path: root/arch/powerpc/oprofile/cell/spu_task_sync.c

/*
 * Cell Broadband Engine OProfile Support
 *
 * (C) Copyright IBM Corporation 2006
 *
 * Author: Maynard Johnson <maynardj@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.
 */

/* The purpose of this file is to handle SPU event task switching
 * and to record SPU context information into the OProfile
 * event buffer.
 *
 * Additionally, the spu_sync_buffer function is provided as a helper
 * for recoding actual SPU program counter samples to the event buffer.
 */
#include <linux/dcookies.h>
#include <linux/kref.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/numa.h>
#include <linux/oprofile.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include "pr_util.h"

#define RELEASE_ALL 9999

static DEFINE_SPINLOCK(buffer_lock);
static DEFINE_SPINLOCK(cache_lock);
static int num_spu_nodes;
int spu_prof_num_nodes;

struct spu_buffer spu_buff[MAX_NUMNODES * SPUS_PER_NODE];
struct delayed_work spu_work;
static unsigned max_spu_buff;

static void spu_buff_add(unsigned long int value, int spu)
{
	/* spu buff is a circular buffer.  Add entries to the
	 * head.  Head is the index to store the next value.
	 * The buffer is full when there is one available entry
	 * in the queue, i.e. head and tail can't be equal.
	 * That way we can tell the difference between the
	 * buffer being full versus empty.
	 *
	 *  ASSUMPTION: the buffer_lock is held when this function
	 *             is called to lock the buffer, head and tail.
	 */
	int full = 1;

	if (spu_buff[spu].head >= spu_buff[spu].tail) {
		if ((spu_buff[spu].head - spu_buff[spu].tail)
		    <  (max_spu_buff - 1))
			full = 0;

	} else if (spu_buff[spu].tail > spu_buff[spu].head) {
		if ((spu_buff[spu].tail - spu_buff[spu].head)
		    > 1)
			full = 0;
	}

	if (!full) {
		spu_buff[spu].buff[spu_buff[spu].head] = value;
		spu_buff[spu].head++;

		if (spu_buff[spu].head >= max_spu_buff)
			spu_buff[spu].head = 0;
	} else {
		/* From the user's perspective make the SPU buffer
		 * size management/overflow look like we are using
		 * per cpu buffers.  The user uses the same
		 * per cpu parameter to adjust the SPU buffer size.
		 * Increment the sample_lost_overflow to inform
		 * the user the buffer size needs to be increased.
		 */
		oprofile_cpu_buffer_inc_smpl_lost();
	}
}

/* This function copies the per SPU buffers to the
 * OProfile kernel buffer.
 */
void sync_spu_buff(void)
{
	int spu;
	unsigned long flags;
	int curr_head;

	for (spu = 0; spu < num_spu_nodes; spu++) {
		/* In case there was an issue and the buffer didn't
		 * get created skip it.
		 */
		if (spu_buff[spu].buff == NULL)
			continue;

		/* Hold the lock to make sure the head/tail
		 * doesn't change while spu_buff_add() is
		 * deciding if the buffer is full or not.
		 * Being a little paranoid.
		 */
		spin_lock_irqsave(&buffer_lock, flags);
		curr_head = spu_buff[spu].head;
		spin_unlock_irqrestore(&buffer_lock, flags);

		/* Transfer the current contents to the kernel buffer.
		 * data can still be added to the head of the buffer.
		 */
		oprofile_put_buff(spu_buff[spu].buff,
				  spu_buff[spu].tail,
				  curr_head, max_spu_buff);

		spin_lock_irqsave(&buffer_lock, flags);
		spu_buff[spu].tail = curr_head;
		spin_unlock_irqrestore(&buffer_lock, flags);
	}

}

static void wq_sync_spu_buff(struct work_struct *work)
{
	/* move data from spu buffers to kernel buffer */
	sync_spu_buff();

