xnu-2782.10.72.tar.gz

[apple/xnu.git] / libsyscall / wrappers / kdebug_trace.c

diff --git a/libsyscall/wrappers/kdebug_trace.c b/libsyscall/wrappers/kdebug_trace.c
new file mode 100644 (file)
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+++ b/libsyscall/wrappers/kdebug_trace.c
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+/*
+ * Copyright (c) 2014 Apple Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#include <stdint.h>
+#include <machine/cpu_capabilities.h>
+#include <sys/kdebug.h>
+#include <sys/errno.h>
+
+#define CLASS_MASK      0xff000000
+#define CLASS_OFFSET    24
+#define SUBCLASS_MASK   0x00ff0000
+#define SUBCLASS_OFFSET 16
+
+#define EXTRACT_CLASS(debugid)          ((uint8_t)(((debugid) & CLASS_MASK) >> CLASS_OFFSET))
+#define EXTRACT_SUBCLASS(debugid)       ( (uint8_t) ( ((debugid) & SUBCLASS_MASK) >> SUBCLASS_OFFSET ) )
+
+extern int __kdebug_trace64(uint32_t code, uint64_t arg1, uint64_t arg2, uint64_t arg3, uint64_t arg4);
+
+int
+kdebug_trace(uint32_t code, uint64_t arg1, uint64_t arg2, uint64_t arg3, uint64_t arg4)
+{
+       uint8_t code_class;
+       volatile uint32_t *kdebug_enable_address = (volatile uint32_t *)(uintptr_t)(_COMM_PAGE_KDEBUG_ENABLE);
+
+       /*
+        * This filtering is also done in the kernel, but we also do it here so that errors
+        * are returned in all cases, not just when the system call is actually performed.
+        */
+       code_class = EXTRACT_CLASS(code);
+       switch (code_class) {
+               case DBG_TRACE:
+                       errno = EPERM;
+                       return -1;
+       }
+
+       if (*kdebug_enable_address == 0) {
+               return 0;
+       }
+       
+       return __kdebug_trace64(code, arg1, arg2, arg3, arg4);
+}