[CELL] oprofile: add support to OProfile for profiling CELL BE SPUs

From: Maynard Johnson <mpjohn@us.ibm.com>

This patch updates the existing arch/powerpc/oprofile/op_model_cell.c
to add in the SPU profiling capabilities.  In addition, a 'cell' subdirectory
was added to arch/powerpc/oprofile to hold Cell-specific SPU profiling code.
Exports spu_set_profile_private_kref and spu_get_profile_private_kref which
are used by OProfile to store private profile information in spufs data
structures.

Also incorporated several fixes from other patches (rrn).  Check pointer
returned from kzalloc.  Eliminated unnecessary cast.  Better error
handling and cleanup in the related area.  64-bit unsigned long parameter
was being demoted to 32-bit unsigned int and eventually promoted back to
unsigned long.

Signed-off-by: Carl Love <carll@us.ibm.com>
Signed-off-by: Maynard Johnson <mpjohn@us.ibm.com>
Signed-off-by: Bob Nelson <rrnelson@us.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>

1 files changed, 221 insertions, 0 deletions

diff --git a/arch/powerpc/oprofile/cell/spu_profiler.c b/arch/powerpc/oprofile/cell/spu_profiler.c
new file mode 100644
index 0000000..380d7e2
--- /dev/null
+++ b/arch/powerpc/oprofile/cell/spu_profiler.c
@@ -0,0 +1,221 @@
+/*
+ * Cell Broadband Engine OProfile Support
+ *
+ * (C) Copyright IBM Corporation 2006
+ *
+ * Authors: Maynard Johnson <maynardj@us.ibm.com>
+ *	    Carl Love <carll@us.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/hrtimer.h>
+#include <linux/smp.h>
+#include <linux/slab.h>
+#include <asm/cell-pmu.h>
+#include "pr_util.h"
+
+#define TRACE_ARRAY_SIZE 1024
+#define SCALE_SHIFT 14
+
+static u32 *samples;
+
+static int spu_prof_running;
+static unsigned int profiling_interval;
+
+#define NUM_SPU_BITS_TRBUF 16
+#define SPUS_PER_TB_ENTRY   4
+#define SPUS_PER_NODE	     8
+
+#define SPU_PC_MASK	     0xFFFF
+
+static DEFINE_SPINLOCK(sample_array_lock);
+unsigned long sample_array_lock_flags;
+
+void set_spu_profiling_frequency(unsigned int freq_khz, unsigned int cycles_reset)
+{
+	unsigned long ns_per_cyc;
+
+	if (!freq_khz)
+		freq_khz = ppc_proc_freq/1000;
+
+	/* To calculate a timeout in nanoseconds, the basic
+	 * formula is ns = cycles_reset * (NSEC_PER_SEC / cpu frequency).
+	 * To avoid floating point math, we use the scale math
+	 * technique as described in linux/jiffies.h.  We use
+	 * a scale factor of SCALE_SHIFT, which provides 4 decimal places
+	 * of precision.  This is close enough for the purpose at hand.
+	 *
+	 * The value of the timeout should be small enough that the hw
+	 * trace buffer will not get more then about 1/3 full for the
+	 * maximum user specified (the LFSR value) hw sampling frequency.
+	 * This is to ensure the trace buffer will never fill even if the
+	 * kernel thread scheduling varies under a heavy system load.
+	 */
+
+	ns_per_cyc = (USEC_PER_SEC << SCALE_SHIFT)/freq_khz;
+	profiling_interval = (ns_per_cyc * cycles_reset) >> SCALE_SHIFT;
+
+}
+
+/*
+ * Extract SPU PC from trace buffer entry
+ */
+static void spu_pc_extract(int cpu, int entry)
+{
+	/* the trace buffer is 128 bits */
+	u64 trace_buffer[2];
+	u64 spu_mask;
+	int spu;
+
+	spu_mask = SPU_PC_MASK;
+
+	/* Each SPU PC is 16 bits; hence, four spus in each of
+	 * the two 64-bit buffer entries that make up the
+	 * 128-bit trace_buffer entry.	Process two 64-bit values
+	 * simultaneously.
+	 * trace[0] SPU PC contents are: 0 1 2 3
+	 * trace[1] SPU PC contents are: 4 5 6 7
+	 */
+
+	cbe_read_trace_buffer(cpu, trace_buffer);
+
