arch/powerpc/platforms/pseries/dtl.c - kernel/quantenna - Git at Google

 /*
  * Virtual Processor Dispatch Trace Log
  *
  * (C) Copyright IBM Corporation 2009
  *
  * Author: Jeremy Kerr <jk@ozlabs.org>
  *
  * 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, or (at your option)
  * any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */

 #include <linux/slab.h>
 #include <linux/debugfs.h>
 #include <linux/spinlock.h>
 #include <asm/smp.h>
 #include <asm/uaccess.h>
 #include <asm/firmware.h>
 #include <asm/lppaca.h>
 #include <asm/debug.h>
 #include <asm/plpar_wrappers.h>
 #include <asm/machdep.h>

 struct dtl {
 	struct dtl_entry	*buf;
 	struct dentry		*file;
 	int			cpu;
 	int			buf_entries;
 	u64			last_idx;
 	spinlock_t		lock;
 };
 static DEFINE_PER_CPU(struct dtl, cpu_dtl);

 /*
  * Dispatch trace log event mask:
  * 0x7: 0x1: voluntary virtual processor waits
  *      0x2: time-slice preempts
  *      0x4: virtual partition memory page faults
  */
 static u8 dtl_event_mask = 0x7;


 /*
  * Size of per-cpu log buffers. Firmware requires that the buffer does
  * not cross a 4k boundary.
  */
 static int dtl_buf_entries = N_DISPATCH_LOG;

 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
 struct dtl_ring {
 	u64	write_index;
 	struct dtl_entry *write_ptr;
 	struct dtl_entry *buf;
 	struct dtl_entry *buf_end;
 	u8	saved_dtl_mask;
 };

 static DEFINE_PER_CPU(struct dtl_ring, dtl_rings);

 static atomic_t dtl_count;

 /*
  * The cpu accounting code controls the DTL ring buffer, and we get
  * given entries as they are processed.
  */
 static void consume_dtle(struct dtl_entry *dtle, u64 index)
 {
 	struct dtl_ring *dtlr = this_cpu_ptr(&dtl_rings);
 	struct dtl_entry *wp = dtlr->write_ptr;
 	struct lppaca *vpa = local_paca->lppaca_ptr;

 	if (!wp)
 		return;

 	*wp = *dtle;
 	barrier();

 	/* check for hypervisor ring buffer overflow, ignore this entry if so */
 	if (index + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx))
 		return;

 	++wp;
 	if (wp == dtlr->buf_end)
 		wp = dtlr->buf;
 	dtlr->write_ptr = wp;

 	/* incrementing write_index makes the new entry visible */
 	smp_wmb();
 	++dtlr->write_index;
 }

 static int dtl_start(struct dtl *dtl)
 {
 	struct dtl_ring *dtlr = &per_cpu(dtl_rings, dtl->cpu);

 	dtlr->buf = dtl->buf;
 	dtlr->buf_end = dtl->buf + dtl->buf_entries;
 	dtlr->write_index = 0;

 	/* setting write_ptr enables logging into our buffer */
 	smp_wmb();
 	dtlr->write_ptr = dtl->buf;

 	/* enable event logging */
 	dtlr->saved_dtl_mask = lppaca_of(dtl->cpu).dtl_enable_mask;
 	lppaca_of(dtl->cpu).dtl_enable_mask |= dtl_event_mask;

 	dtl_consumer = consume_dtle;
 	atomic_inc(&dtl_count);
 	return 0;
 }

 static void dtl_stop(struct dtl *dtl)
 {
 	struct dtl_ring *dtlr = &per_cpu(dtl_rings, dtl->cpu);

 	dtlr->write_ptr = NULL;
 	smp_wmb();

 	dtlr->buf = NULL;

 	/* restore dtl_enable_mask */
 	lppaca_of(dtl->cpu).dtl_enable_mask = dtlr->saved_dtl_mask;

 	if (atomic_dec_and_test(&dtl_count))
 		dtl_consumer = NULL;
 }

 static u64 dtl_current_index(struct dtl *dtl)
 {
 	return per_cpu(dtl_rings, dtl->cpu).write_index;
 }

 #else /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */

 static int dtl_start(struct dtl *dtl)
 {
 	unsigned long addr;
 	int ret, hwcpu;

