Allow setting of stack-clash via configure options.

This patch defines a configure option to allow the setting of the default
guard size via configure flags when building the target.

The new flag is:

 * --with-stack-clash-protection-guard-size=<num>

The patch defines a new macro DEFAULT_STK_CLASH_GUARD_SIZE which targets need
to use explicitly is they want to support this configure flag and values that
users may have set.

gcc/

	PR target/86486
	* configure.ac: Add stack-clash-protection-guard-size.
	* doc/install.texi: Document it.
	* config.in (DEFAULT_STK_CLASH_GUARD_SIZE): New.
	* params.def: Update comment for guard-size.
	(PARAM_STACK_CLASH_PROTECTION_GUARD_SIZE,
	PARAM_STACK_CLASH_PROTECTION_PROBE_INTERVAL): Update description.
	* configure: Regenerate.

From-SVN: r264752

gcc/ChangeLog

 2018-10-01  Tamar Christina  <tamar.christina@arm.com>
 
 	PR target/86486
+	* configure.ac: Add stack-clash-protection-guard-size.
+	* doc/install.texi: Document it.
+	* config.in (DEFAULT_STK_CLASH_GUARD_SIZE): New.
+	* params.def: Update comment for guard-size.
+	(PARAM_STACK_CLASH_PROTECTION_GUARD_SIZE,
+	PARAM_STACK_CLASH_PROTECTION_PROBE_INTERVAL): Update description.
+	* configure: Regenerate.
+
+2018-10-01  Tamar Christina  <tamar.christina@arm.com>
+
+	PR target/86486
 	* config/aarch64/aarch64.h (STACK_CLASH_MIN_BYTES_OUTGOING_ARGS,
 	STACK_DYNAMIC_OFFSET): New.
 	* config/aarch64/aarch64.c (aarch64_layout_frame):

gcc/config.in

@@ -55,6 +55,13 @@
 #endif
 
 
+/* Define to larger than zero set to the default stack clash protector size as
+   a power of two in bytes. */
+#ifndef USED_FOR_TARGET
+#undef DEFAULT_STK_CLASH_GUARD_SIZE
+#endif
+
+
 /* Define if you want to use __cxa_atexit, rather than atexit, to register C++
    destructors for local statics and global objects. This is essential for
    fully standards-compliant handling of destructors, but requires

gcc/configure

@@ -906,6 +906,7 @@ enable_valgrind_annotations
 with_stabs
 enable_multilib
 enable_multiarch
+with_stack_clash_protection_guard_size
 enable___cxa_atexit
 enable_decimal_float
 enable_fixed_point
@@ -1727,6 +1728,9 @@ Optional Packages:
   --with-gnu-as           arrange to work with GNU as
   --with-as               arrange to use the specified as (full pathname)
   --with-stabs            arrange to use stabs instead of host debug format
+  --with-stack-clash-protection-guard-size=size
+                          Set the default stack clash protection guard size
+                          for specific targets as a power of two in bytes.
   --with-dwarf2           force the default debug format to be DWARF 2
   --with-specs=SPECS      add SPECS to driver command-line processing
   --with-pkgversion=PKG   Use PKG in the version string in place of "GCC"
@@ -7439,6 +7443,34 @@ $as_echo "$enable_multiarch$ma_msg_suffix" >&6; }
 
 
 
+# default stack clash protection guard size as power of twos in bytes.
+# Please keep these in sync with params.def.
+stk_clash_min=12
+stk_clash_max=30
+
+# Keep the default value when the option is not used to 0, this allows us to
+# distinguish between the cases where the user specifially set a value via
+# configure and when the normal default value is used.
+
+# Check whether --with-stack-clash-protection-guard-size was given.
+if test "${with_stack_clash_protection_guard_size+set}" = set; then :
+  withval=$with_stack_clash_protection_guard_size; DEFAULT_STK_CLASH_GUARD_SIZE="$with_stack_clash_protection_guard_size"
+else
+  DEFAULT_STK_CLASH_GUARD_SIZE=0
+fi
+
+if test $DEFAULT_STK_CLASH_GUARD_SIZE -ne 0 \
+     && (test $DEFAULT_STK_CLASH_GUARD_SIZE -lt $stk_clash_min \
+	 || test $DEFAULT_STK_CLASH_GUARD_SIZE -gt $stk_clash_max); then
+  as_fn_error "Invalid value $DEFAULT_STK_CLASH_GUARD_SIZE for --with-stack-clash-protection-guard-size. Must be between $stk_clash_min and $stk_clash_max." "$LINENO" 5
+fi
+
+
+cat >>confdefs.h <<_ACEOF
+#define DEFAULT_STK_CLASH_GUARD_SIZE $DEFAULT_STK_CLASH_GUARD_SIZE
+_ACEOF
+
+
 # Enable __cxa_atexit for C++.
 # Check whether --enable-__cxa_atexit was given.
 if test "${enable___cxa_atexit+set}" = set; then :
@@ -18463,7 +18495,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18466 "configure"
+#line 18498 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -18569,7 +18601,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 18572 "configure"
+#line 18604 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H

