From: Jakub Sitnicki <jakub@cloudflare.com>
To: John Fastabend <john.fastabend@gmail.com>
Cc: daniel@iogearbox.net, bpf@vger.kernel.org,
netdev@vger.kernel.org, edumazet@google.com, ast@kernel.org,
andrii@kernel.org, will@isovalent.com
Subject: Re: [PATCH bpf v10 14/14] bpf: sockmap, test progs verifier error with latest clang
Date: Tue, 23 May 2023 12:00:07 +0200 [thread overview]
Message-ID: <87wn0z5pl1.fsf@cloudflare.com> (raw)
In-Reply-To: <20230523025618.113937-15-john.fastabend@gmail.com>
On Mon, May 22, 2023 at 07:56 PM -07, John Fastabend wrote:
> With a relatively recent clang (7090c10273119) and with this commit
> to fix warnings in selftests (c8ed668593972) that uses __sink(err)
> to resolve unused variables. We get the following verifier error.
>
> root@6e731a24b33a:/host/tools/testing/selftests/bpf# ./test_sockmap
> libbpf: prog 'bpf_sockmap': BPF program load failed: Permission denied
> libbpf: prog 'bpf_sockmap': -- BEGIN PROG LOAD LOG --
> 0: R1=ctx(off=0,imm=0) R10=fp0
> ; op = (int) skops->op;
> 0: (61) r2 = *(u32 *)(r1 +0) ; R1=ctx(off=0,imm=0) R2_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff))
> ; switch (op) {
> 1: (16) if w2 == 0x4 goto pc+5 ; R2_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff))
> 2: (56) if w2 != 0x5 goto pc+15 ; R2_w=5
> ; lport = skops->local_port;
> 3: (61) r2 = *(u32 *)(r1 +68) ; R1=ctx(off=0,imm=0) R2_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff))
> ; if (lport == 10000) {
> 4: (56) if w2 != 0x2710 goto pc+13 18: R1=ctx(off=0,imm=0) R2=scalar(umax=4294967295,var_off=(0x0; 0xffffffff)) R10=fp0
> ; __sink(err);
> 18: (bc) w1 = w0
> R0 !read_ok
> processed 18 insns (limit 1000000) max_states_per_insn 0 total_states 2 peak_states 2 mark_read 1
> -- END PROG LOAD LOG --
> libbpf: prog 'bpf_sockmap': failed to load: -13
> libbpf: failed to load object 'test_sockmap_kern.bpf.o'
> load_bpf_file: (-1) No such file or directory
> ERROR: (-1) load bpf failed
> libbpf: prog 'bpf_sockmap': BPF program load failed: Permission denied
> libbpf: prog 'bpf_sockmap': -- BEGIN PROG LOAD LOG --
> 0: R1=ctx(off=0,imm=0) R10=fp0
> ; op = (int) skops->op;
> 0: (61) r2 = *(u32 *)(r1 +0) ; R1=ctx(off=0,imm=0) R2_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff))
> ; switch (op) {
> 1: (16) if w2 == 0x4 goto pc+5 ; R2_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff))
> 2: (56) if w2 != 0x5 goto pc+15 ; R2_w=5
> ; lport = skops->local_port;
> 3: (61) r2 = *(u32 *)(r1 +68) ; R1=ctx(off=0,imm=0) R2_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff))
> ; if (lport == 10000) {
> 4: (56) if w2 != 0x2710 goto pc+13 18: R1=ctx(off=0,imm=0) R2=scalar(umax=4294967295,var_off=(0x0; 0xffffffff)) R10=fp0
> ; __sink(err);
> 18: (bc) w1 = w0
> R0 !read_ok
> processed 18 insns (limit 1000000) max_states_per_insn 0 total_states 2 peak_states 2 mark_read 1
> -- END PROG LOAD LOG --
> libbpf: prog 'bpf_sockmap': failed to load: -13
> libbpf: failed to load object 'test_sockhash_kern.bpf.o'
> load_bpf_file: (-1) No such file or directory
> ERROR: (-1) load bpf failed
> libbpf: prog 'bpf_sockmap': BPF program load failed: Permission denied
> libbpf: prog 'bpf_sockmap': -- BEGIN PROG LOAD LOG --
> 0: R1=ctx(off=0,imm=0) R10=fp0
> ; op = (int) skops->op;
> 0: (61) r2 = *(u32 *)(r1 +0) ; R1=ctx(off=0,imm=0) R2_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff))
> ; switch (op) {
> 1: (16) if w2 == 0x4 goto pc+5 ; R2_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff))
