drivers/gator/gator_annotate.c

   1 /**
   2  * Copyright (C) ARM Limited 2010-2013. 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         bool interrupt_context;
  43
  44         if (*offset) {
  45                 return -EINVAL;
  46         }
  47
  48         interrupt_context = in_interrupt();
  49         // Annotations are not supported in interrupt context, but may work if you comment out the the next four lines of code.
  50         //   By doing so, annotations in interrupt context can result in deadlocks and lost data.
  51         if (interrupt_context) {
  52                 printk(KERN_WARNING "gator: Annotations are not supported in interrupt context. Edit gator_annotate.c in the gator driver to enable annotations in interrupt context.\n");
  53                 return -EINVAL;
  54         }
  55
  56  retry:
  57         // synchronize between cores and with collect_annotations
  58         spin_lock(&annotate_lock);
  59
  60         if (!collect_annotations) {
  61                 // Not collecting annotations, tell the caller everything was written
  62                 size = count_orig;
  63                 goto annotate_write_out;
  64         }
  65
  66         // Annotation only uses a single per-cpu buffer as the data must be in order to the engine
  67         cpu = 0;
  68
  69         if (current == NULL) {
  70                 pid = 0;
  71         } else {
  72                 pid = current->pid;
  73         }
  74
  75         // determine total size of the payload
  76         header_size = MAXSIZE_PACK32 * 3 + MAXSIZE_PACK64;
  77         available = buffer_bytes_available(cpu, ANNOTATE_BUF) - header_size;
  78         size = count < available ? count : available;
  79
  80         if (size <= 0) {
  81                 // Buffer is full, wait until space is available
  82                 spin_unlock(&annotate_lock);
  83
  84                 // Drop the annotation as blocking is not allowed in interrupt context
  85                 if (interrupt_context) {
  86                         return -EINVAL;
  87                 }
  88
  89                 wait_event_interruptible(gator_annotate_wait, buffer_bytes_available(cpu, ANNOTATE_BUF) > header_size || !collect_annotations);
  90
  91                 // Check to see if a signal is pending
  92                 if (signal_pending(current)) {
  93                         return -EINTR;
  94                 }
  95
  96                 goto retry;
  97         }
  98
  99         // synchronize shared variables annotateBuf and annotatePos
 100         if (per_cpu(gator_buffer, cpu)[ANNOTATE_BUF]) {
 101                 u64 time = gator_get_time();
 102                 gator_buffer_write_packed_int(cpu, ANNOTATE_BUF, get_physical_cpu());
 103                 gator_buffer_write_packed_int(cpu, ANNOTATE_BUF, pid);
 104                 gator_buffer_write_packed_int64(cpu, ANNOTATE_BUF, time);
 105                 gator_buffer_write_packed_int(cpu, ANNOTATE_BUF, size);
 106
 107                 // determine the sizes to capture, length1 + length2 will equal size
 108                 contiguous = contiguous_space_available(cpu, ANNOTATE_BUF);
 109                 if (size < contiguous) {
 110                         length1 = size;
 111                         length2 = 0;
 112                 } else {
 113                         length1 = contiguous;
 114                         length2 = size - contiguous;
 115                 }
 116
 117                 if (annotate_copy(file, buf, length1) != 0) {
 118                         size = -EINVAL;
 119                         goto annotate_write_out;
 120                 }
 121
 122                 if (length2 > 0 && annotate_copy(file, &buf[length1], length2) != 0) {
 123                         size = -EINVAL;
 124                         goto annotate_write_out;
 125                 }
 126
 127                 // Check and commit; commit is set to occur once buffer is 3/4 full
 128                 buffer_check(cpu, ANNOTATE_BUF, time);
 129         }
 130
 131 annotate_write_out:
 132         spin_unlock(&annotate_lock);
 133
 134         // return the number of bytes written
 135         return size;
 136 }
 137
 138 #include "gator_annotate_kernel.c"
 139
 140 static int annotate_release(struct inode *inode, struct file *file)
 141 {
 142         int cpu = 0;
 143
 144         // synchronize between cores
 145         spin_lock(&annotate_lock);
 146
 147         if (per_cpu(gator_buffer, cpu)[ANNOTATE_BUF] && buffer_check_space(cpu, ANNOTATE_BUF, MAXSIZE_PACK64 + 3 * MAXSIZE_PACK32)) {
 148                 uint32_t pid = current->pid;
 149                 gator_buffer_write_packed_int(cpu, ANNOTATE_BUF, get_physical_cpu());
 150                 gator_buffer_write_packed_int(cpu, ANNOTATE_BUF, pid);
 151                 gator_buffer_write_packed_int64(cpu, ANNOTATE_BUF, 0);  // time
 152                 gator_buffer_write_packed_int(cpu, ANNOTATE_BUF, 0);    // size
 153         }
 154
 155         // Check and commit; commit is set to occur once buffer is 3/4 full
 156         buffer_check(cpu, ANNOTATE_BUF, gator_get_time());
 157
 158         spin_unlock(&annotate_lock);
 159
 160         return 0;
 161 }
 162
 163 static const struct file_operations annotate_fops = {
 164         .write = annotate_write,
 165         .release = annotate_release
 166 };
 167
 168 static int gator_annotate_create_files(struct super_block *sb, struct dentry *root)
 169 {
 170         return gatorfs_create_file_perm(sb, root, "annotate", &annotate_fops, 0666);
 171 }
 172
 173 static int gator_annotate_start(void)
 174 {
 175         collect_annotations = true;
 176         return 0;
 177 }
 178
 179 static void gator_annotate_stop(void)
 180 {
 181         // the spinlock here will ensure that when this function exits, we are not in the middle of an annotation
 182         spin_lock(&annotate_lock);
 183         collect_annotations = false;
 184         wake_up(&gator_annotate_wait);
 185         spin_unlock(&annotate_lock);
 186 }