xnu-7195.101.1.tar.gz

[apple/xnu.git] / bsd / sys / linker_set.h

diff --git a/bsd/sys/linker_set.h b/bsd/sys/linker_set.h
index a4373b0cf9cfdf2b39429d3a7479bd7752452c9d..23b3a38a31e5a985e924a176a864327ba23fb579 100644 (file)
--- a/bsd/sys/linker_set.h
+++ b/bsd/sys/linker_set.h
@@ -1,33 +1,31 @@
 /*
 /*

- * Copyright (c) 2006 Apple Computer, Inc. All Rights Reserved.
- * 
- * @APPLE_LICENSE_OSREFERENCE_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.  The rights granted to you under the 
- * License may not be used to create, or enable the creation or 
- * redistribution of, unlawful or unlicensed copies of an Apple operating 
- * system, or to circumvent, violate, or enable the circumvention or 
- * violation of, any terms of an Apple operating system software license 
- * agreement.
- *
- * 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 
+ * Copyright (c) 2006-2008 Apple Inc. All rights reserved.
+ *
+ * @APPLE_OSREFERENCE_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. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
+ *
+ * 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.
  *
  * limitations under the License.
  *

- * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
- */
-/*-
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
+ *
+ *

  * Copyright (c) 1999 John D. Polstra
  * All rights reserved.
  *
  * Copyright (c) 1999 John D. Polstra
  * All rights reserved.
  *


@@ -58,55 +56,208 @@
 #define _SYS_LINKER_SET_H_
 
 #include <sys/appleapiopts.h>
 #define _SYS_LINKER_SET_H_
 
 #include <sys/appleapiopts.h>

-

 #if !defined(KERNEL) || defined(__APPLE_API_PRIVATE)
 #if !defined(KERNEL) || defined(__APPLE_API_PRIVATE)

+

 /*
  * The following macros are used to declare global sets of objects, which
 /*
  * The following macros are used to declare global sets of objects, which

- * are collected by the linker into a `struct linker_set' as defined below.
- * For ELF, this is done by constructing a separate segment for each set.
- * For a.out, it is done automatically by the linker.
+ * are collected by the linker into a `linker set' as defined below.
+ * For Mach-O, this is done by constructing a separate segment inside the
+ * __DATA_CONST section for each set.  The contents of this segment are an array
+ * of pointers to the objects in the set.
+ *
+ * Note that due to limitations of the Mach-O format, there cannot
+ * be more than 255 sections in a segment, so linker set usage should be
+ * conserved.  Set names may not exceed 16 characters.

  */
 
  */
 

-#define __ELF__
-#ifdef __ELF__
+#ifdef KERNEL
+# include <mach-o/loader.h>
+# include <libkern/kernel_mach_header.h>

 
 

-#define MAKE_SET(seg, set, sym)                                                \
-       static void const * const __set_##set##_sym_##sym = &sym;       \
-       __asm(".section  seg, " #set "");       \
-       __asm(".long " #sym);                                           
+# define MACH_HEADER_TYPE kernel_mach_header_t
+# define GETSECTIONDATA_VARIANT getsectdatafromheader
+# define SECTDATA_SIZE_TYPE unsigned long
+# define MH_EXECUTE_HEADER &_mh_execute_header
+# define IMAGE_SLIDE_CORRECT 0
+#else
+# include <mach-o/ldsyms.h>
+# include <mach-o/getsect.h>
+# include <mach-o/loader.h>
+# include <mach-o/dyld.h>
+# include <crt_externs.h>

 
 

-/*     __asm(".previous") */
+# if __LP64__
+#  define MACH_HEADER_TYPE struct mach_header_64
+#  define GETSECTIONDATA_VARIANT getsectdatafromheader_64
+#  define SECTDATA_SIZE_TYPE uint64_t
+#  define MH_EXECUTE_HEADER _NSGetMachExecuteHeader()
+# else
+#  define MACH_HEADER_TYPE struct mach_header
+#  define GETSECTIONDATA_VARIANT getsectdatafromheader
+#  define SECTDATA_SIZE_TYPE uint32_t
+#  define MH_EXECUTE_HEADER _NSGetMachExecuteHeader()
+# endif
+#endif

 
 

