kernel.git/tools/testing/selftests/bpf/progs, branch linux-rolling-lts

bpf: collect only live registers in linked regs

2026-03-12T11:10:02Z

[ Upstream commit 2658a1720a1944fbaeda937000ad2b3c3dfaf1bb ] Fix an inconsistency between func_states_equal() and collect_linked_regs(): - regsafe() uses check_ids() to verify that cached and current states have identical register id mapping. - func_states_equal() calls regsafe() only for registers computed as live by compute_live_registers(). - clean_live_states() is supposed to remove dead registers from cached states, but it can skip states belonging to an iterator-based loop. - collect_linked_regs() collects all registers sharing the same id, ignoring the marks computed by compute_live_registers(). Linked registers are stored in the state's jump history. - backtrack_insn() marks all linked registers for an instruction as precise whenever one of the linked registers is precise. The above might lead to a scenario: - There is an instruction I with register rY known to be dead at I. - Instruction I is reached via two paths: first A, then B. - On path A: - There is an id link between registers rX and rY. - Checkpoint C is created at I. - Linked register set {rX, rY} is saved to the jump history. - rX is marked as precise at I, causing both rX and rY to be marked precise at C. - On path B: - There is no id link between registers rX and rY, otherwise register states are sub-states of those in C. - Because rY is dead at I, check_ids() returns true. - Current state is considered equal to checkpoint C, propagate_precision() propagates spurious precision mark for register rY along the path B. - Depending on a program, this might hit verifier_bug() in the backtrack_insn(), e.g. if rY ∈ [r1..r5] and backtrack_insn() spots a function call. The reproducer program is in the next patch. This was hit by sched_ext scx_lavd scheduler code. Changes in tests: - verifier_scalar_ids.c selftests need modification to preserve some registers as live for __msg() checks. - exceptions_assert.c adjusted to match changes in the verifier log, R0 is dead after conditional instruction and thus does not get range. - precise.c adjusted to match changes in the verifier log, register r9 is dead after comparison and it's range is not important for test. Reported-by: Emil Tsalapatis Fixes: 0fb3cf6110a5 ("bpf: use register liveness information for func_states_equal") Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20260306-linked-regs-and-propagate-precision-v1-1-18e859be570d@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

selftests/bpf: Fix OOB read in dmabuf_collector

2026-03-12T11:09:21Z

[ Upstream commit 6881af27f9ea0f5ca8f606f573ef5cc25ca31fe4 ] Dmabuf name allocations can be less than DMA_BUF_NAME_LEN characters, but bpf_probe_read_kernel always tries to read exactly that many bytes. If a name is less than DMA_BUF_NAME_LEN characters, bpf_probe_read_kernel will read past the end. bpf_probe_read_kernel_str stops at the first NUL terminator so use it instead, like iter_dmabuf_for_each already does. Fixes: ae5d2c59ecd7 ("selftests/bpf: Add test for dmabuf_iter") Reported-by: Jerome Lee Signed-off-by: T.J. Mercier Link: https://lore.kernel.org/r/20260225003349.113746-1-tjmercier@google.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

selftests/bpf: Test bpf_skb_check_mtu(BPF_MTU_CHK_SEGS) when transport_header is not set

2026-02-26T22:59:47Z

commit 6cc73f35406cae1f053e984e8de40e6dc9681446 upstream. Add a test to check that bpf_skb_check_mtu(BPF_MTU_CHK_SEGS) is rejected (-EINVAL) if skb->transport_header is not set. The test needs to lower the MTU of the loopback device. Thus, take this opportunity to run the test in a netns by adding "ns_" to the test name. The "serial_" prefix can then be removed. Signed-off-by: Martin KaFai Lau Link: https://lore.kernel.org/r/20251112232331.1566074-2-martin.lau@linux.dev Signed-off-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman

