_mem_data_src *data_src = &data->data_src;
>> + u64 op_data3 = ibs_data->regs[ibs_op_msr_idx(MSR_AMD64_IBSOPDATA3)];
>> + u64 phy_addr_valid = op_data3 & IBS_DC_PHY_ADDR_VALID_MASK;
>> +
>> + if (!(event->attr.sample_type & PERF_SAMPLE_DATA_SRC))
>> + perf_ibs_get_mem_op(op_data3, data);
>> +
>> + if ((data_src->mem_op != PERF_MEM_OP_LOAD &&
>> + data_src->mem_op != PERF_MEM_OP_STORE) ||
>> + !phy_addr_valid) {
>> + data->phys_addr = 0x0;
>> + return;
>> + }
>> +
>> + data->phys_addr = ibs_data->regs[ibs_op_msr_idx(MSR_AMD64_IBSDCPHYSAD)];
>> +}
>
> perf_prepare_sample() will unconditionally overwrite data->phys_addr.
> There is currently no facility to let the driver set this field.

Thanks for pointing it Peter. Would you mind if I add:

diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index c719020c0e83..fbd1f4e94d47 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c
@@ -986,6 +986,19 @@ static void perf_ibs_get_data_addr(struct perf_event *event,
data->addr = ibs_data->regs[ibs_op_msr_idx(MSR_AMD64_IBSDCLINAD)];
}

+/* data_src->mem_op should have been set by perf_ibs_get_phy_addr() */
+bool perf_arch_phys_addr_set(struct perf_event *event,
+ struct perf_sample_data *data)
+{
+ union perf_mem_data_src *data_src = &data->data_src;
+
+ if (event->pmu != &perf_ibs_op.pmu)
+ return false;
+
+ return (data_src->mem_op == PERF_MEM_OP_LOAD ||
+ data_src->mem_op == PERF_MEM_OP_STORE);
+}
+
static void perf_ibs_get_phy_addr(struct perf_event *event,
struct perf_ibs_data *ibs_data,
struct perf_sample_data *data)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index da759560eec5..67402af3b70f 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1477,6 +1477,8 @@ extern void perf_event_task_tick(void);
extern int perf_event_account_interrupt(struct perf_event *event);
extern int perf_event_period(struct perf_event *event, u64 value);
extern u64 perf_event_pause(struct perf_event *event, bool reset);
+bool perf_arch_phys_addr_set(struct perf_event *event,
+ struct perf_sample_data *data);
#else /* !CONFIG_PERF_EVENTS: */
static inline void *
perf_aux_output_begin(struct perf_output_handle *handle,
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 7699be46f3a1..9baeb2d21bc0 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7283,6 +7283,12 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs)
return callchain ?: &__empty_callchain;
}

+bool __weak perf_arch_phys_addr_set(struct perf_event *event,
+ struct perf_sample_data *data)
+{
+ return false;
+}
+
void perf_prepare_sample(struct perf_event_header *header,
struct perf_sample_data *data,
struct perf_event *event,
@@ -7404,8 +7410,10 @@ void perf_prepare_sample(struct perf_event_header *header,
header->size += size;
}

- if (sample_type & PERF_SAMPLE_PHYS_ADDR)
+ if (sample_type & PERF_SAMPLE_PHYS_ADDR &&
+ !perf_arch_phys_addr_set(event, data)) {
data->phys_addr = perf_virt_to_phys(data->addr);
+ }

#ifdef CONFIG_CGROUP_PERF
if (sample_type & PERF_SAMPLE_CGROUP) {
Thanks,
Ravi

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