From 8404ea0aee930f59088d839ba6f2271ed5b5221d Mon Sep 17 00:00:00 2001
From: Thomas Letan <lthms@nomadic-labs.com>
Date: Wed, 17 Dec 2025 19:08:42 +0100
Subject: [PATCH] EVM Kernel: Enable migration logic for predeployed contracts

* What

The initialization mechanism for predeployed contracts (such as the
withdrawal and bridge contracts) is updated to support overwriting
existing bytecode with a newer version, effectively enabling migration
logic during kernel initialization.

* Why

Previously, the initialization logic would strictly check if any code
existed at the target address. If the code hash was not empty, it
assumed the contract was already correctly deployed and skipped
execution. This behavior prevented the kernel from updating these
predeployed contracts when their Solidity implementation changed, as the
presence of the old version blocked the installation of the new one.

* How

The `init_precompile_bytecode` function is modified to accept the
expected `code_hash` as an argument. Instead of returning early merely
if the account code is not empty, it now returns early only if the
current on-chain code hash matches the expected hash. If there is a
mismatch (and the account is not empty), the function now explicitly
deletes the old code via `CodeStorage::delete` before proceeding to
write the new bytecode. The call sites in `init_precompile_bytecodes`
are updated to pass the specific code hashes for the internal
forwarder, withdrawal, and FA bridge contracts.
---
 .../revm/src/precompiles/initializer.rs       | 38 ++++++++++++++++---
 1 file changed, 33 insertions(+), 5 deletions(-)

diff --git a/etherlink/kernel_latest/revm/src/precompiles/initializer.rs b/etherlink/kernel_latest/revm/src/precompiles/initializer.rs
index dbacb1037a8a..4c2f99091142 100644
--- a/etherlink/kernel_latest/revm/src/precompiles/initializer.rs
+++ b/etherlink/kernel_latest/revm/src/precompiles/initializer.rs
@@ -4,7 +4,7 @@
 // SPDX-License-Identifier: MIT
 
 use revm::{
-    primitives::{hex::FromHex, Address, Bytes, KECCAK_EMPTY},
+    primitives::{hex::FromHex, Address, Bytes, FixedBytes, KECCAK_EMPTY},
     state::Bytecode,
 };
 use tezos_evm_runtime::runtime::Runtime;
@@ -20,22 +20,50 @@ use crate::{
     Error,
 };
 
+use super::constants::{
+    FA_BRIDGE_SOL_CODE_HASH, INTERNAL_FORWARDER_SOL_CODE_HASH, WITHDRAWAL_SOL_CODE_HASH,
+};
+
 pub fn init_precompile_bytecodes<Host: Runtime>(host: &'_ mut Host) -> Result<(), Error> {
-    init_precompile_bytecode(host, &Address::ZERO, INTERNAL_FORWARDER_SOL_CONTRACT)?;
-    init_precompile_bytecode(host, &WITHDRAWAL_SOL_ADDR, WITHDRAWAL_SOL_CONTRACT)?;
-    init_precompile_bytecode(host, &FA_BRIDGE_SOL_ADDR, FA_BRIDGE_SOL_CONTRACT)
+    init_precompile_bytecode(
+        host,
+        &Address::ZERO,
+        INTERNAL_FORWARDER_SOL_CONTRACT,
+        &INTERNAL_FORWARDER_SOL_CODE_HASH,
+    )?;
+    init_precompile_bytecode(
+        host,
+        &WITHDRAWAL_SOL_ADDR,
+        WITHDRAWAL_SOL_CONTRACT,
+        &WITHDRAWAL_SOL_CODE_HASH,
+    )?;
+    init_precompile_bytecode(
+        host,
+        &FA_BRIDGE_SOL_ADDR,
+        FA_BRIDGE_SOL_CONTRACT,
+        &FA_BRIDGE_SOL_CODE_HASH,
+    )?;
+
+    Ok(())
 }
 
 fn init_precompile_bytecode<Host: Runtime>(
     host: &'_ mut Host,
     addr: &Address,
     hex_bytes: &str,
+    code_hash: &FixedBytes<32>,
 ) -> Result<(), Error> {
     let mut created_account = StorageAccount::from_address(addr)?;
     let mut account_info = created_account.info(host).map_err(custom)?;
-    if account_info.code_hash != KECCAK_EMPTY {
+
+    if account_info.code_hash == *code_hash {
         return Ok(());
     }
+
+    if account_info.code_hash != KECCAK_EMPTY {
+        CodeStorage::delete(host, &account_info.code_hash)?;
+    }
+
     let code = Bytecode::new_legacy(Bytes::from_hex(hex_bytes).map_err(custom)?);
     let code_hash = bytes_hash(code.original_byte_slice());
     account_info.code_hash = code_hash;
-- 
GitLab