+#if __LP64__
+# define LINKER_SET_ENTRY_PACKED
+# define LINKER_SET_SEGMENT __DATA_CONST
+# define LINKER_SET_SEGMENT_CSTR "__DATA_CONST"
+#else
+# define LINKER_SET_ENTRY_PACKED __attribute__((packed))
+# define LINKER_SET_SEGMENT __DATA
+# define LINKER_SET_SEGMENT_CSTR "__DATA"
+#endif

 
 

-#define TEXT_SET(set, sym) MAKE_SET(__TEXT, set, sym)
-#define DATA_SET(set, sym) MAKE_SET(__DATA, set, sym)
-#define BSS_SET(set, sym)  MAKE_SET(__BSS,  set, sym)
-#define ABS_SET(set, sym)  MAKE_SET(__ABS,  set, sym)
+/*
+ * Private macros, not to be used outside this header file.
+ *
+ * The objective of this macro stack is to produce the following output,
+ * given SET and SYM as arguments:
+ *
+ *  void const * __set_SET_sym_SYM __attribute__((section("__DATA_CONST,SET"))) = & SYM
+ */

 
 

-#else
+/* Wrap entries in a type that can be blacklisted from KASAN */
+struct linker_set_entry {
+       void *ptr;
+} LINKER_SET_ENTRY_PACKED;
+
+#ifdef __LS_VA_STRINGIFY__
+#  undef __LS_VA_STRINGIFY__
+#endif
+#ifdef __LS_VA_STRCONCAT__
+#  undef __LS_VA_STRCONCAT__
+#endif
+#define __LS_VA_STRINGIFY(_x ...)        #_x
+#define __LS_VA_STRCONCAT(_x, _y)        __LS_VA_STRINGIFY(_x,_y)
+#define __LINKER_MAKE_SET(_set, _sym)                                   \
+       /*__unused*/ /*static*/ const struct linker_set_entry /*const*/ __set_##_set##_sym_##_sym               \
+       __attribute__ ((section(__LS_VA_STRCONCAT(LINKER_SET_SEGMENT,_set)),used)) = { (void *)&_sym }
+/* the line above is very fragile - if your compiler breaks linker sets,
+ *  just play around with "static", "const", "used" etc. :-) */
+
+/*
+ * Public macros.
+ */
+#define LINKER_SET_ENTRY(_set, _sym)    __LINKER_MAKE_SET(_set, _sym)

 
 /*
 
 /*

- * NB: the constants defined below must match those defined in
- * nlist.h.  Since their calculation requires arithmetic, we
- * can't name them symbolically (e.g., 7 is N_DATA | N_EXT).
+ * FreeBSD compatibility.

  */
  */

-#define MAKE_SET(set, sym, type) \
-       static void const * const __set_##set##_sym_##sym = &sym; \
-       __asm(".stabs \"_" #set "\", " #type ", 0, 0, _" #sym)
+#ifdef __APPLE_API_OBSOLETE
+# define TEXT_SET(_set, _sym)   __LINKER_MAKE_SET(_set, _sym)
+# define DATA_SET(_set, _sym)   __LINKER_MAKE_SET(_set, _sym)
+# define BSS_SET(_set, _sym)    __LINKER_MAKE_SET(_set, _sym)
+# define ABS_SET(_set, _sym)    __LINKER_MAKE_SET(_set, _sym)
+# define SET_ENTRY(_set, _sym)  __LINKER_MAKE_SET(_set, _sym)
+#endif /* __APPLE_API_OBSOLETE */

 
 

