Re: [PATCH 7/7, GCC, ARM, V8M] Added support for ARMV8-M Security Extension cmse_nonsecure_caller intrinsic

[Andre Vieira (lists)]

Hi,

I changed the testcase with this patch since the old testcase was
casting a function pointer to another function pointer and using that
pointer to call the function. This is undefined behavior. The new test
reflects a more sane use of the intrinsics.

Cheers,
Andre

diff --git a/gcc/config/arm/arm-builtins.c b/gcc/config/arm/arm-builtins.c
index 
5ed38d1608cfbfbd1248d76705fcf675bc36c2b2..14444206814fb95268ba5ba008245513b0dc94f1
 100644
--- a/gcc/config/arm/arm-builtins.c
+++ b/gcc/config/arm/arm-builtins.c
@@ -528,6 +528,8 @@ enum arm_builtins
   ARM_BUILTIN_GET_FPSCR,
   ARM_BUILTIN_SET_FPSCR,
 
+  ARM_BUILTIN_CMSE_NONSECURE_CALLER,
+
 #undef CRYPTO1
 #undef CRYPTO2
 #undef CRYPTO3
@@ -1833,6 +1835,17 @@ arm_init_builtins (void)
        = add_builtin_function ("__builtin_arm_stfscr", ftype_set_fpscr,
                                ARM_BUILTIN_SET_FPSCR, BUILT_IN_MD, NULL, 
NULL_TREE);
     }
+
+  if (use_cmse)
+    {
+      tree ftype_cmse_nonsecure_caller
+       = build_function_type_list (unsigned_type_node, NULL);
+      arm_builtin_decls[ARM_BUILTIN_CMSE_NONSECURE_CALLER]
+       = add_builtin_function ("__builtin_arm_cmse_nonsecure_caller",
+                               ftype_cmse_nonsecure_caller,
+                               ARM_BUILTIN_CMSE_NONSECURE_CALLER, BUILT_IN_MD,
+                               NULL, NULL_TREE);
+    }
 }
 
 /* Return the ARM builtin for CODE.  */
@@ -2453,6 +2466,12 @@ arm_expand_builtin (tree exp,
       emit_insn (pat);
       return target;
 
+    case ARM_BUILTIN_CMSE_NONSECURE_CALLER:
+      target = gen_reg_rtx (SImode);
+      op0 = arm_return_addr (0, NULL_RTX);
+      emit_insn (gen_addsi3 (target, op0, const1_rtx));
+      return target;
+
     case ARM_BUILTIN_TEXTRMSB:
     case ARM_BUILTIN_TEXTRMUB:
     case ARM_BUILTIN_TEXTRMSH:
diff --git a/gcc/config/arm/arm_cmse.h b/gcc/config/arm/arm_cmse.h
index 
894343bb835b61e09c14668d45aa43a8693fd011..82b58b1c4f4a12ba6062e2cc2632653788d0eeb7
 100644
--- a/gcc/config/arm/arm_cmse.h
+++ b/gcc/config/arm/arm_cmse.h
@@ -163,6 +163,13 @@ __attribute__ ((__always_inline__))
 cmse_TTAT (void *__p)
 __CMSE_TT_ASM (at)
 
+/* FIXME: diagnose use outside cmse_nonsecure_entry functions.  */
+__extension__ static __inline int __attribute__ ((__always_inline__))
+cmse_nonsecure_caller (void)
+{
+  return __builtin_arm_cmse_nonsecure_caller ();
+}
+
 #define CMSE_AU_NONSECURE      2
 #define CMSE_MPU_NONSECURE     16
 #define CMSE_NONSECURE         18
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 
e8d8deefca87eacbdde6042fc1885c0d0a85a5b8..587a30d7efc6b1f2653efe96ed233828ebeb570a
 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -12640,6 +12640,7 @@ cmse_address_info_t cmse_TTAT_fptr (FPTR)
 void * cmse_check_address_range (void *, size_t, int)
 typeof(p) cmse_nsfptr_create (FPTR p)
 intptr_t cmse_is_nsfptr (FPTR)
+int cmse_nonsecure_caller (void)
 @end smallexample
 
 @node AVR Built-in Functions
diff --git a/gcc/testsuite/gcc.target/arm/cmse/cmse-1.c 
b/gcc/testsuite/gcc.target/arm/cmse/cmse-1.c
index 
d5b9a2d9d59569de170da814ae660e9fb2b943e7..c13272eed683aa06db027cd4646e5fe67817212b
 100644
--- a/gcc/testsuite/gcc.target/arm/cmse/cmse-1.c
+++ b/gcc/testsuite/gcc.target/arm/cmse/cmse-1.c
@@ -65,3 +65,42 @@ int foo (char * p)
 /* { dg-final { scan-assembler-times "ttat " 2 } } */
 /* { dg-final { scan-assembler-times "bl.cmse_check_address_range" 7 } } */
 /* { dg-final { scan-assembler-not "cmse_check_pointed_object" } } */
+
+int __attribute__ ((cmse_nonsecure_entry))
+baz (void)
+{
+  return cmse_nonsecure_caller ();
+}
+
+typedef int __attribute__ ((cmse_nonsecure_call)) (int_nsfunc_t) (void);
+
+int default_callback (void)
+{
+  return 0;
+}
+
+int_nsfunc_t * fp = (int_nsfunc_t *) default_callback;
+
+void __attribute__ ((cmse_nonsecure_entry))
+qux (int_nsfunc_t * callback)
+{
+  fp = cmse_nsfptr_create (callback);
+}
+
+int call_callback (void)
+{
+  if (cmse_is_nsfptr (fp))
+      return fp ();
+  else
+    return default_callback ();
+}
+/* { dg-final { scan-assembler "baz:" } } */
+/* { dg-final { scan-assembler "__acle_se_baz:" } } */
+/* { dg-final { scan-assembler "qux:" } } */
+/* { dg-final { scan-assembler "__acle_se_qux:" } } */
+/* { dg-final { scan-assembler-not "\tcmse_nonsecure_caller" } } */
+/* { dg-final { scan-rtl-dump "and.*reg.*const_int 1" expand } } */
+/* { dg-final { scan-assembler "bic" } } */
+/* { dg-final { scan-assembler "push\t\{r4, r5, r6" } } */
+/* { dg-final { scan-assembler "msr\tAPSR_nzcvq" } } */
+/* { dg-final { scan-assembler-times "bl\\s+__gnu_cmse_nonsecure_call" 1 } } */