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authorDaniel Borkmann <daniel@iogearbox.net>2019-12-09 16:08:03 +0100
committerAlexei Starovoitov <ast@kernel.org>2019-12-11 16:16:01 -0800
commit81c22041d9f19df07b9cba95e3cd02e0f41bc1e1 (patch)
tree3ea69cf58495130fa4eefa49a072a2dbeeeb8318 /arch/arm64/Kconfig
parentbpf: Emit audit messages upon successful prog load and unload (diff)
downloadlinux-dev-81c22041d9f19df07b9cba95e3cd02e0f41bc1e1.tar.xz
linux-dev-81c22041d9f19df07b9cba95e3cd02e0f41bc1e1.zip
bpf, x86, arm64: Enable jit by default when not built as always-on
After Spectre 2 fix via 290af86629b2 ("bpf: introduce BPF_JIT_ALWAYS_ON config") most major distros use BPF_JIT_ALWAYS_ON configuration these days which compiles out the BPF interpreter entirely and always enables the JIT. Also given recent fix in e1608f3fa857 ("bpf: Avoid setting bpf insns pages read-only when prog is jited"), we additionally avoid fragmenting the direct map for the BPF insns pages sitting in the general data heap since they are not used during execution. Latter is only needed when run through the interpreter. Since both x86 and arm64 JITs have seen a lot of exposure over the years, are generally most up to date and maintained, there is more downside in !BPF_JIT_ALWAYS_ON configurations to have the interpreter enabled by default rather than the JIT. Add a ARCH_WANT_DEFAULT_BPF_JIT config which archs can use to set the bpf_jit_{enable,kallsyms} to 1. Back in the days the bpf_jit_kallsyms knob was set to 0 by default since major distros still had /proc/kallsyms addresses exposed to unprivileged user space which is not the case anymore. Hence both knobs are set via BPF_JIT_DEFAULT_ON which is set to 'y' in case of BPF_JIT_ALWAYS_ON or ARCH_WANT_DEFAULT_BPF_JIT. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Will Deacon <will@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/f78ad24795c2966efcc2ee19025fa3459f622185.1575903816.git.daniel@iogearbox.net
Diffstat (limited to 'arch/arm64/Kconfig')
-rw-r--r--arch/arm64/Kconfig1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index b1b4476ddb83..29d03459de20 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -69,6 +69,7 @@ config ARM64
select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 && (GCC_VERSION >= 50000 || CC_IS_CLANG)
select ARCH_SUPPORTS_NUMA_BALANCING
select ARCH_WANT_COMPAT_IPC_PARSE_VERSION if COMPAT
+ select ARCH_WANT_DEFAULT_BPF_JIT
select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
select ARCH_WANT_FRAME_POINTERS
select ARCH_WANT_HUGE_PMD_SHARE if ARM64_4K_PAGES || (ARM64_16K_PAGES && !ARM64_VA_BITS_36)