[newlib-cygwin/main] Cygwin: find_fast_cwd: don't run assembler checking code on ARM64

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=4e77fa9b8bf4818ff90c013f7e7b2b0ac0b968c5

commit 4e77fa9b8bf4818ff90c013f7e7b2b0ac0b968c5
Author:     Corinna Vinschen <corinna@vinschen.de>
AuthorDate: Tue Feb 13 16:47:51 2024 +0100
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Tue Feb 13 16:48:15 2024 +0100

    Cygwin: find_fast_cwd: don't run assembler checking code on ARM64
    
    https://cygwin.com/pipermail/cygwin/2024-February/255397.html
    reports a crash on ARM64 probably related to checking x86_64
    code on the x86_64 emulator on AArch64.
    
    At least for testing, pull the code checking the host HW
    up to be called before trying to evaluate assembler code.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/path.cc | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc
index 69749dc38187..68639f323972 100644
--- a/winsup/cygwin/path.cc
+++ b/winsup/cygwin/path.cc
@@ -4608,29 +4608,27 @@ find_fast_cwd_pointer ()
 static fcwd_access_t **
 find_fast_cwd ()
 {
+  USHORT emulated, hosted;
+  fcwd_access_t **f_cwd_ptr;
+
+  /* First check if we're running in WOW64 on ARM64 emulating AMD64.  Skip
+     fetching FAST_CWD pointer as long as there's no solution for finding
+     it on that system. */
+  if (IsWow64Process2 (GetCurrentProcess (), &emulated, &hosted)
+      && hosted == IMAGE_FILE_MACHINE_ARM64)
+    return NULL;
+
   /* Fetch the pointer but don't set the global fast_cwd_ptr yet.  First
      we have to make sure we know the version of the FAST_CWD structure
      used on the system. */
-  fcwd_access_t **f_cwd_ptr = find_fast_cwd_pointer ();
+  f_cwd_ptr = find_fast_cwd_pointer ();
   if (!f_cwd_ptr)
-    {
-      bool warn = 1;
-      USHORT emulated, hosted;
-
-      /* Check if we're running in WOW64 on ARM64 emulating AMD64.  Skip
-	 warning as long as there's no solution for finding the FAST_CWD
-	 pointer on that system. */
-      if (IsWow64Process2 (GetCurrentProcess (), &emulated, &hosted)
-	  && hosted == IMAGE_FILE_MACHINE_ARM64)
-	warn = 0;
-
-      if (warn)
-	small_printf ("Cygwin WARNING:\n"
+    small_printf ("Cygwin WARNING:\n"
 "  Couldn't compute FAST_CWD pointer.  This typically occurs if you're using\n"
 "  an older Cygwin version on a newer Windows.  Please update to the latest\n"
 "  available Cygwin version from https://cygwin.com/.  If the problem persists,\n"
 "  please see https://cygwin.com/problems.html\n\n");
-    }
+
   /* Eventually, after we set the version as well, set fast_cwd_ptr. */
   return f_cwd_ptr;
 }