Adding a test that will test the correctness of snmalloc

.github/workflows/build.yml

@@ -102,3 +102,5 @@ jobs:
     - name: Run memory allocator stress test
       run: cd ./examples/mem-alloc-test && cargo run
 
+    - name: snmalloc correntness test
+      run: cd ./examples/mem-correctness-test && cargo run

examples/mem-correctness-test/Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "mem-correctness-test"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+crossbeam = "0.8.0"
+rand = "0.8.4"
+num_cpus = "1.14.0"
+sha2 = "0.10"
+
+[package.metadata.fortanix-sgx]
+# heap size (in bytes), the default heap size is 0x2000000.
+heap-size=0x20000000
+debug=false

examples/mem-correctness-test/src/main.rs

@@ -0,0 +1,286 @@
+/* This test based on the following pseudo code and tests correctness of our
+ * new allocator snmalloc
+
+   for 0..num_threads {
+    loop {
+        let mut regions: Vec<(Box<[u8], u8>)>;
+        let mut mem_used = 0u64;
+        match rnd % 4 {
+           0 => // Check area
+           1..2 => // Alloc random area if less than x% of the heap is used (not 100% to
+                   // account for fragmentation, ...) and check area.
+           3 => // Free random area
+        }
+    }
+}
+ * So this basically runs for a long time and should never crash
+ */
+
+use core::arch::asm;
+use rand::Rng;
+use sha2::{Digest, Sha256};
+use std::alloc::{alloc, dealloc, Layout};
+use std::ptr;
+use std::slice;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Barrier;
+use std::sync::{Arc};
+use std::thread;
+
+#[cfg(target_env = "sgx")]
+extern "C" {
+    static HEAP_BASE: u64;
+    static HEAP_SIZE: usize;
+}
+
+const PAGE_SIZE: usize = 4096;
+const TO_KB: usize = 1024;
+const TO_MB: usize = TO_KB * 1024;
+const TO_GB: usize = TO_MB * 1024;
+const ALIGN: usize = PAGE_SIZE;
+
+const NUM_OPERATION_CHOICES: usize = 4;
+static HEAP_ALLOCATED: AtomicUsize = AtomicUsize::new(0);
+
+/* Set of configurable parameters. These will adjusted as necessary while
+ * recording the performance numbers. Since this test will be in CI, I have
+ * kept the parameters to be less memory intensive.
+ */
+const NUM_THREADS: usize = 2;
+/* PER_THREAD_PER_BUFFER_MAX_SIZE is max size of a buffer that a thread can allocate
+ * on each call to add_new_buffer() function. Higher the value, more will be
+ * the total memory consumption and more time taken by the test.
+ */
+const PER_THREAD_PER_BUFFER_MAX_SIZE: usize = 4 * TO_KB;
+/* MAX_BUFFER_CHECKS_PER_THREAD_ITERATION is the maximum number of buffers to
+ * check on each call to select_and_check_random_buffer_contents()
+ */
+const MAX_BUFFER_CHECKS_PER_THREAD_ITERATION: usize = 4;
+/* MAX_INDEX_CHECKS_PER_BUFFER is the number of indices/locations to check
+ * per buffer.
+ */
+const MIN_ALLOWED_FREE_HEAP_PERCENTAGE: f64 = 10.0;
+/* MAX_ITERATIONS_PER_THREAD is the number of operations per thread (1 operation per
+ * per iteration)
+ */
+const MAX_ITERATIONS_PER_THREAD: usize = 4;
+
+#[cfg(target_env = "sgx")]
+#[inline(always)]
+pub fn image_base() -> u64 {
+    let base: u64;
+    unsafe {
+        asm!(
+            "lea IMAGE_BASE(%rip), {}",
+            lateout(reg) base,
+            options(att_syntax, nostack, preserves_flags, nomem, pure),
+        )
+    };
+    base
+}
+
+#[cfg(target_env = "sgx")]
+#[inline(always)]
+pub(crate) unsafe fn rel_ptr_mut<T>(offset: u64) -> *mut T {
+    (image_base() + offset) as *mut T
+}
+
+/* Returns the base memory address of the heap */
+#[cfg(target_env = "sgx")]
+pub(crate) fn heap_base() -> *const u8 {
+    unsafe { rel_ptr_mut(HEAP_BASE) }
+
+}
+
+/* Returns the size of the heap */
+pub(crate) fn heap_size() -> usize {
+    #[cfg(target_env = "sgx")]
+    unsafe { HEAP_SIZE }
+    #[cfg(not(target_env = "sgx"))]
+    usize::MAX
+}
+
+fn update_occupied_heap_size_on_delete(size: usize) {
+    HEAP_ALLOCATED.fetch_sub(size, Ordering::SeqCst);
+}
+
+fn update_occupied_heap_size_on_addition(size: usize) {
+    HEAP_ALLOCATED.fetch_add(size, Ordering::SeqCst);
+}
+
+fn get_occupied_heap_size() -> usize {
+    HEAP_ALLOCATED.load(Ordering::SeqCst)
+}
+
+fn get_free_heap_size_in_bytes() -> usize {
+    heap_size() - get_occupied_heap_size()
+}
+
+fn get_free_heap_percentage() -> f64 {
+    (get_free_heap_size_in_bytes() as f64 / heap_size() as f64) * 100.0
+}
+
+fn get_random_num(start: usize, end: usize) -> usize {
+    let mut rng = rand::thread_rng();
+    rng.gen_range(start..=end)
+}
+
+fn wait_per_thread(barrier_clone: Arc<Barrier>) {
+    barrier_clone.wait();
+}
+
+fn traverse_and_check_buffer(buf: &(*mut u8, usize, String)) -> bool {
+    if buf.2 != compute_sha256_hex(buf.0, buf.1) {
+        return false;
+    }
+    return true;
+}
+
+fn select_and_check_random_buffer_contents(array_of_vectors: &Vec<(*mut u8, usize, String)>) {
+    /* This function selects a random number of buffers and then calls
+     * traverse_and_check_buffer which checks random contents of the set of
+     * randomly selected buffers
