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| author | Daniel Borkmann <daniel@iogearbox.net> | 2019-12-09 16:08:03 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2019-12-11 16:16:01 -0800 |
| commit | 81c22041d9f19df07b9cba95e3cd02e0f41bc1e1 (patch) | |
| tree | 3ea69cf58495130fa4eefa49a072a2dbeeeb8318 /arch/arm64 | |
| parent | bae141f54be83b06652c1d47e50e4e75ed4e9c7e (diff) | |
| download | lwn-81c22041d9f19df07b9cba95e3cd02e0f41bc1e1.tar.gz lwn-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')
| -rw-r--r-- | arch/arm64/Kconfig | 1 |
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) |