gcc/configure.ac

@@ -811,6 +811,29 @@ AC_MSG_RESULT($enable_multiarch$ma_msg_suffix)
 AC_SUBST(with_cpu)
 AC_SUBST(with_float)
 
+# default stack clash protection guard size as power of twos in bytes.
+# Please keep these in sync with params.def.
+stk_clash_min=12
+stk_clash_max=30
+
+# Keep the default value when the option is not used to 0, this allows us to
+# distinguish between the cases where the user specifially set a value via
+# configure and when the normal default value is used.
+AC_ARG_WITH(stack-clash-protection-guard-size,
+[AS_HELP_STRING([--with-stack-clash-protection-guard-size=size],
+[Set the default stack clash protection guard size for specific targets as a power of two in bytes.])],
+[DEFAULT_STK_CLASH_GUARD_SIZE="$with_stack_clash_protection_guard_size"], [DEFAULT_STK_CLASH_GUARD_SIZE=0])
+if test $DEFAULT_STK_CLASH_GUARD_SIZE -ne 0 \
+     && (test $DEFAULT_STK_CLASH_GUARD_SIZE -lt $stk_clash_min \
+	 || test $DEFAULT_STK_CLASH_GUARD_SIZE -gt $stk_clash_max); then
+  AC_MSG_ERROR(m4_normalize([
+		Invalid value $DEFAULT_STK_CLASH_GUARD_SIZE for --with-stack-clash-protection-guard-size. \
+		Must be between $stk_clash_min and $stk_clash_max.]))
+fi
+
+AC_DEFINE_UNQUOTED(DEFAULT_STK_CLASH_GUARD_SIZE, $DEFAULT_STK_CLASH_GUARD_SIZE,
+	[Define to larger than zero set the default stack clash protector size.])
+
 # Enable __cxa_atexit for C++.
 AC_ARG_ENABLE(__cxa_atexit,
 [AS_HELP_STRING([--enable-__cxa_atexit], [enable __cxa_atexit for C++])],

gcc/doc/install.texi

@@ -1414,6 +1414,11 @@ These features are extensions to the traditional
 SVR4-based MIPS ABIs and require support from GNU binutils
 and the runtime C library.
 
+@item --with-stack-clash-protection-guard-size=@var{size}
+On certain targets this option sets the default stack clash protection guard
+size as a power of two in bytes.  On AArch64 @var{size} is required to be either
+12 (4KB) or 16 (64KB).
+
 @item --enable-__cxa_atexit
 Define if you want to use __cxa_atexit, rather than atexit, to
 register C++ destructors for local statics and global objects.

gcc/params.def

@@ -213,14 +213,15 @@ DEFPARAM(PARAM_STACK_FRAME_GROWTH,
 	 "Maximal stack frame growth due to inlining (in percent).",
 	 1000, 0, 0)
 
+/* Keep these up to date with those in configure.ac.  */
 DEFPARAM(PARAM_STACK_CLASH_PROTECTION_GUARD_SIZE,
 	 "stack-clash-protection-guard-size",
-	 "Size of the stack guard expressed as a power of two.",
+	 "Size of the stack guard expressed as a power of two in bytes.",
 	 12, 12, 30)
 
 DEFPARAM(PARAM_STACK_CLASH_PROTECTION_PROBE_INTERVAL,
 	 "stack-clash-protection-probe-interval",
-	 "Interval in which to probe the stack expressed as a power of two.",
+	 "Interval in which to probe the stack expressed as a power of two in bytes.",
 	 12, 10, 16)
 
 /* The GCSE optimization will be disabled if it would require