From f726e03564ef4e754dd93beb54303e2e1671049e Mon Sep 17 00:00:00 2001 From: John Fastabend Date: Mon, 22 May 2023 19:56:18 -0700 Subject: [PATCH] bpf, sockmap: Test progs verifier error with latest clang 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 Signed-off-by: Daniel Borkmann Reviewed-by: Jakub Sitnicki Link: https://lore.kernel.org/bpf/20230523025618.113937-15-john.fastabend@gmail.com --- .../testing/selftests/bpf/progs/test_sockmap_kern.h | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/test_sockmap_kern.h b/tools/testing/selftests/bpf/progs/test_sockmap_kern.h index baf9ebc6d903..99d2ea9fb658 100644 --- a/tools/testing/selftests/bpf/progs/test_sockmap_kern.h +++ b/tools/testing/selftests/bpf/progs/test_sockmap_kern.h @@ -191,7 +191,7 @@ SEC("sockops") int bpf_sockmap(struct bpf_sock_ops *skops) { __u32 lport, rport; - int op, err, ret; + int op, ret; op = (int) skops->op; @@ -203,10 +203,10 @@ int bpf_sockmap(struct bpf_sock_ops *skops) if (lport == 10000) { ret = 1; #ifdef SOCKMAP - err = bpf_sock_map_update(skops, &sock_map, &ret, + bpf_sock_map_update(skops, &sock_map, &ret, BPF_NOEXIST); #else - err = bpf_sock_hash_update(skops, &sock_map, &ret, + bpf_sock_hash_update(skops, &sock_map, &ret, BPF_NOEXIST); #endif } @@ -218,10 +218,10 @@ int bpf_sockmap(struct bpf_sock_ops *skops) if (bpf_ntohl(rport) == 10001) { ret = 10; #ifdef SOCKMAP - err = bpf_sock_map_update(skops, &sock_map, &ret, + bpf_sock_map_update(skops, &sock_map, &ret, BPF_NOEXIST); #else - err = bpf_sock_hash_update(skops, &sock_map, &ret, + bpf_sock_hash_update(skops, &sock_map, &ret, BPF_NOEXIST); #endif } @@ -230,8 +230,6 @@ int bpf_sockmap(struct bpf_sock_ops *skops) break; } - __sink(err); - return 0; } -- 2.34.1