[newlib-cygwin] Drop wow64_has_secondary_stack flag

[Corinna Vinschen <corinna at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=bd4339e2a2905d6f62b9510067360badc27da591

commit bd4339e2a2905d6f62b9510067360badc27da591
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Tue Dec 15 15:48:44 2015 +0100

    Drop wow64_has_secondary_stack flag

Diff:
---
 winsup/cygwin/Makefile.in |   1 -
 winsup/cygwin/dcrt0.cc    |  47 +---------
 winsup/cygwin/init.cc     |  11 +--
 winsup/cygwin/wincap.cc   |   8 --
 winsup/cygwin/wincap.h    |   2 -
 winsup/cygwin/wow64.cc    | 213 ----------------------------------------------
 winsup/cygwin/wow64.h     |  19 -----
 7 files changed, 4 insertions(+), 297 deletions(-)

diff --git a/winsup/cygwin/Makefile.in b/winsup/cygwin/Makefile.in
index 70da06f..7c01df7 100644
--- a/winsup/cygwin/Makefile.in
+++ b/winsup/cygwin/Makefile.in
@@ -395,7 +395,6 @@ DLL_OFILES:= \
 	wincap.o \
 	window.o \
 	winf.o \
-	wow64.o \
 	xsique.o \
 	$(EXTRA_OFILES) \
 	$(MALLOC_OFILES) \
diff --git a/winsup/cygwin/dcrt0.cc b/winsup/cygwin/dcrt0.cc
index fda4b58..822e36e 100644
--- a/winsup/cygwin/dcrt0.cc
+++ b/winsup/cygwin/dcrt0.cc
@@ -35,7 +35,6 @@ details. */
 #include "cygxdr.h"
 #include "fenv.h"
 #include "ntdll.h"
-#include "wow64.h"
 
 #define MAX_AT_FILE_LEVEL 10
 
@@ -406,18 +405,8 @@ child_info NO_COPY *child_proc_info;
 void
 child_info_fork::alloc_stack ()
 {
-  /* Make sure not to try a hard allocation if we have been forked off from
-     the main thread of a Cygwin process which has been started from a 64 bit
-     parent.  In that case the StackBase of the forked child is not the same
-     as the StackBase of the parent (== this.stackbase), but only because the
-     stack of the parent has been slightly rearranged.  See comment in
-     wow64_revert_to_original_stack for details. We check here if the
-     parent stack fits into the child stack. */
   PTEB teb = NtCurrentTeb ();
-  if (teb->Tib.StackBase != stackbase
-      && (!wincap.is_wow64 ()
-	  || stacklimit < teb->DeallocationStack
-	  || stackbase > teb->Tib.StackBase))
+  if (teb->Tib.StackBase != stackbase)
     {
       void *stack_ptr;
       size_t stacksize;
@@ -772,14 +761,6 @@ dll_crt0_0 ()
     {
       setup_cygheap ();
       memory_init ();
-#ifndef __x86_64__
-      /* WOW64 process on XP/64 or Server 2003/64?  Check if we have been
-	 started from 64 bit process and if our stack is at an unusual
-	 address.  Set wow64_needs_stack_adjustment if so.  Problem
-	 description in wow64_test_for_64bit_parent. */
-      if (wincap.wow64_has_secondary_stack ())
-	wow64_needs_stack_adjustment = wow64_test_for_64bit_parent ();
-#endif /* !__x86_64__ */
     }
   else
     {
@@ -1091,32 +1072,6 @@ _dll_crt0 ()
 	fork_info->alloc_stack ();
     }
 #else
-  /* Handle WOW64 process on XP/2K3 which has been started from native 64 bit
-     process.  See comment in wow64_test_for_64bit_parent for a full problem
-     description. */
-  if (wow64_needs_stack_adjustment && !dynamically_loaded)
-    {
-      /* Must be static since it's referenced after the stack and frame
-	 pointer registers have been changed. */
-      static PVOID allocationbase;
-
-      PVOID stackaddr = wow64_revert_to_original_stack (allocationbase);
-      if (stackaddr)
-      	{
-	  /* Set stack pointer to new address.  Set frame pointer to 0. */
-	  __asm__ ("\n\
-		   movl  %[ADDR], %%esp \n\
-		   xorl  %%ebp, %%ebp   \n"
-		   : : [ADDR] "r" (stackaddr));
-	  /* We're back on the original stack now.  Free up space taken by the
-	     former main thread stack and set DeallocationStack correctly. */
-	  VirtualFree (NtCurrentTeb ()->DeallocationStack, 0, MEM_RELEASE);
-	  NtCurrentTeb ()->DeallocationStack = allocationbase;
-	}
-      else
-	/* Fall back to respawning if creating a new stack fails. */
-	wow64_respawn_process ();
-    }
   main_environ = user_data->envptr;
   if (in_forkee)
     fork_info->alloc_stack ();
diff --git a/winsup/cygwin/init.cc b/winsup/cygwin/init.cc
index d1b3428..7285e3d 100644
--- a/winsup/cygwin/init.cc
+++ b/winsup/cygwin/init.cc
@@ -54,14 +54,9 @@ munge_threadfunc ()
     {
       char *threadfunc = NULL;
 
