From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: "Anton Protopopov" <a.s.protopopov@gmail.com>
Cc: <bpf@vger.kernel.org>, <daniel@iogearbox.net>,
<andrii@kernel.org>, <eddyz87@gmail.com>, <memxor@gmail.com>
Subject: Re: [PATCH v2 bpf-next 00/13] bpf: fmod_ret for each function that returns errors
Date: Fri, 13 Nov 2026 16:37:54 +0000 [thread overview]
Message-ID: <DMU8B4CMIGA2.1SOSYSZO7ZY6A@gmail.com> (raw)
In-Reply-To: <avcJ4OWW99bwMlCP@mail.gmail.com>
On Fri, Nov 13, 2026 at 05:00 AM Anton Protopopov <a.s.protopopov@gmail.com> wrote:
> We can have a bit more targets via functions returning ERR_PTR(-errno), plus
> maybe stuff like "if (err == -EINVAL) goto out", but maybe it was simpler
> at IR (see 'bpf: Follow PHIs in bpf_scan_ir' in v3). All this is follow-ups.
Thanks a ton for initial idea and quick reviews.
ERR_PTR() shouldn't be difficult.
"mov $-22,%rax" is a constant in the return value
register, so the data flow finds it as is. int_return_size() skips such
functions today. Just relaxing that part will solve it in decompiler,
but then the verifier need to get smarter in check_fmodret_retval().
> One nit I've just remebered: why to tag functions which aren't attachable?
> My old code stripped them out, they only take space and will be rejected
> in any case.
Makes sense. Will drop them in the next version.
It's 537 of the 12633 tags.
> I've also tested v2 on my x86.
Thanks for testing!
prev parent reply other threads:[~2026-11-13 16:37 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-13 5:08 [PATCH v2 bpf-next 00/13] bpf: fmod_ret for each function that returns errors Alexei Starovoitov
2026-11-13 5:08 ` [PATCH v2 bpf-next 01/13] selftests/bpf: Don't depend on the width of a BTF id in verifier_live_stack Alexei Starovoitov
2026-11-13 11:13 ` Anton Protopopov
2026-11-13 5:08 ` [PATCH v2 bpf-next 02/13] resolve_btfids: Read the code of an ELF file by address Alexei Starovoitov
2026-11-13 5:08 ` [PATCH v2 bpf-next 03/13] resolve_btfids: Describe machine instructions with LLVM's MC layer Alexei Starovoitov
2026-11-13 11:45 ` Anton Protopopov
2026-11-13 5:08 ` [PATCH v2 bpf-next 04/13] resolve_btfids: Find the definitions that reach the return value Alexei Starovoitov
2026-11-13 5:08 ` [PATCH v2 bpf-next 05/13] resolve_btfids: Tag the functions that return errors Alexei Starovoitov
2026-11-13 5:08 ` [PATCH v2 bpf-next 06/13] resolve_btfids: Fold the constants of a select without a branch Alexei Starovoitov
2026-11-13 11:59 ` Anton Protopopov
2026-11-13 5:08 ` [PATCH v2 bpf-next 07/13] resolve_btfids: Say which registers an instruction reads Alexei Starovoitov
2026-11-13 12:03 ` Anton Protopopov
2026-11-13 5:08 ` [PATCH v2 bpf-next 08/13] resolve_btfids: Don't list an error that follows work on an argument Alexei Starovoitov
2026-11-13 5:52 ` bot+bpf-ci
2026-11-13 16:15 ` Alexei Starovoitov
2026-11-13 12:14 ` Anton Protopopov
2026-11-13 5:08 ` [PATCH v2 bpf-next 09/13] bpf: Allow fmod_ret on tagged functions and check the return value Alexei Starovoitov
2026-11-13 5:52 ` bot+bpf-ci
2026-11-13 16:17 ` Alexei Starovoitov
2026-11-13 12:20 ` Anton Protopopov
2026-11-13 16:17 ` Alexei Starovoitov
2026-11-13 5:08 ` [PATCH v2 bpf-next 10/13] selftests/bpf: Test fmod_ret on tagged functions Alexei Starovoitov
2026-11-13 5:08 ` [PATCH v2 bpf-next 11/13] bpf: Mark the arguments of fmod_ret progs as PTR_UNTRUSTED Alexei Starovoitov
2026-11-13 11:09 ` Anton Protopopov
2026-11-13 16:30 ` Alexei Starovoitov
2026-11-13 5:09 ` [PATCH v2 bpf-next 12/13] bpf: Treat the type of an untrusted pointer as a hint Alexei Starovoitov
2026-11-13 5:52 ` bot+bpf-ci
2026-11-13 16:33 ` Alexei Starovoitov
2026-11-13 5:09 ` [PATCH v2 bpf-next 13/13] selftests/bpf: Test untrusted pointers in fmod_ret progs Alexei Starovoitov
2026-11-13 13:00 ` [PATCH v2 bpf-next 00/13] bpf: fmod_ret for each function that returns errors Anton Protopopov
2026-11-13 16:37 ` Alexei Starovoitov [this message]
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