Factor common userland and baremetal C functions

This allows add.c to run unmodified on both!

For that to work, use int main on baremetal, and pass the return value to
the final exit.

userland/Makefile

@@ -1,13 +1,17 @@
 .PHONY: all clean mkdir
 
+CCFLAGS = -ggdb3 -I$(COMMON_DIR) -O0 -Wall -Werror -Wextra -Wno-unused-function $(CCFLAGS_EXTRA) $(CCFLAGS_SCRIPT)
 CFLAGS = -fopenmp -std=c99 $(CCFLAGS) $(CFLAGS_EXTRA)
 CXXFLAGS = -std=c++17 $(CCFLAGS) $(CXXFLAGS_EXTRA)
 # -Wno-unused-function for function definitions on headers,
 #  because we are lazy to make a shared object. TODO.
-CCFLAGS = -ggdb3 -O0 -Wall -Werror -Wextra -Wno-unused-function $(CCFLAGS_EXTRA)
+COMMON_DIR = ..
+COMMON_BASENAME = common
+COMMON_OBJ = $(OUT_DIR)/$(COMMON_BASENAME)$(OBJ_EXT)
 IN_EXT_C = .c
 IN_EXT_CXX = .cpp
 LIBS = -lm
+OBJ_EXT = .o
 OUT_EXT = .out
 OUT_DIR = .
 
@@ -38,14 +42,17 @@ OUTS := $(addprefix $(OUT_DIR)/,$(OUTS))
 
 all: mkdir $(OUTS)
 
-$(OUT_DIR)/%$(OUT_EXT): %$(IN_EXT_C)
-	$(CC) $(CFLAGS) -o '$@' '$<' $(LIBS)
+$(COMMON_OBJ): $(COMMON_DIR)/$(COMMON_BASENAME)$(IN_EXT_C)
+	$(CC) $(CFLAGS) -c -o '$@' '$<' $(LIBS)
 
-$(OUT_DIR)/%$(OUT_EXT): %$(IN_EXT_CXX)
+$(OUT_DIR)/%$(OUT_EXT): %$(IN_EXT_C) $(COMMON_OBJ)
+	$(CC) $(CFLAGS) $(COMMON_OBJ) -o '$@' '$<' $(LIBS)
+
+$(OUT_DIR)/%$(OUT_EXT): %$(IN_EXT_CXX) $(COMMON_OBJ)
 	$(CXX) $(CXXFLAGS) -o '$@' '$<' $(LIBS)
 
 clean:
-	rm -f *'$(OUT_EXT)'
+	rm -f *'$(OBJ_EXT)' *'$(OUT_EXT)'
 
 mkdir:
 	mkdir -p '$(OUT_DIR)'

userland/add.c

@@ -0,0 +1 @@
+../baremetal/add.c

userland/mmap.c

@@ -10,7 +10,7 @@
 #include <sys/mman.h>
 #include <unistd.h> /* sysconf */
 
-#include "common.h" /* virt_to_phys_user */
+#include "common_userland.h" /* virt_to_phys_user */
 
 enum { BUFFER_SIZE = 4 };
 

userland/openblas_hello.c

@@ -1,7 +1,7 @@
 /* https://github.com/cirosantilli/linux-kernel-module-cheat#blas
  * Adapted from: https://github.com/xianyi/OpenBLAS/wiki/User-Manual/59b62f98e7400270fb03ad1d85fba5b64ebbff2b#call-cblas-interface */
 
-#include "common.h"
+#include "common_userland.h"
 
 #include <assert.h>
 #include <cblas.h>

userland/pagemap_dump.c

@@ -9,7 +9,7 @@
 #include <sys/types.h>
 #include <unistd.h>
 
-#include "common.h" /* pagemap_get_entry */
+#include "common_userland.h" /* pagemap_get_entry */
 
 int main(int argc, char **argv)
 {

userland/virt_to_phys_user.c

@@ -4,7 +4,7 @@
 #include <stdio.h> /* printf */
 #include <stdlib.h> /* EXIT_SUCCESS, EXIT_FAILURE, strtoull */
 
-#include "common.h" /* virt_to_phys_user */
+#include "common_userland.h" /* virt_to_phys_user */
 
 int main(int argc, char **argv)
 {