 	/* Register our dtl buffer with the hypervisor. The HV expects the
 	 * buffer size to be passed in the second word of the buffer */
 	((u32 *)dtl->buf)[1] = DISPATCH_LOG_BYTES;

 	hwcpu = get_hard_smp_processor_id(dtl->cpu);
 	addr = __pa(dtl->buf);
 	ret = register_dtl(hwcpu, addr);
 	if (ret) {
 		printk(KERN_WARNING "%s: DTL registration for cpu %d (hw %d) "
 		       "failed with %d\n", __func__, dtl->cpu, hwcpu, ret);
 		return -EIO;
 	}

 	/* set our initial buffer indices */
 	lppaca_of(dtl->cpu).dtl_idx = 0;

 	/* ensure that our updates to the lppaca fields have occurred before
 	 * we actually enable the logging */
 	smp_wmb();

 	/* enable event logging */
 	lppaca_of(dtl->cpu).dtl_enable_mask = dtl_event_mask;

 	return 0;
 }

 static void dtl_stop(struct dtl *dtl)
 {
 	int hwcpu = get_hard_smp_processor_id(dtl->cpu);

 	lppaca_of(dtl->cpu).dtl_enable_mask = 0x0;

 	unregister_dtl(hwcpu);
 }

 static u64 dtl_current_index(struct dtl *dtl)
 {
 	return lppaca_of(dtl->cpu).dtl_idx;
 }
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */

 static int dtl_enable(struct dtl *dtl)
 {
 	long int n_entries;
 	long int rc;
 	struct dtl_entry *buf = NULL;

 	if (!dtl_cache)
 		return -ENOMEM;

 	/* only allow one reader */
 	if (dtl->buf)
 		return -EBUSY;

 	n_entries = dtl_buf_entries;
 	buf = kmem_cache_alloc_node(dtl_cache, GFP_KERNEL, cpu_to_node(dtl->cpu));
 	if (!buf) {
 		printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n",
 				__func__, dtl->cpu);
 		return -ENOMEM;
 	}

 	spin_lock(&dtl->lock);
 	rc = -EBUSY;
 	if (!dtl->buf) {
 		/* store the original allocation size for use during read */
 		dtl->buf_entries = n_entries;
 		dtl->buf = buf;
 		dtl->last_idx = 0;
 		rc = dtl_start(dtl);
 		if (rc)
 			dtl->buf = NULL;
 	}
 	spin_unlock(&dtl->lock);

 	if (rc)
 		kmem_cache_free(dtl_cache, buf);
 	return rc;
 }

 static void dtl_disable(struct dtl *dtl)
 {
 	spin_lock(&dtl->lock);
 	dtl_stop(dtl);
 	kmem_cache_free(dtl_cache, dtl->buf);
 	dtl->buf = NULL;
 	dtl->buf_entries = 0;
 	spin_unlock(&dtl->lock);
 }

 /* file interface */

 static int dtl_file_open(struct inode *inode, struct file *filp)
 {
 	struct dtl *dtl = inode->i_private;
 	int rc;

 	rc = dtl_enable(dtl);
 	if (rc)
 		return rc;

 	filp->private_data = dtl;
 	return 0;
 }

 static int dtl_file_release(struct inode *inode, struct file *filp)
 {
 	struct dtl *dtl = inode->i_private;
 	dtl_disable(dtl);
 	return 0;
 }

 static ssize_t dtl_file_read(struct file *filp, char __user *buf, size_t len,
 		loff_t *pos)
 {
 	long int rc, n_read, n_req, read_size;
 	struct dtl *dtl;
 	u64 cur_idx, last_idx, i;

 	if ((len % sizeof(struct dtl_entry)) != 0)
 		return -EINVAL;

 	dtl = filp->private_data;

 	/* requested number of entries to read */
 	n_req = len / sizeof(struct dtl_entry);

 	/* actual number of entries read */
 	n_read = 0;

 	spin_lock(&dtl->lock);

 	cur_idx = dtl_current_index(dtl);
 	last_idx = dtl->last_idx;

 	if (last_idx + dtl->buf_entries <= cur_idx)
 		last_idx = cur_idx - dtl->buf_entries + 1;

 	if (last_idx + n_req > cur_idx)
 		n_req = cur_idx - last_idx;

 	if (n_req > 0)
 		dtl->last_idx = last_idx + n_req;

 	spin_unlock(&dtl->lock);

 	if (n_req <= 0)
 		return 0;

 	i = last_idx % dtl->buf_entries;

 	/* read the tail of the buffer if we've wrapped */
 	if (i + n_req > dtl->buf_entries) {
 		read_size = dtl->buf_entries - i;

 		rc = copy_to_user(buf, &dtl->buf[i],
 				read_size * sizeof(struct dtl_entry));
 		if (rc)
 			return -EFAULT;

 		i = 0;
 		n_req -= read_size;
 		n_read += read_size;
 		buf += read_size * sizeof(struct dtl_entry);
 	}

