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| author | Alexei Starovoitov <ast@kernel.org> | 2023-03-15 01:28:11 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-03-15 01:28:11 +0300 |
| commit | 3c2611bac08a834697be918ac357eaff2e47d5b3 (patch) | |
| tree | c2664c03c90c3fcde68eafd78437d29cae82369e | |
| parent | 5584d9e63eee25c6ccf36aa5d09efc113d762a05 (diff) | |
| download | linux-3c2611bac08a834697be918ac357eaff2e47d5b3.tar.xz | |
selftests/bpf: Fix trace_virtqueue_add_sgs test issue with LLVM 17.
LLVM commit https://reviews.llvm.org/D143726 introduced hoistMinMax optimization
that transformed
(i < VIRTIO_MAX_SGS) && (i < out_sgs)
into
i < MIN(VIRTIO_MAX_SGS, out_sgs)
and caused the verifier to stop recognizing such loop as bounded.
Which resulted in the following test failure:
libbpf: prog 'trace_virtqueue_add_sgs': BPF program load failed: Bad address
libbpf: prog 'trace_virtqueue_add_sgs': -- BEGIN PROG LOAD LOG --
The sequence of 8193 jumps is too complex.
verification time 789206 usec
stack depth 56
processed 156446 insns (limit 1000000) max_states_per_insn 7 total_states 1746 peak_states 1701 mark_read 12
-- END PROG LOAD LOG --
libbpf: prog 'trace_virtqueue_add_sgs': failed to load: -14
libbpf: failed to load object 'loop6.bpf.o'
Workaround the verifier limitation for now with inline asm that
prevents this particular optimization.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
| -rw-r--r-- | tools/testing/selftests/bpf/progs/loop6.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/loop6.c b/tools/testing/selftests/bpf/progs/loop6.c index 38de0331e6b4..e4ff97fbcce1 100644 --- a/tools/testing/selftests/bpf/progs/loop6.c +++ b/tools/testing/selftests/bpf/progs/loop6.c @@ -5,6 +5,7 @@ #include <linux/bpf.h> #include <bpf/bpf_helpers.h> #include <bpf/bpf_tracing.h> +#include "bpf_misc.h" char _license[] SEC("license") = "GPL"; @@ -76,6 +77,7 @@ int BPF_KPROBE(trace_virtqueue_add_sgs, void *unused, struct scatterlist **sgs, return 0; for (i = 0; (i < VIRTIO_MAX_SGS) && (i < out_sgs); i++) { + __sink(out_sgs); for (n = 0, sgp = get_sgp(sgs, i); sgp && (n < SG_MAX); sgp = __sg_next(sgp)) { bpf_probe_read_kernel(&len, sizeof(len), &sgp->length); @@ -85,6 +87,7 @@ int BPF_KPROBE(trace_virtqueue_add_sgs, void *unused, struct scatterlist **sgs, } for (i = 0; (i < VIRTIO_MAX_SGS) && (i < in_sgs); i++) { + __sink(in_sgs); for (n = 0, sgp = get_sgp(sgs, i); sgp && (n < SG_MAX); sgp = __sg_next(sgp)) { bpf_probe_read_kernel(&len, sizeof(len), &sgp->length); |