libunwind/src/cet_unwind.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef LIBUNWIND_CET_UNWIND_H
  11 #define LIBUNWIND_CET_UNWIND_H
  12
  13 #include "libunwind.h"
  14
  15 // Currently, CET is implemented on Linux x86 platforms.
  16 #if defined(_LIBUNWIND_TARGET_LINUX) && defined(__CET__) && defined(__SHSTK__)
  17 #define _LIBUNWIND_USE_CET 1
  18 #endif
  19
  20 #if defined(_LIBUNWIND_USE_CET)
  21 #include <cet.h>
  22 #include <immintrin.h>
  23
  24 #define _LIBUNWIND_POP_CET_SSP(x)                                              \
  25   do {                                                                         \
  26     unsigned long ssp = _get_ssp();                                            \
  27     if (ssp != 0) {                                                            \
  28       unsigned int tmp = (x);                                                  \
  29       while (tmp > 255) {                                                      \
  30         _inc_ssp(255);                                                         \
  31         tmp -= 255;                                                            \
  32       }                                                                        \
  33       _inc_ssp(tmp);                                                           \
  34     }                                                                          \
  35   } while (0)
  36 #endif
  37
  38 // On AArch64 we use _LIBUNWIND_USE_GCS to indicate that GCS is supported. We
  39 // need to guard any use of GCS instructions with __chkfeat though, as GCS may
  40 // not be enabled.
  41 #if defined(_LIBUNWIND_TARGET_AARCH64) && defined(__ARM_FEATURE_GCS_DEFAULT)
  42 #include <arm_acle.h>
  43
  44 // We can only use GCS if arm_acle.h defines the GCS intrinsics.
  45 #ifdef _CHKFEAT_GCS
  46 #define _LIBUNWIND_USE_GCS 1
  47 #endif
  48
  49 #define _LIBUNWIND_POP_CET_SSP(x)                                              \
  50   do {                                                                         \
  51     if (__chkfeat(_CHKFEAT_GCS)) {                                             \
  52       unsigned tmp = (x);                                                      \
  53       while (tmp--)                                                            \
  54         __gcspopm();                                                           \
  55     }                                                                          \
  56   } while (0)
  57
  58 #endif
  59
  60 extern void *__libunwind_cet_get_registers(unw_cursor_t *);
  61 extern void *__libunwind_cet_get_jump_target(void);
  62
  63 #endif