MIPS: BPF: eBPF JIT: check for MIPS ISA compliance in Kconfig

It is completely wrong to check for compile-time MIPS ISA revision in
the body of bpf_int_jit_compile() as it may lead to get MIPS JIT fully
omitted by the CC while the rest system will think that the JIT is
actually present and works [1].
We can check if the selected CPU really supports MIPS eBPF JIT at
configure time and avoid such situations when kernel can be built
without both JIT and interpreter, but with CONFIG_BPF_SYSCALL=y.

[1] https://lore.kernel.org/linux-mips/09d713a59665d745e21d021deeaebe0a@dlink.ru/

Fixes: 716850ab104d ("MIPS: eBPF: Initial eBPF support for MIPS32 architecture.")
Cc: <stable@vger.kernel.org> # v5.2+
Signed-off-by: Alexander Lobakin <alobakin@dlink.ru>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Hassan Naveed <hnaveed@wavecomp.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: bpf@vger.kernel.org

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 90ee2ed463a813bee3dccd8122d13cbfbdd10453..827bbda105f393b4c5604e6d871bb90a4d110ed1 100644 (file)
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -47,7 +47,7 @@ config MIPS
        select HAVE_ARCH_TRACEHOOK
        select HAVE_ARCH_TRANSPARENT_HUGEPAGE if CPU_SUPPORTS_HUGEPAGES
        select HAVE_ASM_MODVERSIONS
-       select HAVE_EBPF_JIT if (64BIT && !CPU_MICROMIPS)
+       select HAVE_EBPF_JIT if 64BIT && !CPU_MICROMIPS && TARGET_ISA_REV >= 2
        select HAVE_CONTEXT_TRACKING
        select HAVE_COPY_THREAD_TLS
        select HAVE_C_RECORDMCOUNT

diff --git a/arch/mips/net/ebpf_jit.c b/arch/mips/net/ebpf_jit.c
index 46b76751f3a5fface8c7c2578487a3c043f9c258..a2405d5f7d1e85e2e58deb67eb47f97457ae4ced 100644 (file)
--- a/arch/mips/net/ebpf_jit.c
+++ b/arch/mips/net/ebpf_jit.c
@@ -1803,7 +1803,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
        unsigned int image_size;
        u8 *image_ptr;
 
-       if (!prog->jit_requested || MIPS_ISA_REV < 2)
+       if (!prog->jit_requested)
                return prog;
 
        tmp = bpf_jit_blind_constants(prog);