selftests/bpf: Fix selftest verif_scale_strobemeta failure with llvm22

2026-01-23T10:21:23Z

commit 4f8543b5f20f851cedbb23f8eade159871d84e2a upstream. With latest llvm22, I hit the verif_scale_strobemeta selftest failure below: $ ./test_progs -n 618 libbpf: prog 'on_event': BPF program load failed: -E2BIG libbpf: prog 'on_event': -- BEGIN PROG LOAD LOG -- BPF program is too large. Processed 1000001 insn verification time 7019091 usec stack depth 488 processed 1000001 insns (limit 1000000) max_states_per_insn 28 total_states 33927 peak_states 12813 mark_read 0 -- END PROG LOAD LOG -- libbpf: prog 'on_event': failed to load: -E2BIG libbpf: failed to load object 'strobemeta.bpf.o' scale_test:FAIL:expect_success unexpected error: -7 (errno 7) #618 verif_scale_strobemeta:FAIL But if I increase the verificaiton insn limit from 1M to 10M, the above test_progs run actually will succeed. The below is the result from veristat: $ ./veristat strobemeta.bpf.o Processing 'strobemeta.bpf.o'... File Program Verdict Duration (us) Insns States Program size Jited size ---------------- -------- ------- ------------- ------- ------ ------------ ---------- strobemeta.bpf.o on_event success 90250893 9777685 358230 15954 80794 ---------------- -------- ------- ------------- ------- ------ ------------ ---------- Done. Processed 1 files, 0 programs. Skipped 1 files, 0 programs. Further debugging shows the llvm commit [1] is responsible for the verificaiton failure as it tries to convert certain switch statement to if-condition. Such change may cause different transformation compared to original switch statement. In bpf program strobemeta.c case, the initial llvm ir for read_int_var() function is define internal void @read_int_var(ptr noundef %0, i64 noundef %1, ptr noundef %2, ptr noundef %3, ptr noundef %4) #2 !dbg !535 { %6 = alloca ptr, align 8 %7 = alloca i64, align 8 %8 = alloca ptr, align 8 %9 = alloca ptr, align 8 %10 = alloca ptr, align 8 %11 = alloca ptr, align 8 %12 = alloca i32, align 4 ... %20 = icmp ne ptr %19, null, !dbg !561 br i1 %20, label %22, label %21, !dbg !562 21: ; preds = %5 store i32 1, ptr %12, align 4 br label %48, !dbg !563 22: %23 = load ptr, ptr %9, align 8, !dbg !564 ... 47: ; preds = %38, %22 store i32 0, ptr %12, align 4, !dbg !588 br label %48, !dbg !588 48: ; preds = %47, %21 call void @llvm.lifetime.end.p0(ptr %11) #4, !dbg !588 %49 = load i32, ptr %12, align 4 switch i32 %49, label %51 [ i32 0, label %50 i32 1, label %50 ] 50: ; preds = %48, %48 ret void, !dbg !589 51: ; preds = %48 unreachable } Note that the above 'switch' statement is added by clang frontend. Without [1], the switch statement will survive until SelectionDag, so the switch statement acts like a 'barrier' and prevents some transformation involved with both 'before' and 'after' the switch statement. But with [1], the switch statement will be removed during middle end optimization and later middle end passes (esp. after inlining) have more freedom to reorder the code. The following is the related source code: static void *calc_location(struct strobe_value_loc *loc, void *tls_base): bpf_probe_read_user(&tls_ptr, sizeof(void *), dtv); /* if pointer has (void *)-1 value, then TLS wasn't initialized yet */ return tls_ptr && tls_ptr != (void *)-1 ? tls_ptr + tls_index.offset : NULL; In read_int_var() func, we have: void *location = calc_location(&cfg->int_locs[idx], tls_base); if (!location) return; bpf_probe_read_user(value, sizeof(struct strobe_value_generic), location); ... The static func calc_location() is called inside read_int_var(). The asm code without [1]: 77: .123....89 (85) call bpf_probe_read_user#112 78: ........89 (79) r1 = *(u64 *)(r10 -368) 79: .1......89 (79) r2 = *(u64 *)(r10 -8) 80: .12.....89 (bf) r3 = r2 81: .123....89 (0f) r3 += r1 82: ..23....89 (07) r2 += 1 83: ..23....89 (79) r4 = *(u64 *)(r10 -464) 84: ..234...89 (a5) if r2 < 0x2 goto pc+13 85: ...34...89 (15) if r3 == 0x0 goto pc+12 86: ...3....89 (bf) r1 = r10 87: .1.3....89 (07) r1 += -400 88: .1.3....89 (b4) w2 = 16 In this case, 'r2 < 0x2' and 'r3 == 0x0' go to null 'locaiton' place, so the verifier actually prefers to do verification first at 'r1 = r10' etc. The asm code with [1]: 119: .123....89 (85) call bpf_probe_read_user#112 120: ........89 (79) r1 = *(u64 *)(r10 -368) 121: .1......89 (79) r2 = *(u64 *)(r10 -8) 122: .12.....89 (bf) r3 = r2 123: .123....89 (0f) r3 += r1 124: ..23....89 (07) r2 += -1 125: ..23....89 (a5) if r2 < 0xfffffffe goto pc+6 126: ........89 (05) goto pc+17 ... 144: ........89 (b4) w1 = 0 145: .1......89 (6b) *(u16 *)(r8 +80) = r1 In this case, if 'r2 < 0xfffffffe' is true, the control will go to non-null 'location' branch, so 'goto pc+17' will actually go to null 'location' branch. This seems causing tremendous amount of verificaiton state. To fix the issue, rewrite the following code return tls_ptr && tls_ptr != (void *)-1 ? tls_ptr + tls_index.offset : NULL; to if/then statement and hopefully these explicit if/then statements are sticky during middle-end optimizations. Test with llvm20 and llvm21 as well and all strobemeta related selftests are passed. [1] https://github.com/llvm/llvm-project/pull/161000 Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20251014051639.1996331-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov Signed-off-by: Shung-Hsi Yu Signed-off-by: Greg Kroah-Hartman

