From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga09.intel.com ([134.134.136.24]:35216 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752795AbdK0Ved (ORCPT ); Mon, 27 Nov 2017 16:34:33 -0500 From: Andi Kleen Subject: [PATCH 17/21] lto, workaround: Disable LTO for BPF Date: Mon, 27 Nov 2017 13:34:19 -0800 Message-Id: <20171127213423.27218-18-andi@firstfloor.org> In-Reply-To: <20171127213423.27218-1-andi@firstfloor.org> References: <20171127213423.27218-1-andi@firstfloor.org> Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, samitolvanen@google.com, alxmtvv@gmail.com, linux-kbuild@vger.kernel.org, yamada.masahiro@socionext.com, akpm@linux-foundation.org, Andi Kleen From: Andi Kleen 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 --- 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