Calculate the size of the static (and profiled static) execve syscall stub

and store it in a const variable for use by crt0.
help from kettenis and miod

diff --git a/lib/libc/sys/Makefile.inc b/lib/libc/sys/Makefile.inc
index 931ed89..4d2e9b8 100644 (file)
--- a/lib/libc/sys/Makefile.inc
+++ b/lib/libc/sys/Makefile.inc
@@ -1,4 +1,4 @@
-#      $OpenBSD: Makefile.inc,v 1.172 2023/02/21 14:39:35 deraadt Exp $
+#      $OpenBSD: Makefile.inc,v 1.173 2023/02/27 14:59:33 deraadt Exp $
 #      $NetBSD: Makefile.inc,v 1.35 1995/10/16 23:49:07 jtc Exp $
 #      @(#)Makefile.inc        8.1 (Berkeley) 6/17/93
 
@@ -23,6 +23,23 @@ SRCS+=       ptrace.c semctl.c \
 # stack protector helper functions
 SRCS+= stack_protector.c
 
+# Extract execve stub size for static binary pinsyscall(2) in dlfcn/init.c
+SRCS+= _execvesize.c
+CLEANFILES+=_execvesize.c
+_execvesize.c: execve.o execve.po
+       readelf -s execve.po | awk \
+           '/ execve$$/{ printf("#ifdef _PROFILE\nconst int _execve_size = %d;\n", $$3); }' > $@
+       readelf -s execve.o | awk \
+           '/ execve$$/{ printf("#else\nconst int _execve_size = %d;\n#endif\n", $$3); }' >> $@
+
+# _libc_preinit() needs to know if compiled with or without profiling
+_execvesize.po:
+       @echo "${COMPILE.c} -D_PROFILE ${.IMPSRC} -o ${.TARGET}"
+       @${COMPILE.c} ${DFLAGS} -D_PROFILE ${.IMPSRC} -o ${.TARGET}.o
+       @-mv $@.d $*.d
+       @${LD} -X -r ${.TARGET}.o -o ${.TARGET}
+       @rm -f ${.TARGET}.o
+
 # cancelation details
 SRCS+= canceled.c