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From: Andi Kleen <andi@firstfloor.org>
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 <ak@linux.intel.com>
Subject: [PATCH 17/21] lto, workaround: Disable LTO for BPF
Date: Mon, 27 Nov 2017 13:34:19 -0800	[thread overview]
Message-ID: <20171127213423.27218-18-andi@firstfloor.org> (raw)
In-Reply-To: <20171127213423.27218-1-andi@firstfloor.org>

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

  parent reply	other threads:[~2017-11-27 21:36 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-27 21:34 Link time optimization for LTO/x86 Andi Kleen
2017-11-27 21:34 ` [PATCH 01/21] x86/xen: Mark pv stub assembler symbol visible Andi Kleen
2017-11-27 21:34 ` [PATCH 02/21] afs: Fix const confusion in AFS Andi Kleen
2017-11-27 21:34 ` [PATCH 03/21] x86/timer: Don't inline __const_udelay Andi Kleen
2017-11-27 21:34 ` [PATCH 04/21] locking/spinlocks: Mark spinlocks noinline when inline spinlocks are disabled Andi Kleen
2017-11-27 21:34 ` [PATCH 05/21] x86/kvm: Make steal_time visible Andi Kleen
2017-11-27 21:34 ` [PATCH 06/21] x86/syscalls: Make x86 syscalls use real prototypes Andi Kleen
2017-11-27 21:34 ` [PATCH 07/21] x86: Make exception handler functions visible Andi Kleen
2017-11-27 21:34 ` [PATCH 08/21] x86/idt: Make const __initconst Andi Kleen
2017-11-27 21:34 ` [PATCH 09/21] lto: Use C version for SYSCALL_ALIAS Andi Kleen
2017-11-27 21:34 ` [PATCH 10/21] Fix read buffer overflow in delta-ipc Andi Kleen
2017-11-27 21:34 ` [PATCH 11/21] trace: Use -mcount-record for dynamic ftrace Andi Kleen
2017-12-01  0:22   ` Steven Rostedt
2018-05-01 18:42     ` Steven Rostedt
2017-11-27 21:34 ` [PATCH 12/21] ftrace: Mark function tracer test functions noinline/noclone Andi Kleen
2017-11-27 21:34 ` [PATCH 13/21] ftrace: Disable LTO for ftrace self tests Andi Kleen
2017-11-27 21:34 ` [PATCH 14/21] lto, fs: Avoid static variable in linux/fs.h Andi Kleen
2017-11-27 21:34 ` [PATCH 15/21] lto, x86, mm: Disable vmalloc BUILD_BUG_ON for LTO Andi Kleen
2017-11-27 21:34 ` [PATCH 16/21] lto: Add __noreorder and mark initcalls __noreorder Andi Kleen
2017-11-27 21:34 ` Andi Kleen [this message]
2017-11-27 21:34 ` [PATCH 18/21] lto, crypto: Disable LTO for camelia glue Andi Kleen
2017-11-27 21:34 ` [PATCH 19/21] lto, x86: Disable LTO for realmode / vDSO / head64 Andi Kleen
2017-11-27 21:34 ` [PATCH 20/21] Kbuild, lto: Add Link Time Optimization support Andi Kleen
2018-01-27  0:15   ` Arnd Bergmann
2018-01-27  0:55     ` Andi Kleen
2018-01-27 14:26       ` Arnd Bergmann
2018-01-28 18:33         ` Andi Kleen
2017-11-27 21:34 ` [PATCH 21/21] x86: Enable Link Time Optimization Andi Kleen
2017-11-28 16:04 ` [PATCH 02/21] afs: Fix const confusion in AFS David Howells
2017-11-28 16:50   ` Andi Kleen
2017-11-29 23:09 ` Link time optimization for LTO/x86 Sami Tolvanen

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