[PATCH] x86: Allow -fcf-protection with external thunk
H.J. Lu
hjl.tools@gmail.com
Wed Apr 29 01:59:53 GMT 2020
Allow -fcf-protection with external thunk since the external thunk can be
made compatible with -fcf-protection.
OK for master?
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
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