examples/fdpicxip: Build the module fixtures without nuttx/tools/fdpic.

The modules this example and testing/fs/xipfs carry are built by an explicit
'make regen', which reached into nuttx/tools/fdpic for a makefile that builds
a module, a script that turns one into a header, and two more that checked
its imports.  Review of apache/nuttx#19940 asked that NuttX not carry a
module build of its own, and it no longer does: with CONFIG_FDPIC an
ordinary FDPIC module is built by apps/Application.mk like any other.

These are not ordinary modules, which is why they keep a build of their own.
They are fixtures for loader edge cases: a library with a SONAME, a module
with more DT_NEEDED entries than the loader will follow, one whose imports
stay in the lazy binding table, and one naming a symbol the firmware does
not export, which exists to be refused.  Application.mk cannot say any of
that.  So the build stays, and it is here beside them rather than in NuttX.

It is also much smaller.  The generic module makefile is gone: it existed to
be included by anything, and only this one directory ever did, so its dozen
useful lines are rules here.  fdpic-embed.py is gone: xxd does that, as
examples/elf already does it, and the license header it also wrote is a
template beside it.  fdpic-verify.sh and nuttx-exports.sh are gone with no
replacement; they checked at build time what the xipfs suite already asserts
at run time, for two hundred lines.

What the fixtures no longer carry is a crt0 and a linker script.  Both come
from the tree named by NUTTX_DIR, which is where the in-tree module build
takes them, so a fixture is built the way a module is.  The crt0 source is
compiled here rather than the built object taken, because these are
deliberately built for cortex-m3 while the firmware is not: a v7-M module
runs on both the v7-M and v8-M targets, so one set of headers serves the
RP2350 and mps2-an500 alike.

Regenerated qsorter, libshape and cxxuser against a tree configured with
CONFIG_FDPIC.  qsorter is ARM FDPIC, v7-M, two PT_LOAD segments, entering at
_start; libshape carries its SONAME and its DT_INIT_ARRAY.

The committed headers are left as they are.  They will change when they are
next regenerated, because a fixture now carries the tree's crt0 rather than
one of its own, and that is a change the xipfs suite should be run against
rather than made blind.

Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com>

Author: casaroli

examples/fdpicxip/modules/Makefile

@@ -27,7 +27,7 @@
 # asked for: the *_bin.h headers are committed, so both apps build with a
 # plain toolchain and CI covers them, while the link needs
 # arm-uclinuxfdpiceabi binutils, which the tree does not require.  See
-# nuttx/tools/fdpic/README.md and Documentation/components/fdpic.rst.
+# Documentation/components/fdpic.rst.
 #
 # To rebuild the headers from these sources:
 #
@@ -44,19 +44,70 @@
 
 CPU ?= cortex-m3
 
-FDPICDIR  = $(NUTTX_DIR)/tools/fdpic
-MODULE_MK = $(FDPICDIR)/nuttx-fdpic.mk
-EMBED     = $(FDPICDIR)/fdpic-embed.py
+# make has built-in defaults for CC and CXX, so ?= never fires for them and
+# the host compiler silently gets the job.  Test the origin instead.
 
-# Where each generated header goes, and its path from the repository root --
-# fdpic-embed.py puts that on line 2, which is what nxstyle wants.
+ifeq ($(origin CC),default)
+  CC := arm-none-eabi-gcc
+endif
+
+ifeq ($(origin CXX),default)
+  CXX := arm-none-eabi-g++
+endif
+
+ifeq ($(origin LD),default)
+  LD := arm-uclinuxfdpiceabi-ld
+endif
+
+# -mfdpic -fPIC is the whole of what makes an FDPIC object; the rest is what
+# a module needs anywhere.  -fno-use-cxa-atexit puts a static object's
+# destructor in .fini_array, which is where the loader looks for it.
+
+MODCFLAGS   = -mcpu=$(CPU) -mthumb -mfdpic -fPIC -Os -fno-builtin -Wall \
+              -Wa,--noexecstack -D__STDC_NO_ATOMICS__ -D__NuttX__ \
+              -I$(NUTTX_DIR)/include
+MODCXXFLAGS = $(MODCFLAGS) -fno-exceptions -fno-rtti -fno-use-cxa-atexit \
+              -I$(NUTTX_DIR)/include/cxx
+
+# The crt0 and the linker script are the tree's own, the ones the in-tree
+# module build uses.  crt0 is compiled here rather than taken built, because
+# these are built for a different CPU from the firmware.
+
+MODLDFLAGS  = -m armelf_linux_fdpiceabi -shared -z now \
+              -T $(NUTTX_DIR)/libs/libc/elf/gnu-elf.ld
 
 DEMODIR = ..
 DEMOREL = apps/examples/fdpicxip
 TESTDIR = ../../../testing/fs/xipfs
 TESTREL = apps/testing/fs/xipfs
 
