Eric Pouech : dbghelp: Stop unwinding on potential 64bit frame for i386 cpu.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 7de1284b59f18257bebbaa63b9a5ca89291251ed
URL:    https://gitlab.winehq.org/wine/wine/-/commit/7de1284b59f18257bebbaa63b9a5ca8...

Author: Eric Pouech 
Date:   Wed Feb  1 16:22:52 2023 +0100

dbghelp: Stop unwinding on potential 64bit frame for i386 cpu.

Transform potential error on 32 => 64 bit transition with
end of stack (needed in new wow64 for dbghelp's stackwalk tests).

Signed-off-by: Eric Pouech

---

dlls/dbghelp/cpu_i386.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/dlls/dbghelp/cpu_i386.c b/dlls/dbghelp/cpu_i386.c
index c45c45f434c..dcc576cf295 100644
--- a/dlls/dbghelp/cpu_i386.c
+++ b/dlls/dbghelp/cpu_i386.c
@@ -473,7 +473,14 @@ static BOOL i386_stack_walk(struct cpu_stack_walk *csw, STACKFRAME64 *frame,
         union ctx newctx = *context;

if (!fetch_next_frame32(csw, &newctx, frame->AddrPC.Offset - deltapc))
-            goto done_err;
+        {
+            /* When running on wow64 setup, frame below can a 64 bit frame.
+             * As we don't expose 64bit frames for now, pretend it's the first frame.
+             */
+            if (frame->AddrPC.Offset == 0)
+                goto done_err;
+            newctx.x86.Eip = 0;
+        }
         frame->AddrReturn.Mode = AddrModeFlat;
         frame->AddrReturn.Offset = newctx.x86.Eip;