From: Conor Dooley <conor@kernel.org>
To: Pu Lehui <pulehui@huaweicloud.com>
Cc: bpf@vger.kernel.org, linux-riscv@lists.infradead.org,
netdev@vger.kernel.org, "Björn Töpel" <bjorn@kernel.org>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Martin KaFai Lau" <martin.lau@linux.dev>,
"Song Liu" <song@kernel.org>, "Yonghong Song" <yhs@fb.com>,
"John Fastabend" <john.fastabend@gmail.com>,
"KP Singh" <kpsingh@kernel.org>,
"Stanislav Fomichev" <sdf@google.com>,
"Hao Luo" <haoluo@google.com>, "Jiri Olsa" <jolsa@kernel.org>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Luke Nelson" <luke.r.nels@gmail.com>,
"Pu Lehui" <pulehui@huawei.com>
Subject: Re: [PATCH bpf-next 4/4] riscv, bpf: Mixing bpf2bpf and tailcalls
Date: Tue, 19 Sep 2023 11:54:59 +0100 [thread overview]
Message-ID: <20230919-aefdbac65c773c6f02aedc76@fedora> (raw)
In-Reply-To: <20230919-4734211982e4e411a93650a7@fedora>
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On Tue, Sep 19, 2023 at 11:04:53AM +0100, Conor Dooley wrote:
> On Tue, Sep 19, 2023 at 11:57:11AM +0800, Pu Lehui wrote:
> > From: Pu Lehui <pulehui@huawei.com>
> >
> > In the current RV64 JIT, if we just don't initialize the TCC in subprog,
> > the TCC can be propagated from the parent process to the subprocess, but
> > the TCC of the parent process cannot be restored when the subprocess
> > exits. Since the RV64 TCC is initialized before saving the callee saved
> > registers into the stack, we cannot use the callee saved register to
> > pass the TCC, otherwise the original value of the callee saved register
> > will be destroyed. So we implemented mixing bpf2bpf and tailcalls
> > similar to x86_64, i.e. using a non-callee saved register to transfer
> > the TCC between functions, and saving that register to the stack to
> > protect the TCC value. At the same time, we also consider the scenario
> > of mixing trampoline.
> >
> > Tests test_bpf.ko and test_verifier have passed, as well as the relative
> > testcases of test_progs*.
> >
> > Signed-off-by: Pu Lehui <pulehui@huawei.com>
>
> Breaks the build:
> ../arch/riscv/net/bpf_jit_comp64.c:846:14: error: use of undeclared identifier 'BPF_TRAMP_F_TAIL_CALL_CTX'
Probably should have specified, happens with allmodconfig, but not a
defconfig build.
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next prev parent reply other threads:[~2023-09-19 10:55 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-19 3:57 [PATCH bpf-next 0/4] Mixing bpf2bpf and tailcalls for RV64 Pu Lehui
2023-09-19 3:57 ` [PATCH bpf-next 1/4] riscv, bpf: Remove redundant ctx->offset initialization Pu Lehui
2023-09-19 3:57 ` [PATCH bpf-next 2/4] riscv, bpf: Using kvcalloc to allocate cache buffer Pu Lehui
2023-09-19 3:57 ` [PATCH bpf-next 3/4] riscv, bpf: Add RV_TAILCALL_OFFSET macro to format tailcall offset Pu Lehui
2023-09-19 3:57 ` [PATCH bpf-next 4/4] riscv, bpf: Mixing bpf2bpf and tailcalls Pu Lehui
2023-09-19 10:04 ` Conor Dooley
2023-09-19 10:54 ` Conor Dooley [this message]
2023-09-19 11:23 ` Pu Lehui
2023-09-19 11:50 ` Conor Dooley
2023-09-19 12:01 ` Pu Lehui
2023-09-28 9:59 ` Björn Töpel
2023-09-28 10:39 ` Pu Lehui
2024-01-16 14:21 ` Pu Lehui
2024-01-30 8:29 ` Björn Töpel
2024-01-30 9:14 ` Pu Lehui
2024-01-30 13:28 ` Björn Töpel
2024-01-30 14:10 ` Pu Lehui
2024-01-30 16:03 ` Björn Töpel
2024-01-31 9:18 ` Pu Lehui
2024-01-30 3:26 ` Pu Lehui
2023-09-26 13:30 ` [PATCH bpf-next 0/4] Mixing bpf2bpf and tailcalls for RV64 Björn Töpel
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