linux-kernel - [PATCH bpf-next 0/2] Jit BPF_CALL to direct call when possible

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Message-Id: <20220902152043.721806-1-xukuohai@huaweicloud.com>
Date:   Fri,  2 Sep 2022 11:20:40 -0400
From:   Xu Kuohai <xukuohai@...weicloud.com>
To:     bpf@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <martin.lau@...ux.dev>,
        Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Stanislav Fomichev <sdf@...gle.com>,
        Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
        Zi Shen Lim <zlim.lnx@...il.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>
Subject: [PATCH bpf-next 0/2] Jit BPF_CALL to direct call when possible

Currently BPF_CALL is always jited to indirect call, but when target is
in the range of direct call, a BPF_CALL can be jited to direct call.

For example, the following BPF_CALL

    call __htab_map_lookup_elem

is always jited to an indirect call:

    mov     x10, #0xffffffffffff18f4
    movk    x10, #0x821, lsl #16
    movk    x10, #0x8000, lsl #32
    blr     x10

When the target is in the range of a direct call, it can be jited to:

    bl      0xfffffffffd33bc98

This patchset does such jit.

Xu Kuohai (2):
  bpf, arm64: Jit BPF_CALL to direct call when possible
  bpf, arm64: Eliminate false -EFBIG error in bpf trampoline

 arch/arm64/net/bpf_jit_comp.c | 136 ++++++++++++++++++++++------------
 1 file changed, 87 insertions(+), 49 deletions(-)

-- 
2.30.2