sysdeps/aarch64/libc-mtag.h

   1 /* libc-internal interface for tagged (colored) memory support.
   2    Copyright (C) 2020-2022 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _AARCH64_LIBC_MTAG_H
  20 #define _AARCH64_LIBC_MTAG_H 1
  21
  22 #ifndef USE_MTAG
  23 /* Generic bindings for systems that do not support memory tagging.  */
  24 #include_next "libc-mtag.h"
  25 #else
  26
  27 /* Used to ensure additional alignment when objects need to have distinct
  28    tags.  */
  29 #define __MTAG_GRANULE_SIZE 16
  30
  31 /* Non-zero if memory obtained via morecore (sbrk) is not tagged.  */
  32 #define __MTAG_SBRK_UNTAGGED 1
  33
  34 /* Extra flags to pass to mmap to get tagged pages.  */
  35 #define __MTAG_MMAP_FLAGS PROT_MTE
  36
  37 /* Set the tags for a region of memory, which must have size and alignment
  38    that are multiples of __MTAG_GRANULE_SIZE.  Size cannot be zero.  */
  39 void *__libc_mtag_tag_region (void *, size_t);
  40
  41 /* Optimized equivalent to __libc_mtag_tag_region followed by memset to 0.  */
  42 void *__libc_mtag_tag_zero_region (void *, size_t);
  43
  44 /* Convert address P to a pointer that is tagged correctly for that
  45    location.  */
  46 static __always_inline void *
  47 __libc_mtag_address_get_tag (void *p)
  48 {
  49   register void *x0 asm ("x0") = p;
  50   asm (".inst 0xd9600000 /* ldg x0, [x0] */" : "+r" (x0));
  51   return x0;
  52 }
  53
  54 /* Assign a new (random) tag to a pointer P (does not adjust the tag on
  55    the memory addressed).  */
  56 static __always_inline void *
  57 __libc_mtag_new_tag (void *p)
  58 {
  59   register void *x0 asm ("x0") = p;
  60   register unsigned long x1 asm ("x1");
  61   /* Guarantee that the new tag is not the same as now.  */
  62   asm (".inst 0x9adf1401 /* gmi x1, x0, xzr */\n"
  63        ".inst 0x9ac11000 /* irg x0, x0, x1 */" : "+r" (x0), "=r" (x1));
  64   return x0;
  65 }
  66
  67 #endif /* USE_MTAG */
  68
  69 #endif /* _AARCH64_LIBC_MTAG_H */