| Message ID | 20200429015953.1446167-1-hjl.tools@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | x86: Allow -fcf-protection with external thunk | expand |
On Wed, Apr 29, 2020 at 4:22 AM H.J. Lu via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > Allow -fcf-protection with external thunk since the external thunk can be > made compatible with -fcf-protection. > > OK for master? OK. I guess also OK for backporting to branches where CET support is in a reasonable state (not sure to what extent you backported the various fixes in this area). Thanks, Richard. > Thanks. > > H.J. > --- > gcc/ > > PR target/93654 > * config/i386/i386-options.c (ix86_set_indirect_branch_type): > Allow -fcf-protection with -mindirect-branch=thunk-extern and > -mfunction-return=thunk-extern. > * doc/invoke.texi: Update notes for -fcf-protection=branch with > -mindirect-branch=thunk-extern and -mindirect-return=thunk-extern. > > gcc/testsuite/ > > PR target/93654 > * gcc.target/i386/pr93654.c: New test. > --- > gcc/config/i386/i386-options.c | 4 ++++ > gcc/doc/invoke.texi | 10 +++++++--- > gcc/testsuite/gcc.target/i386/pr93654.c | 9 +++++++++ > 3 files changed, 20 insertions(+), 3 deletions(-) > create mode 100644 gcc/testsuite/gcc.target/i386/pr93654.c > > diff --git a/gcc/config/i386/i386-options.c b/gcc/config/i386/i386-options.c > index e0be4932534..5c21fce06a4 100644 > --- a/gcc/config/i386/i386-options.c > +++ b/gcc/config/i386/i386-options.c > @@ -3083,6 +3083,8 @@ ix86_set_indirect_branch_type (tree fndecl) > ? "thunk-extern" : "thunk")); > > if (cfun->machine->indirect_branch_type != indirect_branch_keep > + && (cfun->machine->indirect_branch_type > + != indirect_branch_thunk_extern) > && (flag_cf_protection & CF_RETURN)) > error ("%<-mindirect-branch%> and %<-fcf-protection%> are not " > "compatible"); > @@ -3126,6 +3128,8 @@ ix86_set_indirect_branch_type (tree fndecl) > ? "thunk-extern" : "thunk")); > > if (cfun->machine->function_return_type != indirect_branch_keep > + && (cfun->machine->function_return_type > + != indirect_branch_thunk_extern) > && (flag_cf_protection & CF_RETURN)) > error ("%<-mfunction-return%> and %<-fcf-protection%> are not " > "compatible"); > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi > index fed38e88ae5..5bb7d94833e 100644 > --- a/gcc/doc/invoke.texi > +++ b/gcc/doc/invoke.texi > @@ -30097,9 +30097,9 @@ Note that @option{-mcmodel=large} is incompatible with > @option{-mindirect-branch=thunk-extern} since the thunk function may > not be reachable in the large code model. > > -Note that @option{-mindirect-branch=thunk-extern} is incompatible with > -@option{-fcf-protection=branch} since the external thunk cannot be modified > -to disable control-flow check. > +Note that @option{-mindirect-branch=thunk-extern} is compatible with > +@option{-fcf-protection=branch} since the external thunk can be made > +to enable control-flow check. > > @item -mfunction-return=@var{choice} > @opindex mfunction-return > @@ -30112,6 +30112,10 @@ object file. You can control this behavior for a specific function by > using the function attribute @code{function_return}. > @xref{Function Attributes}. > > +Note that @option{-mindirect-return=thunk-extern} is compatible with > +@option{-fcf-protection=branch} since the external thunk can be made > +to enable control-flow check. > + > Note that @option{-mcmodel=large} is incompatible with > @option{-mfunction-return=thunk} and > @option{-mfunction-return=thunk-extern} since the thunk function may > diff --git a/gcc/testsuite/gcc.target/i386/pr93654.c b/gcc/testsuite/gcc.target/i386/pr93654.c > new file mode 100644 > index 00000000000..ec5bdce86a6 > --- /dev/null > +++ b/gcc/testsuite/gcc.target/i386/pr93654.c > @@ -0,0 +1,9 @@ > +/* { dg-do compile } */ > +/* { dg-options "-O2 -fcf-protection -mfunction-return=thunk-extern -mindirect-branch=thunk-extern" } */ > + > +int > +bar (void (*foo) (void)) > +{ > + foo (); > + return 0; > +} > -- > 2.25.4 >
On Tue, Apr 28, 2020 at 11:38 PM Richard Biener <richard.guenther@gmail.com> wrote: > > On Wed, Apr 29, 2020 at 4:22 AM H.J. Lu via Gcc-patches > <gcc-patches@gcc.gnu.org> wrote: > > > > Allow -fcf-protection with external thunk since the external thunk can be > > made compatible with -fcf-protection. > > > > OK for master? > > OK. I guess also OK for backporting to branches where CET support is > in a reasonable > state (not sure to what extent you backported the various fixes in this area). > > Thanks, > Richard. Fixed on master. I am backporting it to GCC 8 and 9 branches. Thanks.
