Add memory checks for prover_input, as well as range_checks for prove…

…r_input, syscalls/exceptions (#1168)

* Add memory checks for prover_input and range_checks for prover_input, syscalls and exceptions

* Replace u32 by U256, and remove extra CTLs

* Add column in ArithmeticStark to use ctl_arithmetic_base_rows for is_range_check

* Fix CTLs and circuit constraint.

* Fix CTLs

evm/src/arithmetic/arithmetic_stark.rs

@@ -63,6 +63,12 @@ pub(crate) fn ctl_arithmetic_rows<F: Field>() -> TableWithColumns<F> {
     // If an arithmetic operation is happening on the CPU side,
     // the CTL will enforce that the reconstructed opcode value
     // from the opcode bits matches.
+    // These opcodes are missing the syscall and prover_input opcodes,
+    // since `IS_RANGE_CHECK` can be associated to multiple opcodes.
+    // For `IS_RANGE_CHECK`, the opcodes are written in OPCODE_COL,
+    // and we use that column for scaling and the CTL checks.
+    // Note that we ensure in the STARK's constraints that the
+    // value in `OPCODE_COL` is 0 if `IS_RANGE_CHECK` = 0.
     const COMBINED_OPS: [(usize, u8); 16] = [
         (columns::IS_ADD, 0x01),
         (columns::IS_MUL, 0x02),
@@ -89,16 +95,21 @@ pub(crate) fn ctl_arithmetic_rows<F: Field>() -> TableWithColumns<F> {
         columns::OUTPUT_REGISTER,
     ];
 
-    let filter_column = Some(Column::sum(COMBINED_OPS.iter().map(|(c, _v)| *c)));
+    let mut filter_cols = COMBINED_OPS.to_vec();
+    filter_cols.push((columns::IS_RANGE_CHECK, 0x01));
 
+    let filter_column = Some(Column::sum(filter_cols.iter().map(|(c, _v)| *c)));
+
+    let mut all_combined_cols = COMBINED_OPS.to_vec();
+    all_combined_cols.push((columns::OPCODE_COL, 0x01));
     // Create the Arithmetic Table whose columns are those of the
     // operations listed in `ops` whose inputs and outputs are given
     // by `regs`, where each element of `regs` is a range of columns
     // corresponding to a 256-bit input or output register (also `ops`
     // is used as the operation filter).
     TableWithColumns::new(
         Table::Arithmetic,
-        cpu_arith_data_link(&COMBINED_OPS, &REGISTER_MAP),
+        cpu_arith_data_link(&all_combined_cols, &REGISTER_MAP),
         filter_column,
     )
 }
@@ -109,7 +120,7 @@ pub struct ArithmeticStark<F, const D: usize> {
     pub f: PhantomData<F>,
 }
 
-const RANGE_MAX: usize = 1usize << 16; // Range check strict upper bound
+pub(crate) const RANGE_MAX: usize = 1usize << 16; // Range check strict upper bound
 
 impl<F: RichField, const D: usize> ArithmeticStark<F, D> {
     /// Expects input in *column*-major layout
@@ -195,6 +206,10 @@ impl<F: RichField + Extendable<D>, const D: usize> Stark<F, D> for ArithmeticSta
         let lv: &[P; NUM_ARITH_COLUMNS] = vars.get_local_values().try_into().unwrap();
         let nv: &[P; NUM_ARITH_COLUMNS] = vars.get_next_values().try_into().unwrap();
 
+        // Check that `OPCODE_COL` holds 0 if the operation is not a range_check.
+        let opcode_constraint = (P::ONES - lv[columns::IS_RANGE_CHECK]) * lv[columns::OPCODE_COL];
+        yield_constr.constraint(opcode_constraint);
+
         // Check the range column: First value must be 0, last row
         // must be 2^16-1, and intermediate rows must increment by 0
         // or 1.
@@ -231,6 +246,16 @@ impl<F: RichField + Extendable<D>, const D: usize> Stark<F, D> for ArithmeticSta
         let nv: &[ExtensionTarget<D>; NUM_ARITH_COLUMNS] =
             vars.get_next_values().try_into().unwrap();
 
