1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Cell Broadband Engine OProfile Support
4 *
5 * (C) Copyright IBM Corporation 2006
6 *
7 * Authors: Maynard Johnson <maynardj@us.ibm.com>
8 * Carl Love <carll@us.ibm.com>
9 */
10
11 #include <linux/hrtimer.h>
12 #include <linux/smp.h>
13 #include <linux/slab.h>
14 #include <asm/cell-pmu.h>
15 #include <asm/time.h>
16 #include "pr_util.h"
17
18 #define SCALE_SHIFT 14
19
20 static u32 *samples;
21
22 /* spu_prof_running is a flag used to indicate if spu profiling is enabled
23 * or not. It is set by the routines start_spu_profiling_cycles() and
24 * start_spu_profiling_events(). The flag is cleared by the routines
25 * stop_spu_profiling_cycles() and stop_spu_profiling_events(). These
26 * routines are called via global_start() and global_stop() which are called in
27 * op_powerpc_start() and op_powerpc_stop(). These routines are called once
28 * per system as a result of the user starting/stopping oprofile. Hence, only
29 * one CPU per user at a time will be changing the value of spu_prof_running.
30 * In general, OProfile does not protect against multiple users trying to run
31 * OProfile at a time.
32 */
33 int spu_prof_running;
34 static unsigned int profiling_interval;
35
36 #define NUM_SPU_BITS_TRBUF 16
37 #define SPUS_PER_TB_ENTRY 4
38
39 #define SPU_PC_MASK 0xFFFF
40
41 DEFINE_SPINLOCK(oprof_spu_smpl_arry_lck);
42 static unsigned long oprof_spu_smpl_arry_lck_flags;
43
set_spu_profiling_frequency(unsigned int freq_khz,unsigned int cycles_reset)44 void set_spu_profiling_frequency(unsigned int freq_khz, unsigned int cycles_reset)
45 {
46 unsigned long ns_per_cyc;
47
48 if (!freq_khz)
49 freq_khz = ppc_proc_freq/1000;
50
51 /* To calculate a timeout in nanoseconds, the basic
52 * formula is ns = cycles_reset * (NSEC_PER_SEC / cpu frequency).
53 * To avoid floating point math, we use the scale math
54 * technique as described in linux/jiffies.h. We use
55 * a scale factor of SCALE_SHIFT, which provides 4 decimal places
56 * of precision. This is close enough for the purpose at hand.
57 *
58 * The value of the timeout should be small enough that the hw
59 * trace buffer will not get more than about 1/3 full for the
60 * maximum user specified (the LFSR value) hw sampling frequency.
61 * This is to ensure the trace buffer will never fill even if the
62 * kernel thread scheduling varies under a heavy system load.
63 */
64
65 ns_per_cyc = (USEC_PER_SEC << SCALE_SHIFT)/freq_khz;
66 profiling_interval = (ns_per_cyc * cycles_reset) >> SCALE_SHIFT;
67
68 }
69
70 /*
71 * Extract SPU PC from trace buffer entry
72 */
spu_pc_extract(int cpu,int entry)73 static void spu_pc_extract(int cpu, int entry)
74 {
75 /* the trace buffer is 128 bits */
76 u64 trace_buffer[2];
77 u64 spu_mask;
78 int spu;
79
80 spu_mask = SPU_PC_MASK;
81
82 /* Each SPU PC is 16 bits; hence, four spus in each of
83 * the two 64-bit buffer entries that make up the
84 * 128-bit trace_buffer entry. Process two 64-bit values
85 * simultaneously.
