PM_RUN_INST_CMPL, instructions completed with the run latch set, is
the architected PowerISA v3.1 event defined with PMC4SEL = 0xFA.
Implement it by checking for the CTRL RUN bit before incrementing the
counter. To make this work properly we also need to force a new
translation block each time SPR_CTRL is written. A small tweak in
pmu_increment_insns() is then needed to only increment this event
if the thread has the run latch.
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20211201151734.654994-8-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
The PMU is already counting cycles by calculating time elapsed in
nanoseconds. Counting instructions is a different matter and requires
another approach.
This patch adds the capability of counting completed instructions (Perf
event PM_INST_CMPL) by counting the amount of instructions translated in
each translation block right before exiting it.
A new pmu_count_insns() helper in translation.c was added to do that.
After verifying that the PMU is counting instructions, call
helper_insns_inc(). This new helper from power8-pmu.c will add the
instructions to the relevant counters. It'll also be responsible for
triggering counter negative overflows as it is already being done with
cycles.
To verify whether the PMU is counting instructions or now, a new hflags
named 'HFLAGS_INSN_CNT' is introduced. This flag will match the internal
state of the PMU. We're be using this flag to avoid calling
helper_insn_inc() when we do not have a valid instruction event being
sampled.
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20211201151734.654994-7-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
The PowerISA v3.1 defines that if the proper bits are set (MMCR0_PMC1CE
for PMC1 and MMCR0_PMCjCE for the remaining PMCs), counter negative
conditions are enabled. This means that if the counter value overflows
(i.e. exceeds 0x80000000) a performance monitor alert will occur. This alert
can trigger an event-based exception (to be implemented in the next patches)
if the MMCR0_EBE bit is set.
For now, overflowing the counter when the PMC is counting cycles will
just trigger a performance monitor alert. This is done by starting the
overflow timer to expire in the moment the overflow would be occuring. The
timer will call fire_PMC_interrupt() (via cpu_ppc_pmu_timer_cb) which will
trigger the PMU alert and, if the conditions are met, an EBB exception.
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20211201151734.654994-6-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
MMCR1 determines the events to be sampled by the PMU. Updating the
counters at every MMCR1 write ensures that we're not sampling more
or less events by looking only at MMCR0 and the PMCs.
It is worth noticing that both the Book3S PowerPC PMU, and this IBM
Power8+ PMU that we're modeling, also uses MMCRA, MMCR2 and MMCR3 to
control the PMU. These three registers aren't being handled in this
initial implementation, so for now we're controlling all the PMU
aspects using MMCR0, MMCR1 and the PMCs.
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20211201151734.654994-5-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Calling pmu_update_cycles() on every PMC read/write operation ensures
that the values being fetched are up to date with the current PMU state.
In theory we can get away by just trapping PMCs reads, but we're going
to trap PMC writes to deal with counter overflow logic later on. Let's
put the required wiring for that and make our lives a bit easier in the
next patches.
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20211201151734.654994-4-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
This patch adds the barebones of the PMU logic by enabling cycle
counting. The overall logic goes as follows:
- MMCR0 reg initial value is set to 0x80000000 (MMCR0_FC set) to avoid
having to spin the PMU right at system init;
- to retrieve the events that are being profiled, pmc_get_event() will
check the current MMCR0 and MMCR1 value and return the appropriate
PMUEventType. For PMCs 1-4, event 0x2 is the implementation dependent
value of PMU_EVENT_INSTRUCTIONS and event 0x1E is the implementation
dependent value of PMU_EVENT_CYCLES. These events are supported by IBM
Power chips since Power8, at least, and the Linux Perf driver makes use
of these events until kernel v5.15. For PMC1, event 0xF0 is the
architected PowerISA event for cycles. Event 0xFE is the architected
PowerISA event for instructions;
- if the counter is frozen, either via the global MMCR0_FC bit or its
individual frozen counter bits, PMU_EVENT_INACTIVE is returned;
- pmu_update_cycles() will go through each counter and update the
values of all PMCs that are counting cycles. This function will be
called every time a MMCR0 update is done to keep counters values
up to date. Upcoming patches will use this function to allow the
counters to be properly updated during read/write of the PMCs
and MMCR1 writes.
Given that the base CPU frequency is fixed at 1Ghz for both powernv and
pseries clock, cycle calculation assumes that 1 nanosecond equals 1 CPU
cycle. Cycle value is then calculated by adding the elapsed time, in
nanoseconds, of the last cycle update done via pmu_update_cycles().
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20211201151734.654994-3-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
This patch starts an IBM Power8+ compatible PMU implementation by adding
the representation of PMU events that we are going to sample,
PMUEventType. This enum represents a Perf event that is being sampled by
a specific counter 'sprn'. Events that aren't available (i.e. no event
was set in MMCR1) will be of type 'PMU_EVENT_INVALID'. Events that are
inactive due to frozen counter bits state are of type
'PMU_EVENT_INACTIVE'. Other types added in this patch are
PMU_EVENT_CYCLES and PMU_EVENT_INSTRUCTIONS. More types will be added
later on.
Let's also add the required PMU cycle overflow timers. They will be used
to trigger cycle overflows when cycle events are being sampled. This
timer will call cpu_ppc_pmu_timer_cb(), which in turn calls
fire_PMC_interrupt(). Both functions are stubs that will be implemented
later on when EBB support is added.
Two new helper files are created to host this new logic.
cpu_ppc_pmu_init() will init all overflow timers during CPU init time.
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20211201151734.654994-2-danielhb413@gmail.com>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