-BUILD = $(MAKE) -f $(MODULE_MK) NUTTX_DIR=$(NUTTX_DIR) CPU=$(CPU)
+%.o: %.c
+	$(CC) $(MODCFLAGS) -c $< -o $@
+
+%.o: %.cpp
+	$(CXX) $(MODCXXFLAGS) -c $< -o $@
+
+crt0.o: $(NUTTX_DIR)/arch/arm/src/common/crt0.c
+	$(CC) $(MODCFLAGS) -c $< -o $@
+
+# A module is entered at _start and carries crt0.  A library is never
+# entered, so it has neither, and it is named by its SONAME, which is what a
+# consumer records in DT_NEEDED and the loader searches for.
+
+LINKMOD = $(LD) $(MODLDFLAGS) -e _start -o $@ crt0.o
+LINKLIB = $(LD) $(MODLDFLAGS) -e 0 -soname $(@F) -o $@
+
+# EMBED turns a built module into the committed header that carries it: $1
+# the artifact, $2 the symbol, $3 the header's path from the repository root,
+# which nxstyle wants on line 2.
+
+define EMBED
+	{ sed -e "s|@PATH@|$3|" header.template; \
+	  echo "static const unsigned char $2[] ="; echo "{"; \
+	  xxd -i < $1 | sed -e 's/^  /  /'; echo "};"; echo; \
+	  echo "static const unsigned int $2_len = $$(wc -c < $1 | tr -d ' ');"; \
+	} > $@
+endef
 
 # manyneeded needs one library per DT_NEEDED entry, one more than the loader
 # will follow.  They exist only to make the linker record nine entries; the
@@ -93,50 +144,45 @@ endif
 # which is what a consumer records in DT_NEEDED and what the loader searches
 # for at run time.
 
-qsorter.fdpic: qsorter.c
-	$(BUILD) MODULE=qsorter SRCS=qsorter.c
+qsorter.fdpic: qsorter.o crt0.o
+	$(LINKMOD) qsorter.o
 
-callback.fdpic: callback.c
-	$(BUILD) MODULE=callback SRCS=callback.c
+callback.fdpic: callback.o crt0.o
+	$(LINKMOD) callback.o
 
-funcdesc.fdpic: funcdesc.c
-	$(BUILD) MODULE=funcdesc SRCS=funcdesc.c
+funcdesc.fdpic: funcdesc.o crt0.o
+	$(LINKMOD) funcdesc.o
 
-libcounter.so: libcounter.c
-	$(BUILD) MODULE=libcounter SRCS=libcounter.c ENTRY=0 \
-	    EXTRA_LDFLAGS="-soname libcounter.so"
-	mv libcounter.fdpic libcounter.so
+libcounter.so: libcounter.o
+	$(LINKLIB) libcounter.o
 
-user.fdpic: user.c libcounter.so
-	$(BUILD) MODULE=user SRCS=user.c LIBS=libcounter.so
+user.fdpic: user.o crt0.o libcounter.so
+	$(LINKMOD) user.o libcounter.so
 
 # C++ compiles with the stock arm-none-eabi-g++; only the link is FDPIC.
 
-libshape.so: libshape.cpp
-	$(BUILD) MODULE=libshape CXXSRCS=libshape.cpp ENTRY=0 \
-	    EXTRA_LDFLAGS="-soname libshape.so"
-	mv libshape.fdpic libshape.so
+libshape.so: libshape.o
+	$(LINKLIB) libshape.o
 
-cxxuser.fdpic: cxxuser.cpp libshape.so
-	$(BUILD) MODULE=cxxuser CXXSRCS=cxxuser.cpp LIBS=libshape.so
+cxxuser.fdpic: cxxuser.o crt0.o libshape.so
+	$(LINKMOD) cxxuser.o libshape.so
 
 # BINDNOW is emptied so the imported descriptors stay in the lazy binding
 # table, which is the case this module exists to cover.
 
-lazymod.fdpic: lazymod.c
-	$(BUILD) MODULE=lazymod SRCS=lazymod.c BINDNOW=
+lazymod.fdpic: lazymod.o crt0.o
+	$(LD) $(filter-out -z now,$(MODLDFLAGS)) -e _start -o $@ crt0.o lazymod.o
 
 # missingsym is linked with the bare .fdpic target rather than the default
 # 'verify' one, because it is exactly what fdpic-verify.sh is meant to catch.
 
