[PATCH 0/2] MR6139: ntdll: Optimize NtReadVirtualMemory for in-process reads.

[Piotr Caban (＠piotr)]

It improves rendering performance in V-Ray.

[PATCH 1/2] ntdll: Optimize NtReadVirtualMemory for in-process reads.

[Piotr Caban]

From: Piotr Caban

---
 dlls/ntdll/unix/virtual.c | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/dlls/ntdll/unix/virtual.c b/dlls/ntdll/unix/virtual.c
index 0d88315164a..ef206d58652 100644
--- a/dlls/ntdll/unix/virtual.c
+++ b/dlls/ntdll/unix/virtual.c
@@ -6025,7 +6025,26 @@ NTSTATUS WINAPI NtReadVirtualMemory( HANDLE process, const void *addr, void *buf
 {
     unsigned int status;

-    if (virtual_check_buffer_for_write( buffer, size ))
+    if (!virtual_check_buffer_for_write( buffer, size ))
+    {
+        status = STATUS_ACCESS_VIOLATION;
+        size = 0;
+    }
+    else if (process == GetCurrentProcess())
+    {
+        __TRY
+        {
+            memmove( buffer, addr, size );
+            status = STATUS_SUCCESS;
+        }
+        __EXCEPT
+        {
+            status = STATUS_PARTIAL_COPY;
+            size = 0;
+        }
+        __ENDTRY
+    }
+    else
     {
         SERVER_START_REQ( read_process_memory )
         {
@@ -6036,11 +6055,6 @@ NTSTATUS WINAPI NtReadVirtualMemory( HANDLE process, const void *addr, void *buf
         }
         SERVER_END_REQ;
     }
-    else
-    {
-        status = STATUS_ACCESS_VIOLATION;
-        size = 0;
-    }
     if (bytes_read) *bytes_read = size;
     return status;
 }

[PATCH 2/2] kernel32/tests: Test ReadProcessMemory on PAGE_NOACCESS memory.

[Piotr Caban]

From: Piotr Caban

---
 dlls/kernel32/tests/virtual.c | 40 +++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/dlls/kernel32/tests/virtual.c b/dlls/kernel32/tests/virtual.c
index 5fa8a1b5266..12841133c05 100644
--- a/dlls/kernel32/tests/virtual.c
+++ b/dlls/kernel32/tests/virtual.c
@@ -4366,6 +4366,45 @@ static void test_PrefetchVirtualMemory(void)
         "PrefetchVirtualMemory unexpected status on 2 page-aligned entries: %ld\n", GetLastError() );
 }

+static void test_ReadProcessMemory(void)
+{
+    BYTE buf[0x2000];
+    DWORD old_prot;
+    SIZE_T copied;
+    HANDLE hproc;
+    void *ptr;
+    BOOL ret;
+
+    ret = DuplicateHandle(GetCurrentProcess(), GetCurrentProcess(), GetCurrentProcess(),
+            &hproc, 0, FALSE, DUPLICATE_SAME_ACCESS);
+    ok(ret, "DuplicateHandle failed %lu\n", GetLastError());
+    ptr = VirtualAlloc(NULL, 2 * si.dwPageSize, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
+    ok(ptr != NULL, "Virtual failed %lu\n", GetLastError());
+    ret = VirtualProtect(((BYTE *)ptr) + si.dwPageSize, si.dwPageSize, PAGE_NOACCESS, &old_prot);
+    ok(ret, "VirtualProtect failed %lu\n", GetLastError());
+
+    copied = 1;
+    ret = ReadProcessMemory(GetCurrentProcess(), ptr, buf, 2 * si.dwPageSize, &copied);
+    ok(!ret, "ReadProcessMemory succeeded\n");
+    ok(!copied, "copied = %Id\n", copied);
+    ok(GetLastError() == ERROR_PARTIAL_COPY, "GetLastError() = %lu\n", GetLastError());
+
+    ret = ReadProcessMemory(GetCurrentProcess(), ptr, buf, si.dwPageSize, &copied);
+    ok(ret, "ReadProcessMemory failed %lu\n", GetLastError());
+    ok(copied == si.dwPageSize, "copied = %Id\n", copied);
+
+    ret = ReadProcessMemory(hproc, ptr, buf, 2 * si.dwPageSize, &copied);
+    todo_wine ok(!ret, "ReadProcessMemory succeeded\n");
+
+    ret = ReadProcessMemory(hproc, ptr, buf, si.dwPageSize, &copied);
+    ok(ret, "ReadProcessMemory failed %lu\n", GetLastError());
+    ok(copied == si.dwPageSize, "copied = %Id\n", copied);
+
+    ret = VirtualFree(ptr, 0, MEM_RELEASE);
+    ok(ret, "VirtualFree failed %lu\n", GetLastError());
+    CloseHandle(hproc);
+}
+
 START_TEST(virtual)
 {
     int argc;
@@ -4447,6 +4486,7 @@ START_TEST(virtual)
     test_IsBadCodePtr();
     test_write_watch();
     test_PrefetchVirtualMemory();
+    test_ReadProcessMemory();
 #if defined(__i386__) || defined(__x86_64__)
     test_stack_commit();
 #endif