libphobos: libdruntime doesn't support shadow stack (PR95680)

Rather than implementing support within D runtime itself, use libc
getcontext/swapcontext functions if CET is enabled.

Removes whatever CET support was in the switchContext routine for x86
D runtime, along with setting version AsmExternal, so that the fallback
ucontext_t implementation is used, which is capable of doing shadow
stack handling.

libphobos/ChangeLog:

	PR d/95680
	* Makefile.in: Regenerate.
	* configure: Regenerate.
	* configure.ac (DCFG_ENABLE_CET): Substitute.
	* libdruntime/Makefile.in: Regenerate.
	* libdruntime/config/x86/switchcontext.S: Remove CET support code.
	* libdruntime/core/thread.d: Import gcc.config.  Don't set version
	AsmExternal when GNU_Enable_CET is true.
	* libdruntime/gcc/config.d.in (GNU_Enable_CET): Define.
	* src/Makefile.in: Regenerate.
	* testsuite/Makefile.in: Regenerate.

4 files changed, 40 insertions, 31 deletions

diff --git a/libphobos/libdruntime/Makefile.in b/libphobos/libdruntime/Makefile.in
index 3fddbc3..28b4333 100644
--- a/libphobos/libdruntime/Makefile.in
+++ b/libphobos/libdruntime/Makefile.in
@@ -131,6 +131,8 @@ target_triplet = @target@
 subdir = libdruntime
 ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
 am__aclocal_m4_deps = $(top_srcdir)/../config/acx.m4 \
+	$(top_srcdir)/../config/cet.m4 \
+	$(top_srcdir)/../config/enable.m4 \
 	$(top_srcdir)/../config/lead-dot.m4 \
 	$(top_srcdir)/../config/multi.m4 \
 	$(top_srcdir)/../config/override.m4 \
@@ -565,6 +567,7 @@ CC = @CC@
 CCAS = @CCAS@
 CCASFLAGS = @CCASFLAGS@
 CC_FOR_BUILD = @CC_FOR_BUILD@
+CET_FLAGS = @CET_FLAGS@
 CFLAGS = @CFLAGS@
 CFLAGS_FOR_BUILD = @CFLAGS_FOR_BUILD@
 CHECKING_DFLAGS = @CHECKING_DFLAGS@
@@ -573,6 +576,7 @@ CPPFLAGS = @CPPFLAGS@
 CYGPATH_W = @CYGPATH_W@
 DCFG_ARM_EABI_UNWINDER = @DCFG_ARM_EABI_UNWINDER@
 DCFG_DLPI_TLS_MODID = @DCFG_DLPI_TLS_MODID@
+DCFG_ENABLE_CET = @DCFG_ENABLE_CET@
 DCFG_HAVE_64BIT_ATOMICS = @DCFG_HAVE_64BIT_ATOMICS@
 DCFG_HAVE_ATOMIC_BUILTINS = @DCFG_HAVE_ATOMIC_BUILTINS@
 DCFG_HAVE_LIBATOMIC = @DCFG_HAVE_LIBATOMIC@
diff --git a/libphobos/libdruntime/config/x86/switchcontext.S b/libphobos/libdruntime/config/x86/switchcontext.S
index 35063af..85f2e00 100644
--- a/libphobos/libdruntime/config/x86/switchcontext.S
+++ b/libphobos/libdruntime/config/x86/switchcontext.S
@@ -24,13 +24,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 
 #include "../common/threadasm.S"
 
-#ifdef __CET__
-# include <cet.h>
-#else
-# define _CET_ENDBR
-#endif
-
-#if defined(__i386__)
+#if defined(__i386__) && !defined(__CET__)
 
     .text
     .globl CSYM(fiber_switchContext)
@@ -38,7 +32,6 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
     .align 16
 CSYM(fiber_switchContext):
     .cfi_startproc
-    _CET_ENDBR
     // save current stack state
     push %ebp
     mov  %esp, %ebp
@@ -65,7 +58,7 @@ CSYM(fiber_switchContext):
     .cfi_endproc
     .size CSYM(fiber_switchContext),.-CSYM(fiber_switchContext)
 
-#elif defined(__x86_64__) && !defined(__ILP32__)
+#elif defined(__x86_64__) && !defined(__ILP32__) && !defined(__CET__)
 
     .text
     .globl CSYM(fiber_switchContext)
@@ -73,7 +66,6 @@ CSYM(fiber_switchContext):
     .align 16
 CSYM(fiber_switchContext):
     .cfi_startproc
-    _CET_ENDBR
     // Save current stack state.save current stack state
     push %rbp
     mov  %rsp, %rbp
diff --git a/libphobos/libdruntime/core/thread.d b/libphobos/libdruntime/core/thread.d
index e1a6805..8f4603d 100644
--- a/libphobos/libdruntime/core/thread.d
+++ b/libphobos/libdruntime/core/thread.d
@@ -3586,35 +3586,45 @@ private
     }
     else version (X86)
     {
-        version = AsmExternal;
+        import gcc.config;
 
-        version (MinGW)
-        {
-            version = GNU_AsmX86_Windows;
-            version = AlignFiberStackTo16Byte;
-        }
-        else version (Posix)
+        version = AlignFiberStackTo16Byte;
+
+        static if (!GNU_Enable_CET)
         {
-            version = AsmX86_Posix;
-            version (OSX)
-                version = AlignFiberStackTo16Byte;
+            version = AsmExternal;
+
+            version (MinGW)
+            {
+                version = GNU_AsmX86_Windows;
+            }
+            else version (Posix)
+            {
+                version = AsmX86_Posix;
+            }
         }
     }
     else version (X86_64)
     {
-        version (D_X32)
-        {
-            // let X32 be handled by ucontext swapcontext
-        }
-        else
+        import gcc.config;
+
+        version = AlignFiberStackTo16Byte;
+
+        static if (!GNU_Enable_CET)
         {
-            version = AsmExternal;
-            version = AlignFiberStackTo16Byte;
+            version (D_X32)
+            {
+                // let X32 be handled by ucontext swapcontext
+            }
+            else
+            {
+                version = AsmExternal;
 
-            version (MinGW)
-                version = GNU_AsmX86_64_Windows;
-            else version (Posix)
-                version = AsmX86_64_Posix;
+                version (MinGW)
+                    version = GNU_AsmX86_64_Windows;
+                else version (Posix)
+                    version = AsmX86_64_Posix;
+            }
         }
     }
     else version (PPC)
diff --git a/libphobos/libdruntime/gcc/config.d.in b/libphobos/libdruntime/gcc/config.d.in
index 6301aaf..9ac7d05 100644
--- a/libphobos/libdruntime/gcc/config.d.in
+++ b/libphobos/libdruntime/gcc/config.d.in
@@ -49,3 +49,6 @@ enum GNU_Have_LibAtomic = @DCFG_HAVE_LIBATOMIC@;
 
 // Do we have qsort_r function
 enum Have_Qsort_R = @DCFG_HAVE_QSORT_R@;
+
+// Whether libphobos been configured with --enable-cet.
+enum GNU_Enable_CET = @DCFG_ENABLE_CET@;