compel: make plugins .a archives

The objective is to only do parasite code linking once -- when we link
parasite objects with compel plugin(s). So, let's use ar (rather than
ld) here. This way we'll have a single ld invocation with the proper
flags (from compel ldflags) etc.

There are two tricks in doing it:

1. The order of objects while linking is important. Therefore, compel
   plugins should be the last to add to ld command line.

2. Somehow ld doesn't want to include parasite-head.o in the output
   (probably because no one else references it), so we have to force
   it in with the modification to our linker scripts.

NB: compel makefiles are still a big mess, but I'll get there.
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

Makefile.compel

@@ -22,7 +22,7 @@ compel-deps		+= compel/include/asm
 compel-deps		+= $(COMPEL_VERSION_HEADER)
 compel-deps		+= $(CONFIG_HEADER)
 compel-deps		+= include/common/asm
-compel-plugins		+= compel/plugins/std.built-in.o compel/plugins/fds.built-in.o
+compel-plugins		+= compel/plugins/std.lib.a compel/plugins/fds.lib.a
 
 LIBCOMPEL_SO		:= libcompel.so
 LIBCOMPEL_A		:= libcompel.a
@@ -47,13 +47,13 @@ compel/plugins/%: $(compel-deps) .FORCE
 # GNU make 4.x supports targets matching via wide
 # match targeting, where GNU make 3.x series (used on
 # Travis) is not, so we have to write them here explicitly.
-compel/plugins/std.built-in.o: $(compel-deps) .FORCE
+compel/plugins/std.lib.a: $(compel-deps) .FORCE
 	$(Q) $(MAKE) $(build)=compel/plugins $@
 
-compel/plugins/shmem.built-in.o: $(compel-deps) compel/plugins/std.built-in.o .FORCE
+compel/plugins/shmem.lib.a: $(compel-deps) compel/plugins/std.lib.a .FORCE
 	$(Q) $(MAKE) $(build)=compel/plugins $@
 
-compel/plugins/fds.built-in.o: $(compel-deps) compel/plugins/std.built-in.o .FORCE
+compel/plugins/fds.lib.a: $(compel-deps) compel/plugins/std.lib.a .FORCE
 	$(Q) $(MAKE) $(build)=compel/plugins $@
 
 compel/compel: compel/built-in.o compel/$(LIBCOMPEL_A) | $(compel-deps)

compel/arch/aarch64/scripts/compel-pack.lds.S

 OUTPUT_ARCH(aarch64)
+EXTERN(__export_parasite_head_start)
+
 SECTIONS
 {
 	.crblob 0x0 : {
 		*(.head.text)
+		ASSERT(DEFINED(__export_parasite_head_start),
+			"Symbol __export_parasite_head_start is missing");
 		*(.text*)
 		. = ALIGN(32);
 		*(.data*)

compel/arch/arm/plugins/std/syscalls/Makefile.syscalls

@@ -15,7 +15,7 @@ sys-gen			:= $(PLUGIN_ARCH_DIR)/std/syscalls/gen-syscalls.pl
 sys-gen-tbl		:= $(PLUGIN_ARCH_DIR)/std/syscalls/gen-sys-exec-tbl.pl
 
 sys-asm			:= ./$(PLUGIN_ARCH_DIR)/std/syscalls/syscalls.S
-std-obj-y		+= $(sys-asm:.S=).o
+std-lib-y		+= $(sys-asm:.S=).o
 
 ifeq ($(ARCH),arm)
 arch_bits		:= 32

compel/arch/arm/scripts/compel-pack.lds.S

 OUTPUT_ARCH(arm)
+EXTERN(__export_parasite_head_start)
+
 SECTIONS
 {
 	.crblob 0x0 : {
 		*(.head.text)
+		ASSERT(DEFINED(__export_parasite_head_start),
+			"Symbol __export_parasite_head_start is missing");
 		*(.text*)
 		. = ALIGN(32);
 		*(.data*)

compel/arch/ppc64/plugins/std/syscalls/Makefile.syscalls

@@ -12,7 +12,7 @@ sys-asm-types		:= $(obj)/include/uapi/std/asm/syscall-types.h
 sys-exec-tbl		 = $(PLUGIN_ARCH_DIR)/std/sys-exec-tbl.c
 
 sys-asm			:= ./$(PLUGIN_ARCH_DIR)/std/syscalls/syscalls.S
-std-obj-y		+= $(sys-asm:.S=).o
+std-lib-y		+= $(sys-asm:.S=).o
 
 $(sys-codes): $(sys-def)
 	$(E) "  GEN     " $@

compel/arch/ppc64/scripts/compel-pack.lds.S

 OUTPUT_ARCH(powerpc:common64)
+EXTERN(__export_parasite_head_start)
+
 SECTIONS
 {
 	.text : {
 		*(.head.text)
+		ASSERT(DEFINED(__export_parasite_head_start),
+			"Symbol __export_parasite_head_start is missing");
 		*(.text*)
 		*(.compel.exit)
 		*(.compel.init)

compel/arch/x86/plugins/std/syscalls/Makefile.syscalls

-std-obj-y		+= ./$(PLUGIN_ARCH_DIR)/std/syscalls-64.o
+std-lib-y		+= ./$(PLUGIN_ARCH_DIR)/std/syscalls-64.o
 
 sys-proto-types		:= $(obj)/include/uapi/std/syscall-types.h
 sys-proto-generic	:= $(obj)/include/uapi/std/syscall.h

