kbuild: do section mismatch check on full vmlinux

Previously we did do the check on the .o files used to link
vmlinux but that failed to find questionable references across
the .o files.
Create a dedicated vmlinux.o file used only for section mismatch checks
that uses the defualt linker script so section does not get renamed.

The vmlinux.o may later be used as part of the the final link of vmlinux
but for now it is used fo section mismatch only.
For a defconfig build this is instant but for an allyesconfig this
add two minutes to a full build (that anyways takes ~2 hours).

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

diff --git a/Makefile b/Makefile
index ddbfcac299c1c587c2e9f5d172bfb3e052b12118..4f0bd65a38d80397dbb3f38c827b8a587cc0c1da 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -612,7 +612,7 @@ quiet_cmd_vmlinux__ ?= LD      $@
       cmd_vmlinux__ ?= $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) -o $@ \
       -T $(vmlinux-lds) $(vmlinux-init)                          \
       --start-group $(vmlinux-main) --end-group                  \
-      $(filter-out $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) FORCE ,$^)
+      $(filter-out $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o FORCE ,$^)
 
 # Generate new vmlinux version
 quiet_cmd_vmlinux_version = GEN     .version
@@ -736,15 +736,31 @@ debug_kallsyms: .tmp_map$(last_kallsyms)
 
 endif # ifdef CONFIG_KALLSYMS
 
+# Do modpost on a prelinked vmlinux. The finally linked vmlinux has
+# relevant sections renamed as per the linker script.
+quiet_cmd_vmlinux-modpost = LD      $@
+      cmd_vmlinux-modpost = $(LD) $(LDFLAGS) -r -o $@                          \
+        $(vmlinux-init) --start-group $(vmlinux-main) --end-group             \
+        $(filter-out $(vmlinux-init) $(vmlinux-main) $(vmlinux-lds) FORCE ,$^)
+define rule_vmlinux-modpost
+       :
+       +$(call cmd,vmlinux-modpost)
+       $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost $@
+       $(Q)echo 'cmd_$@ := $(cmd_vmlinux-modpost)' > $(dot-target).cmd
+endef
+
 # vmlinux image - including updated kernel symbols
-vmlinux: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) $(kallsyms.o) FORCE
+vmlinux: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) $(kallsyms.o) vmlinux.o FORCE
 ifdef CONFIG_HEADERS_CHECK
        $(Q)$(MAKE) -f $(srctree)/Makefile headers_check
 endif
+       $(call vmlinux-modpost)
        $(call if_changed_rule,vmlinux__)
-       $(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost $@
        $(Q)rm -f .old_version
 
+vmlinux.o: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) $(kallsyms.o) FORCE
+       $(call if_changed_rule,vmlinux-modpost)
+
 # The actual objects are generated when descending, 
 # make sure no implicit rule kicks in
 $(sort $(vmlinux-init) $(vmlinux-main)) $(vmlinux-lds): $(vmlinux-dirs) ;

diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index d5bbbcce31ef2822df654c2fb7656649b50ac866..c6fcc597b3be7c55c82f31d629ca093ce2f1de91 100644 (file)
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -70,10 +70,10 @@ __modpost: $(modules:.ko=.o) FORCE
        $(call cmd,modpost) $(wildcard vmlinux) $(filter-out FORCE,$^)
 
 quiet_cmd_kernel-mod = MODPOST $@
-      cmd_kernel-mod = $(cmd_modpost) $(KBUILD_VMLINUX_OBJS)
+      cmd_kernel-mod = $(cmd_modpost) $@
 
 PHONY += vmlinux
-vmlinux: FORCE
+vmlinux.o: FORCE
        $(call cmd,kernel-mod)
 
 # Declare generated files as targets for modpost

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index bb895b13c1709f155b504995f8a17c924ed2516b..ec036c261fb19546aa309c6e589f34c9a864e7d9 100644 (file)
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -75,7 +75,8 @@ static int is_vmlinux(const char *modname)
        else
                myname = modname;
 
-       return strcmp(myname, "vmlinux") == 0;
+       return (strcmp(myname, "vmlinux") == 0) ||
+              (strcmp(myname, "vmlinux.o") == 0);
 }
 
 void *do_nofail(void *ptr, const char *expr)