intel post-car: Separate files for setup_stack_and_mtrrs()

Have a common romstage.c file to prepare CAR stack guards.

MTRR setup around cbmem_top() is somewhat northbridge specific,
place stubs under northbridge for platrform that will move
to RELOCATABLE_RAMSTAGE.

Change-Id: I3d4fe4145894e83e5980dc2a7bbb8a91acecb3c6
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/15762
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/cpu/intel/car/romstage.c

@@ -1,7 +1,56 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * 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.
+ */
+
+#include <arch/cpu.h>
+#include <console/console.h>
 #include <cpu/intel/romstage.h>
+#include <program_loading.h>
+
+#define DCACHE_RAM_ROMSTAGE_STACK_SIZE 0x800
 
 void * asmlinkage romstage_main(unsigned long bist)
 {
+	int i;
+	void *romstage_stack_after_car;
+	const int num_guards = 4;
+	const u32 stack_guard = 0xdeadbeef;
+	u32 *stack_base = (void *)(CONFIG_DCACHE_RAM_BASE +
+	                           CONFIG_DCACHE_RAM_SIZE -
+	                           DCACHE_RAM_ROMSTAGE_STACK_SIZE);
+
+	for (i = 0; i < num_guards; i++)
+		stack_base[i] = stack_guard;
+
 	mainboard_romstage_entry(bist);
-	return (void*)CONFIG_RAMTOP;
+
+	/* Check the stack. */
+	for (i = 0; i < num_guards; i++) {
+		if (stack_base[i] == stack_guard)
+			continue;
+		printk(BIOS_DEBUG, "Smashed stack detected in romstage!\n");
+	}
+
+	/* Get the stack to use after cache-as-ram is torn down. */
+	if (IS_ENABLED(CONFIG_LATE_CBMEM_INIT))
+		romstage_stack_after_car = (void*)CONFIG_RAMTOP;
+	else
+		romstage_stack_after_car = setup_stack_and_mtrrs();
+
+	return romstage_stack_after_car;
+}
+
+void asmlinkage romstage_after_car(void)
+{
+	/* Load the ramstage. */
+	run_ramstage();
 }