powerpc/perf: Add generic compat mode pmu driver

Most of the power processor generation performance monitoring
unit (PMU) driver code is bundled in the kernel and one of those
is enabled/registered based on the oprofile_cpu_type check at
the boot.

But things get little tricky incase of "compat" mode boot.
IBM POWER System Server based processors has a compactibility
mode feature, which simpily put is, Nth generation processor
(lets say POWER8) will act and appear in a mode consistent
with an earlier generation (N-1) processor (that is POWER7).
And in this "compat" mode boot, kernel modify the
"oprofile_cpu_type" to be Nth generation (POWER8). If Nth
generation pmu driver is bundled (POWER8), it gets registered.

Key dependency here is to have distro support for latest
processor performance monitoring support. Patch here adds
a generic "compat-mode" performance monitoring driver to
be register in absence of powernv platform specific pmu driver.

Driver supports only "cycles" and "instruction" events.
"0x0001e" used as event code for "cycles" and "0x00002"
used as event code for "instruction" events. New file
called "generic-compat-pmu.c" is created to contain the driver
specific code. And base raw event code format modeled
on PPMU_ARCH_207S.

Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
[mpe: Use SPDX tag for license]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/perf/Makefile

@@ -5,7 +5,8 @@ obj-$(CONFIG_PERF_EVENTS)	+= callchain.o perf_regs.o
 obj-$(CONFIG_PPC_PERF_CTRS)	+= core-book3s.o bhrb.o
 obj64-$(CONFIG_PPC_PERF_CTRS)	+= ppc970-pmu.o power5-pmu.o \
 				   power5+-pmu.o power6-pmu.o power7-pmu.o \
-				   isa207-common.o power8-pmu.o power9-pmu.o
+				   isa207-common.o power8-pmu.o power9-pmu.o \
+				   generic-compat-pmu.o
 obj32-$(CONFIG_PPC_PERF_CTRS)	+= mpc7450-pmu.o
 
 obj-$(CONFIG_PPC_POWERNV)	+= imc-pmu.o

arch/powerpc/perf/core-book3s.c

@@ -2318,7 +2318,7 @@ static int __init init_ppc64_pmu(void)
 	else if (!init_ppc970_pmu())
 		return 0;
 	else
-		return -ENODEV;
+		return init_generic_compat_pmu();
 }
 early_initcall(init_ppc64_pmu);
 #endif

