Eric Pouech : winedbg: Correctly read LDT entries for wow64 debuggee.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 44ab1206617a48aeed01fc1349f8309021a8b818
URL:    https://gitlab.winehq.org/wine/wine/-/commit/44ab1206617a48aeed01fc1349f8309...

Author: Eric Pouech 
Date:   Fri Oct 13 09:58:23 2023 +0200

winedbg: Correctly read LDT entries for wow64 debuggee.

This mostly matters for Mac as segment CS is handled as a real LDT
entry.

Signed-off-by: Eric Pouech

---

programs/winedbg/be_i386.c    |  7 ++++++-
 programs/winedbg/tgt_active.c | 10 ++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/programs/winedbg/be_i386.c b/programs/winedbg/be_i386.c
index 9f22dd5f3d4..1bac5f382b2 100644
--- a/programs/winedbg/be_i386.c
+++ b/programs/winedbg/be_i386.c
@@ -40,7 +40,12 @@ static ADDRESS_MODE get_selector_type(HANDLE hThread, const WOW64_CONTEXT *ctx,
     /* null or system selector */
     if (!(sel & 4) || ((sel >> 3) < first_ldt_entry)) return AddrModeFlat;
     if (dbg_curr_process->process_io->get_selector(hThread, sel, &le))
-        return le.HighWord.Bits.Default_Big ? AddrMode1632 : AddrMode1616;
+    {
+        ULONG base = (le.HighWord.Bits.BaseHi << 24) + (le.HighWord.Bits.BaseMid << 16) + le.BaseLow;
+        if (le.HighWord.Bits.Default_Big)
+            return base == 0 ? AddrModeFlat : AddrMode1632;
+        return AddrMode1616;
+    }
     /* selector doesn't exist */
     return -1;
 }
diff --git a/programs/winedbg/tgt_active.c b/programs/winedbg/tgt_active.c
index 5ac9a4d1229..17578857133 100644
--- a/programs/winedbg/tgt_active.c
+++ b/programs/winedbg/tgt_active.c
@@ -1067,7 +1067,17 @@ static BOOL tgt_process_active_write(HANDLE hProcess, void* addr,

static BOOL tgt_process_active_get_selector(HANDLE hThread, DWORD sel, LDT_ENTRY* le)
 {
+#ifdef _WIN64
+    THREAD_DESCRIPTOR_INFORMATION desc = { .Selector = sel };
+    ULONG retlen;
+
+    if (RtlWow64GetThreadSelectorEntry( hThread, &desc, sizeof(desc), &retlen ))
+        return FALSE;
+    *le = desc.Entry;
+    return TRUE;
+#else
     return GetThreadSelectorEntry( hThread, sel, le );
+#endif
 }

static struct be_process_io be_process_active_io =