-#define TEXT_SET(set, sym) MAKE_SET(set, sym, 5)
-#define DATA_SET(set, sym) MAKE_SET(set, sym, 7)
-#define BSS_SET(set, sym)  MAKE_SET(set, sym, 9)
-#define ABS_SET(set, sym)  MAKE_SET(set, sym, 3)
+/*
+ * Extended linker set API.
+ *
+ * Since linker sets are per-object-file, and we may have multiple
+ * object files, we need to be able to specify which object's set
+ * to scan.
+ *
+ * The set itself is a contiguous array of pointers to the objects
+ * within the set.
+ */
+
+/*
+ * Public interface.
+ *
+ * void **LINKER_SET_OBJECT_BEGIN(_object, _set)
+ *     Preferred interface to linker_set_object_begin(), takes set name unquoted.
+ * void **LINKER_SET_OBJECT_LIMIT(_object, _set)
+ *     Preferred interface to linker_set_object_begin(), takes set name unquoted.
+ * LINKER_SET_OBJECT_FOREACH(_object, (set_member_type **)_pvar, _cast, _set)
+ *     Iterates over the members of _set within _object.  Since the set contains
+ *     pointers to its elements, for a set of elements of type etyp, _pvar must
+ *     be (etyp **).
+ * LINKER_SET_FOREACH((set_member_type **)_pvar, _cast, _set)
+ *
+ * Example of _cast: For the _pvar "struct sysctl_oid **oidpp", _cast would be
+ *                   "struct sysctl_oid **"
+ *
+ */
+
+#define LINKER_SET_OBJECT_BEGIN(_object, _set)  __linker_set_object_begin(_object, _set)
+#define LINKER_SET_OBJECT_LIMIT(_object, _set)  __linker_set_object_limit(_object, _set)
+
+#define LINKER_SET_OBJECT_FOREACH(_object, _pvar, _cast, _set)          \
+       for (_pvar = (_cast) LINKER_SET_OBJECT_BEGIN(_object, _set);    \
+            _pvar < (_cast) LINKER_SET_OBJECT_LIMIT(_object, _set);    \
+            _pvar++)
+
+#define LINKER_SET_OBJECT_ITEM(_object, _cast, _set, _i)                \
+       (((_cast)(LINKER_SET_OBJECT_BEGIN(_object, _set)))[_i])

 
 

+#define LINKER_SET_FOREACH(_pvar, _cast, _set)                                  \
+       LINKER_SET_OBJECT_FOREACH((MACH_HEADER_TYPE *)MH_EXECUTE_HEADER, _pvar, _cast, _set)
+
+/*
+ * Implementation.
+ *
+ * void **__linker_set_object_begin(_header, _set)
+ *     Returns a pointer to the first pointer in the linker set.
+ * void **__linker_set_object_limi(_header, _set)
+ *     Returns an upper bound to the linker set (base + size).
+ */
+
+static __inline intptr_t
+__linker_get_slide(struct mach_header *_header)
+{
+#ifndef KERNEL
+       /*
+        * Gross.
+        *
+        * We cannot get the image slide directly from the header, so we need to
+        * determine the image's index and ask for the slide of that index.
+        */
+       uint32_t i = 0;
+       for (i = 0; i < _dyld_image_count(); i++) {
+               const struct mach_header *hdr = _dyld_get_image_header(i);
+               if (_header == hdr) {
+                       return _dyld_get_image_vmaddr_slide(i);
+               }
+       }
+       return 0;
+#else
+       (void)_header;
+       return 0;

 #endif
 #endif

+}
+
+static __inline void **
+__linker_set_object_begin(MACH_HEADER_TYPE *_header, const char *_set)
+__attribute__((__const__));
+static __inline void **
+__linker_set_object_begin(MACH_HEADER_TYPE *_header, const char *_set)
+{
+       char *_set_begin;
+       SECTDATA_SIZE_TYPE _size;
+
+       _set_begin = (char *)GETSECTIONDATA_VARIANT(_header, LINKER_SET_SEGMENT_CSTR, _set, &_size);
+       _set_begin += __linker_get_slide((struct mach_header *)_header);
+       return (void **)(uintptr_t)_set_begin;
+}
+
+static __inline void **
+__linker_set_object_limit(MACH_HEADER_TYPE *_header, const char *_set)
+__attribute__((__const__));
+static __inline void **
+__linker_set_object_limit(MACH_HEADER_TYPE *_header, const char *_set)
+{
+       char *_set_begin;
+       SECTDATA_SIZE_TYPE _size;
+
+       _set_begin = (char *)GETSECTIONDATA_VARIANT(_header, LINKER_SET_SEGMENT_CSTR, _set, &_size);
+       _set_begin += __linker_get_slide((struct mach_header *)_header);
+
+       return (void **) ((uintptr_t) _set_begin + _size);
+}

 
 

-struct linker_set {
-       int             ls_length;
-       const void      *ls_items[1];           /* really ls_length of them,
-                                                * trailing NULL */
-};

 #endif /* !KERNEL || __APPLE_API_PRIVATE */
 
 #endif /* _SYS_LINKER_SET_H_ */
 #endif /* !KERNEL || __APPLE_API_PRIVATE */
 
 #endif /* _SYS_LINKER_SET_H_ */

-