 	/* .. and now the head */
 	rc = copy_to_user(buf, &dtl->buf[i], n_req * sizeof(struct dtl_entry));
 	if (rc)
 		return -EFAULT;

 	n_read += n_req;

 	return n_read * sizeof(struct dtl_entry);
 }

 static const struct file_operations dtl_fops = {
 	.open		= dtl_file_open,
 	.release	= dtl_file_release,
 	.read		= dtl_file_read,
 	.llseek		= no_llseek,
 };

 static struct dentry *dtl_dir;

 static int dtl_setup_file(struct dtl *dtl)
 {
 	char name[10];

 	sprintf(name, "cpu-%d", dtl->cpu);

 	dtl->file = debugfs_create_file(name, 0400, dtl_dir, dtl, &dtl_fops);
 	if (!dtl->file)
 		return -ENOMEM;

 	return 0;
 }

 static int dtl_init(void)
 {
 	struct dentry *event_mask_file, *buf_entries_file;
 	int rc, i;

 	if (!firmware_has_feature(FW_FEATURE_SPLPAR))
 		return -ENODEV;

 	/* set up common debugfs structure */

 	rc = -ENOMEM;
 	dtl_dir = debugfs_create_dir("dtl", powerpc_debugfs_root);
 	if (!dtl_dir) {
 		printk(KERN_WARNING "%s: can't create dtl root dir\n",
 				__func__);
 		goto err;
 	}

 	event_mask_file = debugfs_create_x8("dtl_event_mask", 0600,
 				dtl_dir, &dtl_event_mask);
 	buf_entries_file = debugfs_create_u32("dtl_buf_entries", 0400,
 				dtl_dir, &dtl_buf_entries);

 	if (!event_mask_file || !buf_entries_file) {
 		printk(KERN_WARNING "%s: can't create dtl files\n", __func__);
 		goto err_remove_dir;
 	}

 	/* set up the per-cpu log structures */
 	for_each_possible_cpu(i) {
 		struct dtl *dtl = &per_cpu(cpu_dtl, i);
 		spin_lock_init(&dtl->lock);
 		dtl->cpu = i;

 		rc = dtl_setup_file(dtl);
 		if (rc)
 			goto err_remove_dir;
 	}

 	return 0;

 err_remove_dir:
 	debugfs_remove_recursive(dtl_dir);
 err:
 	return rc;
 }
 machine_arch_initcall(pseries, dtl_init);
	/*
	* Virtual Processor Dispatch Trace Log
	*
	* (C) Copyright IBM Corporation 2009
	*
	* Author: Jeremy Kerr <jk@ozlabs.org>
	*
	* 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, or (at your option)
	* any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	*/

	#include <linux/slab.h>
	#include <linux/debugfs.h>
	#include <linux/spinlock.h>
	#include <asm/smp.h>
	#include <asm/uaccess.h>
	#include <asm/firmware.h>
	#include <asm/lppaca.h>
	#include <asm/debug.h>
	#include <asm/plpar_wrappers.h>
	#include <asm/machdep.h>

	struct dtl {
	struct dtl_entry *buf;
	struct dentry *file;
	int cpu;
	int buf_entries;
	u64 last_idx;
	spinlock_t lock;
	};
	static DEFINE_PER_CPU(struct dtl, cpu_dtl);

	/*
	* Dispatch trace log event mask:
	* 0x7: 0x1: voluntary virtual processor waits
	* 0x2: time-slice preempts
	* 0x4: virtual partition memory page faults
	*/
	static u8 dtl_event_mask = 0x7;


	/*
	* Size of per-cpu log buffers. Firmware requires that the buffer does
	* not cross a 4k boundary.
	*/
	static int dtl_buf_entries = N_DISPATCH_LOG;

	#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
	struct dtl_ring {
	u64 write_index;
	struct dtl_entry *write_ptr;
	struct dtl_entry *buf;
	struct dtl_entry *buf_end;
	u8 saved_dtl_mask;
	};

	static DEFINE_PER_CPU(struct dtl_ring, dtl_rings);

	static atomic_t dtl_count;

	/*
	* The cpu accounting code controls the DTL ring buffer, and we get
	* given entries as they are processed.
	*/
	static void consume_dtle(struct dtl_entry *dtle, u64 index)
	{
	struct dtl_ring *dtlr = this_cpu_ptr(&dtl_rings);
	struct dtl_entry *wp = dtlr->write_ptr;
	struct lppaca *vpa = local_paca->lppaca_ptr;

	if (!wp)
	return;

	wp = dtle;
	barrier();

