libkldelf: add a private library for kernel/kld-related ELF parsing

The libkldelf library was originally a part of kldxref(8). It exposed
ELF parsing helpers specialized in parsing KLDs and the kernel
executable. The library can be used to read metadata such as linker_set,
mod_depend, mod_version and PNP match info, and raw data from the ELF.

To promote the reuse of the facilities the ELF parsing code is separated
from kldxref(8) into a new private library.

kldxref(8) is modified to link against the libkldelf library.

Sponsored by:	Juniper Networks, Inc.
Reviewed by:	markj
Differential Revision:	https://reviews.freebsd.org/D46719

Makefile.inc1

@@ -2509,8 +2509,12 @@ ${_bt}-lib/libdwarf: ${_bt_m4_depend}
 _bt_libelf_depend=${_bt}-lib/libelf
 .endif
 
+_libkldelf=	lib/libkldelf
+${_bt}-lib/libkldelf: ${_bt_libelf_depend}
+_bt_libkldelf_depend=${_bt}-lib/libkldelf
+
 _kldxref=	usr.sbin/kldxref
-${_bt}-usr.sbin/kldxref: ${_bt_libelf_depend}
+${_bt}-usr.sbin/kldxref: ${_bt_libelf_depend} ${_bt_libkldelf_depend}
 
 # flua is required to regenerate syscall files.  It first appeared during the
 # 13.0-CURRENT cycle, thus needs to be built on -older releases and stable
@@ -2773,6 +2777,7 @@ bootstrap-tools: ${_bt}-links .PHONY
     ${_cat} \
     ${_kbdcontrol} \
     ${_elftoolchain_libs} \
+    ${_libkldelf} \
     ${_kldxref} \
     lib/libopenbsd \
     usr.bin/mandoc \
@@ -3216,7 +3221,8 @@ _prebuild_libs=	${_kerberos5_lib_libasn1} \
 		lib/libfigpar \
 		${_lib_libgssapi} \
 		lib/libjail \
-		lib/libkiconv lib/libkvm lib/liblzma lib/libmd lib/libnv \
+		lib/libkiconv lib/libkldelf lib/libkvm \
+		lib/liblzma lib/libmd lib/libnv \
 		lib/libzstd \
 		${_lib_casper} \
 		lib/ncurses/tinfo \
@@ -3251,6 +3257,7 @@ _prebuild_libs+= lib/libregex
 .endif
 
 lib/libgeom__L: lib/libexpat__L lib/libsbuf__L
+lib/libkldelf__L: lib/libelf__L
 lib/libkvm__L: lib/libelf__L
 
 .if ${MK_RADIUS_SUPPORT} != "no"

lib/Makefile

@@ -66,6 +66,7 @@ SUBDIR=	${SUBDIR_BOOTSTRAP} \
 	libiscsiutil \
 	libjail \
 	libkiconv \
+	libkldelf \
 	libkvm \
 	liblua \
 	liblzma \

lib/libkldelf/Makefile

@@ -0,0 +1,21 @@
+.include <bsd.own.mk>
+
+PACKAGE=	runtime
+LIB=		kldelf
+PRIVATELIB=	yes
+
+SRCS=	ef.c \
+	ef_obj.c \
+	elf.c \
+	ef_aarch64.c \
+	ef_arm.c \
+	ef_amd64.c \
+	ef_i386.c \
+	ef_mips.c \
+	ef_powerpc.c \
+	ef_riscv.c
+WARNS?=	2
+
+LIBADD=	elf
+
+.include <bsd.lib.mk>

lib/libkldelf/Makefile.depend

@@ -0,0 +1,16 @@
+# Autogenerated - do NOT edit!
+
+DIRDEPS = \
+	include \
+	include/xlocale \
+	lib/${CSU_DIR} \
+	lib/libc \
+	lib/libcompiler_rt \
+	lib/libelf \
+
+
+.include <dirdeps.mk>
+
+.if ${DEP_RELDIR} == ${_DEP_RELDIR}
+# local dependencies - needed for -jN in clean tree
+.endif

lib/libkldelf/ef.c

@@ -41,7 +41,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "ef.h"
+#include "kldelf.h"
 
 #define	MAXSEGS 16
 struct ef_file {

lib/libkldelf/ef_aarch64.c

@@ -31,7 +31,7 @@
 #include <errno.h>
 #include <gelf.h>
 
-#include "ef.h"
+#include "kldelf.h"
 
