[CRIU] [PATCH 18/24] compel cli: add linker script to ldflags / use it

[Kir Kolyshkin]

This commit adds -T path/to/linker_script to the output
of "compel ldflags", so compel user does not have to specify
one manually.

This commit also makes use of this functionality in criu/pie
and compel/test.

NOTE this commit also drops the linker script dependency
in criu/pie/Makefile, meaning if it will be changed that
won't cause a rebuild. I hope it's not a big issue, and it is
sort of inevitable as compel is becoming a separate tool.

Signed-off-by: Kir Kolyshkin <kir at openvz.org>
---
 compel/Makefile             |  1 +
 compel/src/main.c           | 26 ++++++++++++++++++++++++--
 compel/test/infect/Makefile |  4 +---
 criu/pie/Makefile           |  5 ++---
 4 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/compel/Makefile b/compel/Makefile
index 1d2230c..670654e 100644
--- a/compel/Makefile
+++ b/compel/Makefile
@@ -3,6 +3,7 @@ include $(SRC_DIR)/Makefile.versions
 COMPEL_SO_VERSION	:= $(COMPEL_SO_VERSION_MAJOR)$(if $(COMPEL_SO_VERSION_MINOR),.$(COMPEL_SO_VERSION_MINOR))$(if $(COMPEL_SO_VERSION_SUBLEVEL),.$(COMPEL_SO_VERSION_SUBLEVEL))
 COMPEL_SO_VERSION_CODE	:= $(shell expr $(COMPEL_SO_VERSION_MAJOR) \* 65536 \+ $(COMPEL_SO_VERSION_MINOR) \* 256 \+ $(COMPEL_SO_VERSION_SUBLEVEL))
 ccflags-y		+= -DINCLUDEDIR=\"$(INCLUDEDIR)\"
+ccflags-y		+= -DLIBEXECDIR=\"$(LIBEXECDIR)\"
 ccflags-y		+= -iquote compel/arch/$(ARCH)/src/lib/include
 ccflags-y		+= -iquote compel/include
 ccflags-y		+= -fno-strict-aliasing
diff --git a/compel/src/main.c b/compel/src/main.c
index 764c794..c51d05b 100644
--- a/compel/src/main.c
+++ b/compel/src/main.c
@@ -25,22 +25,27 @@
 #define COMPEL_CFLAGS_PIE	CFLAGS_DEFAULT_SET "-fpie"
 #define COMPEL_CFLAGS_NOPIC	CFLAGS_DEFAULT_SET "-fno-pic"
 
-#define COMPEL_LDFLAGS_DEFAULT "-r -z noexecstack"
+#define COMPEL_LDFLAGS_COMMON	"-r -z noexecstack -T "
 
 typedef struct {
+	const char	*arch;		// dir name under arch/
 	const char	*cflags;
 	const char	*cflags_compat;
 } flags_t;
 
 static const flags_t flags = {
 #if defined CONFIG_X86_64
+	.arch		= "x86",
 	.cflags		= COMPEL_CFLAGS_PIE,
 	.cflags_compat	= COMPEL_CFLAGS_NOPIC,
 #elif defined CONFIG_AARCH64
+	.arch		= "aarch64",
 	.cflags		= COMPEL_CFLAGS_PIE,
 #elif defined(CONFIG_ARMV6) || defined(CONFIG_ARMV7)
+	.arch		= "arm",
 	.cflags		= COMPEL_CFLAGS_PIE,
 #elif defined CONFIG_PPC64
+	.arch		= "ppc64",
 	.cflags		= COMPEL_CFLAGS_PIE,
 #else
 #error "CONFIG_<ARCH> not defined, or unsupported ARCH"
@@ -160,6 +165,23 @@ static void print_cflags(bool compat)
 	print_includes();
 }
 
+static void print_ldflags(bool compat)
+{
+	const char *compat_str = (compat) ? "-compat" : "";
+
+	printf("%s", COMPEL_LDFLAGS_COMMON);
+
+	if (uninst_root) {
+		printf("%s/arch/%s/scripts/compel-pack%s.lds.S\n",
+				uninst_root, flags.arch, compat_str);
+	}
+	else {
+		printf("%s/compel/scripts/compel-pack%s.lds.S\n",
+				LIBEXECDIR, compat_str);
+
+	}
+}
+
 int main(int argc, char *argv[])
 {
 	int log_level = DEFAULT_LOGLEVEL;
@@ -234,7 +256,7 @@ int main(int argc, char *argv[])
 	}
 
 	if (!strcmp(action, "ldflags")) {
-		printf("%s", COMPEL_LDFLAGS_DEFAULT);
+		print_ldflags(compat);
 		return 0;
 	}
 
diff --git a/compel/test/infect/Makefile b/compel/test/infect/Makefile
index 8d35c29..e08fa79 100644
--- a/compel/test/infect/Makefile
+++ b/compel/test/infect/Makefile
@@ -1,9 +1,7 @@
 CC	:= gcc
 CFLAGS	?= -O2 -g -Wall -Werror
-ARCH	?= x86
 
 COMPEL		:= ../../../compel/compel-host
-COMPEL_PACK_LDS	:= ../../../compel/arch/$(ARCH)/scripts/compel-pack.lds.S
 COMPEL_PLUGINS	:= ../../../compel/plugins
 COMPEL_LIBRARY	:= ../../../compel/libcompel.a
 
@@ -28,7 +26,7 @@ parasite.h: parasite.po
 		-o $@
 
 parasite.po: parasite.o $(COMPEL_PLUGINS)/std.built-in.o
-	ld -r -T $(COMPEL_PACK_LDS) -o $@ $^
+	ld $(shell $(COMPEL) ldflags) -o $@ $^
 
 parasite.o: parasite.c
 	$(CC) $(CFLAGS) -c $(shell $(COMPEL) cflags) -o $@ $^
diff --git a/criu/pie/Makefile b/criu/pie/Makefile
index 4dcc60a..96647c8 100644
--- a/criu/pie/Makefile
+++ b/criu/pie/Makefile
@@ -1,6 +1,5 @@
 target		+= parasite restorer
 
-compel_lds	:= $(SRC_DIR)/compel/arch/$(ARCH)/scripts/compel-pack.lds.S
 compel_std	:= $(SRC_DIR)/compel/plugins/std.built-in.o
 parasite-obj-e	+= ./compel/plugins/std.built-in.o
 restorer-obj-e	+= ./compel/plugins/std.built-in.o
@@ -54,9 +53,9 @@ endif
 
 $(obj)/restorer.built-in.o: $(compel_std)
 $(obj)/parasite.built-in.o: $(compel_std)
-$(obj)/%.built-in.bin.o: $(obj)/%.built-in.o $(obj)/pie.lib.a $(compel_lds)
+$(obj)/%.built-in.bin.o: $(obj)/%.built-in.o $(obj)/pie.lib.a
 	$(call msg-gen, $@)
-	$(Q) $(LD) -r -T $(compel_lds) -o $@ $< $(obj)/pie.lib.a
+	$(Q) $(LD) $(shell $(COMPEL_BIN) ldflags) -o $@ $< $(obj)/pie.lib.a
 
 $(obj)/%-blob.h: $(obj)/%.built-in.bin.o $(SRC_DIR)/compel/compel-host-bin
 	$(call msg-gen, $@)
-- 
2.7.4