86 * trace[0] SPU PC contents are: 0 1 2 3
87 * trace[1] SPU PC contents are: 4 5 6 7
88 */
89
90 cbe_read_trace_buffer(cpu, trace_buffer);
91
92 for (spu = SPUS_PER_TB_ENTRY-1; spu >= 0; spu--) {
93 /* spu PC trace entry is upper 16 bits of the
94 * 18 bit SPU program counter
95 */
96 samples[spu * TRACE_ARRAY_SIZE + entry]
97 = (spu_mask & trace_buffer[0]) << 2;
98 samples[(spu + SPUS_PER_TB_ENTRY) * TRACE_ARRAY_SIZE + entry]
99 = (spu_mask & trace_buffer[1]) << 2;
100
101 trace_buffer[0] = trace_buffer[0] >> NUM_SPU_BITS_TRBUF;
102 trace_buffer[1] = trace_buffer[1] >> NUM_SPU_BITS_TRBUF;
103 }
104 }
105
cell_spu_pc_collection(int cpu)106 static int cell_spu_pc_collection(int cpu)
107 {
108 u32 trace_addr;
109 int entry;
110
111 /* process the collected SPU PC for the node */
112
113 entry = 0;
114
115 trace_addr = cbe_read_pm(cpu, trace_address);
116 while (!(trace_addr & CBE_PM_TRACE_BUF_EMPTY)) {
117 /* there is data in the trace buffer to process */
118 spu_pc_extract(cpu, entry);
119
120 entry++;
121
122 if (entry >= TRACE_ARRAY_SIZE)
123 /* spu_samples is full */
124 break;
125
126 trace_addr = cbe_read_pm(cpu, trace_address);
127 }
128
129 return entry;
130 }
131
132
profile_spus(struct hrtimer * timer)133 static enum hrtimer_restart profile_spus(struct hrtimer *timer)
134 {
135 ktime_t kt;
136 int cpu, node, k, num_samples, spu_num;
137
138 if (!spu_prof_running)
139 goto stop;
140
141 for_each_online_cpu(cpu) {
142 if (cbe_get_hw_thread_id(cpu))
143 continue;
144
145 node = cbe_cpu_to_node(cpu);
146
147 /* There should only be one kernel thread at a time processing
148 * the samples. In the very unlikely case that the processing
149 * is taking a very long time and multiple kernel threads are
150 * started to process the samples. Make sure only one kernel
151 * thread is working on the samples array at a time. The
152 * sample array must be loaded and then processed for a given
153 * cpu. The sample array is not per cpu.
154 */
155 spin_lock_irqsave(&oprof_spu_smpl_arry_lck,
156 oprof_spu_smpl_arry_lck_flags);
157 num_samples = cell_spu_pc_collection(cpu);
158
159 if (num_samples == 0) {
160 spin_unlock_irqrestore(&oprof_spu_smpl_arry_lck,
161 oprof_spu_smpl_arry_lck_flags);
162 continue;
163 }
164
165 for (k = 0; k < SPUS_PER_NODE; k++) {
166 spu_num = k + (node * SPUS_PER_NODE);
167 spu_sync_buffer(spu_num,
168 samples + (k * TRACE_ARRAY_SIZE),
169 num_samples);
170 }
171
172 spin_unlock_irqrestore(&oprof_spu_smpl_arry_lck,
173 oprof_spu_smpl_arry_lck_flags);
174
175 }
176 smp_wmb(); /* insure spu event buffer updates are written */
177 /* don't want events intermingled... */
178
179 kt = profiling_interval;
180 if (!spu_prof_running)
181 goto stop;
182 hrtimer_forward(timer, timer->base->get_time(), kt);
183 return HRTIMER_RESTART;
184
185 stop:
186 printk(KERN_INFO "SPU_PROF: spu-prof timer ending\n");
187 return HRTIMER_NORESTART;
188 }
189
190 static struct hrtimer timer;
191 /*
192 * Entry point for SPU cycle profiling.
193 * NOTE: SPU profiling is done system-wide, not per-CPU.
194 *
195 * cycles_reset is the count value specified by the user when
196 * setting up OProfile to count SPU_CYCLES.
197 */
start_spu_profiling_cycles(unsigned int cycles_reset)198 int start_spu_profiling_cycles(unsigned int cycles_reset)
199 {
200 ktime_t kt;
201
202 pr_debug("timer resolution: %lu\n", TICK_NSEC);
203 kt = profiling_interval;
204 hrtimer_init(&timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
205 hrtimer_set_expires(&timer, kt);
206 timer.function = profile_spus;
207
208 /* Allocate arrays for collecting SPU PC samples */
209 samples = kcalloc(SPUS_PER_NODE * TRACE_ARRAY_SIZE, sizeof(u32),
210 GFP_KERNEL);
211
212 if (!samples)
213 return -ENOMEM;
214
215 spu_prof_running = 1;
216 hrtimer_start(&timer, kt, HRTIMER_MODE_REL);
217 schedule_delayed_work(&spu_work, DEFAULT_TIMER_EXPIRE);
218
219 return 0;
220 }
221
222 /*
223 * Entry point for SPU event profiling.
224 * NOTE: SPU profiling is done system-wide, not per-CPU.
225 *
226 * cycles_reset is the count value specified by the user when
227 * setting up OProfile to count SPU_CYCLES.
228 */
start_spu_profiling_events(void)229 void start_spu_profiling_events(void)
230 {
231 spu_prof_running = 1;
232 schedule_delayed_work(&spu_work, DEFAULT_TIMER_EXPIRE);
233
234 return;
235 }
236
stop_spu_profiling_cycles(void)237 void stop_spu_profiling_cycles(void)
238 {
239 spu_prof_running = 0;
240 hrtimer_cancel(&timer);
241 kfree(samples);
242 pr_debug("SPU_PROF: stop_spu_profiling_cycles issued\n");
243 }
244
stop_spu_profiling_events(void)245 void stop_spu_profiling_events(void)
246 {
247 spu_prof_running = 0;
248 }
249
