netdev - [PATCH bpf-next v4 0/3] Add 12-argument support for RV64 bpf trampoline

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Message-Id: <20240518032856.2721688-1-pulehui@huaweicloud.com>
Date: Sat, 18 May 2024 03:28:53 +0000
From: Pu Lehui <pulehui@...weicloud.com>
To: bpf@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	netdev@...r.kernel.org
Cc: Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>,
	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>,
	Björn Töpel <bjorn@...nel.org>,
	Pu Lehui <pulehui@...wei.com>,
	Puranjay Mohan <puranjay@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Menglong Dong <imagedong@...cent.com>,
	Pu Lehui <pulehui@...il.com>
Subject: [PATCH bpf-next v4 0/3] Add 12-argument support for RV64 bpf trampoline

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]

v4:
- Separate many args test logic from tracing_struct. (Daniel)

v3: https://lore.kernel.org/all/20240403072818.1462811-1-pulehui@huaweicloud.com/
- 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/20240403041710.1416369-1-pulehui@huaweicloud.com/
- 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/20240331092405.822571-1-pulehui@huaweicloud.com/

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 | 46 ++++++++-
 .../selftests/bpf/progs/tracing_struct.c      | 54 -----------
 .../bpf/progs/tracing_struct_many_args.c      | 97 +++++++++++++++++++
 6 files changed, 206 insertions(+), 77 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/tracing_struct_many_args.c

-- 
2.34.1