arch/powerpc/platforms/pseries/dtl.c - kernel/prism - 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/init.h>
 #include <linux/debugfs.h>
 #include <asm/smp.h>
 #include <asm/system.h>
 #include <asm/uaccess.h>
 #include <asm/firmware.h>

 #include "plpar_wrappers.h"

 /*
  * Layout of entries in the hypervisor's DTL buffer. Although we don't
  * actually access the internals of an entry (we only need to know the size),
  * we might as well define it here for reference.
  */
 struct dtl_entry {
 	u8	dispatch_reason;
 	u8	preempt_reason;
 	u16	processor_id;
 	u32	enqueue_to_dispatch_time;
 	u32	ready_to_enqueue_time;
 	u32	waiting_to_ready_time;
 	u64	timebase;
 	u64	fault_addr;
 	u64	srr0;
 	u64	srr1;
 };

 struct dtl {
 	struct dtl_entry	*buf;
 	struct dentry		*file;
 	int			cpu;
 	int			buf_entries;
 	u64			last_idx;
 };
 static DEFINE_PER_CPU(struct dtl, 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. Default is just under 16 pages worth.
  */
 static int dtl_buf_entries = (16 * 85);


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

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

 	/* we need to store the original allocation size for use during read */
 	dtl->buf_entries = dtl_buf_entries;

 	dtl->buf = kmalloc_node(dtl->buf_entries * sizeof(struct dtl_entry),
 			GFP_KERNEL, cpu_to_node(dtl->cpu));
 	if (!dtl->buf) {
 		printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n",
 				__func__, dtl->cpu);
 		return -ENOMEM;
 	}

 	/* 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] = dtl->buf_entries * sizeof(struct dtl_entry);

 	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);
 		kfree(dtl->buf);
 		return -EIO;
 	}

 	/* set our initial buffer indices */
 	dtl->last_idx = lppaca[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[dtl->cpu].dtl_enable_mask = dtl_event_mask;

 	return 0;
 }

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

 	lppaca[dtl->cpu].dtl_enable_mask = 0x0;

 	unregister_dtl(hwcpu, __pa(dtl->buf));

 	kfree(dtl->buf);
 	dtl->buf = NULL;
 	dtl->buf_entries = 0;
 }

 /* 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)
 {
 	int rc, cur_idx, last_idx, n_read, n_req, read_size;
 	struct dtl *dtl;

 	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;

 	cur_idx = lppaca[dtl->cpu].dtl_idx;
 	last_idx = dtl->last_idx;

 	if (cur_idx - last_idx > dtl->buf_entries) {
 		pr_debug("%s: hv buffer overflow for cpu %d, samples lost\n",
 				__func__, dtl->cpu);
 	}

 	cur_idx  %= dtl->buf_entries;
 	last_idx %= dtl->buf_entries;

 	/* read the tail of the buffer if we've wrapped */
 	if (last_idx > cur_idx) {
 		read_size = min(n_req, dtl->buf_entries - last_idx);

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

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

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

 	n_read += read_size;
 	dtl->last_idx += n_read;

 	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", 0600,
 				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(dtl, i);
 		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;
 }
 arch_initcall(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/init.h>
	#include <linux/debugfs.h>
	#include <asm/smp.h>
	#include <asm/system.h>
	#include <asm/uaccess.h>
	#include <asm/firmware.h>

	#include "plpar_wrappers.h"

	/*
	* Layout of entries in the hypervisor's DTL buffer. Although we don't
	* actually access the internals of an entry (we only need to know the size),
	* we might as well define it here for reference.
	*/
	struct dtl_entry {
	u8 dispatch_reason;
	u8 preempt_reason;
	u16 processor_id;
	u32 enqueue_to_dispatch_time;
	u32 ready_to_enqueue_time;
	u32 waiting_to_ready_time;
	u64 timebase;
	u64 fault_addr;
	u64 srr0;
	u64 srr1;
	};

	struct dtl {
	struct dtl_entry *buf;
	struct dentry *file;
	int cpu;
	int buf_entries;
	u64 last_idx;
	};
	static DEFINE_PER_CPU(struct dtl, 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. Default is just under 16 pages worth.
	*/
	static int dtl_buf_entries = (16 * 85);


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

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

	/* we need to store the original allocation size for use during read */
	dtl->buf_entries = dtl_buf_entries;

	dtl->buf = kmalloc_node(dtl->buf_entries * sizeof(struct dtl_entry),
	GFP_KERNEL, cpu_to_node(dtl->cpu));
	if (!dtl->buf) {
	printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n",
	__func__, dtl->cpu);
	return -ENOMEM;
	}

	/* 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] = dtl->buf_entries sizeof(struct dtl_entry);

	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);
	kfree(dtl->buf);
	return -EIO;
	}

	/* set our initial buffer indices */
	dtl->last_idx = lppaca[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[dtl->cpu].dtl_enable_mask = dtl_event_mask;

	return 0;
	}

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

	lppaca[dtl->cpu].dtl_enable_mask = 0x0;

	unregister_dtl(hwcpu, __pa(dtl->buf));

	kfree(dtl->buf);
	dtl->buf = NULL;
	dtl->buf_entries = 0;
	}

	/* 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)
	{
	int rc, cur_idx, last_idx, n_read, n_req, read_size;
	struct dtl *dtl;

	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;

	cur_idx = lppaca[dtl->cpu].dtl_idx;
	last_idx = dtl->last_idx;

	if (cur_idx - last_idx > dtl->buf_entries) {
	pr_debug("%s: hv buffer overflow for cpu %d, samples lost\n",
	__func__, dtl->cpu);
	}

	cur_idx %= dtl->buf_entries;
	last_idx %= dtl->buf_entries;

	/* read the tail of the buffer if we've wrapped */
	if (last_idx > cur_idx) {
	read_size = min(n_req, dtl->buf_entries - last_idx);

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

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

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

	n_read += read_size;
	dtl->last_idx += n_read;

	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", 0600,
	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(dtl, i);
	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;
	}
	arch_initcall(dtl_init);