Add an elf note on ARM to store the MACHINE_ARCH an executable was built

for. This is useful for software needing to know which architecture a
binary is built for as arm and armv6 have slight differences meaning only
some binaries build for one will work as expected on the other. It is
expected pkgng will be able to make use of this to simplify the logic to
determine which package ABI to use.

Approved by:	re (kib)

contrib/binutils/binutils/readelf.c

@@ -9169,6 +9169,8 @@ get_freebsd_note_type (unsigned e_type)
 	return _("NT_FREEBSD_ABI_TAG");
       case NT_FREEBSD_NOINIT_TAG:
 	return _("NT_FREEBSD_NOINIT_TAG");
+      case NT_FREEBSD_ARCH_TAG:
+	return _("NT_FREEBSD_ARCH_TAG");
       default:
 	break;
       }

contrib/binutils/include/elf/common.h

@@ -456,6 +456,7 @@
 
 #define NT_FREEBSD_TAG		1
 #define NT_FREEBSD_NOINIT_TAG	2
+#define NT_FREEBSD_ARCH_TAG	3
 
 /* These three macros disassemble and assemble a symbol table st_info field,
    which contains the symbol binding and symbol type.  The STB_ and STT_

lib/csu/arm/crt1.c

@@ -115,6 +115,20 @@ __start(int argc, char **argv, char **env, struct ps_strings *ps_strings,
 	exit(main(argc, argv, env));
 }
 
+static const struct {
+	int32_t	namesz;
+	int32_t	descsz;
+	int32_t	type;
+	char	name[sizeof(NOTE_FREEBSD_VENDOR)];
+	char	desc[sizeof(MACHINE_ARCH)];
+} archtag __attribute__ ((section (NOTE_SECTION), aligned(4))) __used = {
+	.namesz = sizeof(NOTE_FREEBSD_VENDOR),
+	.descsz = sizeof(int32_t),
+	.type = ARCH_NOTETYPE,
+	.name = NOTE_FREEBSD_VENDOR,
+	.desc = MACHINE_ARCH
+};
+
 #ifdef GCRT
 __asm__(".text");
 __asm__("eprol:");

lib/csu/common/notes.h

@@ -34,5 +34,6 @@
 
 #define ABI_NOTETYPE		1
 #define	CRT_NOINIT_NOTETYPE	2
+#define	ARCH_NOTETYPE		3
 
 #endif