selftests/bpf: Improve reliability of test_perf_branches_no_hw()

2025-12-18T13:03:11Z

[ Upstream commit ae24fc8a16b0481ea8c5acbc66453c49ec0431c4 ] Currently, test_perf_branches_no_hw() relies on the busy loop within test_perf_branches_common() being slow enough to allow at least one perf event sample tick to occur before starting to tear down the backing perf event BPF program. With a relatively small fixed iteration count of 1,000,000, this is not guaranteed on modern fast CPUs, resulting in the test run to subsequently fail with the following: bpf_testmod.ko is already unloaded. Loading bpf_testmod.ko... Successfully loaded bpf_testmod.ko. test_perf_branches_common:PASS:test_perf_branches_load 0 nsec test_perf_branches_common:PASS:attach_perf_event 0 nsec test_perf_branches_common:PASS:set_affinity 0 nsec check_good_sample:PASS:output not valid 0 nsec check_good_sample:PASS:read_branches_size 0 nsec check_good_sample:PASS:read_branches_stack 0 nsec check_good_sample:PASS:read_branches_stack 0 nsec check_good_sample:PASS:read_branches_global 0 nsec check_good_sample:PASS:read_branches_global 0 nsec check_good_sample:PASS:read_branches_size 0 nsec test_perf_branches_no_hw:PASS:perf_event_open 0 nsec test_perf_branches_common:PASS:test_perf_branches_load 0 nsec test_perf_branches_common:PASS:attach_perf_event 0 nsec test_perf_branches_common:PASS:set_affinity 0 nsec check_bad_sample:FAIL:output not valid no valid sample from prog Summary: 0/1 PASSED, 0 SKIPPED, 1 FAILED Successfully unloaded bpf_testmod.ko. On a modern CPU (i.e. one with a 3.5 GHz clock rate), executing 1 million increments of a volatile integer can take significantly less than 1 millisecond. If the spin loop and detachment of the perf event BPF program elapses before the first 1 ms sampling interval elapses, the perf event will never end up firing. Fix this by bumping the loop iteration counter a little within test_perf_branches_common(), along with ensuring adding another loop termination condition which is directly influenced by the backing perf event BPF program executing. Notably, a concious decision was made to not adjust the sample_freq value as that is just not a reliable way to go about fixing the problem. It effectively still leaves the race window open. Fixes: 67306f84ca78c ("selftests/bpf: Add bpf_read_branch_records() selftest") Signed-off-by: Matt Bobrowski Reviewed-by: Jiri Olsa Link: https://lore.kernel.org/r/20251119143540.2911424-1-mattbobrowski@google.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

