From ab70bc536d3a849b1f331d84d34579afe9235bd2 Mon Sep 17 00:00:00 2001
From: Linda Guiga <101227802+LindaGuiga@users.noreply.github.com>
Date: Mon, 27 Nov 2023 12:34:41 -0500
Subject: [PATCH] Fix run_syscall in interpreter. (#1351)

* Fix syscall and change sload test to catch the error

* Update comment

* Cleanup
---
 evm/src/cpu/kernel/interpreter.rs        |  3 +--
 evm/src/cpu/kernel/tests/account_code.rs | 16 +++++++++++-----
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/evm/src/cpu/kernel/interpreter.rs b/evm/src/cpu/kernel/interpreter.rs
index 6c5c1a87..37de2314 100644
--- a/evm/src/cpu/kernel/interpreter.rs
+++ b/evm/src/cpu/kernel/interpreter.rs
@@ -1047,7 +1047,7 @@ impl<'a> Interpreter<'a> {
         let new_program_counter =
             u256_to_usize(handler_addr).map_err(|_| anyhow!("The program counter is too large"))?;
 
-        let syscall_info = U256::from(self.generation_state.registers.program_counter + 1)
+        let syscall_info = U256::from(self.generation_state.registers.program_counter)
             + U256::from((self.generation_state.registers.is_kernel as usize) << 32)
             + (U256::from(self.generation_state.registers.gas_used) << 192);
         self.generation_state.registers.program_counter = new_program_counter;
@@ -1057,7 +1057,6 @@ impl<'a> Interpreter<'a> {
         self.generation_state.registers.gas_used = 0;
         self.push(syscall_info);
 
-        self.run().map_err(|_| anyhow!("Syscall failed"))?;
         Ok(())
     }
 
diff --git a/evm/src/cpu/kernel/tests/account_code.rs b/evm/src/cpu/kernel/tests/account_code.rs
index b7b6debb..919b9f2f 100644
--- a/evm/src/cpu/kernel/tests/account_code.rs
+++ b/evm/src/cpu/kernel/tests/account_code.rs
@@ -322,8 +322,10 @@ fn sload() -> Result<()> {
     let addr_nibbles = Nibbles::from_bytes_be(addr_hashed.as_bytes()).unwrap();
 
     // This code is similar to the one in add11_yml's contract, but we pop the added value
-    // and carry out an SLOAD instead of an SSTORE.
-    let code = [0x60, 0x01, 0x60, 0x01, 0x01, 0x50, 0x60, 0x00, 0x54, 0x00];
+    // and carry out an SLOAD instead of an SSTORE. We also add a PUSH at the end.
+    let code = [
+        0x60, 0x01, 0x60, 0x01, 0x01, 0x50, 0x60, 0x00, 0x54, 0x60, 0x03, 0x00,
+    ];
     let code_hash = keccak(code);
 
     let account_before = AccountRlp {
@@ -350,9 +352,13 @@ fn sload() -> Result<()> {
     prepare_interpreter_all_accounts(&mut interpreter, trie_inputs, addr, &code)?;
 
     interpreter.run()?;
-    // We check that no value was found.
-    let value = interpreter.pop();
-    assert_eq!(value, 0.into());
+
+    // The SLOAD in the provided code should return 0, since
+    // the storage trie is empty. The last step in the code
+    // pushes the value 3.
+    assert_eq!(interpreter.stack(), vec![0x0.into(), 0x3.into()]);
+    interpreter.pop();
+    interpreter.pop();
     // Now, execute mpt_hash_state_trie. We check that the state trie has not changed.
     let mpt_hash_state_trie = KERNEL.global_labels["mpt_hash_state_trie"];
     interpreter.generation_state.registers.program_counter = mpt_hash_state_trie;