	/* only reschedule if profiling is not done */
	if (spu_prof_running)
		schedule_delayed_work(&spu_work, DEFAULT_TIMER_EXPIRE);
}

/* Container for caching information about an active SPU task. */
struct cached_info {
	struct vma_to_fileoffset_map *map;
	struct spu *the_spu;	/* needed to access pointer to local_store */
	struct kref cache_ref;
};

static struct cached_info *spu_info[MAX_NUMNODES * 8];

static void destroy_cached_info(struct kref *kref)
{
	struct cached_info *info;

	info = container_of(kref, struct cached_info, cache_ref);
	vma_map_free(info->map);
	kfree(info);
	module_put(THIS_MODULE);
}

/* Return the cached_info for the passed SPU number.
 * ATTENTION:  Callers are responsible for obtaining the
 *	       cache_lock if needed prior to invoking this function.
 */
static struct cached_info *get_cached_info(struct spu *the_spu, int spu_num)
{
	struct kref *ref;
	struct cached_info *ret_info;

	if (spu_num >= num_spu_nodes) {
		printk(KERN_ERR "SPU_PROF: "
		       "%s, line %d: Invalid index %d into spu info cache\n",
		       __func__, __LINE__, spu_num);
		ret_info = NULL;
		goto out;
	}
	if (!spu_info[spu_num] && the_spu) {
		ref = spu_get_profile_private_kref(the_spu->ctx);
		if (ref) {
			spu_info[spu_num] = container_of(ref, struct cached_info, cache_ref);
			kref_get(&spu_info[spu_num]->cache_ref);
		}
	}

	ret_info = spu_info[spu_num];
 out:
	return ret_info;
}


/* Looks for cached info for the passed spu.  If not found, the
 * cached info is created for the passed spu.
 * Returns 0 for success; otherwise, -1 for error.
 */
static int
prepare_cached_spu_info(struct spu *spu, unsigned long objectId)
{
	unsigned long flags;
	struct vma_to_fileoffset_map *new_map;
	int retval = 0;
	struct cached_info *info;

	/* We won't bother getting cache_lock here since
	 * don't do anything with the cached_info that's returned.
	 */
	info = get_cached_info(spu, spu->number);

	if (info) {
		pr_debug("Found cached SPU info.\n");
		goto out;
	}

	/* Create cached_info and set spu_info[spu->number] to point to it.
	 * spu->number is a system-wide value, not a per-node value.
	 */
	info = kzalloc(sizeof(struct cached_info), GFP_KERNEL);
	if (!info) {
		printk(KERN_ERR "SPU_PROF: "
		       "%s, line %d: create vma_map failed\n",
		       __func__, __LINE__);
		retval = -ENOMEM;
		goto err_alloc;
	}
	new_map = create_vma_map(spu, objectId);
	if (!new_map) {
		printk(KERN_ERR "SPU_PROF: "
		       "%s, line %d: create vma_map failed\n",
		       __func__, __LINE__);
		retval = -ENOMEM;
		goto err_alloc;
	}

	pr_debug("Created vma_map\n");
	info->map = new_map;
	info->the_spu = spu;
	kref_init(&info->cache_ref);
	spin_lock_irqsave(&cache_lock, flags);
	spu_info[spu->number] = info;
	/* Increment count before passing off ref to SPUFS. */
	kref_get(&info->cache_ref);

	/* We increment the module refcount here since SPUFS is
	 * responsible for the final destruction of the cached_info,
	 * and it must be able to access the destroy_cached_info()
	 * function defined in the OProfile module.  We decrement
	 * the module refcount in destroy_cached_info.
	 */
	try_module_get(THIS_MODULE);
	spu_set_profile_private_kref(spu->ctx, &info->cache_ref,
				destroy_cached_info);
	spin_unlock_irqrestore(&cache_lock, flags);
	goto out;

err_alloc:
	kfree(info);
out:
	return retval;
}<