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    Subject[PATCH 17/21] lto, workaround: Disable LTO for BPF
    Date
    From: Andi Kleen <ak@linux.intel.com>

    Disable LTO for the BPF interpreter. This works around a gcc bug in the LTO
    partitioner that partitions the jumptable used the BPF interpreter
    into a different LTO unit. This in term causes assembler
    errors because the jump table contains references to the
    code labels in the original file.

    gcc problem tracked in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=50676

    Signed-off-by: Andi Kleen <ak@linux.intel.com>
    ---
    kernel/bpf/Makefile | 5 +++++
    1 file changed, 5 insertions(+)

    diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
    index e691da0b3bab..409d4b6762ee 100644
    --- a/kernel/bpf/Makefile
    +++ b/kernel/bpf/Makefile
    @@ -16,3 +16,8 @@ ifeq ($(CONFIG_PERF_EVENTS),y)
    obj-$(CONFIG_BPF_SYSCALL) += stackmap.o
    endif
    obj-$(CONFIG_CGROUP_BPF) += cgroup.o
    +
    +# various version of gcc have a LTO bug where the &&labels used in the
    +# BPF interpreter can cause linker errors when spread incorrectly over
    +# partitions. Disable LTO for BPF for now
    +CFLAGS_core.o = $(DISABLE_LTO)
    --
    2.13.6
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