Remove futility linker script.

The futility.lds linker script was used to generate a table with
all the symbols in a specific section called .futil_cmds listed
in order under the symbol "futil_cmds". This allows the source files
to define a command and let the linker figure out the list of
compiled commands. Nevertheless, passing this linker script
makes the linker leave a gap of about 2MiB in the output ELF file.

Instead of mess up with linker scripts just to generate a table of
commands, this patch generates such table in the Makefile looking
at the included sources and compiling that table. The result is a
futility binary of about 88 KiB instead of the 2.1 MiB required
originally.

This patch also adds sys-boot/chromeos-u-boot to the list of ebuilds
tested by emerge_test.sh.

BUG=chromium:408926
BRANCH=None
TEST=BOARD=link ./emerge_test.sh
TEST=BOARD=daisy_spring ./emerge_test.sh
TEST=`readelf -S futility` shows no gap.
TEST=/usr/bin/futility shows no difference in the help output.

Change-Id: I9c0febc76140b404d48aa13e7f948e8ea77a41b5
Reviewed-on: https://chromium-review.googlesource.com/215496
Tested-by: Alex Deymo <deymo@chromium.org>
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/227859
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
Commit-Queue: Daisuke Nojiri <dnojiri@chromium.org>

4 files changed, 41 insertions, 30 deletions

diff --git a/Makefile b/Makefile
index d50cc4ff..ec551b38 100644
--- a/Makefile
+++ b/Makefile
@@ -551,10 +551,13 @@ FUTIL_SRCS += \
 	futility/cmd_vb2_verify_fw.c
 endif
 
-FUTIL_LDS = futility/futility.lds
+# List of commands built in futility and futility_s.
+FUTIL_STATIC_CMD_LIST = ${BUILD}/gen/futility_static_cmds.c
+FUTIL_CMD_LIST = ${BUILD}/gen/futility_cmds.c
 
-FUTIL_STATIC_OBJS = ${FUTIL_STATIC_SRCS:%.c=${BUILD}/%.o}
-FUTIL_OBJS = ${FUTIL_SRCS:%.c=${BUILD}/%.o}
+FUTIL_STATIC_OBJS = ${FUTIL_STATIC_SRCS:%.c=${BUILD}/%.o} \
+	${FUTIL_STATIC_CMD_LIST:%.c=%.o}
+FUTIL_OBJS = ${FUTIL_SRCS:%.c=${BUILD}/%.o} ${FUTIL_CMD_LIST:%.c=%.o}
 
 ALL_OBJS += ${FUTIL_OBJS}
 
@@ -880,12 +883,12 @@ signing_install: ${SIGNING_SCRIPTS} ${SIGNING_SCRIPTS_DEV} ${SIGNING_COMMON}
 .PHONY: futil
 futil: ${FUTIL_STATIC_BIN} ${FUTIL_BIN}
 
-${FUTIL_STATIC_BIN}: ${FUTIL_LDS} ${FUTIL_STATIC_OBJS} ${UTILLIB}
+${FUTIL_STATIC_BIN}: ${FUTIL_STATIC_OBJS} ${UTILLIB}
 	@$(PRINTF) "    LD            $(subst ${BUILD}/,,$@)\n"
 	${Q}${LD} -o $@ ${CFLAGS} ${LDFLAGS} -static $^ ${LDLIBS}
 
 ${FUTIL_BIN}: LDLIBS += ${CRYPTO_LIBS}
-${FUTIL_BIN}: ${FUTIL_LDS} ${FUTIL_OBJS} ${UTILLIB}
+${FUTIL_BIN}: ${FUTIL_OBJS} ${UTILLIB}
 	@$(PRINTF) "    LD            $(subst ${BUILD}/,,$@)\n"
 	${Q}${LD} -o $@ ${CFLAGS} ${LDFLAGS} $^ ${LDLIBS}
 
@@ -942,6 +945,10 @@ ${BUILD}/%.o: %.c
 	@$(PRINTF) "    CC            $(subst ${BUILD}/,,$@)\n"
 	${Q}${CC} ${CFLAGS} ${INCLUDES} -c -o $@ $<
 
+${BUILD}/%.o: ${BUILD}/%.c
+	@$(PRINTF) "    CC            $(subst ${BUILD}/,,$@)\n"
+	${Q}${CC} ${CFLAGS} ${INCLUDES} -c -o $@ $<
+
 # Rules to recompile a single source file for library and test
 # TODO: is there a tidier way to do this?
 ${BUILD}/%_for_lib.o: CFLAGS += -DFOR_LIBRARY
@@ -962,11 +969,6 @@ ${BUILD}/%.o: %.cc
 # ----------------------------------------------------------------------------
 # Here are the special tweaks to the generic rules.
 
