[PATCH v4] lib: pmu: support the event ID encoded by a bitmap.
Vincent Chen
vincent.chen at sifive.com
Thu Apr 14 19:32:20 PDT 2022
On Fri, Apr 8, 2022 at 1:51 PM Vincent Chen <vincent.chen at sifive.com> wrote:
>
> On Thu, Dec 2, 2021 at 9:45 AM Atish Patra <atishp at rivosinc.com> wrote:
> >
> > From: Vincent Chen <vincent.chen at sifive.com>
> >
> > RISC-V privilege specification does not specify how to encode the event ID.
> > Therefore, each platform is allowed to customize its own encoding rule.
> > The common encoding methods are as follow, directly assigning a number to an
> > event, or every bit in the mphmevent CSR controls one specified event or
> > mixes the above two methods.
> >
> > To enable OpenSBI to support the above three encoding methods simultaneously,
> > this patch repurpose the dt property "riscv,raw-event-to-mhpmcounters". The
> > "riscv,raw-event-to-mhpmcounters" will describes the one or multiple raw
> > events that could be counted by a set of counters. But, the column number
> > of "riscv,raw-event-to-mhpmcounters" is extended from 2 to 3. The 1st column
> > (64bit) is the ID of the raw events. The 2nd column (64bit) represents a
> > select_mask now to represent the bits used for event ID encoding.
> > If a platform directly encodes each raw PMU event as a unique ID,
> > the value of select_mask will be 0xffffffff_ffffffff.
> >
> > Signed-off-by: Vincent Chen <vincent.chen at sifive.com>
> > Signed-off-by: Atish Patra<atishp at rivosinc.com>
> > ---
> > Changes from v3->v4:
> > 1. Fixed few instances of pmu prefix.
> > 2. Improved the DT property description.
> > 3. Simplified *find_hw implementation by just masking the selector_mask to
> > event_data and comparing it with the select value.
> > 4. Dropped the reviewed by recieved in PATCH 3 as the selector/mask scheme
> > is changed in this patch.
> >
> > Changes from v2->v3:
> > 1. Rebased on top of the master which changed the dt property prefix to riscv.
> > 2. Fixed typos.
> > ---
> > ---
> > docs/pmu_support.md | 24 ++++++++++++++++--------
> > include/sbi/sbi_pmu.h | 2 +-
> > lib/sbi/sbi_pmu.c | 35 ++++++++++++++++++++++++-----------
> > lib/utils/fdt/fdt_pmu.c | 16 +++++++++-------
> > 4 files changed, 50 insertions(+), 27 deletions(-)
> >
> > diff --git a/docs/pmu_support.md b/docs/pmu_support.md
> > index a60b75cf9efa..b9803f643593 100644
> > --- a/docs/pmu_support.md
> > +++ b/docs/pmu_support.md
> > @@ -50,12 +50,20 @@ event-to-mhpmevent is present. Otherwise, it can be omitted. This property
> > shouldn't encode any raw event.
> >
> > * **riscv,raw-event-to-mhpmcounters**(Optional) - It represents an ONE-to-MANY
> > -mapping between a raw event and all the MHPMCOUNTERx in a bitmap format that can
> > -be used to monitor that raw event. The information is encoded in a table format
> > -where each raw represent a specific raw event. The first column stores the
> > -expected event selector value that should be encoded in the expected value to be
> > -written in MHPMEVENTx. The second column stores a bitmap of all the MHPMCOUNTERx
> > -that can be used for monitoring the specified event.
> > +or MANY-to-MANY mapping between the raw event(s) and all the MHPMCOUNTERx in
> > +a bitmap format that can be used to monitor that raw event, which depends on
> > +how the platform encodes the monitor events. Currently, only the following three
> > +encoding methods are supported, encoding each event as a number, using a bitmap
> > +to encode monitor events, and mixing the previous two methods. The information
> > +is encoded in a table format where each row represent the specific raw event(s).
> > +The first column represents a 64-bit selector value which can indicate an
> > +monitor event ID (encoded by a number) or an event set (encoded by a bitmap).
> > +In case of the latter, the lower bits used to encode a set of events should be
> > +set to zero. The second column is a 64-bit selector mask where any bits used
> > +for event encoding will be cleared. If a platform directly encodes each raw PMU
> > +event as a unique ID, the value of select_mask will be 0xffffffff_ffffffff.
> > +The third column represent a bitmap of all the MHPMCOUNTERx that can be used for
> > +monitoring the specified event(s).
> >
> > *Note:* A platform may choose to provide the mapping between event & counters
> > via platform hooks rather than the device tree.
