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bpf/verifier: display non-spill stack slot types in print_verifier_state
If a stack slot does not hold a spilled register (STACK_SPILL), then each of its eight bytes could potentially have a different slot_type. This information can be important for debugging, and previously we either did not print anything for the stack slot, or just printed fp-X=0 in the case where its first byte was STACK_ZERO. Instead, print eight characters with either 0 (STACK_ZERO), m (STACK_MISC) or ? (STACK_INVALID) for any stack slot which is neither STACK_SPILL nor entirely STACK_INVALID. Signed-off-by: Edward Cree <ecree@solarflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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679c782de1
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8efea21d33
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@ -263,6 +263,13 @@ static const char * const reg_type_str[] = {
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[PTR_TO_PACKET_END] = "pkt_end",
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[PTR_TO_PACKET_END] = "pkt_end",
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};
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};
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static char slot_type_char[] = {
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[STACK_INVALID] = '?',
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[STACK_SPILL] = 'r',
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[STACK_MISC] = 'm',
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[STACK_ZERO] = '0',
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};
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static void print_liveness(struct bpf_verifier_env *env,
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static void print_liveness(struct bpf_verifier_env *env,
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enum bpf_reg_liveness live)
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enum bpf_reg_liveness live)
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{
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{
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@ -349,15 +356,26 @@ static void print_verifier_state(struct bpf_verifier_env *env,
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}
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}
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}
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}
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for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
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for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
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if (state->stack[i].slot_type[0] == STACK_SPILL) {
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char types_buf[BPF_REG_SIZE + 1];
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verbose(env, " fp%d",
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bool valid = false;
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(-i - 1) * BPF_REG_SIZE);
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int j;
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print_liveness(env, state->stack[i].spilled_ptr.live);
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for (j = 0; j < BPF_REG_SIZE; j++) {
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if (state->stack[i].slot_type[j] != STACK_INVALID)
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valid = true;
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types_buf[j] = slot_type_char[
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state->stack[i].slot_type[j]];
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}
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types_buf[BPF_REG_SIZE] = 0;
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if (!valid)
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continue;
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verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE);
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print_liveness(env, state->stack[i].spilled_ptr.live);
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if (state->stack[i].slot_type[0] == STACK_SPILL)
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verbose(env, "=%s",
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verbose(env, "=%s",
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reg_type_str[state->stack[i].spilled_ptr.type]);
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reg_type_str[state->stack[i].spilled_ptr.type]);
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}
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else
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if (state->stack[i].slot_type[0] == STACK_ZERO)
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verbose(env, "=%s", types_buf);
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verbose(env, " fp%d=0", (-i - 1) * BPF_REG_SIZE);
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}
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}
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verbose(env, "\n");
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verbose(env, "\n");
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}
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}
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