+        // Check that `OPCODE_COL` holds 0 if the operation is not a range_check.
+        let opcode_constraint = builder.arithmetic_extension(
+            F::NEG_ONE,
+            F::ONE,
+            lv[columns::IS_RANGE_CHECK],
+            lv[columns::OPCODE_COL],
+            lv[columns::OPCODE_COL],
+        );
+        yield_constr.constraint(builder, opcode_constraint);
+
         // Check the range column: First value must be 0, last row
         // must be 2^16-1, and intermediate rows must increment by 0
         // or 1.

evm/src/arithmetic/columns.rs

@@ -38,8 +38,10 @@ pub(crate) const IS_GT: usize = IS_LT + 1;
 pub(crate) const IS_BYTE: usize = IS_GT + 1;
 pub(crate) const IS_SHL: usize = IS_BYTE + 1;
 pub(crate) const IS_SHR: usize = IS_SHL + 1;
-
-pub(crate) const START_SHARED_COLS: usize = IS_SHR + 1;
+pub(crate) const IS_RANGE_CHECK: usize = IS_SHR + 1;
+/// Column that stores the opcode if the operation is a range check.
+pub(crate) const OPCODE_COL: usize = IS_RANGE_CHECK + 1;
+pub(crate) const START_SHARED_COLS: usize = OPCODE_COL + 1;
 
 /// Within the Arithmetic Unit, there are shared columns which can be
 /// used by any arithmetic circuit, depending on which one is active

evm/src/arithmetic/mod.rs

@@ -1,6 +1,11 @@
 use ethereum_types::U256;
 use plonky2::field::types::PrimeField64;
 
+use self::columns::{
+    INPUT_REGISTER_0, INPUT_REGISTER_1, INPUT_REGISTER_2, OPCODE_COL, OUTPUT_REGISTER,
+};
+use self::utils::u256_to_array;
+use crate::arithmetic::columns::IS_RANGE_CHECK;
 use crate::extension_tower::BN_BASE;
 use crate::util::{addmod, mulmod, submod};
 
@@ -135,6 +140,7 @@ impl TernaryOperator {
 }
 
 /// An enum representing arithmetic operations that can be either binary or ternary.
+#[allow(clippy::enum_variant_names)]
 #[derive(Debug)]
 pub(crate) enum Operation {
     BinaryOperation {
@@ -150,6 +156,13 @@ pub(crate) enum Operation {
         input2: U256,
         result: U256,
     },
+    RangeCheckOperation {
+        input0: U256,
+        input1: U256,
+        input2: U256,
+        opcode: U256,
+        result: U256,
+    },
 }
 
 impl Operation {
@@ -195,11 +208,28 @@ impl Operation {
         }
     }
 
+    pub(crate) fn range_check(
+        input0: U256,
+        input1: U256,
+        input2: U256,
+        opcode: U256,
+        result: U256,
+    ) -> Self {
+        Self::RangeCheckOperation {
+            input0,
+            input1,
+            input2,
+            opcode,
+            result,
+        }
+    }
+
     /// Gets the result of an arithmetic operation.
     pub(crate) fn result(&self) -> U256 {
         match self {
             Operation::BinaryOperation { result, .. } => *result,
             Operation::TernaryOperation { result, .. } => *result,
+            _ => panic!("This function should not be called for range checks."),
         }
     }
 
