drivers/gator/gator_events_block.c

   1 /**
   2  * Copyright (C) ARM Limited 2010-2014. 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 "gator.h"
  11 #include <trace/events/block.h>
  12
  13 #define BLOCK_RQ_WR             0
  14 #define BLOCK_RQ_RD             1
  15
  16 #define BLOCK_TOTAL             (BLOCK_RQ_RD+1)
  17
  18 #if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 36)
  19 #define EVENTWRITE REQ_RW
  20 #else
  21 #define EVENTWRITE REQ_WRITE
  22 #endif
  23
  24 static ulong block_rq_wr_enabled;
  25 static ulong block_rq_rd_enabled;
  26 static ulong block_rq_wr_key;
  27 static ulong block_rq_rd_key;
  28 static atomic_t blockCnt[BLOCK_TOTAL];
  29 static int blockGet[BLOCK_TOTAL * 4];
  30
  31 // Tracepoint changed in 3.15 backported to older kernels. The Makefile tries to autodetect the correct value, but if it fails change the #if below
  32 #if OLD_BLOCK_RQ_COMPLETE
  33 GATOR_DEFINE_PROBE(block_rq_complete, TP_PROTO(struct request_queue *q, struct request *rq))
  34 #else
  35 GATOR_DEFINE_PROBE(block_rq_complete, TP_PROTO(struct request_queue *q, struct request *rq, unsigned int nr_bytes))
  36 #endif
  37 {
  38         int write;
  39         unsigned int size;
  40
  41         if (!rq)
  42                 return;
  43
  44         write = rq->cmd_flags & EVENTWRITE;
  45 #if OLD_BLOCK_RQ_COMPLETE
  46         size = rq->resid_len;
  47 #else
  48         size = nr_bytes;
  49 #endif
  50
  51         if (!size)
  52                 return;
  53
  54         if (write) {
  55                 if (block_rq_wr_enabled) {
  56                         atomic_add(size, &blockCnt[BLOCK_RQ_WR]);
  57                 }
  58         } else {
  59                 if (block_rq_rd_enabled) {
  60                         atomic_add(size, &blockCnt[BLOCK_RQ_RD]);
  61                 }
  62         }
  63 }
  64
  65 static int gator_events_block_create_files(struct super_block *sb, struct dentry *root)
  66 {
  67         struct dentry *dir;
  68
  69         /* block_complete_wr */
  70         dir = gatorfs_mkdir(sb, root, "Linux_block_rq_wr");
  71         if (!dir) {
  72                 return -1;
  73         }
  74         gatorfs_create_ulong(sb, dir, "enabled", &block_rq_wr_enabled);
  75         gatorfs_create_ro_ulong(sb, dir, "key", &block_rq_wr_key);
  76
  77         /* block_complete_rd */
  78         dir = gatorfs_mkdir(sb, root, "Linux_block_rq_rd");
  79         if (!dir) {
  80                 return -1;
  81         }
  82         gatorfs_create_ulong(sb, dir, "enabled", &block_rq_rd_enabled);
  83         gatorfs_create_ro_ulong(sb, dir, "key", &block_rq_rd_key);
  84
  85         return 0;
  86 }
  87
  88 static int gator_events_block_start(void)
  89 {
  90         // register tracepoints
  91         if (block_rq_wr_enabled || block_rq_rd_enabled)
  92                 if (GATOR_REGISTER_TRACE(block_rq_complete))
  93                         goto fail_block_rq_exit;
  94         pr_debug("gator: registered block event tracepoints\n");
  95
  96         return 0;
  97
  98         // unregister tracepoints on error
  99 fail_block_rq_exit:
 100         pr_err("gator: block event tracepoints failed to activate, please verify that tracepoints are enabled in the linux kernel\n");
 101
 102         return -1;
 103 }
 104
 105 static void gator_events_block_stop(void)
 106 {
 107         if (block_rq_wr_enabled || block_rq_rd_enabled)
 108                 GATOR_UNREGISTER_TRACE(block_rq_complete);
 109         pr_debug("gator: unregistered block event tracepoints\n");
 110
 111         block_rq_wr_enabled = 0;
 112         block_rq_rd_enabled = 0;
 113 }
 114
 115 static int gator_events_block_read(int **buffer)
 116 {
 117         int len, value, data = 0;
 118
 119         if (!on_primary_core()) {
 120                 return 0;
 121         }
 122
 123         len = 0;
 124         if (block_rq_wr_enabled && (value = atomic_read(&blockCnt[BLOCK_RQ_WR])) > 0) {
 125                 atomic_sub(value, &blockCnt[BLOCK_RQ_WR]);
 126                 blockGet[len++] = block_rq_wr_key;
 127                 blockGet[len++] = 0;    // indicates to Streamline that value bytes were written now, not since the last message
 128                 blockGet[len++] = block_rq_wr_key;
 129                 blockGet[len++] = value;
 130                 data += value;
 131         }
 132         if (block_rq_rd_enabled && (value = atomic_read(&blockCnt[BLOCK_RQ_RD])) > 0) {
 133                 atomic_sub(value, &blockCnt[BLOCK_RQ_RD]);
 134                 blockGet[len++] = block_rq_rd_key;
 135                 blockGet[len++] = 0;    // indicates to Streamline that value bytes were read now, not since the last message
 136                 blockGet[len++] = block_rq_rd_key;
 137                 blockGet[len++] = value;
 138                 data += value;
 139         }
 140
 141         if (buffer)
 142                 *buffer = blockGet;
 143
 144         return len;
 145 }
 146
 147 static struct gator_interface gator_events_block_interface = {
 148         .create_files = gator_events_block_create_files,
 149         .start = gator_events_block_start,
 150         .stop = gator_events_block_stop,
 151         .read = gator_events_block_read,
 152 };
 153
 154 int gator_events_block_init(void)
 155 {
 156         block_rq_wr_enabled = 0;
 157         block_rq_rd_enabled = 0;
 158
 159         block_rq_wr_key = gator_events_get_key();
 160         block_rq_rd_key = gator_events_get_key();
 161
 162         return gator_events_install(&gator_events_block_interface);
 163 }