Uniformise the .note.GNU-stack section output

Uniformly rely on the detection during `configure` of whether the
`.note.GNU-stack` section is supported to decide whether to output it

- On x86_64:
  - it was generated by `emit.mlp` only on Linux and FreeBSD
  - it was present in `amd64.S` only on Linux and FreeBSD
- On ARM:
  - it was generated by `emit.mlp` only on Linux
  - it was present in `arm64.S` except on macOS
- On RISC-V:
  - it was never generated by `emit.mlp`
  - it was always present in `riscv.S`
- On POWER:
  - it was always generated by `emit.mlp`
  - it was always present in `power.S`
- on S/390:
  - it was always generated by `emit.mlp`
  - it was always present in `s390x.S`

asmcomp/amd64/emit.mlp

@@ -1085,7 +1085,7 @@ let end_assembly() =
     D.size frametable (ConstSub (ConstThis, ConstLabel frametable))
   end;
 
-  if system = S_linux || system = S_freebsd then
+  if Config.linker_support_note_gnu_stack_noexec then
     (* Mark stack as non-executable, PR#4564 *)
     D.section [".note.GNU-stack"] (Some "") [ "%progbits" ];
 

asmcomp/arm64/emit.mlp

@@ -1224,9 +1224,7 @@ let end_assembly () =
       efa_string = (fun s -> emit_string_directive "	.asciz	" s) };
   emit_symbol_type emit_symbol lbl "object";
   emit_symbol_size lbl;
-  begin match Config.system with
-  | "linux" ->
-      (* Mark stack as non-executable *)
-      `	.section	.note.GNU-stack,\"\",%progbits\n`
-  | _ -> ()
+  if Config.linker_support_note_gnu_stack_noexec then begin
+    (* Mark stack as non-executable *)
+    `	.section .note.GNU-stack,\"\",%progbits\n`
   end

asmcomp/power/emit.mlp

@@ -1170,4 +1170,7 @@ let end_assembly() =
   emit_string toc_space;
   emit_toctable();
   Hashtbl.clear tocref_entries;
-  `	.section .note.GNU-stack,\"\",%progbits\n`
+  if Config.linker_support_note_gnu_stack_noexec then begin
+    (* Mark stack as non-executable *)
+    `	.section .note.GNU-stack,\"\",%progbits\n`
+  end

asmcomp/riscv/emit.mlp

@@ -759,4 +759,8 @@ let end_assembly() =
                            `	.long	({emit_label lbl} - .) + {emit_int32 ofs}\n`);
       efa_def_label = (fun l -> `{emit_label l}:\n`);
       efa_string = (fun s -> emit_bytes_directive "	.byte	" (s ^ "\000"))
-     }
+     };
+  if Config.linker_support_note_gnu_stack_noexec then begin
+    (* Mark stack as non-executable *)
+    `	.section .note.GNU-stack,\"\",%progbits\n`
+  end

asmcomp/s390x/emit.mlp

@@ -865,5 +865,7 @@ let end_assembly() =
       efa_def_label = (fun l -> `{emit_label l}:\n`);
       efa_string = (fun s -> emit_bytes_directive "	.byte	" (s ^ "\000"))
      };
-   (* Mark stack as non-executable *)
-   `	.section .note.GNU-stack,\"\",%progbits\n`
+  if Config.linker_support_note_gnu_stack_noexec then begin
+    (* Mark stack as non-executable *)
+    `	.section .note.GNU-stack,\"\",%progbits\n`
+  end

runtime/amd64.S

@@ -1377,7 +1377,7 @@ G(caml_negf_mask):
 G(caml_absf_mask):
         .quad   0x7FFFFFFFFFFFFFFF, 0xFFFFFFFFFFFFFFFF
 
