aboutsummaryrefslogtreecommitdiff
path: root/config/cet.m4
blob: 911fbd4647577dd2adae4dcee316ea58eaf0cc8f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
dnl
dnl GCC_CET_FLAGS
dnl    (SHELL-CODE_HANDLER)
dnl
AC_DEFUN([GCC_CET_FLAGS],[dnl
GCC_ENABLE(cet, auto, ,[enable Intel CET in target libraries],
	   permit yes|no|auto)
AC_MSG_CHECKING([for CET support])

# NB: Avoid nested save_CFLAGS and save_LDFLAGS.
case "$host" in
  i[[34567]]86-*-linux* | x86_64-*-linux*)
    case "$enable_cet" in
      auto)
	# Check if target supports multi-byte NOPs
	# and if assembler supports CET insn.
	cet_save_CFLAGS="$CFLAGS"
	CFLAGS="$CFLAGS -fcf-protection"
	AC_COMPILE_IFELSE(
	 [AC_LANG_PROGRAM(
	  [],
	  [
#if !defined(__SSE2__)
#error target does not support multi-byte NOPs
#else
asm ("setssbsy");
#endif
	  ])],
	 [enable_cet=yes],
	 [enable_cet=no])
	CFLAGS="$cet_save_CFLAGS"
	;;
      yes)
	# Check if assembler supports CET.
	AC_COMPILE_IFELSE(
	 [AC_LANG_PROGRAM(
	  [],
	  [asm ("setssbsy");])],
	 [],
	 [AC_MSG_ERROR([assembler with CET support is required for --enable-cet])])
	;;
    esac
    ;;
  *)
    enable_cet=no
    ;;
esac
if test x$enable_cet = xyes; then
  $1="-fcf-protection -mshstk"
  AC_MSG_RESULT([yes])
else
  AC_MSG_RESULT([no])
fi
])

dnl
dnl GCC_CET_HOST_FLAGS
dnl    (SHELL-CODE_HANDLER)
dnl
AC_DEFUN([GCC_CET_HOST_FLAGS],[dnl
GCC_ENABLE(cet, auto, ,[enable Intel CET in host libraries],
	   permit yes|no|auto)
AC_MSG_CHECKING([for CET support])

case "$host" in
  i[[34567]]86-*-linux* | x86_64-*-linux*)
    may_have_cet=yes
    cet_save_CFLAGS="$CFLAGS"
    CFLAGS="$CFLAGS -fcf-protection"
    case "$enable_cet" in
      auto)
	# Check if target supports multi-byte NOPs
	# and if assembler supports CET insn.
	AC_COMPILE_IFELSE(
	 [AC_LANG_PROGRAM(
	  [],
	  [
#if !defined(__SSE2__)
#error target does not support multi-byte NOPs
#else
asm ("setssbsy");
#endif
	  ])],
	 [enable_cet=yes],
	 [enable_cet=no])
	;;
      yes)
	# Check if assembler supports CET.
	AC_COMPILE_IFELSE(
	 [AC_LANG_PROGRAM(
	  [],
	  [asm ("setssbsy");])],
	 [],
	 [AC_MSG_ERROR([assembler with CET support is required for --enable-cet])])
	;;
    esac
    CFLAGS="$cet_save_CFLAGS"
    ;;
  *)
    may_have_cet=no
    enable_cet=no
    ;;
esac

cet_save_CFLAGS="$CFLAGS"
CFLAGS="$CFLAGS -fcf-protection=none"
cet_save_LDFLAGS="$LDFLAGS"
LDFLAGS="$LDFLAGS -Wl,-z,ibt,-z,shstk"
if test x$may_have_cet = xyes; then
  # Check whether -fcf-protection=none -Wl,-z,ibt,-z,shstk work.
  AC_TRY_LINK(
    [],[return 0;],
    [may_have_cet=yes],
    [may_have_cet=no])
fi

if test x$may_have_cet = xyes; then
  if test x$cross_compiling = xno; then
    AC_TRY_RUN([
static void
foo (void)
{
}

static void
__attribute__ ((noinline, noclone))
xxx (void (*f) (void))
{
  f ();
}

static void
__attribute__ ((noinline, noclone))
bar (void)
{
  xxx (foo);
}

int
main ()
{
  bar ();
  return 0;
}
    ],
    [have_cet=no],
    [have_cet=yes])
    if test x$enable_cet = xno -a x$have_cet = xyes; then
      AC_MSG_ERROR([Intel CET must be enabled on Intel CET enabled host])
    fi
  fi
else
  # Enable CET in cross compiler if possible so that it will run on both
  # CET and non-CET hosts.
  have_cet=yes
fi
if test x$enable_cet = xyes; then
  $1="-fcf-protection"
  AC_MSG_RESULT([yes])
else
  AC_MSG_RESULT([no])
fi
CFLAGS="$cet_save_CFLAGS"
LDFLAGS="$cet_save_LDFLAGS"
])