summaryrefslogtreecommitdiffstats
path: root/drivers/perf/arm_pmu_acpi.c
blob: 705f1a390e3123a2d305e0468cec8194d972ed39 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
/*
 * ACPI probing code for ARM performance counters.
 *
 * Copyright (C) 2017 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/acpi.h>
#include <linux/cpumask.h>
#include <linux/init.h>
#include <linux/percpu.h>
#include <linux/perf/arm_pmu.h>

#include <asm/cputype.h>

static DEFINE_PER_CPU(struct arm_pmu *, probed_pmus);
static DEFINE_PER_CPU(int, pmu_irqs);

static int arm_pmu_acpi_register_irq(int cpu)
{
	struct acpi_madt_generic_interrupt *gicc;
	int gsi, trigger;

	gicc = acpi_cpu_get_madt_gicc(cpu);
	if (WARN_ON(!gicc))
		return -EINVAL;

	gsi = gicc->performance_interrupt;

	/*
	 * Per the ACPI spec, the MADT cannot describe a PMU that doesn't
	 * have an interrupt. QEMU advertises this by using a GSI of zero,
	 * which is not known to be valid on any hardware despite being
	 * valid per the spec. Take the pragmatic approach and reject a
	 * GSI of zero for now.
	 */
	if (!gsi)
		return 0;

	if (gicc->flags & ACPI_MADT_PERFORMANCE_IRQ_MODE)
		trigger = ACPI_EDGE_SENSITIVE;
	else
		trigger = ACPI_LEVEL_SENSITIVE;

	/*
	 * Helpfully, the MADT GICC doesn't have a polarity flag for the
	 * "performance interrupt". Luckily, on compliant GICs the polarity is
	 * a fixed value in HW (for both SPIs and PPIs) that we cannot change
	 * from SW.
	 *
	 * Here we pass in ACPI_ACTIVE_HIGH to keep the core code happy. This
	 * may not match the real polarity, but that should not matter.
	 *
	 * Other interrupt controllers are not supported with ACPI.
	 */
	return acpi_register_gsi(NULL, gsi, trigger, ACPI_ACTIVE_HIGH);
}

static void arm_pmu_acpi_unregister_irq(int cpu)
{
	struct acpi_madt_generic_interrupt *gicc;
	int gsi;

	gicc = acpi_cpu_get_madt_gicc(cpu);
	if (!gicc)
		return;

	gsi = gicc->performance_interrupt;
	acpi_unregister_gsi(gsi);
}

static int arm_pmu_acpi_parse_irqs(void)
{
	int irq, cpu, irq_cpu, err;

	for_each_possible_cpu(cpu) {
		irq = arm_pmu_acpi_register_irq(cpu);
		if (irq < 0) {
			err = irq;
			pr_warn("Unable to parse ACPI PMU IRQ for CPU%d: %d\n",
				cpu, err);
			goto out_err;
		} else if (irq == 0) {
			pr_warn("No ACPI PMU IRQ for CPU%d\n", cpu);
		}

		per_cpu(pmu_irqs, cpu) = irq;
	}

	return 0;

out_err:
	for_each_possible_cpu(cpu) {
		irq = per_cpu(pmu_irqs, cpu);
		if (!irq)
			continue;

		arm_pmu_acpi_unregister_irq(cpu);

		/*
		 * Blat all copies of the IRQ so that we only unregister the
		 * corresponding GSI once (e.g. when we have PPIs).
		 */
		for_each_possible_cpu(irq_cpu) {
			if (per_cpu(pmu_irqs, irq_cpu) == irq)
				per_cpu(pmu_irqs, irq_cpu) = 0;
		}
	}

	return err;
}

static struct arm_pmu *arm_pmu_acpi_find_alloc_pmu(void)
{
	unsigned long cpuid = read_cpuid_id();
	struct arm_pmu *pmu;
	int cpu;

	for_each_possible_cpu(cpu) {
		pmu = per_cpu(probed_pmus, cpu);
		if (!pmu || pmu->acpi_cpuid != cpuid)
			continue;

		return pmu;
	}

	pmu = armpmu_alloc();
	if (!pmu) {
		pr_warn("Unable to allocate PMU for CPU%d\n",
			smp_processor_id());
		return NULL;
	}

