1 /* 2 * Virtual Processor Dispatch Trace Log 3 * 4 * (C) Copyright IBM Corporation 2009 5 * 6 * Author: Jeremy Kerr <jk@ozlabs.org> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation; either version 2, or (at your option) 11 * any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 21 */ 22 23 #include <linux/init.h> 24 #include <linux/debugfs.h> 25 #include <asm/smp.h> 26 #include <asm/system.h> 27 #include <asm/uaccess.h> 28 #include <asm/firmware.h> 29 30 #include "plpar_wrappers.h" 31 32 /* 33 * Layout of entries in the hypervisor's DTL buffer. Although we don't 34 * actually access the internals of an entry (we only need to know the size), 35 * we might as well define it here for reference. 36 */ 37 struct dtl_entry { 38 u8 dispatch_reason; 39 u8 preempt_reason; 40 u16 processor_id; 41 u32 enqueue_to_dispatch_time; 42 u32 ready_to_enqueue_time; 43 u32 waiting_to_ready_time; 44 u64 timebase; 45 u64 fault_addr; 46 u64 srr0; 47 u64 srr1; 48 }; 49 50 struct dtl { 51 struct dtl_entry *buf; 52 struct dentry *file; 53 int cpu; 54 int buf_entries; 55 u64 last_idx; 56 }; 57 static DEFINE_PER_CPU(struct dtl, dtl); 58 59 /* 60 * Dispatch trace log event mask: 61 * 0x7: 0x1: voluntary virtual processor waits 62 * 0x2: time-slice preempts 63 * 0x4: virtual partition memory page faults 64 */ 65 static u8 dtl_event_mask = 0x7; 66 67 68 /* 69 * Size of per-cpu log buffers. Default is just under 16 pages worth. 70 */ 71 static int dtl_buf_entries = (16 * 85); 72 73 74 static int dtl_enable(struct dtl *dtl) 75 { 76 unsigned long addr; 77 int ret, hwcpu; 78 79 /* only allow one reader */ 80 if (dtl->buf) 81 return -EBUSY; 82 83 /* we need to store the original allocation size for use during read */ 84 dtl->buf_entries = dtl_buf_entries; 85 86 dtl->buf = kmalloc_node(dtl->buf_entries * sizeof(struct dtl_entry), 87 GFP_KERNEL, cpu_to_node(dtl->cpu)); 88 if (!dtl->buf) { 89 printk(KERN_WARNING "%s: buffer alloc failed for cpu %d\n", 90 __func__, dtl->cpu); 91 return -ENOMEM; 92 } 93 94 /* Register our dtl buffer with the hypervisor. The HV expects the 95 * buffer size to be passed in the second word of the buffer */ 96 ((u32 *)dtl->buf)[1] = dtl->buf_entries * sizeof(struct dtl_entry); 97 98 hwcpu = get_hard_smp_processor_id(dtl->cpu); 99 addr = __pa(dtl->buf); 100 ret = register_dtl(hwcpu, addr); 101 if (ret) { 102 printk(KERN_WARNING "%s: DTL registration for cpu %d (hw %d) " 103 "failed with %d\n", __func__, dtl->cpu, hwcpu, ret); 104 kfree(dtl->buf); 105 return -EIO; 106 } 107 108 /* set our initial buffer indices */ 109 dtl->last_idx = lppaca[dtl->cpu].dtl_idx = 0; 110 111 /* ensure that our updates to the lppaca fields have occurred before 112 * we actually enable the logging */ 113 smp_wmb(); 114 115 /* enable event logging */ 116 lppaca[dtl->cpu].dtl_enable_mask = dtl_event_mask; 117 118 return 0; 119 } 120 121 static void dtl_disable(struct dtl *dtl) 122 { 123 int hwcpu = get_hard_smp_processor_id(dtl->cpu); 124 125 lppaca[dtl->cpu].dtl_enable_mask = 0x0; 126 127 unregister_dtl(hwcpu, __pa(dtl->buf)); 128 129 kfree(dtl->buf); 130 dtl->buf = NULL; 131 dtl->buf_entries = 0; 132 } 133 134 /* file interface */ 135 136 static int dtl_file_open(struct inode *inode, struct file *filp) 137 { 138 struct dtl *dtl = inode->i_private; 139 int rc; 140 141 rc = dtl_enable(dtl); 