CFI-ed _start

crt.diff

diff --git a/usr/src/lib/crt/amd64/mach-crt1.s b/usr/src/lib/crt/amd64/mach-crt1.s
index 9a334f84e4..c17e352b96 100644
--- a/usr/src/lib/crt/amd64/mach-crt1.s
+++ b/usr/src/lib/crt/amd64/mach-crt1.s
@@ -60,6 +60,10 @@
  */

 ENTRY_NP(_start)
+       .cfi_startproc
+       .cfi_undefined %rip
+       .cfi_undefined %rbp
+
 /*
  * Allocate a NULL return address and a NULL previous %rbp as if
  * there was a genuine call to _start.
@@ -86,6 +90,7 @@ ENTRY_NP(_start)
        /* NB: rt_do_exit, if applicable, is already in %rdx */
        call    _start_crt
        hlt
+       .cfi_endproc
 SET_SIZE(_start)

 /*