+	for (spu = SPUS_PER_TB_ENTRY-1; spu >= 0; spu--) {
+		/* spu PC trace entry is upper 16 bits of the
+		 * 18 bit SPU program counter
+		 */
+		samples[spu * TRACE_ARRAY_SIZE + entry]
+			= (spu_mask & trace_buffer[0]) << 2;
+		samples[(spu + SPUS_PER_TB_ENTRY) * TRACE_ARRAY_SIZE + entry]
+			= (spu_mask & trace_buffer[1]) << 2;
+
+		trace_buffer[0] = trace_buffer[0] >> NUM_SPU_BITS_TRBUF;
+		trace_buffer[1] = trace_buffer[1] >> NUM_SPU_BITS_TRBUF;
+	}
+}
+
+static int cell_spu_pc_collection(int cpu)
+{
+	u32 trace_addr;
+	int entry;
+
+	/* process the collected SPU PC for the node */
+
+	entry = 0;
+
+	trace_addr = cbe_read_pm(cpu, trace_address);
+	while (!(trace_addr & CBE_PM_TRACE_BUF_EMPTY)) {
+		/* there is data in the trace buffer to process */
+		spu_pc_extract(cpu, entry);
+
+		entry++;
+
+		if (entry >= TRACE_ARRAY_SIZE)
+			/* spu_samples is full */
+			break;
+
+		trace_addr = cbe_read_pm(cpu, trace_address);
+	}
+
+	return entry;
+}
+
+
+static enum hrtimer_restart profile_spus(struct hrtimer *timer)
+{
+	ktime_t kt;
+	int cpu, node, k, num_samples, spu_num;
+
+	if (!spu_prof_running)
+		goto stop;
+
+	for_each_online_cpu(cpu) {
+		if (cbe_get_hw_thread_id(cpu))
+			continue;
+
+		node = cbe_cpu_to_node(cpu);
+
+		/* There should only be one kernel thread at a time processing
+		 * the samples.	 In the very unlikely case that the processing
+		 * is taking a very long time and multiple kernel threads are
+		 * started to process the samples.  Make sure only one kernel
+		 * thread is working on the samples array at a time.  The
+		 * sample array must be loaded and then processed for a given
+		 * cpu.	 The sample array is not per cpu.
+		 */
+		spin_lock_irqsave(&sample_array_lock,
+				  sample_array_lock_flags);
+		num_samples = cell_spu_pc_collection(cpu);
+
+		if (num_samples == 0) {
+			spin_unlock_irqrestore(&sample_array_lock,
+					       sample_array_lock_flags);
+			continue;
+		}
+
+		for (k = 0; k < SPUS_PER_NODE; k++) {
+			spu_num = k + (node * SPUS_PER_NODE);
+			spu_sync_buffer(spu_num,
+					samples + (k * TRACE_ARRAY_SIZE),
+					num_samples);
+		}
+
+		spin_unlock_irqrestore(&sample_array_lock,
+				       sample_array_lock_flags);
+
+	}
+	smp_wmb();	/* insure spu event buffer updates are written */
+			/* don't want events intermingled... */
+
+	kt = ktime_set(0, profiling_interval);
+	if (!spu_prof_running)
+		goto stop;
+	hrtimer_forward(timer, timer->base->get_time(), kt);
+	return HRTIMER_RESTART;
+
+ stop:
+	printk(KERN_INFO "SPU_PROF: spu-prof timer ending\n");
+	return HRTIMER_NORESTART;
+}
+
+static struct hrtimer timer;
+/*
+ * Entry point for SPU profiling.
+ * NOTE:  SPU profiling is done system-wide, not per-CPU.
+ *
+ * cycles_reset is the count value specified by the user when
+ * setting up OProfile to count SPU_CYCLES.
+ */
+int start_spu_profiling(unsigned int cycles_reset)
+{
+	ktime_t kt;
+
+	pr_debug("timer resolution: %lu\n", TICK_NSEC);
+	kt = ktime_set(0, profiling_interval);
+	hrtimer_init(&timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	timer.expires = kt;
+	timer.function = profile_spus;
+
+	/* Allocate arrays for collecting SPU PC samples */
+	samples = kzalloc(SPUS_PER_NODE *
+			  TRACE_ARRAY_SIZE * sizeof(u32), GFP_KERNEL);
+
+	if (!samples)
+		return -ENOMEM;
+
+	spu_prof_running = 1;
+	hrtimer_start(&timer, kt, HRTIMER_MODE_REL);
+
+	return 0;
+}
+
+void stop_spu_profiling(void)
+{
+	spu_prof_running = 0;
+	hrtimer_cancel(&timer);
+	kfree(samples);
+	pr_debug("SPU_PROF: stop_spu_profiling issued\n");
+}