tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Performance event support - PPC 8xx
3 *
4 * Copyright 2016 Christophe Leroy, CS Systemes d'Information
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/kernel.h>
13#include <linux/sched.h>
14#include <linux/perf_event.h>
15#include <linux/percpu.h>
16#include <linux/hardirq.h>
17#include <asm/pmc.h>
18#include <asm/machdep.h>
19#include <asm/firmware.h>
20#include <asm/ptrace.h>
21
22#define PERF_8xx_ID_CPU_CYCLES 1
23#define PERF_8xx_ID_HW_INSTRUCTIONS 2
24#define PERF_8xx_ID_ITLB_LOAD_MISS 3
25#define PERF_8xx_ID_DTLB_LOAD_MISS 4
26
27#define C(x) PERF_COUNT_HW_CACHE_##x
28#define DTLB_LOAD_MISS (C(DTLB) | (C(OP_READ) << 8) | (C(RESULT_MISS) << 16))
29#define ITLB_LOAD_MISS (C(ITLB) | (C(OP_READ) << 8) | (C(RESULT_MISS) << 16))
30
31extern unsigned long itlb_miss_counter, dtlb_miss_counter;
32extern atomic_t instruction_counter;
33
34static atomic_t insn_ctr_ref;
35
36static s64 get_insn_ctr(void)
37{
38 int ctr;
39 unsigned long counta;
40
41 do {
42 ctr = atomic_read(&instruction_counter);
43 counta = mfspr(SPRN_COUNTA);
44 } while (ctr != atomic_read(&instruction_counter));
45
46 return ((s64)ctr << 16) | (counta >> 16);
47}
48
49static int event_type(struct perf_event *event)
50{
51 switch (event->attr.type) {
52 case PERF_TYPE_HARDWARE:
53 if (event->attr.config == PERF_COUNT_HW_CPU_CYCLES)
54 return PERF_8xx_ID_CPU_CYCLES;
55 if (event->attr.config == PERF_COUNT_HW_INSTRUCTIONS)
56 return PERF_8xx_ID_HW_INSTRUCTIONS;
57 break;
58 case PERF_TYPE_HW_CACHE:
59 if (event->attr.config == ITLB_LOAD_MISS)
60 return PERF_8xx_ID_ITLB_LOAD_MISS;
61 if (event->attr.config == DTLB_LOAD_MISS)
62 return PERF_8xx_ID_DTLB_LOAD_MISS;
63 break;
64 case PERF_TYPE_RAW:
65 break;
66 default:
67 return -ENOENT;
68 }
69 return -EOPNOTSUPP;
70}
71
72static int mpc8xx_pmu_event_init(struct perf_event *event)
73{
74 int type = event_type(event);
75
76 if (type < 0)
77 return type;
78 return 0;
79}
80
81static int mpc8xx_pmu_add(struct perf_event *event, int flags)
82{
83 int type = event_type(event);
84 s64 val = 0;
85
86 if (type < 0)
87 return type;
88
89 switch (type) {
90 case PERF_8xx_ID_CPU_CYCLES:
91 val = get_tb();
92 break;
93 case PERF_8xx_ID_HW_INSTRUCTIONS:
94 if (atomic_inc_return(&insn_ctr_ref) == 1)
95 mtspr(SPRN_ICTRL, 0xc0080007);
96 val = get_insn_ctr();
97 break;
98 case PERF_8xx_ID_ITLB_LOAD_MISS:
99 val = itlb_miss_counter;
100 break;
101 case PERF_8xx_ID_DTLB_LOAD_MISS:
102 val = dtlb_miss_counter;
103 break;
104 }
105 local64_set(&event->hw.prev_count, val);
106 return 0;
107}
108
109static void mpc8xx_pmu_read(struct perf_event *event)
110{
111 int type = event_type(event);
112 s64 prev, val = 0, delta = 0;
113
114 if (type < 0)
115 return;
116
117 do {
118 prev = local64_read(&event->hw.prev_count);
119 switch (type) {
120 case PERF_8xx_ID_CPU_CYCLES:
121 val = get_tb();
122 delta = 16 * (val - prev);
123 break;
124 case PERF_8xx_ID_HW_INSTRUCTIONS:
125 val = get_insn_ctr();
126 delta = prev - val;
127 if (delta < 0)
128 delta += 0x1000000000000LL;
129 break;
130 case PERF_8xx_ID_ITLB_LOAD_MISS:
131 val = itlb_miss_counter;
132 delta = (s64)((s32)val - (s32)prev);
133 break;
134 case PERF_8xx_ID_DTLB_LOAD_MISS:
135 val = dtlb_miss_counter;
136 delta = (s64)((s32)val - (s32)prev);
137 break;
138 }
139 } while (local64_cmpxchg(&event->hw.prev_count, prev, val) != prev);
140
141 local64_add(delta, &event->count);
142}
143
144static void mpc8xx_pmu_del(struct perf_event *event, int flags)
145{
146 mpc8xx_pmu_read(event);
147 if (event_type(event) != PERF_8xx_ID_HW_INSTRUCTIONS)
148 return;
149
150 /* If it was the last user, stop counting to avoid useles overhead */
151 if (atomic_dec_return(&insn_ctr_ref) == 0)
152 mtspr(SPRN_ICTRL, 7);
153}
154
155static struct pmu mpc8xx_pmu = {
156 .event_init = mpc8xx_pmu_event_init,
157 .add = mpc8xx_pmu_add,
158 .del = mpc8xx_pmu_del,
159 .read = mpc8xx_pmu_read,
160 .capabilities = PERF_PMU_CAP_NO_INTERRUPT |
161 PERF_PMU_CAP_NO_NMI,
162};
163
164static int init_mpc8xx_pmu(void)
165{
166 mtspr(SPRN_ICTRL, 7);
167 mtspr(SPRN_CMPA, 0);
168 mtspr(SPRN_COUNTA, 0xffff);
169
170 return perf_pmu_register(&mpc8xx_pmu, "cpu", PERF_TYPE_RAW);
171}
172
173early_initcall(init_mpc8xx_pmu);