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 4b1b1950aecabcc737a62b07e125cb46a82b12a7..f8d54b51e795bd9f1ea54c57517ece9ee0afcd0b 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -653,6 +653,8 @@ 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)
 
@@ -785,7 +787,7 @@ KBUILD_CFLAGS       += $(call cc-option,-fdata-sections,)
 endif
 
 # arch Makefile may override CC so keep this after arch Makefile is included
-NOSTDINC_FLAGS += -nostdinc -isystem $(call shell-cached,$(CC) -print-file-name=include)
+NOSTDINC_FLAGS += -isystem $(call shell-cached,$(CC) -print-file-name=include)
 CHECKFLAGS     += $(NOSTDINC_FLAGS)
 
 # warn about C99 declaration after statement

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 065324a8046ff8e0af179e6e90f335afb8d99179..ec6cf17ca63df83bb5031903dda450b51a72de9e 100644 (file)
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -194,7 +194,7 @@ 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)
@@ -204,23 +204,24 @@ hostcc-option = $(call __cc-option, $(HOSTCC),\
 # cc-option-yn
 # Usage: flag := $(call cc-option-yn,-march=winchip-c6)
 cc-option-yn = $(call try-run-cached,\
-       $(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-cached,\
-       $(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 = $(call shell-cached,$(CC) -v 2>&1 | grep -q "clang version" && echo clang || echo gcc)
 
 # cc-version
-cc-version = $(call shell-cached,$(CONFIG_SHELL) $(srctree)/scripts/gcc-version.sh $(CC))
+cc-version = $(call shell-cached,$(CONFIG_SHELL) \
+       $(srctree)/scripts/gcc-version.sh $(CC) $(NOSTDINC_FLAGS))
 
 # cc-fullversion
 cc-fullversion = $(call shell-cached,$(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)
@@ -238,7 +239,7 @@ cc-ldoption = $(call try-run-cached,\
 # ld-option
 # Usage: LDFLAGS += $(call ld-option, -X)
 ld-option = $(call try-run-cached,\
-       $(CC) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -x c /dev/null -c -o "$$TMPO"; \
+       $(CC) $(NOSTDINC_FLAGS) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -x c /dev/null -c -o "$$TMPO"; \
        $(LD) $(LDFLAGS) $(1) "$$TMPO" -o "$$TMP",$(1),$(2))
 
 # ar-option