From b9b58272c5d26d58e553db456a162a0203cf576c Mon Sep 17 00:00:00 2001 From: Igor Tsimbalist Date: Fri, 15 Dec 2017 19:29:47 +0300 Subject: [PATCH] Add -mcheck-shstk-compat -fcf-protection -mcet is incompatible with makecontext family functions since they can't properly set up and destroy shadow stack pointer. This change provides a mechanism to help detection shadow stack compatibility. The current proposal is to add -mcheck-shstk-compat option which will predefine __CHECK_SHSTK_COMPAT__ macro. The macro can be used to guard a code which is not compatible with Intel shadow stack technology. The option will be set on by default. Then we can add the code #if defined __SHSTK__ && defined __CHECK_SHSTK_COMPAT__ # error This source is incompatible with -mshstk #endif to . gcc/ * config/i386/i386-c.c: Add definition of __CHECK_SHSTK_COMPAT__ macro. * config/i386/i386.opt: Add -mcheck-shstk-compat option. * doc/invoke.texi: Add -mcheck-shstk-compat option. * testsuite/gcc.target/i386/pr81842-1.c: New test. * testsuite/gcc.target/i386/pr81842-2.c: Likewise. --- gcc/ChangeLog | 8 ++++++++ gcc/config/i386/i386-c.c | 2 ++ gcc/config/i386/i386.opt | 4 ++++ gcc/doc/invoke.texi | 9 +++++++++ gcc/testsuite/ChangeLog | 6 ++++++ gcc/testsuite/gcc.target/i386/pr81842-1.c | 7 +++++++ gcc/testsuite/gcc.target/i386/pr81842-2.c | 6 ++++++ 7 files changed, 42 insertions(+) create mode 100644 gcc/testsuite/gcc.target/i386/pr81842-1.c create mode 100644 gcc/testsuite/gcc.target/i386/pr81842-2.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index a00bff3..6640b95 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,11 @@ +2017-12-18 Igor Tsimbalist + + PR target/81842 + * config/i386/i386-c.c: Add definition of __CHECK_SHSTK_COMPAT__ + macro. + * config/i386/i386.opt: Add -mcheck-shstk-compat option. + * doc/invoke.texi: Add -mcheck-shstk-compat option. + 2017-12-11 Bin Cheng PR tree-optimization/83320 diff --git a/gcc/config/i386/i386-c.c b/gcc/config/i386/i386-c.c index fc667a7..c387dbb 100644 --- a/gcc/config/i386/i386-c.c +++ b/gcc/config/i386/i386-c.c @@ -479,6 +479,8 @@ ix86_target_macros_internal (HOST_WIDE_INT isa_flag, if (isa_flag2 & OPTION_MASK_ISA_SHSTK) { def_or_undef (parse_in, "__SHSTK__"); + if (ix86_check_shstk_compat) + def_or_undef (parse_in, "__CHECK_SHSTK_COMPAT__"); if (flag_cf_protection != CF_NONE) def_or_undef (parse_in, "__CET__"); } diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt index 6632ba8..9ae3ad6 100644 --- a/gcc/config/i386/i386.opt +++ b/gcc/config/i386/i386.opt @@ -1001,6 +1001,10 @@ Target Report Mask(ISA_SHSTK) Var(ix86_isa_flags2) Save Specifically enables an shadow stack support feature from Control-flow Enforcment Technology (CET). +mcheck-shstk-compat +Target Report Var(ix86_check_shstk_compat) Init(1) +Check shadow stack compatibility + mcet-switch Target Report Undocumented Var(flag_cet_switch) Init(0) Turn on CET instrumentation for switch statements, which use jump table and diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 1413095..7b4223a 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -26225,6 +26225,15 @@ The option has effect only if the @option{-fcf-protection=full} or @option{-mshstk} is on by default when the @option{-mcet} option is specified. +@item -mcheck-shstk-compat +@opindex mcheck-shstk-compat +This option predefines __CHECK_SHSTK_COMPAT__ macro, which can be used +to add a guard to the C/C++ sources which are incompatible with Intel +shadow stack technology. A typical case would be issuing an error when +both __SHSTK__ and __CHECK_SHSTK_COMPAT__ macro are defined. The option +@option{-mcheck-shstk-compat} is on by default when the @code{-mshstk} +option is specified. + @item -mcrc32 @opindex mcrc32 This option enables built-in functions @code{__builtin_ia32_crc32qi}, diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 4795a1d..5c361d8 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,9 @@ +2017-12-18 Igor Tsimbalist + + PR target/81842 + * gcc.target/i386/pr81842-1.c: New test. + * gcc.target/i386/pr81842-2.c: Likewise. + 2017-12-10 Dominique d'Humieres PR fortran/53478 diff --git a/gcc/testsuite/gcc.target/i386/pr81842-1.c b/gcc/testsuite/gcc.target/i386/pr81842-1.c new file mode 100644 index 0000000..face279 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr81842-1.c @@ -0,0 +1,7 @@ +/* { dg-do compile { target *-*-linux* } } */ +/* { dg-options "-fcf-protection -mcet" } */ + +#if defined __SHSTK__ && defined __CHECK_SHSTK_COMPAT__ +# error This source is incompatible with -mshstk +#endif +/* { dg-error "This source is incompatible with -mshstk" "" { target *-*-* } .-2 } */ diff --git a/gcc/testsuite/gcc.target/i386/pr81842-2.c b/gcc/testsuite/gcc.target/i386/pr81842-2.c new file mode 100644 index 0000000..ddcf4ce --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr81842-2.c @@ -0,0 +1,6 @@ +/* { dg-do compile { target *-*-linux* } } */ +/* { dg-options "-fcf-protection -mcet -mno-check-shstk-compat" } */ + +#if defined __SHSTK__ && defined __CHECK_SHSTK_COMPAT__ +# error This source is incompatible with -mshstk +#endif -- 1.8.3.1