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On Hardened we add some options like -fstack-clash-protection.
--- a/gcc/common.opt
+++ a/gcc/common.opt
@@ -2698,7 +2698,7 @@ Common Alias(fstack-check=, specific, no
Insert stack checking code into the program. Same as -fstack-check=specific.
fstack-clash-protection
-Common Var(flag_stack_clash_protection) Optimization
+Common 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
+++ b/gcc/defaults.h
@@ -1425,6 +1425,15 @@ 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 EXTRA_OPTIONS
+#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.cc
+++ b/gcc/toplev.cc
@@ -1610,6 +1610,10 @@ 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
+++ b/libgcc/Makefile.in
@@ -246,7 +246,7 @@ 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.
@@ -302,7 +302,7 @@ INTERNAL_CFLAGS = $(CFLAGS) $(LIBGCC2_CF
$(NO_PIE_CFLAGS) -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) $(USE_TM_CLONE_REGISTRY)
+ -fno-stack-clash-protection $(INHIBIT_LIBC_CFLAGS) $(USE_TM_CLONE_REGISTRY)
# Extra flags to use when compiling crt{begin,end}.o.
CRTSTUFF_T_CFLAGS =
|
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