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 08/13] selftests/bpf: adjust OP_EQ/OP_NE handling to use subranges for branch taken
Date: Sat, 11 Nov 2023 17:06:04 -0800 [thread overview]
Message-ID: <20231112010609.848406-9-andrii@kernel.org> (raw)
In-Reply-To: <20231112010609.848406-1-andrii@kernel.org>
Similar to kernel-side BPF verifier logic enhancements, use 32-bit
subrange knowledge for is_branch_taken() logic in reg_bounds selftests.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
.../selftests/bpf/prog_tests/reg_bounds.c | 30 ++++++++++++++++---
1 file changed, 26 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c
index 7a524b381ed3..10f3b6898274 100644
--- a/tools/testing/selftests/bpf/prog_tests/reg_bounds.c
+++ b/tools/testing/selftests/bpf/prog_tests/reg_bounds.c
@@ -748,16 +748,38 @@ static int reg_state_branch_taken_op(enum num_t t, struct reg_state *x, struct r
/* OP_EQ and OP_NE are sign-agnostic */
enum num_t tu = t_unsigned(t);
enum num_t ts = t_signed(t);
- int br_u, br_s;
+ int br_u, br_s, br;
br_u = range_branch_taken_op(tu, x->r[tu], y->r[tu], op);
br_s = range_branch_taken_op(ts, x->r[ts], y->r[ts], op);
if (br_u >= 0 && br_s >= 0 && br_u != br_s)
ASSERT_FALSE(true, "branch taken inconsistency!\n");
- if (br_u >= 0)
- return br_u;
- return br_s;
+
+ /* if 64-bit ranges are indecisive, use 32-bit subranges to
+ * eliminate always/never taken branches, if possible
+ */
+ if (br_u == -1 && (t == U64 || t == S64)) {
+ br = range_branch_taken_op(U32, x->r[U32], y->r[U32], op);
+ /* we can only reject for OP_EQ, never take branch
+ * based on lower 32 bits
+ */
+ if (op == OP_EQ && br == 0)
+ return 0;
+ /* for OP_NEQ we can be conclusive only if lower 32 bits
+ * differ and thus inequality branch is always taken
+ */
+ if (op == OP_NE && br == 1)
+ return 1;
+
+ br = range_branch_taken_op(S32, x->r[S32], y->r[S32], op);
+ if (op == OP_EQ && br == 0)
+ return 0;
+ if (op == OP_NE && br == 1)
+ return 1;
+ }
+
+ return br_u >= 0 ? br_u : br_s;
}
return range_branch_taken_op(t, x->r[t], y->r[t], op);
}
--
2.34.1
next prev parent reply other threads:[~2023-11-12 1:06 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-12 1:05 [PATCH v2 bpf-next 00/13] BPF register bounds range vs range support Andrii Nakryiko
2023-11-12 1:05 ` [PATCH v2 bpf-next 01/13] bpf: generalize reg_set_min_max() to handle non-const register comparisons Andrii Nakryiko
2023-11-13 4:35 ` Shung-Hsi Yu
2023-11-12 1:05 ` [PATCH v2 bpf-next 02/13] bpf: generalize is_scalar_branch_taken() logic Andrii Nakryiko
2023-11-13 4:46 ` Shung-Hsi Yu
2023-11-12 1:05 ` [PATCH v2 bpf-next 03/13] bpf: enhance BPF_JEQ/BPF_JNE is_branch_taken logic Andrii Nakryiko
2023-11-12 1:06 ` [PATCH v2 bpf-next 04/13] bpf: add register bounds sanity checks and sanitization Andrii Nakryiko
2023-11-13 4:53 ` Shung-Hsi Yu
2023-11-15 20:25 ` Alexei Starovoitov
2023-11-15 22:06 ` Andrii Nakryiko
2023-11-16 19:37 ` Alexei Starovoitov
2023-11-12 1:06 ` [PATCH v2 bpf-next 05/13] bpf: remove redundant s{32,64} -> u{32,64} deduction logic Andrii Nakryiko
2023-11-12 1:06 ` [PATCH v2 bpf-next 06/13] bpf: make __reg{32,64}_deduce_bounds logic more robust Andrii Nakryiko
2023-11-12 1:06 ` [PATCH v2 bpf-next 07/13] selftests/bpf: BPF register range bounds tester Andrii Nakryiko
2023-11-13 4:55 ` Shung-Hsi Yu
2023-11-12 1:06 ` Andrii Nakryiko [this message]
2023-11-13 23:46 ` [PATCH v2 bpf-next 08/13] selftests/bpf: adjust OP_EQ/OP_NE handling to use subranges for branch taken Eduard Zingerman
2023-11-12 1:06 ` [PATCH v2 bpf-next 09/13] selftests/bpf: add range x range test to reg_bounds Andrii Nakryiko
2023-11-12 1:06 ` [PATCH v2 bpf-next 10/13] selftests/bpf: add randomized reg_bounds tests Andrii Nakryiko
2023-11-19 19:53 ` Alexei Starovoitov
2023-11-12 1:06 ` [PATCH v2 bpf-next 11/13] selftests/bpf: set BPF_F_TEST_SANITY_SCRIPT by default Andrii Nakryiko
2023-11-12 1:06 ` [PATCH v2 bpf-next 12/13] veristat: add ability to set BPF_F_TEST_SANITY_STRICT flag with -r flag Andrii Nakryiko
2023-11-12 1:06 ` [PATCH v2 bpf-next 13/13] selftests/bpf: add iter test requiring range x range logic Andrii Nakryiko
2023-11-15 20:30 ` [PATCH v2 bpf-next 00/13] BPF register bounds range vs range support patchwork-bot+netdevbpf
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