> > @@ -72,8 +80,8 @@ pmu {
> > <0x00002 0x00002 0x00000004>,
> > <0x00003 0x0000A 0x00000ff8>,
> > <0x10000 0x10033 0x000ff000>,
> > - riscv,raw-event-to-mhpmcounters = <0x0000 0x0002 0x00000f8>,
> > - <0x0000 0x0003 0x00000ff0>,
> > + riscv,raw-event-to-mhpmcounters = <0x0000 0x0002 0xffffffff 0xffffffff 0x00000f8>,
> > + <0xffffffff 0xfffffff0 0xffffffff 0xfffffff0 0x00000ff0>,
> > };
> >
> > ```
> > diff --git a/include/sbi/sbi_pmu.h b/include/sbi/sbi_pmu.h
> > index f0185566cd6d..6a1c62ccfbef 100644
> > --- a/include/sbi/sbi_pmu.h
> > +++ b/include/sbi/sbi_pmu.h
> > @@ -51,7 +51,7 @@ int sbi_pmu_add_hw_event_counter_map(u32 eidx_start, u32 eidx_end, u32 cmap);
> > * @return 0 on success, error otherwise.
> > */
> >
> > -int sbi_pmu_add_raw_event_counter_map(uint64_t select, u32 cmap);
> > +int sbi_pmu_add_raw_event_counter_map(uint64_t select, uint64_t select_mask, u32 cmap);
> >
> > int sbi_pmu_ctr_read(uint32_t cidx, unsigned long *cval);
> >
> > diff --git a/lib/sbi/sbi_pmu.c b/lib/sbi/sbi_pmu.c
> > index 5950a2001637..10668a358cb2 100644
> > --- a/lib/sbi/sbi_pmu.c
> > +++ b/lib/sbi/sbi_pmu.c
> > @@ -21,8 +21,16 @@ struct sbi_pmu_hw_event {
> > uint32_t counters;
> > uint32_t start_idx;
> > uint32_t end_idx;
> > - /* Event selector value used only for raw events */
> > + /* Event selector value used only for raw events. The event select value
> > + * can be a even id or a selector value for set of events encoded in few
> > + * bits. In case latter, the bits used for encoding of the events should
> > + * be zeroed out in the select value.
> > + */
> > uint64_t select;
> > + /**
> > + * The select_mask indicates which bits are encoded for the event(s).
> > + */
> > + uint64_t select_mask;
> > };
> >
> > /** Representation of a firmware event */
> > @@ -91,9 +99,9 @@ static bool pmu_event_range_overlap(struct sbi_pmu_hw_event *evtA,
> > }
> >
> > static bool pmu_event_select_overlap(struct sbi_pmu_hw_event *evt,
> > - uint64_t select_val)
> > + uint64_t select_val, uint64_t select_mask)
> > {
> > - if (evt->select == select_val)
> > + if ((evt->select == select_val) && (evt->select_mask == select_mask))
> > return TRUE;
> >
> > return FALSE;
> > @@ -168,7 +176,7 @@ int sbi_pmu_ctr_read(uint32_t cidx, unsigned long *cval)
> > }
> >
> > static int pmu_add_hw_event_map(u32 eidx_start, u32 eidx_end, u32 cmap,
> > - uint64_t select)
> > + uint64_t select, uint64_t select_mask)
> > {
> > int i = 0;
> > bool is_overlap;
> > @@ -191,13 +199,15 @@ static int pmu_add_hw_event_map(u32 eidx_start, u32 eidx_end, u32 cmap,
> > for (i = 0; i < num_hw_events; i++) {
> > if (eidx_start == SBI_PMU_EVENT_RAW_IDX)
> > /* All raw events have same event idx. Just do sanity check on select */
> > - is_overlap = pmu_event_select_overlap(&hw_event_map[i], select);
> > + is_overlap = pmu_event_select_overlap(&hw_event_map[i],
> > + select, select_mask);
> > else
> > is_overlap = pmu_event_range_overlap(&hw_event_map[i], event);
> > if (is_overlap)
> > goto reset_event;
> > }
> >
> > + event->select_mask = select_mask;
> > event->counters = cmap;
> > event->select = select;
> > num_hw_events++;
> > @@ -221,13 +231,13 @@ int sbi_pmu_add_hw_event_counter_map(u32 eidx_start, u32 eidx_end, u32 cmap)
> > eidx_end == SBI_PMU_EVENT_RAW_IDX)
> > return SBI_EINVAL;
> >
> > - return pmu_add_hw_event_map(eidx_start, eidx_end, cmap, 0);
> > + return pmu_add_hw_event_map(eidx_start, eidx_end, cmap, 0, 0);
> > }
> >
> > -int sbi_pmu_add_raw_event_counter_map(uint64_t select, u32 cmap)
> > +int sbi_pmu_add_raw_event_counter_map(uint64_t select, uint64_t select_mask, u32 cmap)
> > {
> > return pmu_add_hw_event_map(SBI_PMU_EVENT_RAW_IDX,
> > - SBI_PMU_EVENT_RAW_IDX, cmap, select);
> > + SBI_PMU_EVENT_RAW_IDX, cmap, select, select_mask);
> > }
> >
> > static int pmu_ctr_enable_irq_hw(int ctr_idx)
> > @@ -514,9 +524,13 @@ static int pmu_ctr_find_hw(unsigned long cbase, unsigned long cmask, unsigned lo
> > continue;
> >
> > /* For raw events, event data is used as the select value */
> > - if ((event_idx == SBI_PMU_EVENT_RAW_IDX) && temp->select != data)
> > - continue;
> > + if (event_idx == SBI_PMU_EVENT_RAW_IDX) {
> > + uint64_t select_mask = temp->select_mask;
> >
> > + /* The non-event map bits of data should match the selector */
> > + if (temp->select != (data & select_mask))
> > + continue;
>
> Dear Atish:
> I am sorry that I didn't follow up on this change at that time, so
> this is a late reply.
