armv7: add ARM-encoded bootblock_exit() stub

This replaces the call() function with a stub which is compiled
separately using -marm. See http://review.coreboot.org/#/c/2175/
for details.

Change-Id: I7f8c45b5e63ec97b0a82294488129d1c97ec0cbf
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: http://review.coreboot.org/2180
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/arch/armv7/Makefile.inc

@@ -239,10 +239,19 @@ $(objgenerated)/bootblock_inc.S: $$(bootblock_inc)
 	@printf "    GEN        $(subst $(obj)/,,$(@))\n"
 	printf '$(foreach crt0,$(bootblock_inc),#include "$(crt0)"\n)' > $@
 
+bootblock_exit_c = $(src)/arch/armv7/bootblock_exit.c
+bootblock_exit_o = $(obj)/arch/armv7/bootblock_exit.o
+
+$(bootblock_exit_o): $(bootblock_exit_c)
+	@printf "    CC         $(subst $(obj)/,,$(@))\n"
+	$(CC) -Wa,-acdlns -I. $(INCLUDES) -c -o $@ $< -marm
+
 $(objgenerated)/bootblock.o: $(objgenerated)/bootblock.s
 	@printf "    CC         $(subst $(obj)/,,$(@))\n"
 	$(CC) -Wa,-acdlns -c -o $@ $<  > $(basename $@).disasm
 
+BOOTBLOCK_OBJS = $(objgenerated)/bootblock.o $(bootblock_exit_o)
+
 $(objgenerated)/bootblock.s: $(objgenerated)/bootblock_inc.S $(obj)/config.h $(obj)/build.h
 	@printf "    CC         $(subst $(obj)/,,$(@))\n"
 	$(CC) -MMD -x assembler-with-cpp -E -I$(src)/include -I$(src)/arch/armv7/include -I$(obj) -include $(obj)/build.h -include $(obj)/config.h -I. -I$(src) $< -o $@
@@ -253,12 +262,12 @@ $(objgenerated)/bootblock.inc: $(src)/arch/armv7/$(subst ",,$(CONFIG_BOOTBLOCK_S
 		$< > $(objgenerated)/bootblock.inc.d
 	$(CC) -c -S $(CFLAGS) -I. $(INCLUDES) $< -o $@
 
-$(objcbfs)/bootblock.debug: $(objgenerated)/bootblock.o $(objgenerated)/bootblock.ld
+$(objcbfs)/bootblock.debug: $(BOOTBLOCK_OBJS) $(objgenerated)/bootblock.ld
 	@printf "    LINK       $(subst $(obj)/,,$(@))\n"
 ifeq ($(CONFIG_COMPILER_LLVM_CLANG),y)
 	$(LD) -m armelf_linux_eabi -static -o $@.tmp -L$(obj) $< -T $(objgenerated)/bootblock.ld
 else
-	$(CC) -nostdlib -nostartfiles -static -o $@ -L$(obj) -T $(objgenerated)/bootblock.ld -Wl,--start-group $< $(LIBGCC_FILE_NAME) -Wl,--end-group
+	$(CC) -nostdlib -nostartfiles -static -o $@ -L$(obj) -T $(objgenerated)/bootblock.ld -Wl,--start-group $(BOOTBLOCK_OBJS) $(LIBGCC_FILE_NAME) -Wl,--end-group
 endif
 
 ################################################################################

src/arch/armv7/bootblock_exit.c

@@ -0,0 +1,28 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2013 Google Inc
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2 of
+ * the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ */
+
+#include <arch/bootblock_exit.h>
+
+void bootblock_exit(unsigned long addr)
+{
+	__attribute__((noreturn)) void (*doit)(void) = (void *)addr;
+	doit();
+}

src/arch/armv7/bootblock_simple.c

@@ -20,6 +20,7 @@
  */
 
 #include <bootblock_common.h>
+#include <arch/bootblock_exit.h>
 #include <arch/cbfs.h>
 #include <arch/hlt.h>
 
@@ -36,7 +37,7 @@ static int boot_cpu(void)
 void main(unsigned long bist)
 {
 	const char *target1 = "fallback/romstage";
-	unsigned long entry;
+	unsigned long romstage_entry;
 
 	if (boot_cpu()) {
 		bootblock_cpu_init();
@@ -44,8 +45,8 @@ void main(unsigned long bist)
 	}
 
 	printk(BIOS_INFO, "bootblock main(): loading romstage\n");
-	entry = loadstage(target1);
+	romstage_entry = loadstage(target1);
 	printk(BIOS_INFO, "bootblock main(): jumping to romstage\n");
-	if (entry) call(entry);
+	if (romstage_entry) bootblock_exit(romstage_entry);
 	hlt();
 }

src/arch/armv7/include/arch/bootblock_exit.h

@@ -0,0 +1,26 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2013 Google Inc
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2 of
+ * the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ */
+
+/**
+ * This is a shim that is to be compiled for the instruction set matching
+ * that of the entry point for the next boot stage (romstage).
+ */
+void bootblock_exit(unsigned long addr);

src/arch/armv7/include/arch/cbfs.h

@@ -98,21 +98,4 @@ static unsigned long loadstage(const char* target)
 			return 0;
 	}
 }
-
-static inline void call(unsigned long addr)
-{
-	__attribute__((noreturn)) void (*doit)(void) = (void *)addr;
-	printk(BIOS_INFO, "addr: %08lx, doit: %p\n", addr, doit);
-	/* FIXME: dumping SRAM content for sanity checking */
-	int i;
-	for (i = 0; i < 128; i++) {
-		if (i % 16 == 0)
-			printk(BIOS_INFO, "\n0x%08lx: ", addr + i);
-		else
-			printk(BIOS_INFO, " ");
-		printk(BIOS_INFO, "%02x", *(uint8_t *)(addr + i));
-	}
-	/* FIXME: do we need to change to/from arm/thumb? */
-	doit();
-}
 #endif