From: Alexander Lobakin <alobakin@dlink.ru> To: Paul Burton <paul.burton@mips.com> Cc: Hassan Naveed <hnaveed@wavecomp.com>, Ralf Baechle <ralf@linux-mips.org>, James Hogan <jhogan@kernel.org>, Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org Subject: MIPS eBPF JIT support on pre-32R2 Date: Thu, 05 Dec 2019 15:45:27 +0300 Message-ID: <09d713a59665d745e21d021deeaebe0a@dlink.ru> (raw) Hey all, I'm writing about lines arch/mips/net/ebpf_jit.c:1806-1807: if (!prog->jit_requested || MIPS_ISA_REV < 2) return prog; Do pre-32R2 architectures (32R1, maybe even R3000-like) actually support this eBPF JIT code? If they do, then the condition 'MIPS_ISA_REV < 2' should be removed as it is always true for them and tells CC to remove JIT completely. If they don't support instructions from this JIT, then the line arch/mips/Kconfig:50: select HAVE_EBPF_JIT if (!CPU_MICROMIPS) should be changed to something like: select HAVE_EBPF_JIT if !CPU_MICROMIPS && TARGET_ISA_REV >= 2 (and then the mentioned 'if' condition would become redundant) At the moment it is possible to build a kernel without both JIT and interpreter, but with CONFIG_BPF_SYSCALL=y (what should not be allowed I suppose?) within the following configuration: - select any pre-32R2 CPU (e.g. CONFIG_CPU_MIPS32_R1); - enable CONFIG_BPF_JIT (CONFIG_MIPS_EBPF_JIT will be autoselected); - enable CONFIG_BPF_JIT_ALWAYS_ON (this removes BPF interpreter from the system). I may prepare a proper patch by myself if needed (after clarification). Thanks. Regards, ᚷ ᛖ ᚢ ᚦ ᚠ ᚱ
next reply index Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-05 12:45 Alexander Lobakin [this message] 2019-12-05 13:04 ` Daniel Borkmann 2019-12-05 18:44 ` Paul Burton 2019-12-06 7:20 ` Alexander Lobakin 2019-12-06 8:11 ` Alexander Lobakin
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