Merge branch 'rc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild

Pull kbuild fixes from Michal Marek:
 "Here are some regression fixes for kbuild:

   - modversion support for exported asm symbols (Nick Piggin). The
     affected architectures need separate patches adding
     asm-prototypes.h.

   - fix rebuilds of lib-ksyms.o (Nick Piggin)

   - -fno-PIE builds (Sebastian Siewior and Borislav Petkov). This is
     not a kernel regression, but one of the Debian gcc package.
     Nevertheless, it's quite annoying, so I think it should go into
     mainline and stable now"

* 'rc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
  kbuild: Steal gcc's pie from the very beginning
  kbuild: be more careful about matching preprocessed asm ___EXPORT_SYMBOL
  x86/kexec: add -fno-PIE
  scripts/has-stack-protector: add -fno-PIE
  kbuild: add -fno-PIE
  kbuild: modversions for EXPORT_SYMBOL() for asm
  kbuild: prevent lib-ksyms.o rebuilds

Makefile

@@ -399,11 +399,12 @@ KBUILD_CFLAGS   := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
 		   -fno-strict-aliasing -fno-common \
 		   -Werror-implicit-function-declaration \
 		   -Wno-format-security \
-		   -std=gnu89
+		   -std=gnu89 $(call cc-option,-fno-PIE)
+
 
 KBUILD_AFLAGS_KERNEL :=
 KBUILD_CFLAGS_KERNEL :=
-KBUILD_AFLAGS   := -D__ASSEMBLY__
+KBUILD_AFLAGS   := -D__ASSEMBLY__ $(call cc-option,-fno-PIE)
 KBUILD_AFLAGS_MODULE  := -DMODULE
 KBUILD_CFLAGS_MODULE  := -DMODULE
 KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds

arch/x86/purgatory/Makefile

@@ -16,6 +16,7 @@ KCOV_INSTRUMENT := n
 
 KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes -fno-zero-initialized-in-bss -fno-builtin -ffreestanding -c -MD -Os -mcmodel=large
 KBUILD_CFLAGS += -m$(BITS)
+KBUILD_CFLAGS += $(call cc-option,-fno-PIE)
 
 $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
 		$(call if_changed,ld)

scripts/Makefile.build

@@ -159,7 +159,8 @@ cmd_cpp_i_c       = $(CPP) $(c_flags) -o $@ $<
 $(obj)/%.i: $(src)/%.c FORCE
 	$(call if_changed_dep,cpp_i_c)
 
-cmd_gensymtypes =                                                           \
+# These mirror gensymtypes_S and co below, keep them in synch.
+cmd_gensymtypes_c =                                                         \
     $(CPP) -D__GENKSYMS__ $(c_flags) $< |                                   \
     $(GENKSYMS) $(if $(1), -T $(2))                                         \
      $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX))             \
@@ -169,7 +170,7 @@ cmd_gensymtypes =                                                           \
 quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
 cmd_cc_symtypes_c =                                                         \
     set -e;                                                                 \
-    $(call cmd_gensymtypes,true,$@) >/dev/null;                             \
+    $(call cmd_gensymtypes_c,true,$@) >/dev/null;                           \
     test -s $@ || rm -f $@
 
 $(obj)/%.symtypes : $(src)/%.c FORCE
@@ -198,9 +199,10 @@ else
 #   the actual value of the checksum generated by genksyms
 
 cmd_cc_o_c = $(CC) $(c_flags) -c -o $(@D)/.tmp_$(@F) $<
-cmd_modversions =								\
+
+cmd_modversions_c =								\
 	if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then		\
-		$(call cmd_gensymtypes,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
+		$(call cmd_gensymtypes_c,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
 		    > $(@D)/.tmp_$(@F:.o=.ver);					\
 										\
 		$(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) 			\
@@ -268,13 +270,14 @@ endif # CONFIG_STACK_VALIDATION
 define rule_cc_o_c
 	$(call echo-cmd,checksrc) $(cmd_checksrc)			  \
 	$(call cmd_and_fixdep,cc_o_c)					  \
-	$(cmd_modversions)						  \
+	$(cmd_modversions_c)						  \
 	$(cmd_objtool)						          \
 	$(call echo-cmd,record_mcount) $(cmd_record_mcount)
 endef
 
 define rule_as_o_S
 	$(call cmd_and_fixdep,as_o_S)					  \
+	$(cmd_modversions_S)						  \
 	$(cmd_objtool)
 endef
 
@@ -314,6 +317,39 @@ modkern_aflags := $(KBUILD_AFLAGS_KERNEL) $(AFLAGS_KERNEL)
 $(real-objs-m)      : modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
 $(real-objs-m:.o=.s): modkern_aflags := $(KBUILD_AFLAGS_MODULE) $(AFLAGS_MODULE)
 
