src/core/fnrec.c

   1 /*
   2  * Copyright (C) 2010 Stefan Hajnoczi <stefanha@gmail.com>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 #include <stdlib.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <gpxe/init.h>
  25 #include <gpxe/uaccess.h>
  26
  27 /** @file
  28  *
  29  * Function trace recorder for crash and hang debugging
  30  *
  31  */
  32
  33 enum {
  34         /** Constant for identifying valid trace buffers */
  35         fnrec_magic = 'f' << 24 | 'n' << 16 | 'r' << 8 | 'e',
  36
  37         /** Trace buffer length */
  38         fnrec_buffer_length = 4096 / sizeof ( unsigned long ),
  39 };
  40
  41 /** A trace buffer */
  42 struct fnrec_buffer {
  43         /** Constant for identifying valid trace buffers */
  44         uint32_t magic;
  45
  46         /** Next trace buffer entry to fill */
  47         uint32_t idx;
  48
  49         /** Function address trace buffer */
  50         unsigned long data[fnrec_buffer_length];
  51 };
  52
  53 /** The trace buffer */
  54 static struct fnrec_buffer *fnrec_buffer;
  55
  56 /**
  57  * Test whether the trace buffer is valid
  58  *
  59  * @ret is_valid        Buffer is valid
  60  */
  61 static int fnrec_is_valid ( void ) {
  62         return fnrec_buffer && fnrec_buffer->magic == fnrec_magic;
  63 }
  64
  65 /**
  66  * Reset the trace buffer and clear entries
  67  */
  68 static void fnrec_reset ( void ) {
  69         memset ( fnrec_buffer, 0, sizeof ( *fnrec_buffer ) );
  70         fnrec_buffer->magic = fnrec_magic;
  71 }
  72
  73 /**
  74  * Write a value to the end of the buffer if it is not a repetition
  75  *
  76  * @v l                 Value to append
  77  */
  78 static void fnrec_append_unique ( unsigned long l ) {
  79         static unsigned long lastval;
  80         uint32_t idx = fnrec_buffer->idx;
  81
  82         /* Avoid recording the same value repeatedly */
  83         if ( l == lastval )
  84                 return;
  85
  86         fnrec_buffer->data[idx] = l;
  87         fnrec_buffer->idx = ( idx + 1 ) % fnrec_buffer_length;
  88         lastval = l;
  89 }
  90
  91 /**
  92  * Print the contents of the trace buffer in chronological order
  93  */
  94 static void fnrec_dump ( void ) {
  95         size_t i;
  96
  97         if ( !fnrec_is_valid() ) {
  98                 printf ( "fnrec buffer not found\n" );
  99                 return;
 100         }
 101
 102         printf ( "fnrec buffer dump:\n" );
 103         for ( i = 0; i < fnrec_buffer_length; i++ ) {
 104                 unsigned long l = fnrec_buffer->data[
 105                         ( fnrec_buffer->idx + i ) % fnrec_buffer_length];
 106                 printf ( "%08lx%c", l, i % 8 == 7 ? '\n' : ' ' );
 107         }
 108 }
 109
 110 /**
 111  * Function tracer initialisation function
 112  */
 113 static void fnrec_init ( void ) {
 114         /* Hardcoded to 17 MB */
 115         fnrec_buffer = phys_to_virt ( 17 * 1024 * 1024 );
 116         fnrec_dump();
 117         fnrec_reset();
 118 }
 119
 120 struct init_fn fnrec_init_fn __init_fn ( INIT_NORMAL ) = {
 121         .initialise = fnrec_init,
 122 };
 123
 124 /*
 125  * These functions are called from every C function.  The compiler inserts
 126  * these calls when -finstrument-functions is used.
 127  */
 128 void __cyg_profile_func_enter ( void *called_fn, void *call_site __unused ) {
 129         if ( fnrec_is_valid() )
 130                 fnrec_append_unique ( ( unsigned long ) called_fn );
 131 }
 132
 133 void __cyg_profile_func_exit ( void *called_fn __unused, void *call_site __unused ) {
 134 }