From 7ed53142a03fdc4e9443bdd8349665c2fb2c28a6 Mon Sep 17 00:00:00 2001
From: Daniel Lubarov <daniel@lubarov.com>
Date: Sun, 19 Mar 2023 14:13:42 -0700
Subject: [PATCH] Fix reads from not-found ext nodes

---
 evm/src/cpu/kernel/asm/core/transfer.asm | 12 ------------
 evm/src/cpu/kernel/asm/mpt/read.asm      | 13 ++++++++-----
 evm/src/generation/state.rs              |  3 ++-
 evm/src/witness/operation.rs             |  2 +-
 4 files changed, 11 insertions(+), 19 deletions(-)

diff --git a/evm/src/cpu/kernel/asm/core/transfer.asm b/evm/src/cpu/kernel/asm/core/transfer.asm
index 8ae2d854..c001e726 100644
--- a/evm/src/cpu/kernel/asm/core/transfer.asm
+++ b/evm/src/cpu/kernel/asm/core/transfer.asm
@@ -23,18 +23,6 @@ global transfer_eth_failure:
 %%after:
 %endmacro
 
-// Pre stack: should_transfer, from, to, amount
-// Post stack: (empty)
-%macro maybe_transfer_eth
-    %jumpi(%%transfer)
-    // We're skipping the transfer, so just pop the arguments and return.
-    %pop3
-    %jump(%%after)
-%%transfer:
-    %transfer_eth
-%%after:
-%endmacro
-
 // Returns 0 on success, or 1 if addr has insufficient balance. Panics if addr isn't found in the trie.
 // Pre stack: addr, amount, retdest
 // Post stack: status (0 indicates success)
diff --git a/evm/src/cpu/kernel/asm/mpt/read.asm b/evm/src/cpu/kernel/asm/mpt/read.asm
index 08aa02c3..94cfbaf5 100644
--- a/evm/src/cpu/kernel/asm/mpt/read.asm
+++ b/evm/src/cpu/kernel/asm/mpt/read.asm
@@ -23,6 +23,7 @@ global mpt_read_state_trie:
 // - the virtual address of the trie to search in
 // - the number of nibbles in the key (should start at 64)
 // - the key, as a U256
+// - return destination
 //
 // This function returns a pointer to the value, or 0 if the key is not found.
 global mpt_read:
@@ -43,13 +44,13 @@ global mpt_read:
     // it means the prover failed to provide necessary Merkle data, so panic.
     PANIC
 
-mpt_read_empty:
+global mpt_read_empty:
     // Return 0 to indicate that the value was not found.
     %stack (node_type, node_payload_ptr, num_nibbles, key, retdest)
         -> (retdest, 0)
     JUMP
 
-mpt_read_branch:
+global mpt_read_branch:
     // stack: node_type, node_payload_ptr, num_nibbles, key, retdest
     POP
     // stack: node_payload_ptr, num_nibbles, key, retdest
@@ -71,7 +72,7 @@ mpt_read_branch:
     // stack: child_ptr, num_nibbles, key, retdest
     %jump(mpt_read) // recurse
 
-mpt_read_branch_end_of_key:
+global mpt_read_branch_end_of_key:
     %stack (node_payload_ptr, num_nibbles, key, retdest) -> (node_payload_ptr, retdest)
     // stack: node_payload_ptr, retdest
     %add_const(16) // skip over the 16 child nodes
@@ -81,7 +82,7 @@ mpt_read_branch_end_of_key:
     SWAP1
     JUMP
 
-mpt_read_extension:
+global mpt_read_extension:
     // stack: node_type, node_payload_ptr, num_nibbles, key, retdest
     %stack (node_type, node_payload_ptr, num_nibbles, key)
         -> (num_nibbles, key, node_payload_ptr)
@@ -100,8 +101,9 @@ mpt_read_extension:
     // stack: node_key, key_part, key_part, future_nibbles, key, node_payload_ptr, retdest
     EQ // does the first part of our key match the node's key?
     %jumpi(mpt_read_extension_found)
+global mpt_read_extension_not_found:
     // Not found; return 0.
-    %stack (key_part, future_nibbles, node_payload_ptr, retdest) -> (retdest, 0)
+    %stack (key_part, future_nibbles, key, node_payload_ptr, retdest) -> (retdest, 0)
     JUMP
 mpt_read_extension_found:
     // stack: key_part, future_nibbles, key, node_payload_ptr, retdest
@@ -135,6 +137,7 @@ mpt_read_leaf:
     AND
     // stack: keys_match && num_nibbles_match, node_payload_ptr, retdest
     %jumpi(mpt_read_leaf_found)
+global mpt_read_leaf_not_found:
     // Not found; return 0.
     %stack (node_payload_ptr, retdest) -> (retdest, 0)
     JUMP
diff --git a/evm/src/generation/state.rs b/evm/src/generation/state.rs
index 2e3718bf..9399e4b6 100644
--- a/evm/src/generation/state.rs
+++ b/evm/src/generation/state.rs
@@ -99,7 +99,8 @@ impl<F: Field> GenerationState<F> {
     }
 
     pub(crate) fn stack(&self) -> Vec<U256> {
-        (0..self.registers.stack_len)
+        const MAX_TO_SHOW: usize = 10;
+        (0..self.registers.stack_len.min(MAX_TO_SHOW))
             .map(|i| stack_peek(self, i).unwrap())
             .collect()
     }
diff --git a/evm/src/witness/operation.rs b/evm/src/witness/operation.rs
index 035ce6e2..6d42eb48 100644
--- a/evm/src/witness/operation.rs
+++ b/evm/src/witness/operation.rs
@@ -589,7 +589,7 @@ pub(crate) fn generate_exit_kernel<F: Field>(
     state.registers.gas_used = gas_used_val;
     log::debug!(
         "Exiting to {}, is_kernel={}",
-        KERNEL.offset_name(program_counter),
+        program_counter,
         is_kernel_mode
     );