-missingsym.fdpic: missingsym.c
-	$(BUILD) MODULE=missingsym SRCS=missingsym.c missingsym.fdpic
+missingsym.fdpic: missingsym.o crt0.o
+	$(LINKMOD) missingsym.o
 
 need%.so:
 	echo "int need_leaf_$*(void){return $*;}" > need$*.c
-	$(BUILD) MODULE=need$* SRCS=need$*.c ENTRY=0 \
-	    EXTRA_LDFLAGS="-soname need$*.so"
-	mv need$*.fdpic need$*.so
+	$(CC) $(MODCFLAGS) -c need$*.c -o need$*.o
+	$(LINKLIB) need$*.o
 
 manyneeded.c: $(NEEDLIBS)
 	{ for n in 0 1 2 3 4 5 6 7 8; do \
@@ -147,57 +193,56 @@ manyneeded.c: $(NEEDLIBS)
 	  echo "         need_leaf_6() + need_leaf_7() + need_leaf_8();"; \
 	  echo "}"; } > manyneeded.c
 
-manyneeded.fdpic: manyneeded.c $(NEEDLIBS)
-	$(BUILD) MODULE=manyneeded SRCS=manyneeded.c LIBS="$(NEEDLIBS)" \
-	    manyneeded.fdpic
+manyneeded.fdpic: manyneeded.o crt0.o $(NEEDLIBS)
+	$(LINKMOD) manyneeded.o $(NEEDLIBS)
 
 # The headers.  One artifact can be embedded under more than one name: the
 # demo's user_bin.h and the suite's counteruser_bin.h are the same module.
 
 $(DEMODIR)/qsorter_bin.h: qsorter.fdpic
-	$(EMBED) $< g_qsorter_nxf $(DEMOREL)/$(@F) > $@
+	$(call EMBED,$<,g_qsorter_nxf,$(DEMOREL)/$(@F))
 
 $(DEMODIR)/libcounter_bin.h: libcounter.so
-	$(EMBED) $< g_libcounter $(DEMOREL)/$(@F) > $@
+	$(call EMBED,$<,g_libcounter,$(DEMOREL)/$(@F))
 
 $(DEMODIR)/user_bin.h: user.fdpic
-	$(EMBED) $< g_user $(DEMOREL)/$(@F) > $@
+	$(call EMBED,$<,g_user,$(DEMOREL)/$(@F))
 
 $(DEMODIR)/libshape_bin.h: libshape.so
-	$(EMBED) $< g_libshape $(DEMOREL)/$(@F) > $@
+	$(call EMBED,$<,g_libshape,$(DEMOREL)/$(@F))
 
 $(DEMODIR)/cxxuser_bin.h: cxxuser.fdpic
-	$(EMBED) $< g_cxxuser $(DEMOREL)/$(@F) > $@
+	$(call EMBED,$<,g_cxxuser,$(DEMOREL)/$(@F))
 
 $(DEMODIR)/lazymod_bin.h: lazymod.fdpic
-	$(EMBED) $< g_lazymod $(DEMOREL)/$(@F) > $@
+	$(call EMBED,$<,g_lazymod,$(DEMOREL)/$(@F))
 
 $(TESTDIR)/callback_bin.h: callback.fdpic
-	$(EMBED) $< g_callback $(TESTREL)/$(@F) > $@
+	$(call EMBED,$<,g_callback,$(TESTREL)/$(@F))
 
 $(TESTDIR)/counteruser_bin.h: user.fdpic
-	$(EMBED) $< g_counteruser $(TESTREL)/$(@F) > $@
+	$(call EMBED,$<,g_counteruser,$(TESTREL)/$(@F))
 
 $(TESTDIR)/cxxuser_bin.h: cxxuser.fdpic
-	$(EMBED) $< g_cxxuser $(TESTREL)/$(@F) > $@
+	$(call EMBED,$<,g_cxxuser,$(TESTREL)/$(@F))
 
 $(TESTDIR)/funcdesc_bin.h: funcdesc.fdpic
-	$(EMBED) $< g_funcdesc $(TESTREL)/$(@F) > $@
+	$(call EMBED,$<,g_funcdesc,$(TESTREL)/$(@F))
 
 $(TESTDIR)/lazymod_bin.h: lazymod.fdpic
-	$(EMBED) $< g_lazymod $(TESTREL)/$(@F) > $@
+	$(call EMBED,$<,g_lazymod,$(TESTREL)/$(@F))
 
 $(TESTDIR)/libcounter_bin.h: libcounter.so
-	$(EMBED) $< g_libcounter $(TESTREL)/$(@F) > $@
+	$(call EMBED,$<,g_libcounter,$(TESTREL)/$(@F))
 
 $(TESTDIR)/libshape_bin.h: libshape.so
-	$(EMBED) $< g_libshape $(TESTREL)/$(@F) > $@
+	$(call EMBED,$<,g_libshape,$(TESTREL)/$(@F))
 
 $(TESTDIR)/manyneeded_bin.h: manyneeded.fdpic
-	$(EMBED) $< g_manyneeded $(TESTREL)/$(@F) > $@
+	$(call EMBED,$<,g_manyneeded,$(TESTREL)/$(@F))
 
 $(TESTDIR)/missingsym_bin.h: missingsym.fdpic
-	$(EMBED) $< g_missingsym $(TESTREL)/$(@F) > $@
+	$(call EMBED,$<,g_missingsym,$(TESTREL)/$(@F))
 
 # No NUTTX_DIR needed to clean.
 

examples/fdpicxip/modules/header.template

@@ -0,0 +1,24 @@
+/****************************************************************************
+ * @PATH@
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/* Generated from an FDPIC module -- do not edit.  See the Makefile. */
+