This is straightforward. There doesn't seem to be a possibility of shortcuts via a macro, so just add endbr64 to the four functions in this file. I could not find code that actually uses these, but it's probably better to be safe than sorry.
The code is too old to have arm64 assembly. Index: Makefile =================================================================== RCS file: /cvs/ports/multimedia/libdv/Makefile,v diff -u -p -r1.28 Makefile --- Makefile 7 Nov 2023 14:19:39 -0000 1.28 +++ Makefile 28 Feb 2024 19:01:33 -0000 @@ -1,7 +1,7 @@ COMMENT= Quasar DV codec DISTNAME= libdv-1.0.0 -REVISION= 4 +REVISION= 5 CATEGORIES= multimedia Index: patches/patch-libdv_vlc_x86_64_S =================================================================== RCS file: patches/patch-libdv_vlc_x86_64_S diff -N patches/patch-libdv_vlc_x86_64_S --- /dev/null 1 Jan 1970 00:00:00 -0000 +++ patches/patch-libdv_vlc_x86_64_S 28 Feb 2024 19:00:50 -0000 @@ -0,0 +1,35 @@ +Index: libdv/vlc_x86_64.S +--- libdv/vlc_x86_64.S.orig ++++ libdv/vlc_x86_64.S +@@ -6,6 +6,7 @@ + .globl dv_decode_vlc + .type dv_decode_vlc,@function + dv_decode_vlc: ++ endbr64 + push %rbx + push %rbp + +@@ -102,6 +103,7 @@ void __dv_decode_vlc(int bits, dv_vlc_t *result) + .globl __dv_decode_vlc + .type __dv_decode_vlc,@function + __dv_decode_vlc: ++ endbr64 + push %rbx + push %rbp + +@@ -174,6 +176,7 @@ void dv_parse_ac_coeffs_pass0(bitstream_t *bs, + .type dv_parse_ac_coeffs_pass0,@function + + dv_parse_ac_coeffs_pass0: ++ endbr64 + + /* Args are at rdi=bs, rsi=mb, rdx=bl */ + push %r12 +@@ -427,6 +430,7 @@ gint dv_parse_video_segment(dv_videosegment_t *seg, gu + .globl dv_parse_video_segment + .type dv_parse_video_segment,@function + dv_parse_video_segment: ++ endbr64 + + /* Args are at rdi=seg, rsi=quality */ + push %r12
