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On Hardened we add some options like -fstack-clash-protection and -z now
--- a/gcc/common.opt 2018-03-28 16:51:09.000000000 +0200
+++ a/gcc/common.opt 2018-04-30 15:35:55.274096877 +0200
@@ -2367,7 +2367,7 @@ Common Alias(fstack-check=, specific, no
Insert stack checking code into the program. Same as -fstack-check=specific.
fstack-clash-protection
-Common Report Var(flag_stack_clash_protection) Optimization
+Common Report Var(flag_stack_clash_protection) Optimization Init(-1)
Insert code to probe each page of stack space as it is allocated to protect
from stack-clash style attacks.
--- a/gcc/defaults.h 2018-01-03 11:03:58.000000000 +0100
+++ b/gcc/defaults.h 2018-05-01 12:41:29.522851451 +0200
@@ -1435,6 +1435,15 @@ see the files COPYING3 and COPYING.RUNTI
#define STACK_CHECK_MAX_VAR_SIZE (STACK_CHECK_MAX_FRAME_SIZE / 100)
#endif
+/* Default value for flag_clash_protector when flag_clash_protector is
+ initialized to -1. */
+#ifdef ENABLE_ESP
+#define DEFAULT_FLAG_SCP 1
+#endif
+#ifndef DEFAULT_FLAG_SCP
+#define DEFAULT_FLAG_SCP 0
+#endif
+
/* By default, the C++ compiler will use function addresses in the
vtable entries. Setting this nonzero tells the compiler to use
function descriptors instead. The value of this macro says how
--- a/gcc/toplev.c 2018-02-13 17:18:37.000000000 +0100
+++ b/toplev.c 2018-04-30 16:46:37.244027303 +0200
@@ -1682,6 +1682,10 @@ process_options (void)
/* -fstack-clash-protection is not currently supported on targets
where the stack grows up. */
+ if (flag_stack_clash_protection == -1)
+ {
+ flag_stack_clash_protection = DEFAULT_FLAG_SCP;
+ }
if (flag_stack_clash_protection && !STACK_GROWS_DOWNWARD)
{
warning_at (UNKNOWN_LOCATION, 0,
--- a/libgcc/Makefile.in 2011-11-22 04:01:02.000000000 +0100
+++ b/libgcc/Makefile.in 2011-12-25 15:18:22.449610631 +0100
@@ -225,7 +225,7 @@ endif
LIBGCC2_DEBUG_CFLAGS = -g
LIBGCC2_CFLAGS = -O2 $(LIBGCC2_INCLUDES) $(GCC_CFLAGS) $(HOST_LIBGCC2_CFLAGS) \
$(LIBGCC2_DEBUG_CFLAGS) -DIN_LIBGCC2 \
- -fbuilding-libgcc -fno-stack-protector \
+ -fbuilding-libgcc -fno-stack-protector -fno-stack-clash-protection \
$(INHIBIT_LIBC_CFLAGS)
# Additional options to use when compiling libgcc2.a.
@@ -279,7 +290,7 @@ INTERNAL_CFLAGS = $(CFLAGS) $(LIBGCC2_CF
-finhibit-size-directive -fno-inline -fno-exceptions \
-fno-zero-initialized-in-bss -fno-toplevel-reorder -fno-tree-vectorize \
-fbuilding-libgcc -fno-stack-protector $(FORCE_EXPLICIT_EH_REGISTRY) \
- $(INHIBIT_LIBC_CFLAGS)
+ -fno-stack-clash-protection $(INHIBIT_LIBC_CFLAGS)
# Extra flags to use when compiling crt{begin,end}.o.
CRTSTUFF_T_CFLAGS =
--- a/gcc/gcc.c 2016-02-19 23:18:38.000000000 +0100
+++ b/gcc/gcc.c 2016-05-02 22:56:10.185721270 +0200
@@ -868,6 +868,12 @@ proper position among the other output f
#endif
#endif
+#ifdef EXTRA_OPTIONS
+#define LINK_NOW_SPEC "%{!nonow:-z now} "
+#else
+#define LINK_NOW_SPEC ""
+#endif
+
#ifdef ENABLE_DEFAULT_PIE
#define NO_PIE_SPEC "no-pie|static"
#define PIE_SPEC NO_PIE_SPEC "|r|shared:;"
@@ -1013,7 +1020,7 @@ proper position among the other output f
%(linker) " \
LINK_PLUGIN_SPEC \
"%{flto|flto=*:%<fcompare-debug*} \
- %{flto} %{fno-lto} %{flto=*} %l " LINK_PIE_SPEC \
+ %{flto} %{fno-lto} %{flto=*} %l " LINK_PIE_SPEC LINK_NOW_SPEC \
"%{fuse-ld=*:-fuse-ld=%*} " LINK_COMPRESS_DEBUG_SPEC \
"%X %{o*} %{e*} %{N} %{n} %{r}\
%{s} %{t} %{u*} %{z} %{Z} %{!nostdlib:%{!nostartfiles:%S}} \
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