LibC: Communicate malloc() and free() operations to UserspaceEmulator

Use the sneaky SALC secret mechanism of UserspaceEmulator to inform it
about malloc operations.

Libraries/LibC/malloc.cpp

@@ -281,6 +281,10 @@ static void* malloc_impl(size_t size)
 #ifdef MALLOC_DEBUG
     dbgprintf("LibC: allocated %p (chunk in block %p, size %zu)\n", ptr, block, block->bytes_per_chunk());
 #endif
+
+    // Tell UserspaceEmulator about this malloc()
+    send_secret_data_to_userspace_emulator(1, size, reinterpret_cast<FlatPtr>(ptr));
+
     if (s_scrub_malloc)
         memset(ptr, MALLOC_SCRUB_BYTE, block->m_size);
     return ptr;
@@ -382,6 +386,9 @@ void free(void* ptr)
     if (s_profiling)
         perf_event(PERF_EVENT_FREE, reinterpret_cast<FlatPtr>(ptr), 0);
     free_impl(ptr);
+
+    // Tell UserspaceEmulator about this free()
+    send_secret_data_to_userspace_emulator(2, reinterpret_cast<FlatPtr>(ptr), 0);
 }
 
 void* calloc(size_t count, size_t size)

Libraries/LibC/serenity.h

@@ -70,4 +70,21 @@ int perf_event(int type, uintptr_t arg1, uintptr_t arg2);
 
 int get_stack_bounds(uintptr_t* user_stack_base, size_t* user_stack_size);
 
+ALWAYS_INLINE void send_secret_data_to_userspace_emulator(uintptr_t data1, uintptr_t data2, uintptr_t data3)
+{
+    asm volatile(
+        ".byte 0xd6\n"
+        ".byte 0xd6\n" ::
+            : "eax");
+    asm volatile(
+        "push %%eax\n"
+        "push %%ecx\n"
+        "push %%edx\n"
+        "pop %%edx\n"
+        "pop %%ecx\n"
+        "pop %%eax\n" ::"a"(data1),
+        "c"(data2), "d"(data3)
+        : "memory");
+}
+
 __END_DECLS