Subject: Re: [PATCH bpf-next v6 0/3] Add 12-argument support for RV64 bpf trampoline

From: Jiri Olsa <[email-masked]>
Date: Tue, 2 Jul 2024 15:57:47 +0200

On Tue, Jul 02, 2024 at 12:19:41PM +0000, Pu Lehui wrote:
> This patch adds 12 function arguments support for riscv64 bpf
> trampoline. The current bpf trampoline supports <= sizeof(u64) bytes
> scalar arguments [0] and <= 16 bytes struct arguments [1]. Therefore, we
> focus on the situation where scalars are at most XLEN bits and
> aggregates whose total size does not exceed 2×XLEN bits in the riscv
> calling convention [2].
> 
> Link: https://elixir.bootlin.com/linux/v6.8/source/kernel/bpf/btf.c#L6184 [0]
> Link: https://elixir.bootlin.com/linux/v6.8/source/kernel/bpf/btf.c#L6769 [1]
> Link: https://github.com/riscv-non-isa/riscv-elf-psabi-doc/releases/download/draft-20230929-e5c800e661a53efe3c2678d71a306323b60eb13b/riscv-abi.pdf [2]
> 
> v6:
> - Remove unnecessary skel detach ops as it will be covered by skel destroy ops.

selftests bits lgtm

Acked-by: Jiri Olsa <[email-masked]>

jirka

> 
> v5: https://lore.kernel.org/all/[email-masked]/
> - Remove unnecessary copyright.
> 
> v4: https://lore.kernel.org/all/[email-masked]/
> - Separate many args test logic from tracing_struct. (Daniel)
> 
> v3: https://lore.kernel.org/all/[email-masked]/
> - Variable and macro name alignment:
>   nr_reg_args: number of args in reg
>   nr_stack_args: number of args on stack
>   RV_MAX_REG_ARGS: macro for riscv max args in reg
> 
> v2: https://lore.kernel.org/all/[email-masked]/
> - Add tracing_struct to DENYLIST.aarch64 while aarch64 does not yet support
>   bpf trampoline with more than 8 args.
> - Change the macro RV_MAX_ARG_REGS to RV_MAX_ARGS_REG to synchronize with
>   the variable definition below.
> - Add some comments for stk_arg_off and magic number of skip slots for loading
>   args on stack.
> 
> v1: https://lore.kernel.org/all/[email-masked]/
> 
> Pu Lehui (3):
>   riscv, bpf: Add 12-argument support for RV64 bpf trampoline
>   selftests/bpf: Factor out many args tests from tracing_struct
>   selftests/bpf: Add testcase where 7th argment is struct
> 
>  arch/riscv/net/bpf_jit_comp64.c               | 66 +++++++++----
>  tools/testing/selftests/bpf/DENYLIST.aarch64  |  1 +
>  .../selftests/bpf/bpf_testmod/bpf_testmod.c   | 19 ++++
>  .../selftests/bpf/prog_tests/tracing_struct.c | 44 ++++++++-
>  .../selftests/bpf/progs/tracing_struct.c      | 54 -----------
>  .../bpf/progs/tracing_struct_many_args.c      | 95 +++++++++++++++++++
>  6 files changed, 202 insertions(+), 77 deletions(-)
>  create mode 100644 tools/testing/selftests/bpf/progs/tracing_struct_many_args.c
> 
> -- 
> 2.34.1
>