Call stack depth (#1081)

evm/src/cpu/kernel/asm/core/call.asm

@@ -22,14 +22,15 @@ global sys_call:
     // stack: address, gas, kexit_info, value, args_offset, args_size, ret_offset, ret_size
     %u256_to_addr // Truncate to 160 bits
     DUP1 %insert_accessed_addresses
-    %checkpoint // Checkpoint
     DUP2 %insert_touched_addresses
 
     %call_charge_gas(1, 1)
+    %check_depth
+
+    %checkpoint // Checkpoint
 
     %create_context
     // stack: new_ctx, kexit_info, callgas, address, value, args_offset, args_size, ret_offset, ret_size
-    // TODO: Consider call depth
 
     %stack (new_ctx, kexit_info, callgas, address, value, args_offset, args_size, ret_offset, ret_size) ->
           (new_ctx, args_offset, args_size, new_ctx, kexit_info, callgas, address, value, args_offset, args_size, ret_offset, ret_size)
@@ -74,9 +75,11 @@ global sys_callcode:
     // stack: address, gas, kexit_info, value, args_offset, args_size, ret_offset, ret_size
     %u256_to_addr // Truncate to 160 bits
     DUP1 %insert_accessed_addresses
-    %checkpoint // Checkpoint
 
     %call_charge_gas(1, 0)
+    %check_depth
+
+    %checkpoint // Checkpoint
 
     // stack: kexit_info, callgas, address, value, args_offset, args_size, ret_offset, ret_size
     %create_context
@@ -127,12 +130,14 @@ global sys_staticcall:
     // stack: address, gas, kexit_info, args_offset, args_size, ret_offset, ret_size
     %u256_to_addr // Truncate to 160 bits
     DUP1 %insert_accessed_addresses
-    %checkpoint // Checkpoint
     DUP2 %insert_touched_addresses
 
     // Add a value of 0 to the stack. Slightly inefficient but that way we can reuse %call_charge_gas.
     %stack (cold_access, address, gas, kexit_info) -> (cold_access, address, gas, kexit_info, 0)
     %call_charge_gas(0, 1)
+    %check_depth
+
+    %checkpoint // Checkpoint
 
     // stack: kexit_info, callgas, address, value, args_offset, args_size, ret_offset, ret_size
     %create_context
@@ -180,11 +185,13 @@ global sys_delegatecall:
     // stack: address, gas, kexit_info, args_offset, args_size, ret_offset, ret_size
     %u256_to_addr // Truncate to 160 bits
     DUP1 %insert_accessed_addresses
-    %checkpoint // Checkpoint
 
     // Add a value of 0 to the stack. Slightly inefficient but that way we can reuse %call_charge_gas.
     %stack (cold_access, address, gas, kexit_info) -> (cold_access, address, gas, kexit_info, 0)
     %call_charge_gas(0, 0)
+    %check_depth
+
+    %checkpoint // Checkpoint
 
     // stack: kexit_info, callgas, address, value, args_offset, args_size, ret_offset, ret_size
     %create_context
@@ -244,6 +251,20 @@ call_insufficient_balance:
     %mstore_context_metadata(@CTX_METADATA_RETURNDATA_SIZE, 0)
     EXIT_KERNEL
 
+%macro check_depth
+    %call_depth
+    %gt_const(@CALL_STACK_LIMIT)
+    %jumpi(call_too_deep)
+%endmacro
+
+call_too_deep:
+    %stack (kexit_info, callgas, address, value, args_offset, args_size, ret_offset, ret_size) ->
+        (callgas, kexit_info, 0)
+    %shl_const(192) SWAP1 SUB
+    // stack: kexit_info', 0
+    %mstore_context_metadata(@CTX_METADATA_RETURNDATA_SIZE, 0)
+    EXIT_KERNEL
+
 // Set @CTX_METADATA_STATIC to 1. Note that there is no corresponding set_static_false routine
 // because it will already be 0 by default.
 %macro set_static_true
@@ -342,6 +363,7 @@ call_insufficient_balance:
     DUP1 // new_ctx
     SET_CONTEXT
     %checkpoint // Checkpoint
+    %increment_call_depth
     // Perform jumpdest analyis
     PUSH %%after
     %mload_context_metadata(@CTX_METADATA_CODE_SIZE)