-# Because we play some clever linker script games to add new commands without
-# changing any header files, futility must be linked with ld.bfd, not gold.
-${FUTIL_BIN}: LDFLAGS += -fuse-ld=bfd
-${FUTIL_STATIC_BIN}: LDFLAGS += -fuse-ld=bfd
-
 # Some utilities need external crypto functions
 CRYPTO_LIBS := $(shell ${PKG_CONFIG} --libs libcrypto)
 
@@ -1029,6 +1031,32 @@ ${TLCL_TEST_BINS}: OBJS += ${BUILD}/tests/tpm_lite/tlcl_tests.o
 ${TLCL_TEST_BINS}: ${BUILD}/tests/tpm_lite/tlcl_tests.o
 ALL_OBJS += ${BUILD}/tests/tpm_lite/tlcl_tests.o
 
+# ----------------------------------------------------------------------------
+# Here are the special rules that don't fit in the generic rules.
+
+# Generates the list of commands defined in futility by running grep in the
+# source files looking for the DECLARE_FUTIL_COMMAND() macro usage.
+${FUTIL_STATIC_CMD_LIST}: ${FUTIL_STATIC_SRCS}
+${FUTIL_CMD_LIST}: ${FUTIL_SRCS}
+${FUTIL_CMD_LIST} ${FUTIL_STATIC_CMD_LIST}:
+	@$(PRINTF) "    GEN           $(subst ${BUILD}/,,$@)\n"
+	${Q}rm -f $@ $@_t $@_commands
+	${Q}mkdir -p ${BUILD}/gen
+	${Q}grep -hoRE '^DECLARE_FUTIL_COMMAND\([^,]+' $^ -R \
+		| sed 's/DECLARE_FUTIL_COMMAND(\(.*\)/_CMD(\1)/' \
+		| sort >>$@_commands
+	${Q}echo '#define _CMD(NAME) extern const struct' \
+		'futil_cmd_t __cmd_##NAME;' >> $@_t
+	${Q}cat $@_commands >> $@_t
+	${Q}echo '#undef _CMD' >> $@_t
+	${Q}echo '#define _CMD(NAME) &__cmd_##NAME,' >> $@_t
+	${Q}echo 'const struct futil_cmd_t *const futil_cmds[] = {' >> $@_t
+	${Q}cat $@_commands >> $@_t
+	${Q}echo '0};  /* null-terminated */' >> $@_t
+	${Q}echo '#undef _CMD' >> $@_t
+	${Q}mv $@_t $@
+	${Q}rm -f $@_commands
+
 ##############################################################################
 # Targets that exist just to run tests
 
diff --git a/emerge_test.sh b/emerge_test.sh
index cbe51444..5861aa25 100755
--- a/emerge_test.sh
+++ b/emerge_test.sh
@@ -11,6 +11,7 @@
 # Required ebuilds:
 TEST_EBUILDS="
   sys-boot/chromeos-bootimage
+  sys-boot/chromeos-u-boot
   sys-boot/coreboot
   sys-boot/depthcharge
   chromeos-base/chromeos-cryptohome
diff --git a/futility/futility.h b/futility/futility.h
index 32c553db..dfccf6f9 100644
--- a/futility/futility.h
+++ b/futility/futility.h
@@ -23,14 +23,11 @@ struct futil_cmd_t {
  * to them without explictly declaring every function in a header somewhere.
  */
 #define DECLARE_FUTIL_COMMAND(NAME, HANDLER, SHORTHELP)           \
-        static const struct futil_cmd_t __cmd_##NAME = {          \
+        const struct futil_cmd_t __cmd_##NAME = {                 \
                 .name = #NAME,                                    \
                 .handler = HANDLER,                               \
                 .shorthelp = SHORTHELP                            \
-        };                                                        \
-        const struct futil_cmd_t * const __cmd_ptr_##NAME         \
-        __attribute__((section(".futil_cmds." #NAME)))            \
-          = &__cmd_##NAME
+        };
 
 /* This is the list of pointers to all commands. */
 extern const struct futil_cmd_t *const futil_cmds[];
diff --git a/futility/futility.lds b/futility/futility.lds
deleted file mode 100644
index 0650507f..00000000
--- a/futility/futility.lds
+++ /dev/null
@@ -1,15 +0,0 @@
-/*
- * Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-SECTIONS
-{
-  .rodata : {
-    . = ALIGN(32);
-    futil_cmds = .;                           /* Create the list of commands */
-    *(SORT(.futil_cmds.*));
-    QUAD(0);                                  /* Null-terminated */
-  }
-}