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SubjectRe: [PATCH bpf-next v6 0/4] bpf trampoline for arm64
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Hey Mark,

On 6/25/22 6:12 PM, Xu Kuohai wrote:
> This patchset introduces bpf trampoline on arm64. A bpf trampoline converts
> native calling convention to bpf calling convention and is used to implement
> various bpf features, such as fentry, fexit, fmod_ret and struct_ops.
>
> The trampoline introduced does essentially the same thing as the bpf
> trampoline does on x86.
>
> Tested on raspberry pi 4b and qemu:
>
> #18 /1 bpf_tcp_ca/dctcp:OK
> #18 /2 bpf_tcp_ca/cubic:OK
> #18 /3 bpf_tcp_ca/invalid_license:OK
> #18 /4 bpf_tcp_ca/dctcp_fallback:OK
> #18 /5 bpf_tcp_ca/rel_setsockopt:OK
> #18 bpf_tcp_ca:OK
> #51 /1 dummy_st_ops/dummy_st_ops_attach:OK
> #51 /2 dummy_st_ops/dummy_init_ret_value:OK
> #51 /3 dummy_st_ops/dummy_init_ptr_arg:OK
> #51 /4 dummy_st_ops/dummy_multiple_args:OK
> #51 dummy_st_ops:OK
> #57 /1 fexit_bpf2bpf/target_no_callees:OK
> #57 /2 fexit_bpf2bpf/target_yes_callees:OK
> #57 /3 fexit_bpf2bpf/func_replace:OK
> #57 /4 fexit_bpf2bpf/func_replace_verify:OK
> #57 /5 fexit_bpf2bpf/func_sockmap_update:OK
> #57 /6 fexit_bpf2bpf/func_replace_return_code:OK
> #57 /7 fexit_bpf2bpf/func_map_prog_compatibility:OK
> #57 /8 fexit_bpf2bpf/func_replace_multi:OK
> #57 /9 fexit_bpf2bpf/fmod_ret_freplace:OK
> #57 fexit_bpf2bpf:OK
> #237 xdp_bpf2bpf:OK
>
> v6:
> - Since Mark is refactoring arm64 ftrace to support long jump and reduce the
> ftrace trampoline overhead, it's not clear how we'll attach bpf trampoline
> to regular kernel functions, so remove ftrace related patches for now.
> - Add long jump support for attaching bpf trampoline to bpf prog, since bpf
> trampoline and bpf prog are allocated via vmalloc, there is chance the
> distance exceeds the max branch range.
> - Collect ACK/Review-by, not sure if the ACK and Review-bys for bpf_arch_text_poke()
> should be kept, since the changes to it is not trivial
> - Update some commit messages and comments

Given you've been taking a look and had objections in v5, would be great if you
can find some cycles for this v6.

Thanks a lot,
Daniel

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