arch/powerpc/perf/generic-compat-pmu.c

@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Copyright 2019 Madhavan Srinivasan, IBM Corporation.
+
+#define pr_fmt(fmt)	"generic-compat-pmu: " fmt
+
+#include "isa207-common.h"
+
+/*
+ * Raw event encoding:
+ *
+ *        60        56        52        48        44        40        36        32
+ * | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - |
+ *
+ *        28        24        20        16        12         8         4         0
+ * | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - | - - - - |
+ *                                 [ pmc ]   [unit ]   [ ]   m   [    pmcxsel    ]
+ *                                                     |     |
+ *                                                     |     *- mark
+ *                                                     |
+ *                                                     |
+ *                                                     *- combine
+ *
+ * Below uses IBM bit numbering.
+ *
+ * MMCR1[x:y] = unit    (PMCxUNIT)
+ * MMCR1[24]   = pmc1combine[0]
+ * MMCR1[25]   = pmc1combine[1]
+ * MMCR1[26]   = pmc2combine[0]
+ * MMCR1[27]   = pmc2combine[1]
+ * MMCR1[28]   = pmc3combine[0]
+ * MMCR1[29]   = pmc3combine[1]
+ * MMCR1[30]   = pmc4combine[0]
+ * MMCR1[31]   = pmc4combine[1]
+ *
+ */
+
+/*
+ * Some power9 event codes.
+ */
+#define EVENT(_name, _code)	_name = _code,
+
+enum {
+EVENT(PM_CYC,					0x0001e)
+EVENT(PM_INST_CMPL,				0x00002)
+};
+
+#undef EVENT
+
+GENERIC_EVENT_ATTR(cpu-cycles,			PM_CYC);
+GENERIC_EVENT_ATTR(instructions,		PM_INST_CMPL);
+
+static struct attribute *generic_compat_events_attr[] = {
+	GENERIC_EVENT_PTR(PM_CYC),
+	GENERIC_EVENT_PTR(PM_INST_CMPL),
+	NULL
+};
+
+static struct attribute_group generic_compat_pmu_events_group = {
+	.name = "events",
+	.attrs = generic_compat_events_attr,
+};
+
+PMU_FORMAT_ATTR(event,		"config:0-19");
+PMU_FORMAT_ATTR(pmcxsel,	"config:0-7");
+PMU_FORMAT_ATTR(mark,		"config:8");
+PMU_FORMAT_ATTR(combine,	"config:10-11");
+PMU_FORMAT_ATTR(unit,		"config:12-15");
+PMU_FORMAT_ATTR(pmc,		"config:16-19");
+
+static struct attribute *generic_compat_pmu_format_attr[] = {
+	&format_attr_event.attr,
+	&format_attr_pmcxsel.attr,
+	&format_attr_mark.attr,
+	&format_attr_combine.attr,
+	&format_attr_unit.attr,
+	&format_attr_pmc.attr,
+	NULL,
+};
+
+static struct attribute_group generic_compat_pmu_format_group = {
+	.name = "format",
+	.attrs = generic_compat_pmu_format_attr,
+};
+
+static const struct attribute_group *generic_compat_pmu_attr_groups[] = {
+	&generic_compat_pmu_format_group,
+	&generic_compat_pmu_events_group,
+	NULL,
+};
+
+static int compat_generic_events[] = {
+	[PERF_COUNT_HW_CPU_CYCLES] =			PM_CYC,
+	[PERF_COUNT_HW_INSTRUCTIONS] =			PM_INST_CMPL,
+};
+
+#define C(x)	PERF_COUNT_HW_CACHE_##x
+
+/*
+ * Table of generalized cache-related events.
+ * 0 means not supported, -1 means nonsensical, other values
+ * are event codes.
+ */
+static int generic_compat_cache_events[C(MAX)][C(OP_MAX)][C(RESULT_MAX)] = {
+	[ C(L1D) ] = {
+		[ C(OP_READ) ] = {