-#if defined(SYS_linux) || defined(SYS_freebsd)
+#ifdef SUPPORT_NOTE_GNU_STACK_NOEXEC
     /* Mark stack as non-executable, PR#4564 */
         .section .note.GNU-stack,"",%progbits
 #endif

runtime/arm64.S

@@ -1291,7 +1291,7 @@ OBJECT(caml_system$frametable)
         .align 3
         END_OBJECT(caml_system$frametable)
 
-#if !defined(SYS_macosx)
+#ifdef SUPPORT_NOTE_GNU_STACK_NOEXEC
 /* Mark stack as non-executable */
         .section .note.GNU-stack,"",%progbits
 #endif

runtime/power.S

@@ -1223,5 +1223,7 @@ TOCENTRY(caml_array_bound_error_asm)
 TOCENTRYLABEL(fiber_exn_handler)
 TOCENTRYLABEL(trap_handler)
 
+#ifdef SUPPORT_NOTE_GNU_STACK_NOEXEC
 /* Mark stack as non-executable */
         .section .note.GNU-stack,"",%progbits
+#endif

runtime/riscv.S

@@ -1258,5 +1258,8 @@ OBJECT(caml_system$frametable)
         .short  0                 /* no roots */
         .align  3
 END_OBJECT(caml_system$frametable)
+
+#ifdef SUPPORT_NOTE_GNU_STACK_NOEXEC
 /* Mark stack as non-executable */
         .section .note.GNU-stack,"",%progbits
+#endif

runtime/s390x.S

@@ -1217,5 +1217,7 @@ OBJECT(caml_system$frametable)
         .align  8
 ENDOBJECT(caml_system$frametable)
 
+#ifdef SUPPORT_NOTE_GNU_STACK_NOEXEC
 /* Mark stack as non-executable */
         .section .note.GNU-stack,"",%progbits
+#endif

testsuite/tools/asmgen_arm.S

@@ -13,6 +13,8 @@
 /*                                                                        */
 /**************************************************************************/
 
+#include "caml/m.h"
+
         .text
 
         .global call_gen_code
@@ -38,5 +40,7 @@ caml_c_call:
     @ function to call is in r10
         bx      r10
 
+#ifdef SUPPORT_NOTE_GNU_STACK_NOEXEC
 /* Mark stack as non-executable */
         .section .note.GNU-stack,"",%progbits
+#endif

testsuite/tools/asmgen_arm64.S

@@ -13,6 +13,8 @@
 /*                                                                        */
 /**************************************************************************/
 
+#include "caml/m.h"
+
 #if defined(SYS_macosx)
 #define G(sym) _##sym
 #else
@@ -60,7 +62,7 @@ G(call_gen_code):
 G(caml_c_call):
         br      x15
 
-#if !defined(SYS_macosx)
+#ifdef SUPPORT_NOTE_GNU_STACK_NOEXEC
 /* Mark stack as non-executable */
         .section .note.GNU-stack,"",%progbits
 #endif

testsuite/tools/asmgen_power.S

@@ -10,6 +10,8 @@
 /*                                                                   */
 /*********************************************************************/
 
+#include "caml/m.h"
+
 #define RESERVED_STACK 32
 #define LR_SAVE_AREA 16
 
@@ -131,5 +133,7 @@ FUNCTION(caml_c_call)
         mr      12, 28
         bctr
 
+#ifdef SUPPORT_NOTE_GNU_STACK_NOEXEC
 /* Mark stack as non-executable */
         .section .note.GNU-stack,"",%progbits
+#endif

testsuite/tools/asmgen_s390x.S

@@ -1,3 +1,5 @@
+#include "caml/m.h"
+
 #define ALIGN 8
 
 #define CALL_GEN_CODE call_gen_code
@@ -63,5 +65,7 @@ CAML_ABSF_MASK:
 
         .comm   young_limit, 8
 
+#ifdef SUPPORT_NOTE_GNU_STACK_NOEXEC
 /* Mark stack as non-executable */
         .section .note.GNU-stack,"",%progbits
+#endif