kbuild: Use -nostdinc in compile tests

gcc 4.8 and later include <stdc-predef.h> by default.  In some
versions of eglibc that includes <bits/predefs.h>, but that may be
missing when building with a biarch compiler.  Also <stdc-predef.h>
itself could be missing as we are only trying to build a kernel, not
userland.

The -nostdinc option disables this, though it isn't explicitly
documented.  This option is already used when actually building
the kernel, but not by cc-option and other tests.  This can result
in silently miscompiling the kernel.

References: https://bugs.debian.org/717557
References: https://bugs.debian.org/726861
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Gbp-Pq: Topic bugfix/all
Gbp-Pq: Name kbuild-use-nostdinc-in-compile-tests.patch

diff --git a/Makefile b/Makefile
index f8f6daf74949a44c700c31a3f1df321c4d6fed32..fc8fc5be67cde54a9fb7aae5b73495b6cd9a792d 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -677,6 +677,8 @@ endif
 KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \
                        $(call cc-disable-warning,maybe-uninitialized,))
 
+NOSTDINC_FLAGS += -nostdinc
+
 # Tell gcc to never replace conditional load with a non-conditional one
 KBUILD_CFLAGS  += $(call cc-option,--param=allow-store-data-races=0)
 
@@ -784,7 +786,7 @@ KBUILD_CFLAGS_KERNEL        += $(call cc-option,-fdata-sections,)
 endif
 
 # arch Makefile may override CC so keep this after arch Makefile is included
-NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
+NOSTDINC_FLAGS += -isystem $(shell $(CC) -print-file-name=include)
 
 # warn about C99 declaration after statement
 KBUILD_CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index ed303f552f9d05a20e46f369266bd4b6f79da380..81559c90121f574ed38cf55ffc496ecebc5569d7 100644 (file)
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -121,7 +121,7 @@ CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))
 # Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)
 
 cc-option = $(call __cc-option, $(CC),\
-       $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS),$(1),$(2))
+       $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS),$(1),$(2))
 
 # hostcc-option
 # Usage: cflags-y += $(call hostcc-option,-march=winchip-c6,-march=i586)
@@ -131,23 +131,24 @@ hostcc-option = $(call __cc-option, $(HOSTCC),\
 # cc-option-yn
 # Usage: flag := $(call cc-option-yn,-march=winchip-c6)
 cc-option-yn = $(call try-run,\
-       $(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
+       $(CC) -Werror $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
 
 # cc-disable-warning
 # Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
 cc-disable-warning = $(call try-run,\
-       $(CC) -Werror $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
+       $(CC) -Werror $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
 
 # cc-name
 # Expands to either gcc or clang
 cc-name = $(shell $(CC) -v 2>&1 | grep -q "clang version" && echo clang || echo gcc)
 
 # cc-version
-cc-version = $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))
+cc-version = $(shell $(CONFIG_SHELL) \
+       $(srctree)/scripts/gcc-version.sh $(CC) $(NOSTDINC_FLAGS))
 
 # cc-fullversion
 cc-fullversion = $(shell $(CONFIG_SHELL) \
-       $(srctree)/scripts/gcc-version.sh -p $(CC))
+       $(srctree)/scripts/gcc-version.sh -p $(CC) $(NOSTDINC_FLAGS))
 
 # cc-ifversion
 # Usage:  EXTRA_CFLAGS += $(call cc-ifversion, -lt, 0402, -O1)
@@ -160,7 +161,7 @@ cc-if-fullversion = $(shell [ $(cc-fullversion) $(1) $(2) ] && echo $(3) || echo
 # cc-ldoption
 # Usage: ldflags += $(call cc-ldoption, -Wl$(comma)--hash-style=both)
 cc-ldoption = $(call try-run,\
-       $(CC) $(1) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
+       $(CC) $(1) $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -nostdlib -x c /dev/null -o "$$TMP",$(1),$(2))
 
 # ld-option
 # Usage: LDFLAGS += $(call ld-option, -X)