+			[ C(RESULT_ACCESS) ] = 0,
+			[ C(RESULT_MISS)   ] = 0,
+		},
+		[ C(OP_WRITE) ] = {
+			[ C(RESULT_ACCESS) ] = 0,
+			[ C(RESULT_MISS)   ] = 0,
+		},
+		[ C(OP_PREFETCH) ] = {
+			[ C(RESULT_ACCESS) ] = 0,
+			[ C(RESULT_MISS)   ] = 0,
+		},
+	},
+	[ C(L1I) ] = {
+		[ C(OP_READ) ] = {
+			[ C(RESULT_ACCESS) ] = 0,
+			[ C(RESULT_MISS)   ] = 0,
+		},
+		[ C(OP_WRITE) ] = {
+			[ C(RESULT_ACCESS) ] = 0,
+			[ C(RESULT_MISS)   ] = -1,
+		},
+		[ C(OP_PREFETCH) ] = {
+			[ C(RESULT_ACCESS) ] = 0,
+			[ C(RESULT_MISS)   ] = 0,
+		},
+	},
+	[ C(LL) ] = {
+		[ C(OP_READ) ] = {
+			[ C(RESULT_ACCESS) ] = 0,
+			[ C(RESULT_MISS)   ] = 0,
+		},
+		[ C(OP_WRITE) ] = {
+			[ C(RESULT_ACCESS) ] = 0,
+			[ C(RESULT_MISS)   ] = 0,
+		},
+		[ C(OP_PREFETCH) ] = {
+			[ C(RESULT_ACCESS) ] = 0,
+			[ C(RESULT_MISS)   ] = 0,
+		},
+	},
+	[ C(DTLB) ] = {
+		[ C(OP_READ) ] = {
+			[ C(RESULT_ACCESS) ] = 0,
+			[ C(RESULT_MISS)   ] = 0,
+		},
+		[ C(OP_WRITE) ] = {
+			[ C(RESULT_ACCESS) ] = -1,
+			[ C(RESULT_MISS)   ] = -1,
+		},
+		[ C(OP_PREFETCH) ] = {
+			[ C(RESULT_ACCESS) ] = -1,
+			[ C(RESULT_MISS)   ] = -1,
+		},
+	},
+	[ C(ITLB) ] = {
+		[ C(OP_READ) ] = {
+			[ C(RESULT_ACCESS) ] = 0,
+			[ C(RESULT_MISS)   ] = 0,
+		},
+		[ C(OP_WRITE) ] = {
+			[ C(RESULT_ACCESS) ] = -1,
+			[ C(RESULT_MISS)   ] = -1,
+		},
+		[ C(OP_PREFETCH) ] = {
+			[ C(RESULT_ACCESS) ] = -1,
+			[ C(RESULT_MISS)   ] = -1,
+		},
+	},
+	[ C(BPU) ] = {
+		[ C(OP_READ) ] = {
+			[ C(RESULT_ACCESS) ] = 0,
+			[ C(RESULT_MISS)   ] = 0,
+		},
+		[ C(OP_WRITE) ] = {
+			[ C(RESULT_ACCESS) ] = -1,
+			[ C(RESULT_MISS)   ] = -1,
+		},
+		[ C(OP_PREFETCH) ] = {
+			[ C(RESULT_ACCESS) ] = -1,
+			[ C(RESULT_MISS)   ] = -1,
+		},
+	},
+	[ C(NODE) ] = {
+		[ C(OP_READ) ] = {
+			[ C(RESULT_ACCESS) ] = -1,
+			[ C(RESULT_MISS)   ] = -1,
+		},
+		[ C(OP_WRITE) ] = {
+			[ C(RESULT_ACCESS) ] = -1,
+			[ C(RESULT_MISS)   ] = -1,
+		},
+		[ C(OP_PREFETCH) ] = {
+			[ C(RESULT_ACCESS) ] = -1,
+			[ C(RESULT_MISS)   ] = -1,
+		},
+	},
+};
+
+#undef C
+
+static struct power_pmu generic_compat_pmu = {
+	.name			= "GENERIC_COMPAT",
+	.n_counter		= MAX_PMU_COUNTERS,
+	.add_fields		= ISA207_ADD_FIELDS,
+	.test_adder		= ISA207_TEST_ADDER,
+	.compute_mmcr		= isa207_compute_mmcr,
+	.get_constraint		= isa207_get_constraint,
+	.disable_pmc		= isa207_disable_pmc,
+	.flags			= PPMU_HAS_SIER | PPMU_ARCH_207S,
+	.n_generic		= ARRAY_SIZE(compat_generic_events),
+	.generic_events		= compat_generic_events,
+	.cache_events		= &generic_compat_cache_events,
+	.attr_groups		= generic_compat_pmu_attr_groups,
+};
+
+int init_generic_compat_pmu(void)
+{
+	int rc = 0;
+
+	rc = register_power_pmu(&generic_compat_pmu);
+	if (rc)
+		return rc;
+
+	/* Tell userspace that EBB is supported */
+	cur_cpu_spec->cpu_user_features2 |= PPC_FEATURE2_EBB;
+
+	return 0;
+}

arch/powerpc/perf/internal.h

@@ -9,3 +9,4 @@ extern int init_power6_pmu(void);
 extern int init_power7_pmu(void);
 extern int init_power8_pmu(void);
 extern int init_power9_pmu(void);
+extern int init_generic_compat_pmu(void);