1  /* libc-internal interface for tagged (colored) memory support.
       2     Copyright (C) 2020-2023 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 */