Remove BPF Loader's use of GenericError (#8284)

Cargo.lock

@@ -3645,9 +3645,12 @@ dependencies = [
  "byteorder 1.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.66 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-derive 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "solana-logger 0.24.0",
  "solana-sdk 0.24.0",
  "solana_rbpf 0.1.21 (registry+https://github.com/rust-lang/crates.io-index)",
+ "thiserror 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]

programs/bpf_loader/Cargo.toml

@@ -13,9 +13,12 @@ bincode = "1.2.1"
 byteorder = "1.3.2"
 libc = "0.2.66"
 log = "0.4.8"
+num-derive = { version = "0.3" }
+num-traits = { version = "0.2" }
 solana-logger = { path = "../../logger", version = "0.24.0" }
 solana-sdk = { path = "../../sdk", version = "0.24.0" }
 solana_rbpf = "=0.1.21"
+thiserror = "1.0"
 
 [lib]
 crate-type = ["lib", "cdylib"]

programs/bpf_loader/src/lib.rs

@@ -5,12 +5,14 @@ pub mod helpers;
 
 use byteorder::{ByteOrder, LittleEndian, WriteBytesExt};
 use log::*;
+use num_derive::{FromPrimitive, ToPrimitive};
 use solana_rbpf::{memory_region::MemoryRegion, EbpfVm};
 use solana_sdk::{
     account::KeyedAccount,
     entrypoint::SUCCESS,
     instruction::InstructionError,
     loader_instruction::LoaderInstruction,
+    program_utils::DecodeError,
     program_utils::{is_executable, limited_deserialize, next_keyed_account},
     pubkey::Pubkey,
     sysvar::rent,
@@ -19,6 +21,7 @@ use std::{
     io::{prelude::*, Error},
     mem,
 };
+use thiserror::Error;
 
 solana_sdk::declare_program!(
     solana_sdk::bpf_loader::ID,
@@ -26,6 +29,20 @@ solana_sdk::declare_program!(
     process_instruction
 );
 
+#[derive(Error, Debug, Clone, PartialEq, FromPrimitive, ToPrimitive)]
+pub enum BPFLoaderError {
+    #[error("Failed to create virtual machine")]
+    VirtualMachineCreationFailed,
+    #[error("Virtual machine failed to run the program to completion")]
+    VirtualMachineFailedToRunProgram,
+}
+
+impl<E> DecodeError<E> for BPFLoaderError {
+    fn type_of() -> &'static str {
+        "BPFLoaderError"
+    }
+}
+
 pub fn create_vm(prog: &[u8]) -> Result<(EbpfVm, MemoryRegion), Error> {
     let mut vm = EbpfVm::new(None)?;
     vm.set_verifier(bpf_verifier::check)?;
@@ -138,7 +155,7 @@ pub fn process_instruction(
             Ok(info) => info,
             Err(e) => {
                 warn!("Failed to create BPF VM: {}", e);
-                return Err(InstructionError::GenericError);
+                return Err(BPFLoaderError::VirtualMachineCreationFailed.into());
             }
         };
         let parameter_accounts = keyed_accounts_iter.as_slice();
@@ -156,7 +173,7 @@ pub fn process_instruction(
             }
             Err(e) => {
                 warn!("BPF VM failed to run program: {}", e);
-                return Err(InstructionError::GenericError);
+                return Err(BPFLoaderError::VirtualMachineFailedToRunProgram.into());
             }
         }
         deserialize_parameters(parameter_accounts, &parameter_bytes)?;