From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>,
<martin.lau@kernel.org>
Cc: <andrii@kernel.org>, <kernel-team@meta.com>
Subject: [PATCH v2 bpf-next 09/10] selftests/bpf: validate precision logic in partial_stack_load_preserves_zeros
Date: Mon, 20 Nov 2023 16:22:20 -0800 [thread overview]
Message-ID: <20231121002221.3687787-10-andrii@kernel.org> (raw)
In-Reply-To: <20231121002221.3687787-1-andrii@kernel.org>
Enhance partial_stack_load_preserves_zeros subtest with detailed
precision propagation log checks. We know expect fp-16 to be spilled,
initially imprecise, zero const register, which is later marked as
precise even when partial stack slot load is performed, even if it's not
a register fill (!).
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
.../selftests/bpf/progs/verifier_spill_fill.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
index 60ad2e0247b4..e443009bf9b6 100644
--- a/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
+++ b/tools/testing/selftests/bpf/progs/verifier_spill_fill.c
@@ -491,6 +491,21 @@ char single_byte_buf[1] SEC(".data.single_byte_buf");
SEC("raw_tp")
__log_level(2)
__success
+/* make sure fp-8 is all STACK_ZERO */
+__msg("2: (7a) *(u64 *)(r10 -8) = 0 ; R10=fp0 fp-8_w=00000000")
+/* but fp-16 is spilled IMPRECISE zero const reg */
+__msg("4: (7b) *(u64 *)(r10 -16) = r0 ; R0_w=0 R10=fp0 fp-16_w=0")
+/* and now check that precision propagation works even for such tricky case */
+__msg("9: (71) r2 = *(u8 *)(r10 -9) ; R2_w=P0 R10=fp0 fp-16_w=0")
+__msg("10: (0f) r1 += r2")
+__msg("mark_precise: frame0: last_idx 10 first_idx 0 subseq_idx -1")
+__msg("mark_precise: frame0: regs=r2 stack= before 9: (71) r2 = *(u8 *)(r10 -9)")
+__msg("mark_precise: frame0: regs= stack=-16 before 8: (bf) r1 = r6")
+__msg("mark_precise: frame0: regs= stack=-16 before 7: (0f) r1 += r2")
+__msg("mark_precise: frame0: regs= stack=-16 before 6: (71) r2 = *(u8 *)(r10 -1)")
+__msg("mark_precise: frame0: regs= stack=-16 before 5: (bf) r1 = r6")
+__msg("mark_precise: frame0: regs= stack=-16 before 4: (7b) *(u64 *)(r10 -16) = r0")
+__msg("mark_precise: frame0: regs=r0 stack= before 3: (b7) r0 = 0")
__naked void partial_stack_load_preserves_zeros(void)
{
asm volatile (
--
2.34.1
next prev parent reply other threads:[~2023-11-21 0:23 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-21 0:22 [PATCH v2 bpf-next 00/10] Complete BPF verifier precision tracking support for register spills Andrii Nakryiko
2023-11-21 0:22 ` [PATCH v2 bpf-next 01/10] bpf: support non-r10 register spill/fill to/from stack in precision tracking Andrii Nakryiko
2023-11-21 0:22 ` [PATCH v2 bpf-next 02/10] selftests/bpf: add stack access precision test Andrii Nakryiko
2023-11-21 0:42 ` Eduard Zingerman
2023-11-21 0:22 ` [PATCH v2 bpf-next 03/10] bpf: fix check for attempt to corrupt spilled pointer Andrii Nakryiko
2023-11-21 0:22 ` [PATCH v2 bpf-next 04/10] bpf: preserve STACK_ZERO slots on partial reg spills Andrii Nakryiko
2023-11-21 0:22 ` [PATCH v2 bpf-next 05/10] selftests/bpf: validate STACK_ZERO is preserved on subreg spill Andrii Nakryiko
2023-11-21 0:55 ` Eduard Zingerman
2023-11-21 0:22 ` [PATCH v2 bpf-next 06/10] bpf: preserve constant zero when doing partial register restore Andrii Nakryiko
2023-11-21 16:20 ` Eduard Zingerman
2023-11-21 18:14 ` Andrii Nakryiko
2023-11-21 20:22 ` Eduard Zingerman
2023-11-21 0:22 ` [PATCH v2 bpf-next 07/10] selftests/bpf: validate zero preservation for sub-slot loads Andrii Nakryiko
2023-11-21 16:20 ` Eduard Zingerman
2023-11-21 18:15 ` Andrii Nakryiko
2023-11-21 0:22 ` [PATCH v2 bpf-next 08/10] bpf: track aligned STACK_ZERO cases as imprecise spilled registers Andrii Nakryiko
2023-11-21 20:38 ` Alexei Starovoitov
2023-11-21 22:01 ` Andrii Nakryiko
2023-11-21 0:22 ` Andrii Nakryiko [this message]
2023-11-21 16:20 ` [PATCH v2 bpf-next 09/10] selftests/bpf: validate precision logic in partial_stack_load_preserves_zeros Eduard Zingerman
2023-11-21 0:22 ` [PATCH v2 bpf-next 10/10] bpf: use common instruction history across all states Andrii Nakryiko
2023-11-21 16:20 ` Eduard Zingerman
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