libc: Teach libc about the BTI elf note

Add the Branch Target Identification (BTI) note to libc assembly
sources. As all obect files need the note for the library to have it
we need to insert it in all asm files.

Reviewed by:	emaste, markj
Sponsored by:	Arm Ltd
Differential Revision:	https://reviews.freebsd.org/D42228

(cherry picked from commit fd5aaf2ea0178b03aa93c35245053247e5d3840c)

lib/libc/aarch64/gen/_ctx_start.S

@@ -27,9 +27,13 @@
  */
 
 #include <machine/asm.h>
+#include <sys/elf_common.h>
+
 ENTRY(_ctx_start)
 	blr	x19		/* Call func from makecontext */
 	mov	x0, x20		/* Load ucp saved in makecontext */
 	bl	_C_LABEL(ctx_done)
 	bl	_C_LABEL(abort)
 END(_ctx_start)
+
+GNU_PROPERTY_AARCH64_FEATURE_1_NOTE(GNU_PROPERTY_AARCH64_FEATURE_1_VAL)

lib/libc/aarch64/gen/_setjmp.S

@@ -30,6 +30,7 @@
 
 #include <machine/asm.h>
 #include <machine/setjmp.h>
+#include <sys/elf_common.h>
 
 ENTRY(_setjmp)
 	/* Store the magic value and stack pointer */
@@ -101,3 +102,5 @@ botch:
 	bl	_C_LABEL(abort)
 #endif
 END(_longjmp)
+
+GNU_PROPERTY_AARCH64_FEATURE_1_NOTE(GNU_PROPERTY_AARCH64_FEATURE_1_VAL)

lib/libc/aarch64/gen/fabs.S

@@ -24,7 +24,11 @@
  */
 
 #include <machine/asm.h>
+#include <sys/elf_common.h>
+
 ENTRY(fabs)
 	fabs d0, d0
 	ret
 END(fabs)
+
+GNU_PROPERTY_AARCH64_FEATURE_1_NOTE(GNU_PROPERTY_AARCH64_FEATURE_1_VAL)

lib/libc/aarch64/gen/setjmp.S

@@ -30,6 +30,7 @@
 
 #include <machine/asm.h>
 #include <machine/setjmp.h>
+#include <sys/elf_common.h>
 
 ENTRY(setjmp)
 	sub	sp, sp, #16
@@ -119,3 +120,5 @@ botch:
 	bl	_C_LABEL(longjmperror)
 	bl	_C_LABEL(abort)
 END(longjmp)
+
+GNU_PROPERTY_AARCH64_FEATURE_1_NOTE(GNU_PROPERTY_AARCH64_FEATURE_1_VAL)

lib/libc/aarch64/gen/sigsetjmp.S

@@ -28,6 +28,7 @@
 
 #include <machine/asm.h>
 #include <machine/setjmp.h>
+#include <sys/elf_common.h>
 
 ENTRY(sigsetjmp)
 	cmp	x1, #0
@@ -52,3 +53,5 @@ ENTRY(siglongjmp)
 .Lmagic:
 	.quad	_JB_MAGIC__SETJMP
 END(siglongjmp)
+
+GNU_PROPERTY_AARCH64_FEATURE_1_NOTE(GNU_PROPERTY_AARCH64_FEATURE_1_VAL)

lib/libc/aarch64/string/memmove.S

@@ -3,3 +3,7 @@
  * as it stops MISRCS from picking up the C implementation and rtld expects
  * to copy the memmove object file into its object directory.
  */
+
+#include <machine/asm.h>
+#include <sys/elf_common.h>
+GNU_PROPERTY_AARCH64_FEATURE_1_NOTE(GNU_PROPERTY_AARCH64_FEATURE_1_VAL)

lib/libc/aarch64/sys/cerror.S

@@ -25,6 +25,8 @@
  */
 
 #include <machine/asm.h>
+#include <sys/elf_common.h>
+
 ENTRY(cerror)
 	.hidden	cerror
 	sub	sp, sp, #16
@@ -37,3 +39,5 @@ ENTRY(cerror)
 	add	sp, sp, #16
 	ret
 END(cerror)
+
+GNU_PROPERTY_AARCH64_FEATURE_1_NOTE(GNU_PROPERTY_AARCH64_FEATURE_1_VAL)

lib/libc/aarch64/sys/syscall.S

@@ -27,6 +27,9 @@
  */
 
 #include <machine/asm.h>
+#include <sys/elf_common.h>
 #include "SYS.h"
 
 RSYSCALL(syscall)
+
+GNU_PROPERTY_AARCH64_FEATURE_1_NOTE(GNU_PROPERTY_AARCH64_FEATURE_1_VAL)

lib/libc/aarch64/sys/vfork.S

@@ -25,6 +25,7 @@
  */
 
 #include <machine/asm.h>
+#include <sys/elf_common.h>
 #include "SYS.h"
 
 ENTRY(__sys_vfork)
@@ -38,3 +39,5 @@ ENTRY(__sys_vfork)
 	mov	lr, x2
 	ret
 END(__sys_vfork)
+
+GNU_PROPERTY_AARCH64_FEATURE_1_NOTE(GNU_PROPERTY_AARCH64_FEATURE_1_VAL)

lib/libc/sys/Makefile.inc

@@ -131,12 +131,18 @@ NOTE_GNU_STACK='\t.section .note.GNU-stack,"",%%progbits\n'
 .else
 NOTE_GNU_STACK=''
 .endif
+.if ${MACHINE_CPUARCH} == "aarch64"
+FEATURE_NOTE='\#include <sys/elf_common.h>\nGNU_PROPERTY_AARCH64_FEATURE_1_NOTE(GNU_PROPERTY_AARCH64_FEATURE_1_VAL)'
+.else
+FEATURE_NOTE=''
+.endif
 
 ${SASM}:
 	printf '/* %sgenerated by libc/sys/Makefile.inc */\n' @ > ${.TARGET}
 	printf '#include "compat.h"\n' >> ${.TARGET}
 	printf '#include "SYS.h"\nRSYSCALL(${.PREFIX})\n' >> ${.TARGET}
 	printf  ${NOTE_GNU_STACK} >>${.TARGET}
+	printf  ${FEATURE_NOTE} >> ${.TARGET}
 
 ${SPSEUDO}:
 	printf '/* %sgenerated by libc/sys/Makefile.inc */\n' @ > ${.TARGET}
@@ -144,6 +150,7 @@ ${SPSEUDO}:
 	printf '#include "SYS.h"\nPSEUDO(${.PREFIX:S/_//})\n' \
 	    >> ${.TARGET}
 	printf ${NOTE_GNU_STACK} >>${.TARGET}
+	printf ${FEATURE_NOTE} >> ${.TARGET}
 
 MAN+=	abort2.2 \
 	accept.2 \