@@ -228,6 +258,13 @@ impl Operation {
                 input2,
                 result,
             } => ternary_op_to_rows(operator.row_filter(), input0, input1, input2, result),
+            Operation::RangeCheckOperation {
+                input0,
+                input1,
+                input2,
+                opcode,
+                result,
+            } => range_check_to_rows(input0, input1, input2, opcode, result),
         }
     }
 }
@@ -293,3 +330,21 @@ fn binary_op_to_rows<F: PrimeField64>(
         }
     }
 }
+
+fn range_check_to_rows<F: PrimeField64>(
+    input0: U256,
+    input1: U256,
+    input2: U256,
+    opcode: U256,
+    result: U256,
+) -> (Vec<F>, Option<Vec<F>>) {
+    let mut row = vec![F::ZERO; columns::NUM_ARITH_COLUMNS];
+    row[IS_RANGE_CHECK] = F::ONE;
+    row[OPCODE_COL] = F::from_canonical_u64(opcode.as_u64());
+    u256_to_array(&mut row[INPUT_REGISTER_0], input0);
+    u256_to_array(&mut row[INPUT_REGISTER_1], input1);
+    u256_to_array(&mut row[INPUT_REGISTER_2], input2);
+    u256_to_array(&mut row[OUTPUT_REGISTER], result);
+
+    (row, None)
+}

evm/src/cpu/cpu_stark.rs

@@ -74,8 +74,8 @@ fn ctl_data_binops<F: Field>() -> Vec<Column<F>> {
 
 /// Creates the vector of `Columns` corresponding to the three inputs and
 /// one output of a ternary operation. By default, ternary operations use
-/// the first three memory channels, and the last one for the result (binary
-/// operations do not use the third inputs).
+/// the first three memory channels, and the next top of the stack for the
+/// result (binary operations do not use the third inputs).
 fn ctl_data_ternops<F: Field>() -> Vec<Column<F>> {
     let mut res = Column::singles(COL_MAP.mem_channels[0].value).collect_vec();
     res.extend(Column::singles(COL_MAP.mem_channels[1].value));
@@ -115,6 +115,9 @@ pub fn ctl_arithmetic_base_rows<F: Field>() -> TableWithColumns<F> {
             COL_MAP.op.fp254_op,
             COL_MAP.op.ternary_op,
             COL_MAP.op.shift,
+            COL_MAP.op.prover_input,
+            COL_MAP.op.syscall,
+            COL_MAP.op.exception,
         ])),
     )
 }

evm/src/cpu/stack.rs

@@ -96,6 +96,12 @@ pub(crate) const STACK_BEHAVIORS: OpsColumnsView<Option<StackBehavior>> = OpsCol
         pushes: true,
         disable_other_channels: true,
     }),
+    prover_input: Some(StackBehavior {
+        num_pops: 0,
+        pushes: true,
+        disable_other_channels: true,
+    }),
+    jumps: None,        // Depends on whether it's a JUMP or a JUMPI.
     prover_input: None, // TODO
     jumps: None,        // Depends on whether it's a JUMP or a JUMPI.
     pc_push0: Some(StackBehavior {

evm/src/witness/operation.rs

@@ -234,7 +234,22 @@ pub(crate) fn generate_prover_input<F: Field>(
     let pc = state.registers.program_counter;
     let input_fn = &KERNEL.prover_inputs[&pc];
     let input = state.prover_input(input_fn)?;
+    let opcode = 0x49.into();
+    // `ArithmeticStark` range checks `mem_channels[0]`, which contains
+    // the top of the stack, `mem_channels[1]`, `mem_channels[2]` and
+    // next_row's `mem_channels[0]` which contains the next top of the stack.
+    // Our goal here is to range-check the input, in the next stack top.
+    let range_check_op = arithmetic::Operation::range_check(
+        state.registers.stack_top,
+        U256::from(0),
+        U256::from(0),
+        opcode,
+        input,
+    );
+
     push_with_write(state, &mut row, input)?;
+
+    state.traces.push_arithmetic(range_check_op);
     state.traces.push_cpu(row);
     Ok(())
 }
@@ -772,10 +787,24 @@ pub(crate) fn generate_syscall<F: Field>(
     let handler_addr = (handler_addr0 << 16) + (handler_addr1 << 8) + handler_addr2;
     let new_program_counter = u256_to_usize(handler_addr)?;
 