On Wed, Apr 29, 2020 at 5:02 AM H.J. Lu <hjl.tools@gmail.com> wrote: > > On Tue, Apr 28, 2020 at 11:38 PM Richard Biener > <richard.guenther@gmail.com> wrote: > > > > On Wed, Apr 29, 2020 at 4:22 AM H.J. Lu via Gcc-patches > > <gcc-patches@gcc.gnu.org> wrote: > > > > > > Allow -fcf-protection with external thunk since the external thunk can be > > > made compatible with -fcf-protection. > > > > > > OK for master? > > > > OK. I guess also OK for backporting to branches where CET support is > > in a reasonable > > state (not sure to what extent you backported the various fixes in this area). > > > > Thanks, > > Richard. > > Fixed on master. I am backporting it to GCC 8 and 9 branches. > No need for GCC 8. It is a regression for GCC 9/10.
diff --git a/gcc/config/i386/i386-options.c b/gcc/config/i386/i386-options.c index e0be4932534..5c21fce06a4 100644 --- a/gcc/config/i386/i386-options.c +++ b/gcc/config/i386/i386-options.c @@ -3083,6 +3083,8 @@ ix86_set_indirect_branch_type (tree fndecl) ? "thunk-extern" : "thunk")); if (cfun->machine->indirect_branch_type != indirect_branch_keep + && (cfun->machine->indirect_branch_type + != indirect_branch_thunk_extern) && (flag_cf_protection & CF_RETURN)) error ("%<-mindirect-branch%> and %<-fcf-protection%> are not " "compatible"); @@ -3126,6 +3128,8 @@ ix86_set_indirect_branch_type (tree fndecl) ? "thunk-extern" : "thunk")); if (cfun->machine->function_return_type != indirect_branch_keep + && (cfun->machine->function_return_type + != indirect_branch_thunk_extern) && (flag_cf_protection & CF_RETURN)) error ("%<-mfunction-return%> and %<-fcf-protection%> are not " "compatible"); diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index fed38e88ae5..5bb7d94833e 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -30097,9 +30097,9 @@ Note that @option{-mcmodel=large} is incompatible with @option{-mindirect-branch=thunk-extern} since the thunk function may not be reachable in the large code model. -Note that @option{-mindirect-branch=thunk-extern} is incompatible with -@option{-fcf-protection=branch} since the external thunk cannot be modified -to disable control-flow check. +Note that @option{-mindirect-branch=thunk-extern} is compatible with +@option{-fcf-protection=branch} since the external thunk can be made +to enable control-flow check. @item -mfunction-return=@var{choice} @opindex mfunction-return @@ -30112,6 +30112,10 @@ object file. You can control this behavior for a specific function by using the function attribute @code{function_return}. @xref{Function Attributes}. +Note that @option{-mindirect-return=thunk-extern} is compatible with +@option{-fcf-protection=branch} since the external thunk can be made +to enable control-flow check. + Note that @option{-mcmodel=large} is incompatible with @option{-mfunction-return=thunk} and @option{-mfunction-return=thunk-extern} since the thunk function may diff --git a/gcc/testsuite/gcc.target/i386/pr93654.c b/gcc/testsuite/gcc.target/i386/pr93654.c new file mode 100644 index 00000000000..ec5bdce86a6 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr93654.c @@ -0,0 +1,9 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fcf-protection -mfunction-return=thunk-extern -mindirect-branch=thunk-extern" } */ + +int +bar (void (*foo) (void)) +{ + foo (); + return 0; +}