riscv, bpf: Add bpf_arch_text_poke support for RV64

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Implement bpf_arch_text_poke for RV64. For call scenario, to make BPF
trampoline compatible with the kernel and BPF context, we follow the
framework of RV64 ftrace to reserve 4 nops for BPF programs as function
entry, and use auipc+jalr instructions for function call. However, since
auipc+jalr call instruction is non-atomic operation, we need to use
stop-machine to make sure instructions patching in atomic context. Also,
we use auipc+jalr pair and need to patch in stop-machine context for
jump scenario.

Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Acked-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/bpf/20230215135205.1411105-4-pulehui@huaweicloud.com

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Pu Lehui 2023-02-15 21:52:04 +08:00 • committed by Daniel Borkmann

parent 0fd1fd0104

commit 596f2e6f9c

2 changed files with 91 additions and 2 deletions

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5

arch/riscv/net/bpf_jit.h

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88

arch/riscv/net/bpf_jit_comp64.c

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