+    let gas = U256::from(state.registers.gas_used);
+
     let syscall_info = U256::from(state.registers.program_counter + 1)
         + (U256::from(u64::from(state.registers.is_kernel)) << 32)
-        + (U256::from(state.registers.gas_used) << 192);
-
+        + (gas << 192);
+
+    // `ArithmeticStark` range checks `mem_channels[0]`, which contains
+    // the top of the stack, `mem_channels[1]`, `mem_channels[2]` and
+    // next_row's `mem_channels[0]` which contains the next top of the stack.
+    // Our goal here is to range-check the gas, contained in syscall_info,
+    // stored in the next stack top.
+    let range_check_op = arithmetic::Operation::range_check(
+        state.registers.stack_top,
+        handler_addr0,
+        handler_addr1,
+        U256::from(opcode),
+        syscall_info,
+    );
     // Set registers before pushing to the stack; in particular, we need to set kernel mode so we
     // can't incorrectly trigger a stack overflow. However, note that we have to do it _after_ we
     // make `syscall_info`, which should contain the old values.
@@ -787,6 +816,7 @@ pub(crate) fn generate_syscall<F: Field>(
 
     log::debug!("Syscall to {}", KERNEL.offset_name(new_program_counter));
 
+    state.traces.push_arithmetic(range_check_op);
     state.traces.push_memory(log_in0);
     state.traces.push_memory(log_in1);
     state.traces.push_memory(log_in2);
@@ -1055,9 +1085,27 @@ pub(crate) fn generate_exception<F: Field>(
     let handler_addr = (handler_addr0 << 16) + (handler_addr1 << 8) + handler_addr2;
     let new_program_counter = u256_to_usize(handler_addr)?;
 
-    let exc_info =
-        U256::from(state.registers.program_counter) + (U256::from(state.registers.gas_used) << 192);
+    let gas = U256::from(state.registers.gas_used);
+
+    let exc_info = U256::from(state.registers.program_counter) + (gas << 192);
 
+    // Get the opcode so we can provide it to the range_check operation.
+    let code_context = state.registers.code_context();
+    let address = MemoryAddress::new(code_context, Segment::Code, state.registers.program_counter);
+    let opcode = state.memory.get(address);
+
+    // `ArithmeticStark` range checks `mem_channels[0]`, which contains
+    // the top of the stack, `mem_channels[1]`, `mem_channels[2]` and
+    // next_row's `mem_channels[0]` which contains the next top of the stack.
+    // Our goal here is to range-check the gas, contained in syscall_info,
+    // stored in the next stack top.
+    let range_check_op = arithmetic::Operation::range_check(
+        state.registers.stack_top,
+        handler_addr0,
+        handler_addr1,
+        opcode,
+        exc_info,
+    );
     // Set registers before pushing to the stack; in particular, we need to set kernel mode so we
     // can't incorrectly trigger a stack overflow. However, note that we have to do it _after_ we
     // make `exc_info`, which should contain the old values.
@@ -1068,7 +1116,7 @@ pub(crate) fn generate_exception<F: Field>(
     push_with_write(state, &mut row, exc_info)?;
 
     log::debug!("Exception to {}", KERNEL.offset_name(new_program_counter));
-
+    state.traces.push_arithmetic(range_check_op);
     state.traces.push_memory(log_in0);
     state.traces.push_memory(log_in1);
     state.traces.push_memory(log_in2);

evm/src/witness/traces.rs

@@ -70,6 +70,7 @@ impl<T: Copy> Traces<T> {
                         BinaryOperator::Div | BinaryOperator::Mod => 2,
                         _ => 1,
                     },
+                    Operation::RangeCheckOperation { .. } => 1,
                 })
                 .sum(),
             byte_packing_len: self.byte_packing_ops.iter().map(|op| op.bytes.len()).sum(),