rmodule: use program.ld for linking

Bring rmodule linking into the common linking method.
The __rmodule_entry symbol was removed while using
a more common _start symbol. The rmodtool will honor
the entry point found within the ELF header. Add
ENV_RMODULE so that one can distinguish the environment
when generating linker scripts for rmodules. Lastly,
directly use program.ld for the rmodule.ld linker script.

BUG=chrome-os-partner:44827
BRANCH=None
TEST=Built rambi and analyzed the relocatable ramstage,
     sipi_vector, and smm rmodules.

Change-Id: Iaa499eb229d8171272add9ee6d27cff75e7534ac
Signed-off-by: Aaron Durbin <adubin@chromium.org>
Reviewed-on: http://review.coreboot.org/11517
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/cpu/x86/Makefile.inc

@@ -20,9 +20,9 @@ $(SIPI_DOTO): $(dir $(SIPI_ELF))sipi_vector.rmodules_$(ARCH-ramstage-y).o
 	$(CC_rmodules_$(ARCH-ramstage-y)) $(CFLAGS_rmodules_$(ARCH-ramstage-y)) -nostdlib -r -o $@ $^
 
 ifeq ($(CONFIG_ARCH_RAMSTAGE_X86_32),y)
-$(eval $(call rmodule_link,$(SIPI_ELF), $(SIPI_ELF:.elf=.o), 0,x86_32))
+$(eval $(call rmodule_link,$(SIPI_ELF), $(SIPI_DOTO), 0,x86_32))
 else
-$(eval $(call rmodule_link,$(SIPI_ELF), $(SIPI_ELF:.elf=.o), 0,x86_64))
+$(eval $(call rmodule_link,$(SIPI_ELF), $(SIPI_DOTO), 0,x86_64))
 endif
 
 $(SIPI_BIN): $(SIPI_RMOD)

src/cpu/x86/sipi_vector.S

@@ -56,10 +56,8 @@ ap_count:
 
 .text
 .code16
-.global ap_start
-.global __rmodule_entry
-__rmodule_entry:
-ap_start:
+.global _start
+_start:
 	cli
 	xorl	%eax, %eax
 	movl	%eax, %cr3    /* Invalidate TLB*/
@@ -74,9 +72,9 @@ ap_start:
 
 	/* The gdtaddr needs to be releative to the data segment in order
 	 * to properly dereference it. The .text section comes first in an
-	 * rmodule so ap_start can be used as a proxy for the load address. */
+	 * rmodule so _start can be used as a proxy for the load address. */
 	movl	$(gdtaddr), %ebx
-	sub	$(ap_start), %ebx
+	sub	$(_start), %ebx
 
 	data32 lgdt (%ebx)
 

src/cpu/x86/smm/smm_stub.S

@@ -59,10 +59,8 @@ fallback_stack_top:
 
 .text
 .code16
-.global smm_handler_start
-.global __rmodule_entry
-__rmodule_entry:
-smm_handler_start:
+.global _start
+_start:
 	movl	$(smm_relocate_gdt), %ebx
 	data32	lgdt (%ebx)