selftests/bpf: Test widen_imprecise_scalars() with different stack depth

2025-11-14T17:26:28Z

A test case for a situation when widen_imprecise_scalars() is called with old->allocated_stack > cur->allocated_stack. Test structure: def widening_stack_size_bug(): r1 = 0 for r6 in 0..1: iterator_with_diff_stack_depth(r1) r1 = 42 def iterator_with_diff_stack_depth(r1): if r1 != 42: use 128 bytes of stack iterator based loop iterator_with_diff_stack_depth() is verified with r1 == 0 first and r1 == 42 next. Causing stack usage of 128 bytes on a first visit and 8 bytes on a second. Such arrangement triggered a KASAN error in widen_imprecise_scalars(). Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20251114025730.772723-2-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov

selftests/bpf: Add mptcp test with sockmap

2025-11-13T21:18:25Z

Add test cases to verify that when MPTCP falls back to plain TCP sockets, they can properly work with sockmap. Additionally, add test cases to ensure that sockmap correctly rejects MPTCP sockets as expected. Signed-off-by: Jiayuan Chen Signed-off-by: Martin KaFai Lau Acked-by: Matthieu Baerts (NGI0) Link: https://patch.msgid.link/20251111060307.194196-4-jiayuan.chen@linux.dev

selftests/bpf: Add stacktrace ips test for raw_tp

2025-11-06T01:05:19Z

Adding test that verifies we get expected initial 2 entries from stacktrace for rawtp probe via ORC unwind. Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20251104215405.168643-5-jolsa@kernel.org Signed-off-by: Alexei Starovoitov Acked-by: Steven Rostedt (Google)

selftests/bpf: Add stacktrace ips test for kprobe_multi/kretprobe_multi

2025-11-06T01:05:19Z

Adding test that attaches kprobe/kretprobe multi and verifies the ORC stacktrace matches expected functions. Adding bpf_testmod_stacktrace_test function to bpf_testmod kernel module which is called through several functions so we get reliable call path for stacktrace. The test is only for ORC unwinder to keep it simple. Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20251104215405.168643-4-jolsa@kernel.org Signed-off-by: Alexei Starovoitov Acked-by: Steven Rostedt (Google)

bpf: add _impl suffix for bpf_stream_vprintk() kfunc

2025-11-05T01:50:25Z

Rename bpf_stream_vprintk() to bpf_stream_vprintk_impl(). This makes bpf_stream_vprintk() follow the already established "_impl" suffix-based naming convention for kfuncs with the bpf_prog_aux argument provided by the verifier implicitly. This convention will be taken advantage of with the upcoming KF_IMPLICIT_ARGS feature to preserve backwards compatibility to BPF programs. Acked-by: Andrii Nakryiko Signed-off-by: Mykyta Yatsenko Link: https://lore.kernel.org/r/20251104-implv2-v3-2-4772b9ae0e06@meta.com Signed-off-by: Alexei Starovoitov Acked-by: Ihor Solodrai