Based on a patch by Dávid Török.
Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=47970 Signed-off-by: Zebediah Figura z.figura12@gmail.com --- Actually, the behaviour of segment registers on x86_64 Windows is more complicated:
* By default, %ss == %ds == %es == %gs == 0x2b; %cs == 0x33; %fs == 0x53.
* NtGetContextThread() does not capture the actual values, but instead returns the default values.
* All system calls restore all segments to their default values, including NtContinue().
* RtlRestoreContext() also restores all segments to their default values.
* SegDs, SegEs, SegFs, SegGs all restore default values in exception handlers; SegSs returns the actual value of %ss.
* RtlCaptureContext() does capture the actual values.
I did not test:
* whether %cs is correctly captured or restored in any functions;
* whether segment registers are restored from exception handlers (either to the default values or to the values set in the context).
We could, to a point, emulate the above, but it gets tricky. According to the Intel 64 and IA-32 Architectures Software Developer's Manual:
* %es, %ds, %ss can point to any segment—the entire contents of the descriptor table are effectively ignored (if I'm reading Volume 3 §3.4.4 right). However, they have to point to a *valid* segment (cf. Volume 1 §3.4.2.1).
* %cs is more restricted—the attributes in the descriptor table are also validated (Volume 3 §5.2.1).
* I don't even know about %fs and %gs; the manual is too vague and confusing.
dlls/ntdll/tests/exception.c | 2 +- dlls/ntdll/unix/signal_x86_64.c | 8 +++----- 2 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/dlls/ntdll/tests/exception.c b/dlls/ntdll/tests/exception.c index e2a8071168d..90af9de1bba 100644 --- a/dlls/ntdll/tests/exception.c +++ b/dlls/ntdll/tests/exception.c @@ -3000,7 +3000,7 @@ static DWORD WINAPI handler( EXCEPTION_RECORD *rec, ULONG64 frame, "%u: Unexpected exception address %p/%p\n", entry, rec->ExceptionAddress, (char*)context->Rip );
- todo_wine ok( context->SegDs == context->SegSs, + ok( context->SegDs == context->SegSs, "%u: ds %#x does not match ss %#x\n", entry, context->SegDs, context->SegSs );
if (except->status == STATUS_BREAKPOINT && is_wow64) diff --git a/dlls/ntdll/unix/signal_x86_64.c b/dlls/ntdll/unix/signal_x86_64.c index 7dab5fbf4ed..814f2824129 100644 --- a/dlls/ntdll/unix/signal_x86_64.c +++ b/dlls/ntdll/unix/signal_x86_64.c @@ -1500,11 +1500,6 @@ static void save_context( struct xcontext *xcontext, const ucontext_t *sigcontex context->SegFs = FS_sig(sigcontext); context->SegGs = GS_sig(sigcontext); context->EFlags = EFL_sig(sigcontext); -#ifdef DS_sig - context->SegDs = DS_sig(sigcontext); -#else - __asm__("movw %%ds,%0" : "=m" (context->SegDs)); -#endif #ifdef ES_sig context->SegEs = ES_sig(sigcontext); #else @@ -1515,6 +1510,9 @@ static void save_context( struct xcontext *xcontext, const ucontext_t *sigcontex #else __asm__("movw %%ss,%0" : "=m" (context->SegSs)); #endif + /* Legends of Runeterra depends on having SegDs == SegSs in an exception + * handler. */ + context->SegDs = context->SegSs; context->Dr0 = amd64_thread_data()->dr0; context->Dr1 = amd64_thread_data()->dr1; context->Dr2 = amd64_thread_data()->dr2;