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SubjectRe: [PATCH 06/13] perf/x86/amd: Support PERF_SAMPLE_PHY_ADDR using IBS_DC_PHYSADDR
On Thu, May 26, 2022 at 04:29:22PM +0530, Ravi Bangoria wrote:
> On 26-May-22 3:26 PM, Peter Zijlstra wrote:
> > On Thu, May 26, 2022 at 02:16:28PM +0530, Ravi Bangoria wrote:
> >> 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:
> >
> > I think it's best if you extend/mimic the __PERF_SAMPLE_CALLCHAIN_EARLY
> > hack. It's more or less the same problem and then at least the solution
> > is consistent.
>
> I've one more identical optimization in my list. IBS_OP_DATA3[IbsDcPgSz]
> can provide PERF_SAMPLE_DATA_PAGE_SIZE. I hope consuming two more bits
> for internal purpose is okay.

Yeah, I suppose so.. we'll need to hunt for bits once we run out, but
that's how it is...

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