compel/arch/x86/scripts/compel-pack-compat.lds.S

 OUTPUT_ARCH(i386)
 TARGET(elf32-i386)
+EXTERN(__export_parasite_head_start)
+
 SECTIONS
 {
 	.text : {
 		*(.head.text)
+		ASSERT(DEFINED(__export_parasite_head_start),
+			"Symbol __export_parasite_head_start is missing");
 		*(.text*)
 		*(.compel.exit)
 		*(.compel.init)

compel/arch/x86/scripts/compel-pack.lds.S

 OUTPUT_ARCH(i386:x86-64)
 TARGET(elf64-x86-64)
+EXTERN(__export_parasite_head_start)
+
 SECTIONS
 {
 	.text : {
 		*(.head.text)
+		ASSERT(DEFINED(__export_parasite_head_start),
+			"Symbol __export_parasite_head_start is missing");
 		*(.text*)
 		*(.compel.exit)
 		*(.compel.init)

compel/plugins/Makefile

@@ -34,30 +34,30 @@ ldflags-y		+= -z noexecstack
 #
 # Shmem plugin
 target			+= shmem
-shmem-obj-y		+= shmem/shmem.o
+shmem-lib-y		+= shmem/shmem.o
 
 #
 # STD plugin
 target			+= std
-std-obj-y		+= std/std.o
-std-obj-y		+= std/fds.o
-std-obj-y		+= std/log.o
-std-obj-y		+= std/string.o
-std-obj-y		+= std/infect.o
-std-obj-y		+= ./$(PLUGIN_ARCH_DIR)/std/parasite-head.o
+std-lib-y		+= std/std.o
+std-lib-y		+= std/fds.o
+std-lib-y		+= std/log.o
+std-lib-y		+= std/string.o
+std-lib-y		+= std/infect.o
+std-lib-y		+= ./$(PLUGIN_ARCH_DIR)/std/parasite-head.o
 
 #
 # FDS plugin
 target			+= fds
-fds-obj-y		+= fds/fds.o
+fds-lib-y		+= fds/fds.o
 
 ifeq ($(SRCARCH),x86)
-	std-obj-y	+= ./$(PLUGIN_ARCH_DIR)/std/memcpy.o
+	std-lib-y	+= ./$(PLUGIN_ARCH_DIR)/std/memcpy.o
 endif
 
 ifeq ($(SRCARCH),ppc64)
-	std-obj-y	+= ./$(PLUGIN_ARCH_DIR)/std/memcpy.o
-	std-obj-y	+= ./$(PLUGIN_ARCH_DIR)/std/memcmp.o
+	std-lib-y	+= ./$(PLUGIN_ARCH_DIR)/std/memcpy.o
+	std-lib-y	+= ./$(PLUGIN_ARCH_DIR)/std/memcmp.o
 endif
 
 include ./$(PLUGIN_ARCH_DIR)/std/syscalls/Makefile.syscalls
@@ -73,15 +73,15 @@ endef
 # Almost all plugins depen on syscall headers
 # and definitions so we have to order their
 # generation manually.
-$(foreach t,$(target),$(eval $(call syscall-priority,$(t)-obj-y,std-headers-deps)))
+$(foreach t,$(target),$(eval $(call syscall-priority,$(t)-lib-y,std-headers-deps)))
 
 #
 # FIXME syscall-types.h should be setup earlier
 #
-install: compel/plugins/std.built-in.o
+install: compel/plugins/std.lib.a compel/plugins/fds.lib.a
 	$(E) "  INSTALL " compel plugins
 	$(Q) mkdir -p $(DESTDIR)$(LIBEXECDIR)/compel/
-	$(Q) install -m 0644 compel/plugins/std.built-in.o $(DESTDIR)$(LIBEXECDIR)/compel/
+	$(Q) install -m 0644 $^ $(DESTDIR)$(LIBEXECDIR)/compel/
 	$(Q) mkdir -p $(DESTDIR)$(LIBEXECDIR)/compel/scripts
 	$(Q) install -m 0644 compel/arch/$(ARCH)/scripts/compel-pack.lds.S $(DESTDIR)$(LIBEXECDIR)/compel/scripts
 	$(E) "  INSTALL " compel plugins uapi
@@ -91,7 +91,7 @@ install: compel/plugins/std.built-in.o
 
 uninstall:
 	$(E) " UNINSTALL" compel plugins
-	$(Q) $(RM) $(addprefix $(DESTDIR)$(LIBEXECDIR)/compel/,std.built-in.o)
+	$(Q) $(RM) $(addprefix $(DESTDIR)$(LIBEXECDIR)/compel/,*.lib.a)
 	$(Q) $(RM) $(addprefix $(DESTDIR)$(LIBEXECDIR)/compel/scripts/,compel-pack.lds.S)
 	$(E) " UNINSTALL" compel and plugins uapi
 	$(Q) $(RM) -rf $(addprefix $(DESTDIR)$(INCLUDEDIR)/,compel/plugins)

compel/src/main.c

@@ -186,12 +186,14 @@ static void print_ldflags(bool compat)
 
 static void print_plugins(const char *list[])
 {
+	const char suffix[] = ".lib.a";
+
 	while (*list != NULL) {
 		if (uninst_root)
-			printf("%s/plugins/%s.built-in.o\n",
-					uninst_root, *list);
+			printf("%s/plugins/%s%s\n",
+					uninst_root, *list, suffix);
 		else
-			printf("%s/compel/%s.built-in.o\n", LIBEXECDIR, *list);
+			printf("%s/compel/%s%s\n", LIBEXECDIR, *list, suffix);
 		list++;
 	}
 }