d2e61c5202
[ Upstream commit 080b6f40763565f65ebb9540219c71ce885cf568 ] Commit3193c0836("bpf: Disable GCC -fgcse optimization for ___bpf_prog_run()") introduced a __no_fgcse macro that expands to a function scope __attribute__((optimize("-fno-gcse"))), to disable a GCC specific optimization that was causing trouble on x86 builds, and was not expected to have any positive effect in the first place. However, as the GCC manual documents, __attribute__((optimize)) is not for production use, and results in all other optimization options to be forgotten for the function in question. This can cause all kinds of trouble, but in one particular reported case, it causes -fno-asynchronous-unwind-tables to be disregarded, resulting in .eh_frame info to be emitted for the function. This reverts commit3193c0836, and instead, it disables the -fgcse optimization for the entire source file, but only when building for X86 using GCC with CONFIG_BPF_JIT_ALWAYS_ON disabled. Note that the original commit states that CONFIG_RETPOLINE=n triggers the issue, whereas CONFIG_RETPOLINE=y performs better without the optimization, so it is kept disabled in both cases. Fixes:3193c0836f("bpf: Disable GCC -fgcse optimization for ___bpf_prog_run()") Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Link: https://lore.kernel.org/lkml/CAMuHMdUg0WJHEcq6to0-eODpXPOywLot6UD2=GFHpzoj_hCoBQ@mail.gmail.com/ Link: https://lore.kernel.org/bpf/20201028171506.15682-2-ardb@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
32 lines
1.1 KiB
Makefile
32 lines
1.1 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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obj-y := core.o
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ifneq ($(CONFIG_BPF_JIT_ALWAYS_ON),y)
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# ___bpf_prog_run() needs GCSE disabled on x86; see 3193c0836f203 for details
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cflags-nogcse-$(CONFIG_X86)$(CONFIG_CC_IS_GCC) := -fno-gcse
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endif
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CFLAGS_core.o += $(call cc-disable-warning, override-init) $(cflags-nogcse-yy)
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obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o
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obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o
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obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o
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obj-$(CONFIG_BPF_SYSCALL) += disasm.o
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obj-$(CONFIG_BPF_SYSCALL) += btf.o
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ifeq ($(CONFIG_NET),y)
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obj-$(CONFIG_BPF_SYSCALL) += devmap.o
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obj-$(CONFIG_BPF_SYSCALL) += cpumap.o
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ifeq ($(CONFIG_XDP_SOCKETS),y)
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obj-$(CONFIG_BPF_SYSCALL) += xskmap.o
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endif
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obj-$(CONFIG_BPF_SYSCALL) += offload.o
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endif
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ifeq ($(CONFIG_PERF_EVENTS),y)
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obj-$(CONFIG_BPF_SYSCALL) += stackmap.o
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endif
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obj-$(CONFIG_CGROUP_BPF) += cgroup.o
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ifeq ($(CONFIG_INET),y)
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obj-$(CONFIG_BPF_SYSCALL) += reuseport_array.o
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endif
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ifeq ($(CONFIG_SYSFS),y)
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obj-$(CONFIG_DEBUG_INFO_BTF) += sysfs_btf.o
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endif
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