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selftests/bpf: adjust OP_EQ/OP_NE handling to use subranges for branch taken
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> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20231112010609.848406-9-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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@ -748,16 +748,38 @@ static int reg_state_branch_taken_op(enum num_t t, struct reg_state *x, struct r
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/* OP_EQ and OP_NE are sign-agnostic */
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enum num_t tu = t_unsigned(t);
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enum num_t ts = t_signed(t);
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int br_u, br_s;
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int br_u, br_s, br;
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br_u = range_branch_taken_op(tu, x->r[tu], y->r[tu], op);
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br_s = range_branch_taken_op(ts, x->r[ts], y->r[ts], op);
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if (br_u >= 0 && br_s >= 0 && br_u != br_s)
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ASSERT_FALSE(true, "branch taken inconsistency!\n");
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if (br_u >= 0)
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return br_u;
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return br_s;
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/* if 64-bit ranges are indecisive, use 32-bit subranges to
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* eliminate always/never taken branches, if possible
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*/
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if (br_u == -1 && (t == U64 || t == S64)) {
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br = range_branch_taken_op(U32, x->r[U32], y->r[U32], op);
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/* we can only reject for OP_EQ, never take branch
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* based on lower 32 bits
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*/
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if (op == OP_EQ && br == 0)
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return 0;
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/* for OP_NEQ we can be conclusive only if lower 32 bits
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* differ and thus inequality branch is always taken
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*/
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if (op == OP_NE && br == 1)
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return 1;
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br = range_branch_taken_op(S32, x->r[S32], y->r[S32], op);
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if (op == OP_EQ && br == 0)
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return 0;
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if (op == OP_NE && br == 1)
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return 1;
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}
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return br_u >= 0 ? br_u : br_s;
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}
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return range_branch_taken_op(t, x->r[t], y->r[t], op);
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}
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