+     */
+    let num_active_vectors = array_of_vectors.len();
+    if num_active_vectors > 0 {
+        let random_buffer_check_count = get_random_num(1, MAX_BUFFER_CHECKS_PER_THREAD_ITERATION);
+        for _i in 1..=random_buffer_check_count {
+            let random_buffer_index_to_check = get_random_num(0, array_of_vectors.len() - 1);
+            assert!(traverse_and_check_buffer(
+                &(array_of_vectors[random_buffer_index_to_check]),
+            ));
+        }
+    }
+}
+
+fn delete_random_buffer(array_of_vectors: &mut Vec<(*mut u8, usize, String)>) {
+    let num_active_vectors = array_of_vectors.len();
+    if num_active_vectors > 0 {
+        let random_index_to_delete = get_random_num(0, array_of_vectors.len() - 1);
+        let len = array_of_vectors[random_index_to_delete].1;
+
+        unsafe {
+            dealloc(
+                array_of_vectors[random_index_to_delete].0,
+                Layout::from_size_align(len, ALIGN).unwrap(),
+            );
+        }
+        array_of_vectors.remove(random_index_to_delete);
+        update_occupied_heap_size_on_delete(len);
+    }
+}
+
+fn add_new_buffer(array_of_vectors: &mut Vec<(*mut u8, usize, String)>) -> bool {
+    /* This function assumes that the percentage of free heap space is more
+     * than MIN_ALLOWED_FREE_HEAP_PERCENTAGE
+     */
+
+    let random_size = get_random_num(1, PER_THREAD_PER_BUFFER_MAX_SIZE);
+
+    // Create a layout based on the size and alignment
+    let layout = Layout::from_size_align(random_size, ALIGN).unwrap();
+
+    // Allocate memory using the global allocator
+    let ptr = unsafe { alloc(layout) };
+    if ptr.is_null() {
+        return false;
+    }
+
+    for i in 0..=random_size - 1 {
+        let random_byte = get_random_num(0, u8::MAX as usize) as u8;
+        unsafe {
+            ptr::write(ptr.offset(i as isize), random_byte);
+        }
+    }
+
+    array_of_vectors.push((ptr, random_size, compute_sha256_hex(ptr, random_size)));
+    update_occupied_heap_size_on_addition(random_size);
+    return true;
+}
+
+fn compute_sha256_hex(ptr: *const u8, size: usize) -> String {
+    let data = unsafe { slice::from_raw_parts(ptr, size) };
+    // Create a SHA-256 hasher object
+    let mut hasher = Sha256::new();
+
+    // Update the hasher with the data
+    hasher.update(data);
+
+    // Finalize the hasher and get the result
+    let result = hasher.finalize();
+
+    // Convert the result into a hexadecimal string
+    format!("{:x}", result)
+}
+
+fn worker_thread(tid: i32, barrier_clone: Arc<Barrier>) {
+    /* Wait for all the threads to be created and then start together */
+    wait_per_thread(barrier_clone);
+
+    let mut array_of_vectors: Vec<(*mut u8, usize, String)> = Vec::new();
+
+    /* Once the thread's allocation and deallocation operations begin, we
+     * shouldn't take any lock as the allocator that we trying to test is a
+     * multithreaded allocator and we should allow as many threads as possible
+     * to get the lock.
+     */
+    for _i in 1..=MAX_ITERATIONS_PER_THREAD {
+        let ran_choice = get_random_num(0, NUM_OPERATION_CHOICES - 1);
+
+        match ran_choice {
+            0 => {
+                select_and_check_random_buffer_contents(&array_of_vectors);
+                println!("T-{} check", tid);
+            }
+            1..=2 => {
+                /* Although  get_free_heap_percentage() is thread safe, this
+                 * match case may not be completely thread safe as we are only
+                 * interested in an approximate value of the remaining free space
+                 * percentage.
+                 */
+                if get_free_heap_percentage() > MIN_ALLOWED_FREE_HEAP_PERCENTAGE {
+                    assert!(add_new_buffer(&mut array_of_vectors));
+                    println!("T-{} allocate", tid);
+                } else {
+                    println!("T-{} SKIP", tid);
+                }
+            }
+            3 => {
+                delete_random_buffer(&mut array_of_vectors);
+                println!("T-{} delete", tid);
+            }
+            _ => {
+                panic!("Invalid random operation choice done");
+            }
+        }
+    }
+}
+
+fn spawn_threads(thread_count: i32) {
+    let mut handles = vec![];
+
+    let barrier = Arc::new(Barrier::new(thread_count as usize));
+    for i in 0..thread_count {
+        /* Spawn a thread that waits till all threads are created */
+        let barrier_clone = Arc::clone(&barrier);
+        let handle = thread::spawn(move || {
+            worker_thread(i, barrier_clone);
+        });
+        handles.push(handle);
+    }
+
+    /* Wait for all threads to finish */
+    for handle in handles {
+        handle.join().unwrap();
+    }
+}
+
+fn start_tests() {
+    let num_threads = NUM_THREADS;
+    spawn_threads(num_threads as i32);
+    println!("All {} threads completed", num_threads);
+}
+
+fn main() {
+    start_tests();
+}