	/* check for hypervisor ring buffer overflow, ignore this entry if so */
	if (index + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx))
	return;

	++wp;
	if (wp == dtlr->buf_end)
	wp = dtlr->buf;
	dtlr->write_ptr = wp;

	/* incrementing write_index makes the new entry visible */
	smp_wmb();
	++dtlr->write_index;
	}

	static int dtl_start(struct dtl *dtl)
	{
	struct dtl_ring *dtlr = &per_cpu(dtl_rings, dtl->cpu);

	dtlr->buf = dtl->buf;
	dtlr->buf_end = dtl->buf + dtl->buf_entries;
	dtlr->write_index = 0;

	/* setting write_ptr enables logging into our buffer */
	smp_wmb();
	dtlr->write_ptr = dtl->buf;

	/* enable event logging */
	dtlr->saved_dtl_mask = lppaca_of(dtl->cpu).dtl_enable_mask;
	lppaca_of(dtl->cpu).dtl_enable_mask \|= dtl_event_mask;

	dtl_consumer = consume_dtle;
	atomic_inc(&dtl_count);
	return 0;
	}

	static void dtl_stop(struct dtl *dtl)
	{
	struct dtl_ring *dtlr = &per_cpu(dtl_rings, dtl->cpu);

	dtlr->write_ptr = NULL;
	smp_wmb();

	dtlr->buf = NULL;

	/* restore dtl_enable_mask */
	lppaca_of(dtl->cpu).dtl_enable_mask = dtlr->saved_dtl_mask;

	if (atomic_dec_and_test(&dtl_count))
	dtl_consumer = NULL;
	}

	static u64 dtl_current_index(struct dtl *dtl)
	{
	return per_cpu(dtl_rings, dtl->cpu).write_index;
	}

	#else /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */

	static int dtl_start(struct dtl *dtl)
	{
	unsigned long addr;
	int ret, hwcpu;

	/* Register our dtl buffer with the hypervisor. The HV expects the
	* buffer size to be passed in the second word of the buffer */
	((u32 *)dtl->buf)[1] = DISPATCH_LOG_BYTES;

	hwcpu = get_hard_smp_processor_id(dtl->cpu);
	addr = __pa(dtl->buf);
	ret = register_dtl(hwcpu, addr);
	if (ret) {
	printk(KERN_WARNING "%s: DTL registration for cpu %d (hw %d) "
	"failed with %d\n", __func__, dtl->cpu, hwcpu, ret);
	return -EIO;
	}

	/* set our initial buffer indices */
	lppaca_of(dtl->cpu).dtl_idx = 0;

	/* ensure that our updates to the lppaca fields have occurred before
	* we actually enable the logging */
	smp_wmb();

	/* enable event logging */
	lppaca_of(dtl->cpu).dtl_enable_mask = dtl_event_mask;

	return 0;
	}

	static void dtl_stop(struct dtl *dtl)
	{
	int hwcpu = get_hard_smp_processor_id(dtl->cpu);

	lppaca_of(dtl->cpu).dtl_enable_mask = 0x0;

	unregister_dtl(hwcpu);
	}

	static u64 dtl_current_index(struct dtl *dtl)
	{
	return lppaca_of(dtl->cpu).dtl_idx;
	}
	#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */

	static int dtl_enable(struct dtl *dtl)
	{
	long int n_entries;
	long int rc;
	struct dtl_entry *buf = NULL;

	if (!dtl_cache)
	return -ENOMEM;

	/* only allow one reader */
	if (dtl->buf)
	return -EBUSY;

	n_entries = dtl_buf_entries;
	buf = kmem_cache_alloc_node(dtl_cache, GFP_KERNEL, cpu_to_node(dtl->cpu));
	if (!buf) {
	printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n",
	__func__, dtl->cpu);
	return -ENOMEM;
	}

	spin_lock(&dtl->lock);
	rc = -EBUSY;
	if (!dtl->buf) {
	/* store the original allocation size for use during read */
	dtl->buf_entries = n_entries;
	dtl->buf = buf;
	dtl->last_idx = 0;
	rc = dtl_start(dtl);
	if (rc)
	dtl->buf = NULL;
	}
	spin_unlock(&dtl->lock);

	if (rc)
	kmem_cache_free(dtl_cache, buf);
	return rc;
	}

	static void dtl_disable(struct dtl *dtl)
	{
	spin_lock(&dtl->lock);
	dtl_stop(dtl);
	kmem_cache_free(dtl_cache, dtl->buf);
	dtl->buf = NULL;
	dtl->buf_entries = 0;
	spin_unlock(&dtl->lock);
	}