evm/src/cpu/kernel/asm/core/terminate.asm

@@ -200,6 +200,7 @@ global terminate_common:
     // Go back to the parent context.
     %mload_context_metadata(@CTX_METADATA_PARENT_CONTEXT)
     SET_CONTEXT
+    %decrement_call_depth
     // stack: (empty)
 
     // Load the fields that we stored in SEGMENT_KERNEL_GENERAL.

evm/src/cpu/kernel/asm/memory/metadata.asm

@@ -325,3 +325,19 @@ global sys_basefee:
     %jumpi(fault_exception)
     // stack: sum
 %endmacro
+
+%macro call_depth
+    %mload_global_metadata(@GLOBAL_METADATA_CALL_STACK_DEPTH)
+%endmacro
+
+%macro increment_call_depth
+    %mload_global_metadata(@GLOBAL_METADATA_CALL_STACK_DEPTH)
+    %increment
+    %mstore_global_metadata(@GLOBAL_METADATA_CALL_STACK_DEPTH)
+%endmacro
+
+%macro decrement_call_depth
+    %mload_global_metadata(@GLOBAL_METADATA_CALL_STACK_DEPTH)
+    %decrement
+    %mstore_global_metadata(@GLOBAL_METADATA_CALL_STACK_DEPTH)
+%endmacro

evm/src/cpu/kernel/constants/global_metadata.rs

@@ -68,10 +68,11 @@ pub(crate) enum GlobalMetadata {
     // Boolean flag indicating if the txn is a contract creation txn.
     ContractCreation = 33,
     IsPrecompileFromEoa = 34,
+    CallStackDepth = 35,
 }
 
 impl GlobalMetadata {
-    pub(crate) const COUNT: usize = 34;
+    pub(crate) const COUNT: usize = 35;
 
     pub(crate) fn all() -> [Self; Self::COUNT] {
         [
@@ -109,6 +110,7 @@ impl GlobalMetadata {
             Self::AccessListRlpLen,
             Self::ContractCreation,
             Self::IsPrecompileFromEoa,
+            Self::CallStackDepth,
         ]
     }
 
@@ -149,6 +151,7 @@ impl GlobalMetadata {
             Self::AccessListRlpLen => "GLOBAL_METADATA_ACCESS_LIST_RLP_LEN",
             Self::ContractCreation => "GLOBAL_METADATA_CONTRACT_CREATION",
             Self::IsPrecompileFromEoa => "GLOBAL_METADATA_IS_PRECOMPILE_FROM_EOA",
+            Self::CallStackDepth => "GLOBAL_METADATA_CALL_STACK_DEPTH",
         }
     }
 }

evm/src/cpu/kernel/constants/mod.rs

@@ -55,6 +55,7 @@ pub fn evm_constants() -> HashMap<String, U256> {
     }
 
     c.insert(MAX_NONCE.0.into(), U256::from(MAX_NONCE.1));
+    c.insert(CALL_STACK_LIMIT.0.into(), U256::from(CALL_STACK_LIMIT.1));
 
     for segment in Segment::all() {
         c.insert(segment.var_name().into(), (segment as u32).into());
@@ -264,3 +265,4 @@ const CODE_SIZE_LIMIT: [(&str, u64); 3] = [
 ];
 
 const MAX_NONCE: (&str, u64) = ("MAX_NONCE", 0xffffffffffffffff);
+const CALL_STACK_LIMIT: (&str, u64) = ("CALL_STACK_LIMIT", 1024);