> I found the v4 patch set lacks the following code which casues the
> bitmap encoding feature not to work properly.
>
> + if (event_idx == SBI_PMU_EVENT_RAW_IDX) {
> + uint64_t select_mask = temp->select_mask;
>
> + /* Check the bit filed encoded by a real number */
> + if ((temp->select & select_mask) != (data & select_mask))
> + continue;
> ********************************* Missing part
> ********************************************
> + /* Check the bit filed encoded by a bitmap */
> + else if ((temp->select & ~select_mask & data) != (~select_mask & data))
> + continue;
> ***********************************************************************************************
> + }
> I found the above code exists in my v2 patch but was removed in your
> v4 patch. I guess this might be an accident. If yes, I can send
> another patch to add this code back. If not, please tell me the reason
> and I need to come out with another solution to get the bitmap
> encoding feature to work.
>
> Sorry again for the late reply.
>
> Regards,
> Vincent
>
>
Hi Atish,
This is a gentle ping. Do you have any idea about this?
If not, I will revise this part code as my v2 patch and send it to the
mailing list for review.
Thank you.
Best regards,
Vincent
> > + }
> > /* Fixed counters should not be part of the search */
> > ctr_mask = temp->counters & (cmask << cbase) &
> > (~SBI_PMU_FIXED_CTR_MASK);
> > @@ -546,7 +560,6 @@ static int pmu_ctr_find_hw(unsigned long cbase, unsigned long cmask, unsigned lo
> > else
> > return SBI_EFAIL;
> > }
> > -
> > ret = pmu_update_hw_mhpmevent(temp, ctr_idx, flags, event_idx, data);
> >
> > if (!ret)
> > diff --git a/lib/utils/fdt/fdt_pmu.c b/lib/utils/fdt/fdt_pmu.c
> > index 529ee420554f..a2b048f0ab29 100644
> > --- a/lib/utils/fdt/fdt_pmu.c
> > +++ b/lib/utils/fdt/fdt_pmu.c
> > @@ -65,7 +65,7 @@ int fdt_pmu_setup(void *fdt)
> > const u32 *event_val;
> > const u32 *event_ctr_map;
> > struct fdt_pmu_hw_event_select *event;
> > - uint64_t raw_selector;
> > + uint64_t raw_selector, select_mask;
> > u32 event_idx_start, event_idx_end, ctr_map;
> >
> > if (!fdt)
> > @@ -99,14 +99,16 @@ int fdt_pmu_setup(void *fdt)
> > }
> >
> > event_val = fdt_getprop(fdt, pmu_offset, "riscv,raw-event-to-mhpmcounters", &len);
> > - if (!event_val || len < 8)
> > + if (!event_val || len < 20)
> > return SBI_EFAIL;
> > - len = len / (sizeof(u32) * 3);
> > + len = len / (sizeof(u32) * 5);
> > for (i = 0; i < len; i++) {
> > - raw_selector = fdt32_to_cpu(event_val[3 * i]);
> > - raw_selector = (raw_selector << 32) | fdt32_to_cpu(event_val[3 * i + 1]);
> > - ctr_map = fdt32_to_cpu(event_val[3 * i + 2]);
> > - result = sbi_pmu_add_raw_event_counter_map(raw_selector, ctr_map);
> > + raw_selector = fdt32_to_cpu(event_val[5 * i]);
> > + raw_selector = (raw_selector << 32) | fdt32_to_cpu(event_val[5 * i + 1]);
> > + select_mask = fdt32_to_cpu(event_val[5 * i + 2]);
> > + select_mask = (select_mask << 32) | fdt32_to_cpu(event_val[5 * i + 3]);
> > + ctr_map = fdt32_to_cpu(event_val[5 * i + 4]);
> > + result = sbi_pmu_add_raw_event_counter_map(raw_selector, select_mask, ctr_map);
> > if (!result)
> > hw_event_count++;
> > }
> > --
> > 2.33.1
> >
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