	/* file interface */

	static int dtl_file_open(struct inode inode, struct file filp)
	{
	struct dtl *dtl = inode->i_private;
	int rc;

	rc = dtl_enable(dtl);
	if (rc)
	return rc;

	filp->private_data = dtl;
	return 0;
	}

	static int dtl_file_release(struct inode inode, struct file filp)
	{
	struct dtl *dtl = inode->i_private;
	dtl_disable(dtl);
	return 0;
	}

	static ssize_t dtl_file_read(struct file filp, char __user buf, size_t len,
	loff_t *pos)
	{
	long int rc, n_read, n_req, read_size;
	struct dtl *dtl;
	u64 cur_idx, last_idx, i;

	if ((len % sizeof(struct dtl_entry)) != 0)
	return -EINVAL;

	dtl = filp->private_data;

	/* requested number of entries to read */
	n_req = len / sizeof(struct dtl_entry);

	/* actual number of entries read */
	n_read = 0;

	spin_lock(&dtl->lock);

	cur_idx = dtl_current_index(dtl);
	last_idx = dtl->last_idx;

	if (last_idx + dtl->buf_entries <= cur_idx)
	last_idx = cur_idx - dtl->buf_entries + 1;

	if (last_idx + n_req > cur_idx)
	n_req = cur_idx - last_idx;

	if (n_req > 0)
	dtl->last_idx = last_idx + n_req;

	spin_unlock(&dtl->lock);

	if (n_req <= 0)
	return 0;

	i = last_idx % dtl->buf_entries;

	/* read the tail of the buffer if we've wrapped */
	if (i + n_req > dtl->buf_entries) {
	read_size = dtl->buf_entries - i;

	rc = copy_to_user(buf, &dtl->buf[i],
	read_size * sizeof(struct dtl_entry));
	if (rc)
	return -EFAULT;

	i = 0;
	n_req -= read_size;
	n_read += read_size;
	buf += read_size * sizeof(struct dtl_entry);
	}

	/* .. and now the head */
	rc = copy_to_user(buf, &dtl->buf[i], n_req * sizeof(struct dtl_entry));
	if (rc)
	return -EFAULT;

	n_read += n_req;

	return n_read * sizeof(struct dtl_entry);
	}

	static const struct file_operations dtl_fops = {
	.open = dtl_file_open,
	.release = dtl_file_release,
	.read = dtl_file_read,
	.llseek = no_llseek,
	};

	static struct dentry *dtl_dir;

	static int dtl_setup_file(struct dtl *dtl)
	{
	char name[10];

	sprintf(name, "cpu-%d", dtl->cpu);

	dtl->file = debugfs_create_file(name, 0400, dtl_dir, dtl, &dtl_fops);
	if (!dtl->file)
	return -ENOMEM;

	return 0;
	}

	static int dtl_init(void)
	{
	struct dentry event_mask_file, buf_entries_file;
	int rc, i;

	if (!firmware_has_feature(FW_FEATURE_SPLPAR))
	return -ENODEV;

	/* set up common debugfs structure */

	rc = -ENOMEM;
	dtl_dir = debugfs_create_dir("dtl", powerpc_debugfs_root);
	if (!dtl_dir) {
	printk(KERN_WARNING "%s: can't create dtl root dir\n",
	__func__);
	goto err;
	}

	event_mask_file = debugfs_create_x8("dtl_event_mask", 0600,
	dtl_dir, &dtl_event_mask);
	buf_entries_file = debugfs_create_u32("dtl_buf_entries", 0400,
	dtl_dir, &dtl_buf_entries);

	if (!event_mask_file \|\| !buf_entries_file) {
	printk(KERN_WARNING "%s: can't create dtl files\n", __func__);
	goto err_remove_dir;
	}

	/* set up the per-cpu log structures */
	for_each_possible_cpu(i) {
	struct dtl *dtl = &per_cpu(cpu_dtl, i);
	spin_lock_init(&dtl->lock);
	dtl->cpu = i;

	rc = dtl_setup_file(dtl);
	if (rc)
	goto err_remove_dir;
	}

	return 0;

	err_remove_dir:
	debugfs_remove_recursive(dtl_dir);
	err:
	return rc;
	}
	machine_arch_initcall(pseries, dtl_init);