libsyscall/wrappers/kdebug_trace.c

   1 /*
   2  * Copyright (c) 2014 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <stdint.h>
  25 #include <machine/cpu_capabilities.h>
  26 #include <sys/kdebug.h>
  27 #include <sys/errno.h>
  28
  29 #define CLASS_MASK      0xff000000
  30 #define CLASS_OFFSET    24
  31 #define SUBCLASS_MASK   0x00ff0000
  32 #define SUBCLASS_OFFSET 16
  33
  34 #define EXTRACT_CLASS(debugid)          ((uint8_t)(((debugid) & CLASS_MASK) >> CLASS_OFFSET))
  35 #define EXTRACT_SUBCLASS(debugid)       ( (uint8_t) ( ((debugid) & SUBCLASS_MASK) >> SUBCLASS_OFFSET ) )
  36
  37 extern int __kdebug_trace64(uint32_t code, uint64_t arg1, uint64_t arg2, uint64_t arg3, uint64_t arg4);
  38
  39 int
  40 kdebug_trace(uint32_t code, uint64_t arg1, uint64_t arg2, uint64_t arg3, uint64_t arg4)
  41 {
  42         uint8_t code_class;
  43         volatile uint32_t *kdebug_enable_address = (volatile uint32_t *)(uintptr_t)(_COMM_PAGE_KDEBUG_ENABLE);
  44
  45         /*
  46          * This filtering is also done in the kernel, but we also do it here so that errors
  47          * are returned in all cases, not just when the system call is actually performed.
  48          */
  49         code_class = EXTRACT_CLASS(code);
  50         switch (code_class) {
  51                 case DBG_TRACE:
  52                         errno = EPERM;
  53                         return -1;
  54         }
  55
  56         if (*kdebug_enable_address == 0) {
  57                 return 0;
  58         }
  59
  60         return __kdebug_trace64(code, arg1, arg2, arg3, arg4);
  61 }