[v2 1/3] ntdll: Set Dr7 when saving context.

[Andrew Wesie]

This is a work-around so that Dr7 is initialized to a reasonable value. Before
it was just uninitialized memory. The test will fail without the work-around,
and shows a todo if Dr7 is zero.

Signed-off-by: Andrew Wesie <awesie at gmail.com>
---
 dlls/ntdll/signal_x86_64.c   |  1 +
 dlls/ntdll/tests/exception.c | 78 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 79 insertions(+)

diff --git a/dlls/ntdll/signal_x86_64.c b/dlls/ntdll/signal_x86_64.c
index f33fe4c..af16cfd 100644
--- a/dlls/ntdll/signal_x86_64.c
+++ b/dlls/ntdll/signal_x86_64.c
@@ -1692,6 +1692,7 @@ static void save_context( CONTEXT *context, const ucontext_t *sigcontext )
         context->u.FltSave = *FPU_sig(sigcontext);
         context->MxCsr = context->u.FltSave.MxCsr;
     }
+    context->Dr7 = 0;
 }
 
 
diff --git a/dlls/ntdll/tests/exception.c b/dlls/ntdll/tests/exception.c
index 3abec1b..446f0da 100644
--- a/dlls/ntdll/tests/exception.c
+++ b/dlls/ntdll/tests/exception.c
@@ -1987,6 +1987,80 @@ static void test___C_specific_handler(void)
     ok(dispatch.ScopeIndex == 1, "dispatch.ScopeIndex = %d\n", dispatch.ScopeIndex);
 }
 
+static DWORD run_exception_test(void *handler, const void* context,
+                               const void *code, unsigned int code_size,
+                               DWORD access)
+{
+    unsigned char buf[8 + 6 + 8 + 8];
+    RUNTIME_FUNCTION runtime_func;
+    UNWIND_INFO *unwind = (UNWIND_INFO *)buf;
+    DWORD (*func)(void) = code_mem;
+    DWORD oldaccess, oldaccess2, result;
+
+    runtime_func.BeginAddress = 0;
+    runtime_func.EndAddress = code_size;
+    runtime_func.UnwindData = 0x1000;
+
+    unwind->Version = 1;
+    unwind->Flags = UNW_FLAG_EHANDLER;
+    unwind->SizeOfProlog = 0;
+    unwind->CountOfCodes = 0;
+    unwind->FrameRegister = 0;
+    unwind->FrameOffset = 0;
+    *(ULONG *)&buf[4] = 0x1010;
+    *(const void **)&buf[8] = context;
+
+    buf[16] = 0xff;
+    buf[17] = 0x25;
+    *(ULONG *)&buf[18] = 0;
+    *(void **)&buf[22] = handler;
+
+    memcpy((unsigned char *)code_mem + 0x1000, buf, sizeof(buf));
+    memcpy(code_mem, code, code_size);
+    if(access)
+        VirtualProtect(code_mem, code_size, access, &oldaccess);
+
+    pRtlAddFunctionTable(&runtime_func, 1, (ULONG_PTR)code_mem);
+    result = func();
+    pRtlDeleteFunctionTable(&runtime_func);
+
+    if(access)
+        VirtualProtect(code_mem, code_size, oldaccess, &oldaccess2);
+
+    return result;
+}
+
+static DWORD WINAPI dr7_handler( EXCEPTION_RECORD *rec, ULONG64 frame,
+                      CONTEXT *context, DISPATCHER_CONTEXT *dispatcher )
+{
+    BOOL todo = context->Dr7 == 0;
+    ULONG_PTR dr7 = **(ULONG_PTR **)(dispatcher->HandlerData);
+
+    if (rec->ExceptionCode != STATUS_BREAKPOINT)
+        return ExceptionContinueSearch;
+
+    todo_wine_if(todo)
+    ok( (context->Dr7 & ~0xdc00) == dr7,
+        "expected %lx, dr7 %lx\n", dr7, context->Dr7 );
+    trace( "dr0 %lx, dr1 %lx, dr2 %lx\n", context->Dr0, context->Dr1, context->Dr2 );
+    trace( "dr3 %lx, dr6 %lx, dr7 %lx\n", context->Dr3, context->Dr6, context->Dr7 );
+
+    context->Rip += 1;
+    return ExceptionContinueExecution;
+}
+
+/* Fill stack area above red zone with 0xff, then trigger exception. */
+static const BYTE dr7_test_code[] = {
+        0x57,                                           /* push %rdi */
+        0x48, 0xc7, 0xc1, 0x00, 0x10, 0x00, 0x00,       /* mov $0x1000, %rcx */
+        0x48, 0x8d, 0xbc, 0x24, 0x80, 0xef, 0xff, 0xff, /* lea -0x1080(%rsp), %rdi */
+        0x48, 0xc7, 0xc0, 0xff, 0x00, 0x00, 0x00,       /* mov $0xff, %rax */
+        0xf3, 0xaa,                                     /* rep stosb */
+        0xcc,                                           /* int3 */
+        0x5f,                                           /* pop %rdi */
+        0xc3,                                           /* ret */
+};
+
 #endif  /* __x86_64__ */
 
 #if defined(__i386__) || defined(__x86_64__)
@@ -2031,6 +2105,10 @@ static void test_debug_registers(void)
         ok(ctx.Dr3 == tests[i].dr3, "test %d: expected %lx, got %lx\n", i, tests[i].dr3, (DWORD_PTR)ctx.Dr3);
         ok((ctx.Dr6 &  0xf00f) == tests[i].dr6, "test %d: expected %lx, got %lx\n", i, tests[i].dr6, (DWORD_PTR)ctx.Dr6);
         ok((ctx.Dr7 & ~0xdc00) == tests[i].dr7, "test %d: expected %lx, got %lx\n", i, tests[i].dr7, (DWORD_PTR)ctx.Dr7);
+
+#if defined(__x86_64__)
+        run_exception_test(dr7_handler, &tests[i].dr7, dr7_test_code, sizeof(dr7_test_code), 0);
+#endif
     }
 }
 
-- 
2.7.4