Restore ability for programs to upgrade themselves (#20265)

* Make helper associated fn

* Add feature definition

* Add handling to preserve program-id write lock when upgradeable loader is present; restore bpf upgrade-self test

* Use single feature

programs/bpf/tests/programs.rs

@@ -1867,7 +1867,7 @@ fn test_program_bpf_upgrade_and_invoke_in_same_tx() {
         "solana_bpf_rust_panic",
     );
 
-    // Attempt to invoke, then upgrade the program in same tx
+    // Invoke, then upgrade the program, and then invoke again in same tx
     let message = Message::new(
         &[
             invoke_instruction.clone(),
@@ -1886,12 +1886,10 @@ fn test_program_bpf_upgrade_and_invoke_in_same_tx() {
         message.clone(),
         bank.last_blockhash(),
     );
-    // program_id is automatically demoted to readonly, preventing the upgrade, which requires
-    // writeability
     let (result, _) = process_transaction_and_record_inner(&bank, tx);
     assert_eq!(
         result.unwrap_err(),
-        TransactionError::InstructionError(1, InstructionError::InvalidArgument)
+        TransactionError::InstructionError(2, InstructionError::ProgramFailedToComplete)
     );
 }
 
@@ -2187,6 +2185,96 @@ fn test_program_bpf_upgrade_via_cpi() {
     assert_ne!(programdata, original_programdata);
 }
 
+#[cfg(feature = "bpf_rust")]
+#[test]
+fn test_program_bpf_upgrade_self_via_cpi() {
+    solana_logger::setup();
+
+    let GenesisConfigInfo {
+        genesis_config,
+        mint_keypair,
+        ..
+    } = create_genesis_config(50);
+    let mut bank = Bank::new_for_tests(&genesis_config);
+    let (name, id, entrypoint) = solana_bpf_loader_program!();
+    bank.add_builtin(&name, id, entrypoint);
+    let (name, id, entrypoint) = solana_bpf_loader_upgradeable_program!();
+    bank.add_builtin(&name, id, entrypoint);
+    let bank = Arc::new(bank);
+    let bank_client = BankClient::new_shared(&bank);
+    let noop_program_id = load_bpf_program(
+        &bank_client,
+        &bpf_loader::id(),
+        &mint_keypair,
+        "solana_bpf_rust_noop",
+    );
+
+    // Deploy upgradeable program
+    let buffer_keypair = Keypair::new();
+    let program_keypair = Keypair::new();
+    let program_id = program_keypair.pubkey();
+    let authority_keypair = Keypair::new();
+    load_upgradeable_bpf_program(
+        &bank_client,
+        &mint_keypair,
+        &buffer_keypair,
+        &program_keypair,
+        &authority_keypair,
+        "solana_bpf_rust_invoke_and_return",
+    );
+
+    let mut invoke_instruction = Instruction::new_with_bytes(
+        program_id,
+        &[0],
+        vec![
+            AccountMeta::new_readonly(noop_program_id, false),
+            AccountMeta::new_readonly(noop_program_id, false),
+            AccountMeta::new_readonly(clock::id(), false),
+        ],
+    );
+
+    // Call the upgraded program
+    invoke_instruction.data[0] += 1;
+    let result =
+        bank_client.send_and_confirm_instruction(&mint_keypair, invoke_instruction.clone());
+    assert!(result.is_ok());
+
+    // Prepare for upgrade
+    let buffer_keypair = Keypair::new();
+    load_upgradeable_buffer(
+        &bank_client,
+        &mint_keypair,
+        &buffer_keypair,
+        &authority_keypair,
+        "solana_bpf_rust_panic",
+    );
+
+    // Invoke, then upgrade the program, and then invoke again in same tx
+    let message = Message::new(
+        &[
+            invoke_instruction.clone(),
+            bpf_loader_upgradeable::upgrade(
+                &program_id,
+                &buffer_keypair.pubkey(),
+                &authority_keypair.pubkey(),
+                &mint_keypair.pubkey(),
+            ),
+            invoke_instruction,
+        ],
+        Some(&mint_keypair.pubkey()),
+    );
+    let tx = Transaction::new(
+        &[&mint_keypair, &authority_keypair],
+        message.clone(),
+        bank.last_blockhash(),
+    );
+    let (result, _) = process_transaction_and_record_inner(&bank, tx);
+    assert_eq!(
+        result.unwrap_err(),
+        TransactionError::InstructionError(2, InstructionError::ProgramFailedToComplete)
+    );
+}
+
 #[cfg(feature = "bpf_rust")]
 #[test]
 fn test_program_bpf_set_upgrade_authority_via_cpi() {