142 if (rc) 143 return rc; 144 145 filp->private_data = dtl; 146 return 0; 147 } 148 149 static int dtl_file_release(struct inode *inode, struct file *filp) 150 { 151 struct dtl *dtl = inode->i_private; 152 dtl_disable(dtl); 153 return 0; 154 } 155 156 static ssize_t dtl_file_read(struct file *filp, char __user *buf, size_t len, 157 loff_t *pos) 158 { 159 int rc, cur_idx, last_idx, n_read, n_req, read_size; 160 struct dtl *dtl; 161 162 if ((len % sizeof(struct dtl_entry)) != 0) 163 return -EINVAL; 164 165 dtl = filp->private_data; 166 167 /* requested number of entries to read */ 168 n_req = len / sizeof(struct dtl_entry); 169 170 /* actual number of entries read */ 171 n_read = 0; 172 173 cur_idx = lppaca[dtl->cpu].dtl_idx; 174 last_idx = dtl->last_idx; 175 176 if (cur_idx - last_idx > dtl->buf_entries) { 177 pr_debug("%s: hv buffer overflow for cpu %d, samples lost\n", 178 __func__, dtl->cpu); 179 } 180 181 cur_idx %= dtl->buf_entries; 182 last_idx %= dtl->buf_entries; 183 184 /* read the tail of the buffer if we've wrapped */ 185 if (last_idx > cur_idx) { 186 read_size = min(n_req, dtl->buf_entries - last_idx); 187 188 rc = copy_to_user(buf, &dtl->buf[last_idx], 189 read_size * sizeof(struct dtl_entry)); 190 if (rc) 191 return -EFAULT; 192 193 last_idx = 0; 194 n_req -= read_size; 195 n_read += read_size; 196 buf += read_size * sizeof(struct dtl_entry); 197 } 198 199 /* .. and now the head */ 200 read_size = min(n_req, cur_idx - last_idx); 201 rc = copy_to_user(buf, &dtl->buf[last_idx], 202 read_size * sizeof(struct dtl_entry)); 203 if (rc) 204 return -EFAULT; 205 206 n_read += read_size; 207 dtl->last_idx += n_read; 208 209 return n_read * sizeof(struct dtl_entry); 210 } 211 212 static struct file_operations dtl_fops = { 213 .open = dtl_file_open, 214 .release = dtl_file_release, 215 .read = dtl_file_read, 216 .llseek = no_llseek, 217 }; 218 219 static struct dentry *dtl_dir; 220 221 static int dtl_setup_file(struct dtl *dtl) 222 { 223 char name[10]; 224 225 sprintf(name, "cpu-%d", dtl->cpu); 226 227 dtl->file = debugfs_create_file(name, 0400, dtl_dir, dtl, &dtl_fops); 228 if (!dtl->file) 229 return -ENOMEM; 230 231 return 0; 232 } 233 234 static int dtl_init(void) 235 { 236 struct dentry *event_mask_file, *buf_entries_file; 237 int rc, i; 238 239 if (!firmware_has_feature(FW_FEATURE_SPLPAR)) 240 return -ENODEV; 241 242 /* set up common debugfs structure */ 243 244 rc = -ENOMEM; 245 dtl_dir = debugfs_create_dir("dtl", powerpc_debugfs_root); 246 if (!dtl_dir) { 247 printk(KERN_WARNING "%s: can't create dtl root dir\n", 248 __func__); 249 goto err; 250 } 251 252 event_mask_file = debugfs_create_x8("dtl_event_mask", 0600, 253 dtl_dir, &dtl_event_mask); 254 buf_entries_file = debugfs_create_u32("dtl_buf_entries", 0600, 255 dtl_dir, &dtl_buf_entries); 256 257 if (!event_mask_file || !buf_entries_file) { 258 printk(KERN_WARNING "%s: can't create dtl files\n", __func__); 259 goto err_remove_dir; 260 } 261 262 /* set up the per-cpu log structures */ 263 for_each_possible_cpu(i) { 264 struct dtl *dtl = &per_cpu(dtl, i); 265 dtl->cpu = i; 266 267 rc = dtl_setup_file(dtl); 268 if (rc) 269 goto err_remove_dir; 270 } 271 272 return 0; 273 274 err_remove_dir: 275 debugfs_remove_recursive(dtl_dir); 276 err: 277 return rc; 278 } 279 arch_initcall(dtl_init); 280