From: Eduard Zingerman <eddyz87@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <martin.lau@linux.dev>,
Kernel Team <kernel-team@fb.com>,
Yonghong Song <yonghong.song@linux.dev>,
"Jose E. Marchesi" <jose.marchesi@oracle.com>
Subject: Re: [bpf-next v3 02/12] bpf: no_caller_saved_registers attribute for helper calls
Date: Mon, 15 Jul 2024 22:34:10 -0700 [thread overview]
Message-ID: <b660e0becf9b629a4d236ec5c03b8cc0dcdc2502.camel@gmail.com> (raw)
In-Reply-To: <CAADnVQJ7MAtt-EZLorjuyhoOFijyff7tNDy4-up0L6pjnrZHvg@mail.gmail.com>
On Mon, 2024-07-15 at 18:51 -0700, Alexei Starovoitov wrote:
> On Mon, Jul 15, 2024 at 4:02 PM Eduard Zingerman <eddyz87@gmail.com> wrote:
> >
> > @@ -21771,6 +22058,12 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr, __u3
> > if (ret == 0)
> > ret = check_max_stack_depth(env);
> >
> > + /* might decrease stack depth, keep it before passes that
> > + * allocate additional slots.
> > + */
> > + if (ret == 0)
> > + ret = remove_nocsr_spills_fills(env);
>
> Probably should be before check_max_stack_depth() above :)
I thought about it, unfortunately, that would be a half-measure.
There are two places where verifier reports stack depth errors:
- check_stack_access_within_bounds() checks for access outside
[-MAX_BPF_STACK..0) region within one subprogram;
- check_max_stack_depth() checks accumulated stack depth across
subprogram calls.
It is possible to move remove_nocsr_spills_fills() before
check_max_stack_depth(), but check_stack_access_within_bounds() would
still report errors for nocsr stack slots, because
check_nocsr_stack_contract() and check_stack_access_within_bounds()
are both invoked during main verification pass and contract validation
is not yet finished.
next prev parent reply other threads:[~2024-07-16 5:34 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-15 23:01 [bpf-next v3 00/12] no_caller_saved_registers attribute for helper calls Eduard Zingerman
2024-07-15 23:01 ` [bpf-next v3 01/12] bpf: add a get_helper_proto() utility function Eduard Zingerman
2024-07-15 23:01 ` [bpf-next v3 02/12] bpf: no_caller_saved_registers attribute for helper calls Eduard Zingerman
2024-07-16 1:51 ` Alexei Starovoitov
2024-07-16 5:34 ` Eduard Zingerman [this message]
2024-07-20 2:00 ` Alexei Starovoitov
2024-07-22 18:42 ` Eduard Zingerman
2024-07-15 23:01 ` [bpf-next v3 03/12] bpf, x86, riscv, arm: no_caller_saved_registers for bpf_get_smp_processor_id() Eduard Zingerman
2024-07-15 23:01 ` [bpf-next v3 04/12] selftests/bpf: extract utility function for BPF disassembly Eduard Zingerman
2024-07-15 23:01 ` [bpf-next v3 05/12] selftests/bpf: print correct offset for pseudo calls in disasm_insn() Eduard Zingerman
2024-07-15 23:01 ` [bpf-next v3 06/12] selftests/bpf: no need to track next_match_pos in struct test_loader Eduard Zingerman
2024-07-15 23:01 ` [bpf-next v3 07/12] selftests/bpf: extract test_loader->expect_msgs as a data structure Eduard Zingerman
2024-07-15 23:01 ` [bpf-next v3 08/12] selftests/bpf: allow checking xlated programs in verifier_* tests Eduard Zingerman
2024-07-15 23:01 ` [bpf-next v3 09/12] selftests/bpf: __arch_* macro to limit test cases to specific archs Eduard Zingerman
2024-07-15 23:01 ` [bpf-next v3 10/12] selftests/bpf: test no_caller_saved_registers spill/fill removal Eduard Zingerman
2024-07-15 23:02 ` [bpf-next v3 11/12] bpf: do check_nocsr_stack_contract() for ARG_ANYTHING helper params Eduard Zingerman
2024-07-16 2:00 ` Alexei Starovoitov
2024-07-16 10:03 ` Eduard Zingerman
2024-07-16 18:15 ` Eduard Zingerman
2024-07-20 1:54 ` Alexei Starovoitov
2024-07-20 1:58 ` Eduard Zingerman
2024-07-15 23:02 ` [bpf-next v3 12/12] selftests/bpf: check nocsr contract for bpf_probe_read_kernel() Eduard Zingerman
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