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From: Ben Hutchings <ben@decadent.org.uk>
Date: Sat, 19 Oct 2013 19:43:35 +0100
Subject: kbuild: Use -nostdinc in compile tests
Bug-Debian: https://bugs.debian.org/726861
Bug-Debian: https://bugs.debian.org/717557
Forwarded: https://marc.info/?l=linux-kbuild&m=141523555023625
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>
---
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -121,7 +121,7 @@ CC_OPTION_CFLAGS = $(filter-out $(GCC_PL
# 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, $(HO
# 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)
@@ -156,7 +157,7 @@ cc-ifversion = $(shell [ $(cc-version) $
# 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: KBUILD_LDFLAGS += $(call ld-option, -X, -Y)
--- a/Makefile
+++ b/Makefile
@@ -661,6 +661,8 @@ else
KBUILD_CFLAGS += -O2
endif
+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)
KBUILD_CFLAGS += $(call cc-option,-fno-allow-store-data-races)
@@ -781,7 +783,7 @@ LDFLAGS_vmlinux += --gc-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,)
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