AGESA,binaryPI: Fix stack location on entry to romstage

For BSP CPU, set up stack location to match the symbol from car.ld.
For AP CPUs the stack is located outside _car_region and is currently
not accounted for in the linker scripts.

Change-Id: I0ec84ae4e73ecca5034f799cdc2a5c1056ad8b74
Signed-off-by: Michał Żygowski <michal.zygowski@3mdeb.com>
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37351
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/drivers/amd/agesa/cache_as_ram.S

@@ -22,6 +22,7 @@
  */
 
 #include "gcccar.inc"
+#include <cpu/x86/lapic_def.h>
 #include <cpu/x86/post_code.h>
 
 .code32
@@ -36,6 +37,19 @@ _cache_as_ram_setup:
 
 	AMD_ENABLE_STACK
 
+	/*
+	 * Set up bootblock stack on BSP.
+	 * AMD_ENABLE_STACK macro sets up a stack for BSP at BSP_STACK_BASE_ADDR
+	 * which is 0x30000 (_car_region_end), but for C bootblock the stack
+	 * begins at _ecar_stack (see arch/x86/car.ld)
+	 */
+	mov	$LAPIC_BASE_MSR, %ecx
+	rdmsr
+	test	$LAPIC_BASE_MSR_BOOTSTRAP_PROCESSOR, %eax
+	jz	ap_entry
+
+	mov	$_ecar_stack, %esp
+
 	/* Align the stack. */
 	and	$0xFFFFFFF0, %esp
 
@@ -47,11 +61,19 @@ _cache_as_ram_setup:
 	pushl	%eax
 	call	romstage_main
 
-	/* Should never see this postcode */
+	/* Never reached. */
-	post_code(0xae)
 
 stop:
+	post_code(POST_DEAD_CODE)
 	hlt
 	jmp	stop
 
+ap_entry:
+	/* Align the stack for call to ap_romstage_main() */
+	and	$0xfffffff0, %esp
+	call	ap_romstage_main
+
+	/* Never reached. */
+	jmp	stop
+
 _cache_as_ram_setup_end:

src/drivers/amd/agesa/romstage.c

@@ -39,7 +39,7 @@ static void fill_sysinfo(struct sysinfo *cb)
 	agesa_set_interface(cb);
 }
 
-static void bsp_romstage_main(void)
+asmlinkage void romstage_main(unsigned long bist)
 {
 	struct postcar_frame pcf;
 	struct sysinfo romstage_state;
@@ -99,7 +99,7 @@ static void bsp_romstage_main(void)
 	/* We do not return. */
 }
 
-static void __noreturn ap_romstage_main(void)
+asmlinkage void ap_romstage_main(void)
 {
 	struct sysinfo romstage_state;
 	struct sysinfo *cb = &romstage_state;
@@ -116,11 +116,3 @@ static void __noreturn ap_romstage_main(void)
 	/* Not reached. */
 	halt();
 }
-
-asmlinkage void romstage_main(unsigned long bist)
-{
-	if (boot_cpu())
-		bsp_romstage_main();
-	else
-		ap_romstage_main();
-}

src/include/cpu/amd/car.h

@@ -4,5 +4,6 @@
 #include <arch/cpu.h>
 
 asmlinkage void romstage_main(unsigned long bist);
+asmlinkage void ap_romstage_main(void);
 
 #endif