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References: <20240325155434.65589-1-puranjay12@gmail.com> <20240325155434.65589-3-puranjay12@gmail.com>
 <20240325-nineteen-unvaried-cb5cb5fd3a73@spud>
In-Reply-To: <20240325-nineteen-unvaried-cb5cb5fd3a73@spud>
From: Puranjay Mohan <puranjay12@gmail.com>
Date: Mon, 25 Mar 2024 20:13:10 +0100
Message-ID: <CANk7y0gWtwN7EJ24aoY9-RB9629d5Ks-9fMc3wnAAjjERcZhFw@mail.gmail.com>
Subject: Re: [PATCH bpf-next v2 2/2] bpf,riscv: Implement bpf_addr_space_cast instruction
To: Conor Dooley <conor@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, 
	Andrii Nakryiko <andrii@kernel.org>, Martin KaFai Lau <martin.lau@linux.dev>, 
	Eduard Zingerman <eddyz87@gmail.com>, Song Liu <song@kernel.org>, 
	Yonghong Song <yonghong.song@linux.dev>, 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>, =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn@kernel.org>, 
	Luke Nelson <luke.r.nels@gmail.com>, Xi Wang <xi.wang@gmail.com>, 
	Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, 
	Albert Ou <aou@eecs.berkeley.edu>, bpf@vger.kernel.org, 
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, 
	Pu Lehui <pulehui@huaweicloud.com>
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On Mon, Mar 25, 2024 at 8:10=E2=80=AFPM Conor Dooley <conor@kernel.org> wro=
te:
>
> On Mon, Mar 25, 2024 at 03:54:34PM +0000, Puranjay Mohan wrote:
> > LLVM generates bpf_addr_space_cast instruction while translating
> > pointers between native (zero) address space and
> > __attribute__((address_space(N))). The addr_space=3D0 is reserved as
> > bpf_arena address space.
> >
> > rY =3D addr_space_cast(rX, 0, 1) is processed by the verifier and
> > converted to normal 32-bit move: wX =3D wY
> >
> > rY =3D addr_space_cast(rX, 1, 0) has to be converted by JIT.
> >
> > Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
>
> Doesn't compile for allmodconfig:
>   ../arch/riscv/net/bpf_jit_comp64.c:1086:7: error: call to undeclared fu=
nction 'insn_is_cast_user'; ISO C99 and later do not support implicit funct=
ion declarations [-Wimplicit-function-declaration]
>
> Cheers,
> Conor.

Yes,
I mentioned in the cover letter that a patch is required.
It just got merged in bpf-next/master:
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=
=3D770546ae9f4c1ae1ebcaf0874f0dd9631d77ec97

So, rebasing on the latest bpf-next/master should fix the issue.

Thanks,
Puranjay