> 2: (56) if w2 != 0x5 goto pc+15 ; R2_w=5
> ; lport = skops->local_port;
> 3: (61) r2 = *(u32 *)(r1 +68) ; R1=ctx(off=0,imm=0) R2_w=scalar(umax=4294967295,var_off=(0x0; 0xffffffff))
> ; if (lport == 10000) {
> 4: (56) if w2 != 0x2710 goto pc+13 18: R1=ctx(off=0,imm=0) R2=scalar(umax=4294967295,var_off=(0x0; 0xffffffff)) R10=fp0
> ; __sink(err);
> 18: (bc) w1 = w0
> R0 !read_ok
> processed 18 insns (limit 1000000) max_states_per_insn 0 total_states 2 peak_states 2 mark_read 1
> -- END PROG LOAD LOG --
>
> To fix simply remove the err value because its not actually used anywhere
> in the testing. We can investigate the root cause later. Future patch should
> probably actually test the err value as well. Although if the map updates
> fail they will get caught eventually by userspace.
>
> Fixes: c8ed668593972 ("selftests/bpf: fix lots of silly mistakes pointed out by compiler")
> Signed-off-by: John Fastabend <john.fastabend@gmail.com>
> ---
I think the problem is that err is not initialized when we hit the default
switch branch. And __sink() generates a read.
Since we don't really consume the error value, this fix LGTM.
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
next prev parent reply other threads:[~2023-05-23 10:06 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-23 2:56 [PATCH bpf v10 00/14] bpf sockmap fixes John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 01/14] bpf: sockmap, pass skb ownership through read_skb John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 02/14] bpf: sockmap, convert schedule_work into delayed_work John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 03/14] bpf: sockmap, reschedule is now done through backlog John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 04/14] bpf: sockmap, improved check for empty queue John Fastabend
2023-05-23 7:35 ` Jakub Sitnicki
2023-05-23 2:56 ` [PATCH bpf v10 05/14] bpf: sockmap, handle fin correctly John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 06/14] bpf: sockmap, TCP data stall on recv before accept John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 07/14] bpf: sockmap, wake up polling after data copy John Fastabend
2023-05-30 6:30 ` Eric Dumazet
2023-05-30 18:34 ` John Fastabend
2023-05-30 18:43 ` John Fastabend
2023-05-30 18:51 ` Eric Dumazet
2023-05-23 2:56 ` [PATCH bpf v10 08/14] bpf: sockmap, incorrectly handling copied_seq John Fastabend
2023-05-23 9:09 ` Jakub Sitnicki
2023-05-23 2:56 ` [PATCH bpf v10 09/14] bpf: sockmap, pull socket helpers out of listen test for general use John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 10/14] bpf: sockmap, build helper to create connected socket pair John Fastabend
2023-05-23 9:23 ` Jakub Sitnicki
2023-05-23 2:56 ` [PATCH bpf v10 11/14] bpf: sockmap, test shutdown() correctly exits epoll and recv()=0 John Fastabend
2023-05-23 9:41 ` Jakub Sitnicki
2023-05-23 2:56 ` [PATCH bpf v10 12/14] bpf: sockmap, test FIONREAD returns correct bytes in rx buffer John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 13/14] bpf: sockmap, test FIONREAD returns correct bytes in rx buffer with drops John Fastabend
2023-05-23 2:56 ` [PATCH bpf v10 14/14] bpf: sockmap, test progs verifier error with latest clang John Fastabend
2023-05-23 10:00 ` Jakub Sitnicki [this message]
2023-05-23 14:31 ` [PATCH bpf v10 00/14] bpf sockmap fixes Daniel Borkmann
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