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    Subject[PING PATCH v2] jump label: fix passing kbuild_cflags when checking for asm goto support
    The latest change of asm goto support check added passing of KBUILD_CFLAGS
    to compiler. When these flags reference gcc plugins that are not built yet,
    the check fails.

    When one runs "make bzImage" followed by "make modules", the kernel is always
    built with HAVE_JUMP_LABEL disabled, while the modules are built depending on
    CONFIG_JUMP_LABEL. If HAVE_JUMP_LABEL macro happens to be different, modules
    are built with undefined references, e.g.:

    ERROR: "static_key_slow_inc" [net/netfilter/xt_TEE.ko] undefined!
    ERROR: "static_key_slow_dec" [net/netfilter/xt_TEE.ko] undefined!
    ERROR: "static_key_slow_dec" [net/netfilter/nft_meta.ko] undefined!
    ERROR: "static_key_slow_inc" [net/netfilter/nft_meta.ko] undefined!
    ERROR: "nf_hooks_needed" [net/netfilter/ipvs/ip_vs.ko] undefined!
    ERROR: "nf_hooks_needed" [net/ipv6/ipv6.ko] undefined!
    ERROR: "static_key_count" [net/ipv6/ipv6.ko] undefined!
    ERROR: "static_key_slow_inc" [net/ipv6/ipv6.ko] undefined!

    This change moves the check before all these references are added
    to KBUILD_CFLAGS. This is correct because subsequent KBUILD_CFLAGS
    modifications are not relevant to this check.

    Reported-by: Anton V. Boyarshinov <boyarsh@altlinux.org>
    Fixes: 35f860f9ba6a ("jump label: pass kbuild_cflags when checking for asm goto support")
    Cc: stable@vger.kernel.org # v4.10
    Signed-off-by: Gleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
    Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
    Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
    Acked-by: David Lin <dtwlin@google.com>
    ---
    v2: update description of the problem fixed by this patch

    Makefile | 12 ++++++------
    1 file changed, 6 insertions(+), 6 deletions(-)

    diff --git a/Makefile b/Makefile
    index 165cf97..7e3aade 100644
    --- a/Makefile
    +++ b/Makefile
    @@ -653,6 +653,12 @@ KBUILD_CFLAGS += $(call cc-ifversion, -lt, 0409, \
    # Tell gcc to never replace conditional load with a non-conditional one
    KBUILD_CFLAGS += $(call cc-option,--param=allow-store-data-races=0)

    +# check for 'asm goto'
    +ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
    + KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
    + KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
    +endif
    +
    include scripts/Makefile.gcc-plugins

    ifdef CONFIG_READABLE_ASM
    @@ -798,12 +804,6 @@ KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
    # use the deterministic mode of AR if available
    KBUILD_ARFLAGS := $(call ar-option,D)

    -# check for 'asm goto'
    -ifeq ($(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-goto.sh $(CC) $(KBUILD_CFLAGS)), y)
    - KBUILD_CFLAGS += -DCC_HAVE_ASM_GOTO
    - KBUILD_AFLAGS += -DCC_HAVE_ASM_GOTO
    -endif
    -
    include scripts/Makefile.kasan
    include scripts/Makefile.extrawarn
    include scripts/Makefile.ubsan
    --
    glebfm

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