/*
* 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/slab.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, 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. 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(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);
