[PATCH] kbuild: no gcc-plugins during cc-option tests

From: Kees Cook
Date: Sat Jun 18 2016 - 14:01:24 EST


From: Emese Revfy <re.emese@xxxxxxxxx>

The gcc-plugins arguments should not be included when performing
cc-option tests.

Steps to reproduce:
1) make mrproper
2) make defconfig
3) enable GCC_PLUGINS, GCC_PLUGIN_CYC_COMPLEXITY
4) enable FUNCTION_TRACER (it will select other options as well)
5) make && make modules

Build errors:
MODPOST 18 modules
ERROR: "__fentry__" [net/netfilter/xt_nat.ko] undefined!
ERROR: "__fentry__" [net/netfilter/xt_mark.ko] undefined!
ERROR: "__fentry__" [net/netfilter/xt_addrtype.ko] undefined!
ERROR: "__fentry__" [net/netfilter/xt_LOG.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat_sip.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat_irc.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat_ftp.ko] undefined!
ERROR: "__fentry__" [net/netfilter/nf_nat.ko] undefined!

Reported-by: Laura Abbott <labbott@xxxxxxxxxx>
Signed-off-by: Emese Revfy <re.emese@xxxxxxxxx>
[kees: renamed variable, clarified commit message]
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
I can carry this in my kspp tree for -next
---
scripts/Kbuild.include | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 0f82314621f2..f585766989c2 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -108,16 +108,19 @@ as-option = $(call try-run,\
as-instr = $(call try-run,\
printf "%b\n" "$(1)" | $(CC) $(KBUILD_AFLAGS) -c -x assembler -o "$$TMP" -,$(2),$(3))

+# Do not attempt to build with gcc plugins during cc-option tests.
+CC_OPTION_CFLAGS = $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS))
+
# cc-option
# Usage: cflags-y += $(call cc-option,-march=winchip-c6,-march=i586)

cc-option = $(call try-run,\
- $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2))
+ $(CC) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2))

# cc-option-yn
# Usage: flag := $(call cc-option-yn,-march=winchip-c6)
cc-option-yn = $(call try-run,\
- $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)
+ $(CC) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) $(1) -c -x c /dev/null -o "$$TMP",y,n)

# cc-option-align
# Prefix align with either -falign or -malign
@@ -127,7 +130,7 @@ cc-option-align = $(subst -functions=0,,\
# cc-disable-warning
# Usage: cflags-y += $(call cc-disable-warning,unused-but-set-variable)
cc-disable-warning = $(call try-run,\
- $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))
+ $(CC) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -W$(strip $(1)) -c -x c /dev/null -o "$$TMP",-Wno-$(strip $(1)))

# cc-name
# Expands to either gcc or clang
--
2.7.4


--
Kees Cook
Chrome OS & Brillo Security