/* * Virtual Processor Dispatch Trace Log * * (C) Copyright IBM Corporation 2009 * * Author: Jeremy Kerr * * 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 #include #include #include #include #include #include #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);