[newlib-cygwin/main] Cygwin: SEH: Fix crash and handle second unwind phase on AArch64

https://sourceware.org/git/gitweb.cgi?p=3Dnewlib-cygwin.git;h=3D4054e78799f=
18feadbc3960898f0e516e31ff12e

commit 4054e78799f18feadbc3960898f0e516e31ff12e
Author:     Igor Podgainoi <[email protected]>
AuthorDate: Tue Mar 31 12:11:52 2026 +0000
Commit:     Corinna Vinschen <[email protected]>
CommitDate: Tue Apr 7 20:54:55 2026 +0200

    Cygwin: SEH: Fix crash and handle second unwind phase on AArch64
   =20
    This patch adds the SEH_CODE macro (defined in cygtls.h) and refactors
    the TRY_HANDLER_DATA metadata, fixing code styling and allowing it to
    be used on both AArch64 and x86_64 architectures.
   =20
    It also makes modifications to the exception handler responsible for the
    __try and __except blocks.
   =20
    The first change to the handler fixes a bug where the existing
    exception context record is reused as an unwind context record, which
    fails with a crash on Windows on Arm (AArch64). The fix is to create a
    new record instead, while leaving the original one intact.
   =20
    The second change adds an additional condition for cases when the
    handler is called again in the second phase of unwinding on certain
    platforms such as Windows on Arm (AArch64). In this case, the value
    ExceptionContinueSearch is simply returned without making any changes.
   =20
    Tests fixed on AArch64:
    winsup.api/ltp/access03.exe
    winsup.api/ltp/access05.exe
    winsup.api/ltp/chdir04.exe
    winsup.api/ltp/mkdir01.exe
    winsup.api/ltp/rename08.exe
    winsup.api/ltp/rmdir05.exe
    winsup.api/ltp/stat03.exe
    winsup.api/ltp/stat06.exe
    winsup.api/ltp/symlink01.exe
    winsup.api/ltp/symlink03.exe
    winsup.api/ltp/times02.exe
    winsup.api/ltp/unlink07.exe
   =20
    Signed-off-by: Igor Podgainoi <[email protected]>

Diff:
---
 winsup/cygwin/exceptions.cc           | 10 +++++++---
 winsup/cygwin/local_includes/cygtls.h | 27 ++++++++++++++++-----------
 2 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index badb11da7323..21af26ac3f30 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -618,10 +618,14 @@ EXCEPTION_DISPOSITION
 exception::myfault (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT *i=
n,
 		    PDISPATCHER_CONTEXT dispatch)
 {
+  if (IS_UNWINDING(e->ExceptionFlags))
+    return ExceptionContinueSearch;
+
   PSCOPE_TABLE table =3D (PSCOPE_TABLE) dispatch->HandlerData;
-  RtlUnwindEx (frame,
-	       (char *) dispatch->ImageBase + table->ScopeRecord[0].JumpTarget,
-	       e, 0, in, dispatch->HistoryTable);
+  void *jump_target =3D ((char *) dispatch->ImageBase) + table->ScopeRecor=
d[0].JumpTarget;
+
+  CONTEXT c;
+  RtlUnwindEx (frame, jump_target, e, 0, &c, dispatch->HistoryTable);
   /* NOTREACHED, make gcc happy. */
   return ExceptionContinueSearch;
 }
diff --git a/winsup/cygwin/local_includes/cygtls.h b/winsup/cygwin/local_in=
cludes/cygtls.h
index 289f395e4b56..0b5255495a23 100644
--- a/winsup/cygwin/local_includes/cygtls.h
+++ b/winsup/cygwin/local_includes/cygtls.h
@@ -344,21 +344,26 @@ public:
   void leave () __attribute__ ((returns_twice));
 };
=20
-#if defined (__aarch64__)
+#if defined(__aarch64__)
 #define EXCEPTION_MYFAULT_REF "_ZN9exception7myfaultEP17_EXCEPTION_RECORDP=
vP8_CONTEXTP25_DISPATCHER_CONTEXT_ARM64"
-#define TRY_HANDLER_DATA (void) &&__l_try;
-#else
+/* An SEH directive that switches back to the code section.  */
+#define SEH_CODE ".text"
+#elif defined(__x86_64__)
 #define EXCEPTION_MYFAULT_REF "_ZN9exception7myfaultEP17_EXCEPTION_RECORDP=
vP8_CONTEXTP19_DISPATCHER_CONTEXT"
-#define TRY_HANDLER_DATA \
-  __asm__ goto ("\n" \
-  "  .seh_handler " EXCEPTION_MYFAULT_REF ", @except			\n" \
-  "  .seh_handlerdata							\n" \
-  "  .long 1								\n" \
-  "  .rva %l[__l_try],%l[__l_endtry],%l[__l_except],%l[__l_except]	\n" \
-  "  .seh_code								\n" \
-  : : : : __l_try, __l_endtry, __l_except)
+#define SEH_CODE ".seh_code"
 #endif
=20
+#define TRY_HANDLER_DATA \
+  __asm__ goto ("\n\
+    .seh_handler "							  \
+      EXCEPTION_MYFAULT_REF ",						  \
+      @except								\n\
+    .seh_handlerdata							\n\
+    .long 1								\n\
+    .rva %l[__l_try],%l[__l_endtry],%l[__l_except],%l[__l_except]	\n"\
+    SEH_CODE "								\n"\
+    : : : : __l_try, __l_endtry, __l_except)
+
 /* Exception handling macros. This is a handmade SEH try/except. */
 #define __mem_barrier	__asm__ __volatile__ ("" ::: "memory")
 #define __try \