New patch to review for coreboot: 33ae80d x86: Update the check for Forbidden global variables

[Furquan Shaikh]

Furquan Shaikh ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/7306

-gerrit

commit 33ae80d7ec76f1f4dfda5297ea00804baebffea1
Author: Furquan Shaikh 
Date:   Thu Oct 30 11:53:38 2014 -0700

x86: Update the check for Forbidden global variables

Add a section .illegal_globals to romstage and check that the section does not
    contain any variables while creating romstage.

Change-Id: I866681f51a44bc21770d32995c281b556a90c153
    Signed-off-by: Furquan Shaikh 
---
 src/arch/x86/Makefile.inc     |  5 +++--
 src/arch/x86/init/romstage.ld | 13 +++++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/arch/x86/Makefile.inc b/src/arch/x86/Makefile.inc
index f99ea15..7ca3ca4 100644
--- a/src/arch/x86/Makefile.inc
+++ b/src/arch/x86/Makefile.inc
@@ -214,9 +214,10 @@ ifeq ($(CONFIG_COMPILER_LLVM_CLANG),y)
 else
    $(CC_romstage) $(CFLAGS_romstage) -nostdlib -nostartfiles -static -o $@ -L$(obj) -T $(objgenerated)/romstage_null.ld -Wl,--wrap,__divdi3 -Wl,--wrap,__udivdi3 -Wl,--wrap,__moddi3 -Wl,--wrap,__umoddi3 -Wl,--start-group $(romstage-objs) $(romstage-libs) $(LIBGCC_FILE_NAME_romstage) -Wl,--end-group
 endif
-	$(NM_romstage) $@ | grep -q " [DdBb] "; if [ $$? -eq 0 ]; then \
+	$(OBJCOPY_romstage) --only-section .illegal_globals $(@) $(objcbfs)/romstage_null.offenders && \
+	$(NM_romstage) $(objcbfs)/romstage_null.offenders | grep -q ""; if [ $$? -eq 0 ]; then \
    	echo "Forbidden global variables in romstage:"; \
-		$(NM_romstage) $@ | grep " [DdBb] "; test "$(CONFIG_CPU_AMD_AGESA)" = y; \
+		$(NM_romstage) $(objcbfs)/romstage_null.offenders; test "$(CONFIG_CPU_AMD_AGESA)" = y; \
    	else true; fi

$(objcbfs)/romstage_xip.debug: $$(romstage-objs) $(objgenerated)/romstage_xip.ld $$(romstage-libs)
diff --git a/src/arch/x86/init/romstage.ld b/src/arch/x86/init/romstage.ld
index d6eb511..f4a4dde 100644
--- a/src/arch/x86/init/romstage.ld
+++ b/src/arch/x86/init/romstage.ld
@@ -43,6 +43,19 @@ SECTIONS
    	_erom = .;
    }

+	/* Global variables are not allowed in romstage
+	 * This section is checked during stage creation to ensure
+	 * that there are no global variables present
+	 */
+	.illegal_globals . : {
+		*(.data)
+		*(.data.*)
+		*(.bss)
+		*(.bss.*)
+		*(.sbss)
+		*(.sbss.*)
+	}
+
    /DISCARD/ : {
    	*(.comment)
    	*(.note)