[PATCH 0/2] MR5473: wow64: Mind generic xstate in a couple of missed places.

[Paul Gofman (＠gofman)]

Fixes some wow64 mode regressions introduced by commit 29c73ee17335b30f3f49c8b3562742c6a35b482c ("ntdll: Support more xstate features.").

That is actually covered by existing ntdll/tests/exception but there are a couple of tests (related to gs override) which crash those tests. Just in case, attaching an ad-hoc patch which comments out those and let the rest run (and succeed here in wow64 mode with these patches). Properly skipping those probably require Wine check I am afraid.

[test.patch](/uploads/9db61a514f4242add75e96cb9493e8c0/test.patch)

[PATCH 1/2] wow64: Support generic xstate in call_user_exception_dispatcher().

[Paul Gofman]

From: Paul Gofman

---
 dlls/wow64/syscall.c | 26 ++++++--------------------
 1 file changed, 6 insertions(+), 20 deletions(-)

diff --git a/dlls/wow64/syscall.c b/dlls/wow64/syscall.c
index 40eb5327934..9ad1194b21e 100644
--- a/dlls/wow64/syscall.c
+++ b/dlls/wow64/syscall.c
@@ -197,17 +197,12 @@ static void __attribute__((used)) call_user_exception_dispatcher( EXCEPTION_RECO
                 ULONG              context_ptr;   /* 004 */
                 EXCEPTION_RECORD32 rec;           /* 008 */
                 I386_CONTEXT       context;       /* 058 */
-                CONTEXT_EX32       context_ex;    /* 324 */
-                BYTE xstate[sizeof(XSTATE)+64];   /* 33c */
-                DWORD             align;          /* 4bc */
             } *stack;
             I386_CONTEXT ctx = { CONTEXT_I386_ALL };
             CONTEXT_EX *context_ex, *src_ex = NULL;
-            ULONG flags;
+            ULONG flags, context_length;

C_ASSERT( offsetof(struct exc_stack_layout32, context) == 0x58 );
-            C_ASSERT( offsetof(struct exc_stack_layout32, xstate) == 0x33c );
-            C_ASSERT( sizeof(struct exc_stack_layout32) == 0x4c0 );

pBTCpuGetContext( GetCurrentThread(), GetCurrentProcess(), NULL, &ctx );

@@ -231,29 +226,20 @@ static void __attribute__((used)) call_user_exception_dispatcher( EXCEPTION_RECO
             flags = ctx.ContextFlags;
             if (src_ex) flags |= CONTEXT_I386_XSTATE;

-            stack = (struct exc_stack_layout32 *)ULongToPtr( ctx.Esp & ~3 ) - 1;
+            RtlGetExtendedContextLength( flags, &context_length );
+
+            stack = (struct exc_stack_layout32 *)ULongToPtr( (ctx.Esp - offsetof(struct exc_stack_layout32, context) - context_length) & ~3 );
             stack->rec_ptr     = PtrToUlong( &stack->rec );
             stack->context_ptr = PtrToUlong( &stack->context );
             stack->rec         = *rec;
             stack->context     = ctx;
             RtlInitializeExtendedContext( &stack->context, flags, &context_ex );
+            if (src_ex) RtlCopyExtendedContext( context_ex, WOW64_CONTEXT_XSTATE, src_ex );
+
             /* adjust Eip for breakpoints in software emulation (hardware exceptions already adjust Rip) */
             if (rec->ExceptionCode == EXCEPTION_BREAKPOINT && (wow64info->CpuFlags & WOW64_CPUFLAGS_SOFTWARE))
                 stack->context.Eip--;

-            if (src_ex)
-            {
-                XSTATE *src_xs = (XSTATE *)((char *)src_ex + src_ex->XState.Offset);
-                XSTATE *dst_xs = (XSTATE *)((char *)context_ex + context_ex->XState.Offset);
-
-                dst_xs->Mask = src_xs->Mask & ~(ULONG64)3;
-                dst_xs->CompactionMask = src_xs->CompactionMask;
-                if ((dst_xs->Mask & 4) &&
-                    src_ex->XState.Length >= sizeof(XSTATE) &&
-                    context_ex->XState.Length >= sizeof(XSTATE))
-                    memcpy( &dst_xs->YmmContext, &src_xs->YmmContext, sizeof(dst_xs->YmmContext) );
-            }
-
             ctx.Esp = PtrToUlong( stack );
             ctx.Eip = pLdrSystemDllInitBlock->pKiUserExceptionDispatcher;
             ctx.EFlags &= ~(0x100|0x400|0x40000);

[PATCH 2/2] ntdll: Preserve untouched parts of xstate in set_thread_wow64_context().

[Paul Gofman]

From: Paul Gofman

---
 dlls/ntdll/unix/signal_x86_64.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/dlls/ntdll/unix/signal_x86_64.c b/dlls/ntdll/unix/signal_x86_64.c
index d8d16917942..4fc2727595d 100644
--- a/dlls/ntdll/unix/signal_x86_64.c
+++ b/dlls/ntdll/unix/signal_x86_64.c
@@ -1281,9 +1281,11 @@ NTSTATUS set_thread_wow64_context( HANDLE handle, const void *ctx, ULONG size )
     {
         CONTEXT_EX *context_ex = (CONTEXT_EX *)(context + 1);
         XSAVE_AREA_HEADER *xs = (XSAVE_AREA_HEADER *)((char *)context_ex + context_ex->XState.Offset);
+        UINT64 mask = frame->xstate.Mask;

if (xstate_compaction_enabled) frame->xstate.CompactionMask |= xstate_extended_features();
         copy_xstate( &frame->xstate, xs, xs->Mask );
+        if (xs->CompactionMask) frame->xstate.Mask |= mask & ~xs->CompactionMask;
         frame->restore_flags |= CONTEXT_XSTATE;
     }
     return STATUS_SUCCESS;