bsd/kern/kern_backtrace.c

   1 /*
   2  * Copyright (c) 2016-2020 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_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. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <kern/backtrace.h>
  30 #include <kern/kalloc.h>
  31 #include <sys/errno.h>
  32 #include <sys/sysctl.h>
  33 #include <sys/systm.h>
  34
  35 #if DEVELOPMENT || DEBUG
  36
  37 #define MAX_BACKTRACE  (128)
  38
  39 #define BACKTRACE_USER (0)
  40
  41 static int backtrace_sysctl SYSCTL_HANDLER_ARGS;
  42
  43 SYSCTL_NODE(_kern, OID_AUTO, backtrace, CTLFLAG_RW | CTLFLAG_LOCKED, 0,
  44     "backtrace");
  45
  46 SYSCTL_PROC(_kern_backtrace, OID_AUTO, user,
  47     CTLFLAG_RW | CTLFLAG_LOCKED, (void *)BACKTRACE_USER,
  48     sizeof(uint64_t), backtrace_sysctl, "O",
  49     "take user backtrace of current thread");
  50
  51 static int
  52 backtrace_sysctl SYSCTL_HANDLER_ARGS
  53 {
  54 #pragma unused(oidp, arg2)
  55         uintptr_t type = (uintptr_t)arg1;
  56         uintptr_t *bt = NULL;
  57         unsigned int bt_len = 0, bt_filled = 0;
  58         size_t bt_size = 0;
  59         int error = 0;
  60
  61         if (type != BACKTRACE_USER) {
  62                 return EINVAL;
  63         }
  64
  65         if (req->oldptr == USER_ADDR_NULL || req->oldlen == 0) {
  66                 return EFAULT;
  67         }
  68
  69         bt_len = req->oldlen > MAX_BACKTRACE ? MAX_BACKTRACE : (unsigned int)req->oldlen;
  70         bt_size = sizeof(bt[0]) * bt_len;
  71         bt = kheap_alloc(KHEAP_TEMP, bt_size, Z_WAITOK | Z_ZERO);
  72         if (!bt) {
  73                 return ENOBUFS;
  74         }
  75         bt_filled = backtrace_user(bt, bt_len, &error, NULL, NULL);
  76         if (error != 0) {
  77                 goto out;
  78         }
  79         bt_filled = min(bt_filled, bt_len);
  80
  81         error = copyout(bt, req->oldptr, sizeof(bt[0]) * bt_filled);
  82         if (error) {
  83                 goto out;
  84         }
  85         req->oldidx = bt_filled;
  86
  87 out:
  88         kheap_free(KHEAP_TEMP, bt, bt_size);
  89         return error;
  90 }
  91
  92 #endif /* DEVELOPMENT || DEBUG */