UserspaceEmulator: Support sys$mremap()

This makes UE able to run dynamically linked executables once again.

DevTools/UserspaceEmulator/Emulator.cpp

@@ -410,6 +410,8 @@ u32 Emulator::virt_syscall(u32 function, u32 arg1, u32 arg2, u32 arg3)
         return virt$mount(arg1);
     case SC_munmap:
         return virt$munmap(arg1, arg2);
+    case SC_mremap:
+        return virt$mremap(arg1);
     case SC_gettid:
         return virt$gettid();
     case SC_getpid:
@@ -1037,6 +1039,24 @@ u32 Emulator::virt$mmap(u32 params_addr)
     return final_address;
 }
 
+FlatPtr Emulator::virt$mremap(FlatPtr params_addr)
+{
+    Syscall::SC_mremap_params params;
+    mmu().copy_from_vm(&params, params_addr, sizeof(params));
+
+    if (auto* region = mmu().find_region({ m_cpu.ds(), params.old_address })) {
+        if (!region->is_mmap())
+            return -EINVAL;
+        ASSERT(region->size() == params.old_size);
+        auto& mmap_region = *(MmapRegion*)region;
+        auto* ptr = mremap(mmap_region.data(), mmap_region.size(), mmap_region.size(), params.flags);
+        if (ptr == MAP_FAILED)
+            return -errno;
+        return (FlatPtr)ptr;
+    }
+    return -EINVAL;
+}
+
 u32 Emulator::virt$mount(u32 params_addr)
 {
     Syscall::SC_mount_params params;

DevTools/UserspaceEmulator/Emulator.h

@@ -103,6 +103,7 @@ private:
     int virt$disown(pid_t);
     int virt$purge(int mode);
     u32 virt$mmap(u32);
+    FlatPtr virt$mremap(FlatPtr);
     u32 virt$mount(u32);
     u32 virt$munmap(FlatPtr address, u32 size);
     u32 virt$gettid();