+# .S file exports must have their C prototypes defined in asm/asm-prototypes.h
+# or a file that it includes, in order to get versioned symbols. We build a
+# dummy C file that includes asm-prototypes and the EXPORT_SYMBOL lines from
+# the .S file (with trailing ';'), and run genksyms on that, to extract vers.
+#
+# This is convoluted. The .S file must first be preprocessed to run guards and
+# expand names, then the resulting exports must be constructed into plain
+# EXPORT_SYMBOL(symbol); to build our dummy C file, and that gets preprocessed
+# to make the genksyms input.
+#
+# These mirror gensymtypes_c and co above, keep them in synch.
+cmd_gensymtypes_S =                                                         \
+    (echo "\#include <linux/kernel.h>" ;                                    \
+     echo "\#include <asm/asm-prototypes.h>" ;                              \
+    $(CPP) $(a_flags) $< |                                                  \
+     grep "\<___EXPORT_SYMBOL\>" |                                          \
+     sed 's/.*___EXPORT_SYMBOL[[:space:]]*\([a-zA-Z0-9_]*\)[[:space:]]*,.*/EXPORT_SYMBOL(\1);/' ) | \
+    $(CPP) -D__GENKSYMS__ $(c_flags) -xc - |                                \
+    $(GENKSYMS) $(if $(1), -T $(2))                                         \
+     $(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX))             \
+     $(if $(KBUILD_PRESERVE),-p)                                            \
+     -r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
+
+quiet_cmd_cc_symtypes_S = SYM $(quiet_modtag) $@
+cmd_cc_symtypes_S =                                                         \
+    set -e;                                                                 \
+    $(call cmd_gensymtypes_S,true,$@) >/dev/null;                           \
+    test -s $@ || rm -f $@
+
+$(obj)/%.symtypes : $(src)/%.S FORCE
+	$(call cmd,cc_symtypes_S)
+
+
 quiet_cmd_cpp_s_S = CPP $(quiet_modtag) $@
 cmd_cpp_s_S       = $(CPP) $(a_flags) -o $@ $<
 
@@ -321,7 +357,37 @@ $(obj)/%.s: $(src)/%.S FORCE
 	$(call if_changed_dep,cpp_s_S)
 
 quiet_cmd_as_o_S = AS $(quiet_modtag)  $@
-cmd_as_o_S       = $(CC) $(a_flags) -c -o $@ $<
+
+ifndef CONFIG_MODVERSIONS
+cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
+
+else
+
+ASM_PROTOTYPES := $(wildcard $(srctree)/arch/$(SRCARCH)/include/asm/asm-prototypes.h)
+
+ifeq ($(ASM_PROTOTYPES),)
+cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
+
+else
+
+# versioning matches the C process described above, with difference that
+# we parse asm-prototypes.h C header to get function definitions.
+
+cmd_as_o_S = $(CC) $(a_flags) -c -o $(@D)/.tmp_$(@F) $<
+
+cmd_modversions_S =								\
+	if $(OBJDUMP) -h $(@D)/.tmp_$(@F) | grep -q __ksymtab; then		\
+		$(call cmd_gensymtypes_S,$(KBUILD_SYMTYPES),$(@:.o=.symtypes))	\
+		    > $(@D)/.tmp_$(@F:.o=.ver);					\
+										\
+		$(LD) $(LDFLAGS) -r -o $@ $(@D)/.tmp_$(@F) 			\
+			-T $(@D)/.tmp_$(@F:.o=.ver);				\
+		rm -f $(@D)/.tmp_$(@F) $(@D)/.tmp_$(@F:.o=.ver);		\
+	else									\
+		mv -f $(@D)/.tmp_$(@F) $@;					\
+	fi;
+endif
+endif
 
 $(obj)/%.o: $(src)/%.S $(objtool_obj) FORCE
 	$(call if_changed_rule,as_o_S)
@@ -430,6 +496,9 @@ cmd_export_list = $(OBJDUMP) -h $< | \
 
 $(obj)/lib-ksyms.o: $(lib-target) FORCE
 	$(call if_changed,export_list)
+
+targets += $(obj)/lib-ksyms.o
+
 endif
 
 #

scripts/gcc-x86_64-has-stack-protector.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-echo "int foo(void) { char X[200]; return 3; }" | $* -S -x c -c -O0 -mcmodel=kernel -fstack-protector - -o - 2> /dev/null | grep -q "%gs"
+echo "int foo(void) { char X[200]; return 3; }" | $* -S -x c -c -O0 -mcmodel=kernel -fno-PIE -fstack-protector - -o - 2> /dev/null | grep -q "%gs"
 if [ "$?" -eq "0" ] ; then
 	echo y
 else