driver/gator_annotate.c

   1 /**
   2  * Copyright (C) ARM Limited 2010-2012. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  */
   9
  10 #include <linux/slab.h>
  11 #include <linux/fs.h>
  12 #include <linux/mm.h>
  13 #include <linux/sched.h>
  14 #include <asm/uaccess.h>
  15 #include <asm/current.h>
  16 #include <linux/spinlock.h>
  17
  18 static DEFINE_SPINLOCK(annotate_lock);
  19 static bool collect_annotations = false;
  20
  21 static int annotate_copy(struct file *file, char const __user *buf, size_t count)
  22 {
  23         int cpu = 0;
  24         int write = per_cpu(gator_buffer_write, cpu)[ANNOTATE_BUF];
  25
  26         if (file == NULL) {
  27                 // copy from kernel
  28                 memcpy(&per_cpu(gator_buffer, cpu)[ANNOTATE_BUF][write], buf, count);
  29         } else {
  30                 // copy from user space
  31                 if (copy_from_user(&per_cpu(gator_buffer, cpu)[ANNOTATE_BUF][write], buf, count) != 0)
  32                         return -1;
  33         }
  34         per_cpu(gator_buffer_write, cpu)[ANNOTATE_BUF] = (write + count) & gator_buffer_mask[ANNOTATE_BUF];
  35
  36         return 0;
  37 }
  38
  39 static ssize_t annotate_write(struct file *file, char const __user *buf, size_t count_orig, loff_t *offset)
  40 {
  41         int pid, cpu, header_size, available, contiguous, length1, length2, size, count = count_orig & 0x7fffffff;
  42
  43         if (*offset) {
  44                 return -EINVAL;
  45         }
  46
  47         // Annotations are not supported in interrupt context
  48         if (in_interrupt()) {
  49                 printk(KERN_WARNING "gator: Annotations are not supported in interrupt context\n");
  50                 return -EINVAL;
  51         }
  52
  53         // synchronize between cores and with collect_annotations
  54         spin_lock(&annotate_lock);
  55
  56         if (!collect_annotations) {
  57                 // Not collecting annotations, tell the caller everything was written
  58                 size = count_orig;
  59                 goto annotate_write_out;
  60         }
  61
  62         // Annotation only uses a single per-cpu buffer as the data must be in order to the engine
  63         cpu = 0;
  64
  65         if (current == NULL) {
  66                 pid = 0;
  67         } else {
  68                 pid = current->pid;
  69         }
  70
  71         // determine total size of the payload
  72         header_size = MAXSIZE_PACK32 * 3 + MAXSIZE_PACK64;
  73         available = buffer_bytes_available(cpu, ANNOTATE_BUF) - header_size;
  74         size = count < available ? count : available;
  75
  76         if (size <= 0) {
  77                 // Buffer is full but don't return an error.  Instead return 0 so the
  78                 // caller knows nothing was written and they can try again.
  79                 size = 0;
  80                 goto annotate_write_out;
  81         }
  82
  83         // synchronize shared variables annotateBuf and annotatePos
  84         if (per_cpu(gator_buffer, cpu)[ANNOTATE_BUF]) {
  85                 gator_buffer_write_packed_int(cpu, ANNOTATE_BUF, smp_processor_id());
  86                 gator_buffer_write_packed_int(cpu, ANNOTATE_BUF, pid);
  87                 gator_buffer_write_packed_int64(cpu, ANNOTATE_BUF, gator_get_time());
  88                 gator_buffer_write_packed_int(cpu, ANNOTATE_BUF, size);
  89
  90                 // determine the sizes to capture, length1 + length2 will equal size
  91                 contiguous = contiguous_space_available(cpu, ANNOTATE_BUF);
  92                 if (size < contiguous) {
  93                         length1 = size;
  94                         length2 = 0;
  95                 } else {
  96                         length1 = contiguous;
  97                         length2 = size - contiguous;
  98                 }
  99
 100                 if (annotate_copy(file, buf, length1) != 0) {
 101                         size = -EINVAL;
 102                         goto annotate_write_out;
 103                 }
 104
 105                 if (length2 > 0 && annotate_copy(file, &buf[length1], length2) != 0) {
 106                         size = -EINVAL;
 107                         goto annotate_write_out;
 108                 }
 109
 110                 // Check and commit; commit is set to occur once buffer is 3/4 full
 111                 buffer_check(cpu, ANNOTATE_BUF);
 112         }
 113
 114 annotate_write_out:
 115         spin_unlock(&annotate_lock);
 116
 117         // return the number of bytes written
 118         return size;
 119 }
 120
 121 #include "gator_annotate_kernel.c"
 122
 123 static int annotate_release(struct inode *inode, struct file *file)
 124 {
 125         int cpu = 0;
 126
 127         // synchronize between cores
 128         spin_lock(&annotate_lock);
 129
 130         if (per_cpu(gator_buffer, cpu)[ANNOTATE_BUF] && buffer_check_space(cpu, ANNOTATE_BUF, MAXSIZE_PACK64 + 3 * MAXSIZE_PACK32)) {
 131                 uint32_t pid = current->pid;
 132                 gator_buffer_write_packed_int(cpu, ANNOTATE_BUF, smp_processor_id());
 133                 gator_buffer_write_packed_int(cpu, ANNOTATE_BUF, pid);
 134                 gator_buffer_write_packed_int64(cpu, ANNOTATE_BUF, 0);  // time
 135                 gator_buffer_write_packed_int(cpu, ANNOTATE_BUF, 0);    // size
 136         }
 137
 138         // Check and commit; commit is set to occur once buffer is 3/4 full
 139         buffer_check(cpu, ANNOTATE_BUF);
 140
 141         spin_unlock(&annotate_lock);
 142
 143         return 0;
 144 }
 145
 146 static const struct file_operations annotate_fops = {
 147         .write = annotate_write,
 148         .release = annotate_release
 149 };
 150
 151 static int gator_annotate_create_files(struct super_block *sb, struct dentry *root)
 152 {
 153         return gatorfs_create_file_perm(sb, root, "annotate", &annotate_fops, 0666);
 154 }
 155
 156 static int gator_annotate_start(void)
 157 {
 158         collect_annotations = true;
 159         return 0;
 160 }
 161
 162 static void gator_annotate_stop(void)
 163 {
 164         // the spinlock here will ensure that when this function exits, we are not in the middle of an annotation
 165         spin_lock(&annotate_lock);
 166         collect_annotations = false;
 167         spin_unlock(&annotate_lock);
 168 }