[PATCH] arm: Fix missing bti instruction for virtual thunks

[PATCH] arm: Fix missing bti instruction for virtual thunks

[Richard Ball]

[-- Attachment #1: Type: text/plain, Size: 264 bytes --]

Adds missing bti instruction at the beginning of a virtual
thunk, when bti is enabled.

gcc/ChangeLog:

	* config/arm/arm.cc (arm_output_mi_thunk): Emit
	insn for bti_c when bti is enabled.

gcc/testsuite/ChangeLog:

        * g++.target/arm/bti_thunk.C: New test.

[-- Attachment #2: bti-thunk.patch --]
[-- Type: text/x-patch, Size: 1240 bytes --]

diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc
index e5a944486d7bd583627b0e22dfe8f95862e975bb..91eee8be7c1a59118fbf443557561fb3e0689d61 100644
--- a/gcc/config/arm/arm.cc
+++ b/gcc/config/arm/arm.cc
@@ -29257,6 +29257,8 @@ arm_output_mi_thunk (FILE *file, tree thunk, HOST_WIDE_INT delta,
   const char *fnname = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (thunk));
 
   assemble_start_function (thunk, fnname);
+  if (aarch_bti_enabled ())
+    emit_insn (aarch_gen_bti_c());
   if (TARGET_32BIT)
     arm32_output_mi_thunk (file, thunk, delta, vcall_offset, function);
   else
diff --git a/gcc/testsuite/g++.target/arm/bti_thunk.C b/gcc/testsuite/g++.target/arm/bti_thunk.C
new file mode 100644
index 0000000000000000000000000000000000000000..5c4a8e5a8d74581eca2b877c000a5b34ddca0e9b
--- /dev/null
+++ b/gcc/testsuite/g++.target/arm/bti_thunk.C
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-march=armv8.1-m.main+pacbti -O1 -mbranch-protection=bti --save-temps" } */
+
+#include <stdio.h>
+
+struct C18 {
+  virtual void f7();
+};
+
+struct C19 : virtual C18 {
+  virtual void f7();
+};
+
+void C19::f7() {
+  printf("foo\n");
+}
+
+/* { dg-final { scan-assembler-times "\tbti" 2 } } */
\ No newline at end of file

Re: [PATCH] arm: Fix missing bti instruction for virtual thunks

[Richard Earnshaw (lists)]

On 23/01/2024 15:53, Richard Ball wrote:
> Adds missing bti instruction at the beginning of a virtual
> thunk, when bti is enabled.
> 
> gcc/ChangeLog:
> 
> 	* config/arm/arm.cc (arm_output_mi_thunk): Emit
> 	insn for bti_c when bti is enabled.
> 
> gcc/testsuite/ChangeLog:
> 
>         * g++.target/arm/bti_thunk.C: New test.


diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc
index e5a944486d7bd583627b0e22dfe8f95862e975bb..91eee8be7c1a59118fbf443557561fb3e0689d61 100644
--- a/gcc/config/arm/arm.cc
+++ b/gcc/config/arm/arm.cc
@@ -29257,6 +29257,8 @@ arm_output_mi_thunk (FILE *file, tree thunk, HOST_WIDE_INT delta,
   const char *fnname = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (thunk));
 
   assemble_start_function (thunk, fnname);
+  if (aarch_bti_enabled ())
+    emit_insn (aarch_gen_bti_c());

Missing space between ...bit_c and the parenthesis.

   if (TARGET_32BIT)
     arm32_output_mi_thunk (file, thunk, delta, vcall_offset, function);
   else

diff --git a/gcc/testsuite/g++.target/arm/bti_thunk.C b/gcc/testsuite/g++.target/arm/bti_thunk.C
new file mode 100644
index 0000000000000000000000000000000000000000..5c4a8e5a8d74581eca2b877c000a5b34ddca0e9b
--- /dev/null
+++ b/gcc/testsuite/g++.target/arm/bti_thunk.C
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-march=armv8.1-m.main+pacbti -O1 -mbranch-protection=bti --save-temps" } */

You can't just add options like this; they may not work with other options passed by the testsuite framework.  Instead, you should a suitable entry to lib/target-supports.exp in the table starting "foreach { armfunc armflag armdefs } {" that tests whether the options can be safely added, and then use dg-require-effective-target and dg-add-options for your new set of options.

\ No newline at end of file

Please add one :)

R.