 /*
  * Apply relocations to the values obtained from the file. `relbase' is the

lib/libkldelf/ef_amd64.c

@@ -33,7 +33,7 @@
 #include <errno.h>
 #include <gelf.h>
 
-#include "ef.h"
+#include "kldelf.h"
 
 /*
  * Apply relocations to the values obtained from the file. `relbase' is the

lib/libkldelf/ef_arm.c

@@ -34,7 +34,7 @@
 #include <errno.h>
 #include <gelf.h>
 
-#include "ef.h"
+#include "kldelf.h"
 
 /*
  * Apply relocations to the values obtained from the file. `relbase' is the

lib/libkldelf/ef_i386.c

@@ -33,7 +33,7 @@
 #include <errno.h>
 #include <gelf.h>
 
-#include "ef.h"
+#include "kldelf.h"
 
 /*
  * Apply relocations to the values obtained from the file. `relbase' is the

lib/libkldelf/ef_mips.c

@@ -36,7 +36,7 @@
 #include <errno.h>
 #include <gelf.h>
 
-#include "ef.h"
+#include "kldelf.h"
 
 /*
  * Apply relocations to the values obtained from the file. `relbase' is the

lib/libkldelf/ef_obj.c

@@ -43,7 +43,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "ef.h"
+#include "kldelf.h"
 
 typedef struct {
 	GElf_Addr	addr;

lib/libkldelf/ef_powerpc.c

@@ -33,7 +33,7 @@
 #include <errno.h>
 #include <gelf.h>
 
-#include "ef.h"
+#include "kldelf.h"
 
 /*
  * Apply relocations to the values obtained from the file. `relbase' is the

lib/libkldelf/ef_riscv.c

@@ -36,7 +36,7 @@
 #include <errno.h>
 #include <gelf.h>
 
-#include "ef.h"
+#include "kldelf.h"
 
 /*
  * Apply relocations to the values obtained from the file. `relbase' is the

lib/libkldelf/elf.c

@@ -44,7 +44,7 @@
 #include <string.h>
 #include <unistd.h>
 
-#include "ef.h"
+#include "kldelf.h"
 
 SET_DECLARE(elf_reloc, struct elf_reloc_data);
 

lib/libkldelf/kldelf.h

@@ -32,8 +32,8 @@
  * SUCH DAMAGE.
  */
 
-#ifndef _EF_H_
-#define _EF_H_
+#ifndef _KLDELF_H_
+#define _KLDELF_H_
 
 #include <sys/linker_set.h>
 #include <stdbool.h>
@@ -312,4 +312,4 @@ int	elf_reloc(struct elf_file *ef, const void *reldata, Elf_Type reltype,
 
 __END_DECLS
 
-#endif /* _EF_H_*/
+#endif /* _KLDELF_H_*/

share/mk/src.libnames.mk

@@ -27,6 +27,7 @@ _PRIVATELIBS=	\
 		gtest_main \
 		heimipcc \
 		heimipcs \
+		kldelf \
 		ldns \
 		sqlite3 \
 		ssh \
@@ -312,6 +313,7 @@ _DP_bsnmp=	crypto
 .endif
 _DP_geom=	bsdxml sbuf
 _DP_cam=	sbuf
+_DP_kldelf=	elf
 _DP_kvm=	elf
 _DP_casper=	nv
 _DP_cap_dns=	nv

usr.sbin/kldxref/Makefile

@@ -1,17 +1,12 @@
 PACKAGE=	runtime
 PROG=	kldxref
 MAN=	kldxref.8
-SRCS=	kldxref.c ef.c ef_obj.c elf.c
-SRCS+=	ef_aarch64.c \
-	ef_arm.c \
-	ef_amd64.c \
-	ef_i386.c \
-	ef_mips.c \
-	ef_powerpc.c \
-	ef_riscv.c
+SRCS=	kldxref.c
+
+CFLAGS+=-I${SRCTOP}/lib/libkldelf
 
 WARNS?=	2
 
-LIBADD=	elf
+LIBADD=	elf kldelf
 
 .include <bsd.prog.mk>

usr.sbin/kldxref/kldxref.c

@@ -51,7 +51,7 @@
 #include <string.h>
 #include <unistd.h>
 
-#include "ef.h"
+#include <kldelf.h>
 
 #define	MAXRECSIZE	(64 << 10)	/* 64k */
 #define check(val)	if ((error = (val)) != 0) break