fix: When track pages receive more writes, treat them as dirty pages (#…

…423)

* chore: Use debug assertions to document get_page_indices input requirements

* fix: When track pages receive more writes, treat them as dirty pages

Credit goes to @mohanson for providing the tests

Co-authored-by: Xuejie Xiao <xxuejie@gmail.com>

src/memory/mod.rs

@@ -102,6 +102,7 @@ pub fn fill_page_data<M: Memory>(
 
 // `size` should be none zero u64
 pub fn get_page_indices(addr: u64, size: u64) -> Result<(u64, u64), Error> {
+    debug_assert!(size > 0);
     let (addr_end, overflowed) = addr.overflowing_add(size);
     if overflowed {
         return Err(Error::MemOutOfBound);

src/snapshot2.rs

@@ -156,9 +156,6 @@ impl<I: Clone + PartialEq, D: DataSource<I>> Snapshot2Context<I, D> {
     pub fn make_snapshot<M: SupportMachine>(&self, machine: &mut M) -> Result<Snapshot2<I>, Error> {
         let mut dirty_pages: Vec<(u64, u8, Vec<u8>)> = vec![];
         for i in 0..machine.memory().memory_pages() as u64 {
-            if self.pages.contains_key(&i) {
-                continue;
-            }
             let flag = machine.memory_mut().fetch_flag(i)?;
             if flag & FLAG_DIRTY == 0 {
                 continue;
@@ -178,6 +175,12 @@ impl<I: Clone + PartialEq, D: DataSource<I>> Snapshot2Context<I, D> {
         let mut pages: Vec<u64> = self.pages.keys().copied().collect();
         pages.sort_unstable();
         for page in pages {
+            // Some pages might be marked as cached pages from data source, but receives
+            // memory writes later(and marked as dirty). We are safely skipping those pages
+            // here as they will be gathered as dirty pages.
+            if machine.memory_mut().fetch_flag(page)? & FLAG_DIRTY != 0 {
+                continue;
+            }
             let address = page * PAGE_SIZE;
             let (id, offset, flag) = &self.pages[&page];
             let mut appended_to_last = false;

tests/test_resume2.rs

@@ -11,7 +11,7 @@ use ckb_vm::machine::{
 use ckb_vm::memory::{sparse::SparseMemory, wxorx::WXorXMemory};
 use ckb_vm::registers::{A0, A1, A7};
 use ckb_vm::snapshot2::{DataSource, Snapshot2, Snapshot2Context};
-use ckb_vm::{DefaultMachineBuilder, Error, Register, Syscalls, ISA_A, ISA_IMC};
+use ckb_vm::{DefaultMachineBuilder, Error, Memory, Register, Syscalls, ISA_A, ISA_IMC};
 use std::collections::HashMap;
 use std::fs::File;
 use std::io::Read;
@@ -531,7 +531,7 @@ impl Machine {
 
     #[cfg(not(feature = "enable-chaos-mode-by-default"))]
     fn full_memory(&mut self) -> Result<Bytes, Error> {
-        use ckb_vm::{Memory, RISCV_MAX_MEMORY};
+        use ckb_vm::RISCV_MAX_MEMORY;
         use Machine::*;
         match self {
             Asm(inner, _) => inner
@@ -659,3 +659,38 @@ pub fn test_store_bytes_twice() {
 
     assert_eq!(mem1, mem2);
 }
+
+#[cfg(not(feature = "enable-chaos-mode-by-default"))]
+#[test]
+pub fn test_mixing_snapshot2_writes_with_machine_raw_writes() {
+    let data_source = load_program("tests/programs/sc_after_snapshot");
+
+    let mut machine = MachineTy::Asm.build(data_source.clone(), VERSION2);
+    machine.set_max_cycles(u64::MAX);
+    machine.load_program(&vec!["main".into()]).unwrap();
+
+    match machine {
+        Machine::Asm(ref mut inner, ref ctx) => {
+            ctx.lock()
+                .unwrap()
+                .store_bytes(&mut inner.machine, 0, &DATA_ID, 0, 29186)
+                .unwrap();
+            inner
+                .machine
+                .memory_mut()
+                .store_bytes(0, &vec![0x42; 29186])
+                .unwrap();
+        }
+        _ => unimplemented!(),
+    }
+
+    let mem1 = machine.full_memory().unwrap();
+
+    let snapshot = machine.snapshot().unwrap();
+    let mut machine2 = MachineTy::Asm.build(data_source.clone(), VERSION2);
+    machine2.resume(snapshot).unwrap();
+    machine2.set_max_cycles(u64::MAX);
+    let mem2 = machine2.full_memory().unwrap();
+
+    assert_eq!(mem1, mem2);
+}