	pmu->acpi_cpuid = cpuid;

	return pmu;
}

/*
 * This must run before the common arm_pmu hotplug logic, so that we can
 * associate a CPU and its interrupt before the common code tries to manage the
 * affinity and so on.
 *
 * Note that hotplug events are serialized, so we cannot race with another CPU
 * coming up. The perf core won't open events while a hotplug event is in
 * progress.
 */
static int arm_pmu_acpi_cpu_starting(unsigned int cpu)
{
	struct arm_pmu *pmu;
	struct pmu_hw_events __percpu *hw_events;
	int irq;

	/* If we've already probed this CPU, we have nothing to do */
	if (per_cpu(probed_pmus, cpu))
		return 0;

	irq = per_cpu(pmu_irqs, cpu);

	pmu = arm_pmu_acpi_find_alloc_pmu();
	if (!pmu)
		return -ENOMEM;

	cpumask_set_cpu(cpu, &pmu->supported_cpus);

	per_cpu(probed_pmus, cpu) = pmu;

	/*
	 * Log and request the IRQ so the core arm_pmu code can manage it.  In
	 * some situations (e.g. mismatched PPIs), we may fail to request the
	 * IRQ. However, it may be too late for us to do anything about it.
	 * The common ARM PMU code will log a warning in this case.
	 */
	hw_events = pmu->hw_events;
	per_cpu(hw_events->irq, cpu) = irq;
	armpmu_request_irq(pmu, cpu);

	/*
	 * Ideally, we'd probe the PMU here when we find the first matching
	 * CPU. We can't do that for several reasons; see the comment in
	 * arm_pmu_acpi_init().
	 *
	 * So for the time being, we're done.
	 */
	return 0;
}

int arm_pmu_acpi_probe(armpmu_init_fn init_fn)
{
	int pmu_idx = 0;
	int cpu, ret;

	/*
	 * Initialise and register the set of PMUs which we know about right
	 * now. Ideally we'd do this in arm_pmu_acpi_cpu_starting() so that we
	 * could handle late hotplug, but this may lead to deadlock since we
	 * might try to register a hotplug notifier instance from within a
	 * hotplug notifier.
	 *
	 * There's also the problem of having access to the right init_fn,
	 * without tying this too deeply into the "real" PMU driver.
	 *
	 * For the moment, as with the platform/DT case, we need at least one
	 * of a PMU's CPUs to be online at probe time.
	 */
	for_each_possible_cpu(cpu) {
		struct arm_pmu *pmu = per_cpu(probed_pmus, cpu);
		char *base_name;

		if (!pmu || pmu->name)
			continue;

		ret = init_fn(pmu);
		if (ret == -ENODEV) {
			/* PMU not handled by this driver, or not present */
			continue;
		} else if (ret) {
			pr_warn("Unable to initialise PMU for CPU%d\n", cpu);
			return ret;
		}

		base_name = pmu->name;
		pmu->name = kasprintf(GFP_KERNEL, "%s_%d", base_name, pmu_idx++);
		if (!pmu->name) {
			pr_warn("Unable to allocate PMU name for CPU%d\n", cpu);
			return -ENOMEM;
		}

		ret = armpmu_register(pmu);
		if (ret) {
			pr_warn("Failed to register PMU for CPU%d\n", cpu);
			kfree(pmu->name);
			return ret;
		}
	}

	return 0;
}

static int arm_pmu_acpi_init(void)
{
	int ret;

	if (acpi_disabled)
		return 0;

	/*
	 * We can't request IRQs yet, since we don't know the cookie value
	 * until we know which CPUs share the same logical PMU. We'll handle
	 * that in arm_pmu_acpi_cpu_starting().
	 */
	ret = arm_pmu_acpi_parse_irqs();
	if (ret)
		return ret;

	ret = cpuhp_setup_state(CPUHP_AP_PERF_ARM_ACPI_STARTING,
				"perf/arm/pmu_acpi:starting",
				arm_pmu_acpi_cpu_starting, NULL);

	return ret;
}
subsys_initcall(arm_pmu_acpi_init)
OpenPOWER on IntegriCloud