Hi Jeff,
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.
Bootstrapped Regtested on aarch64-none-linux-gnu, x86_64-pc-linux-gnu and no
issues.
Both targets were tested with stack clash on and off by default.
Ok for trunk?
Thanks,
Tamar
gcc/
2018-07-24 Tamar Christina <tamar.christ...@arm.com>
PR target/86486
* configure.ac: Add stack-clash-protection-guard-size.
* config.in (DEFAULT_STK_CLASH_GUARD_SIZE): New.
* params.def: Update comment for guard-size.
* configure: Regenerate.
> -----Original Message-----
> From: Jeff Law <l...@redhat.com>
> Sent: Monday, July 23, 2018 23:19
> To: Tamar Christina <tamar.christ...@arm.com>
> Cc: gcc-patches@gcc.gnu.org; nd <n...@arm.com>;
> jos...@codesourcery.com; bonz...@gnu.org; d...@redhat.com;
> nero...@gcc.gnu.org; aol...@redhat.com; ralf.wildenh...@gmx.de
> Subject: Re: [PATCH][GCC][front-end][build-machinery][opt-framework]
> Allow setting of stack-clash via configure options. [Patch (4/6)]
>
> On 07/20/2018 09:39 AM, Tamar Christina wrote:
> >>
> >> On 07/20/2018 05:03 AM, Tamar Christina wrote:
> >>>> Understood. Thanks for verifying. I wonder if we could just bury
> >>>> this entirely in the aarch64 config files and not expose the
> >>>> default into
> >> params.def?
> >>>>
> >>>
> >>> Burying it in config.gcc isn't ideal because if your C runtime is
> >>> configurable (like uClibc) it means you have to go and modify this
> >>> file every time you change something. If the argument is against
> >>> having these defines in the params and not the configure flag itself
> >>> then I
> >> can just have an aarch64 specific configure flag and just use the
> >> created define directly in the AArch64 back-end.
> >> Not config.gcc, but in a .h/.c file for the target.
> >>
> >> If we leave the generic option, but override the default in the target
> >> files.
> >> Would that work?
> >
> > So leaving the generic configure option? Yes that would work too. The
> > only downside is that if we have want to do any validation on the
> > value at configure time it would need to be manually kept in sync with
> > those in params.def. Or we'd just have to not do any checking at
> > configure time. This would mean you can get to the end of your build and
> only when you try to use the compiler would it complain.
> >
> > Both aren't a real deal breaker to me.
> >
> > Shall I then just leave the configure flag but remove the params plumbing?
> Yea, I think any sanity check essentially has to move to when the compiler
> runs. We can always return to param removal at a later point.
>
> Can you post an updated patch? Note I'm on PTO starting Wed for a week.
> If you post it tomorrow I'll try to take a look before I disappear.
>
> jeff
diff --git a/gcc/config.in b/gcc/config.in
index 2856e72d627df537a301a6c7ab6b5bbb75f6b43f..f3b301ef5afdaf0db8865e11601980f19ea0b3dd 100644
--- a/gcc/config.in
+++ b/gcc/config.in
@@ -55,6 +55,12 @@
#endif
+/* Define to larger than zero set the default stack clash protector size. */
+#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
diff --git a/gcc/configure b/gcc/configure
index 60d373982fd38fe51c285e2b02941754d1b833d6..42ec5b536bee90adb319d172eb7cca1a363a87b6 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -905,6 +905,7 @@ enable_valgrind_annotations
with_stabs
enable_multilib
enable_multiarch
+with_stack_clash_protection_guard_size
enable___cxa_atexit
enable_decimal_float
enable_fixed_point
@@ -1724,6 +1725,9 @@ 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.
--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"
@@ -7436,6 +7440,35 @@ $as_echo "$enable_multiarch$ma_msg_suffix" >&6; }
+# default stack clash protection guard size
+# Please keep these in sync with params.def.
+stk_clash_min=12
+stk_clash_max=30
+stk_clash_default=12
+
+# Keep the default value when the option is not used to 0, this allows us to
+# distinguish between the cases where the user specifially set a value via
+# configure and when the normal default value is used.
+
+# Check whether --with-stack-clash-protection-guard-size was given.
+if test "${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 :
@@ -18448,7 +18481,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 18451 "configure"
+#line 18484 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -18554,7 +18587,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 18557 "configure"
+#line 18590 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 010ecd2ccf609ded1f4d2849a2acc13aba43b55b..2ed1806ed87aca3b451ccd4b0848b50e934b75a9 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -811,6 +811,30 @@ AC_MSG_RESULT($enable_multiarch$ma_msg_suffix)
AC_SUBST(with_cpu)
AC_SUBST(with_float)
+# default stack clash protection guard size
+# Please keep these in sync with params.def.
+stk_clash_min=12
+stk_clash_max=30
+stk_clash_default=12
+
+# 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.])],
+[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++])],
diff --git a/gcc/params.def b/gcc/params.def
index a3906c268814bdc3a813416a60b9f666d1568f0a..b968a3fdbb7aef5074a15c3da8613679825aba2f 100644
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -213,6 +213,7 @@ 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.",