-      /* This call to NtQueryInformationThread crashes under WOW64 on
-         64 bit XP and Server 2003. */
-      if (wincap.wow64_has_secondary_stack ())
-	threadfunc = ebp[threadfunc_ix[0]];
-      else
-	NtQueryInformationThread (NtCurrentThread (),
-				  ThreadQuerySetWin32StartAddress,
-				  &threadfunc, sizeof threadfunc, NULL);
+      NtQueryInformationThread (NtCurrentThread (),
+				ThreadQuerySetWin32StartAddress,
+				&threadfunc, sizeof threadfunc, NULL);
       if (!search_for || threadfunc == search_for)
 	{
 	  search_for = NULL;
diff --git a/winsup/cygwin/wincap.cc b/winsup/cygwin/wincap.cc
index 0f38b6a..5605af6 100644
--- a/winsup/cygwin/wincap.cc
+++ b/winsup/cygwin/wincap.cc
@@ -25,7 +25,6 @@ wincaps wincap_xpsp2 __attribute__((section (".cygwin_dll_common"), shared)) = {
   has_gaa_largeaddress_bug:false,
   has_broken_alloc_console:false,
   has_console_logon_sid:false,
-  wow64_has_secondary_stack:false,
   has_program_compatibility_assistant:false,
   has_pipe_reject_remote_clients:false,
   terminate_thread_frees_stack:false,
@@ -47,7 +46,6 @@ wincaps wincap_2003 __attribute__((section (".cygwin_dll_common"), shared)) = {
   has_gaa_largeaddress_bug:false,
   has_broken_alloc_console:false,
   has_console_logon_sid:false,
-  wow64_has_secondary_stack:true,
   has_program_compatibility_assistant:false,
   has_pipe_reject_remote_clients:false,
   terminate_thread_frees_stack:false,
@@ -69,7 +67,6 @@ wincaps wincap_vista __attribute__((section (".cygwin_dll_common"), shared)) = {
   has_gaa_largeaddress_bug:true,
   has_broken_alloc_console:false,
   has_console_logon_sid:false,
-  wow64_has_secondary_stack:false,
   has_program_compatibility_assistant:true,
   has_pipe_reject_remote_clients:true,
   terminate_thread_frees_stack:true,
@@ -91,7 +88,6 @@ wincaps wincap_7 __attribute__((section (".cygwin_dll_common"), shared)) = {
   has_gaa_largeaddress_bug:true,
   has_broken_alloc_console:true,
   has_console_logon_sid:true,
-  wow64_has_secondary_stack:false,
   has_program_compatibility_assistant:true,
   has_pipe_reject_remote_clients:true,
   terminate_thread_frees_stack:true,
@@ -113,7 +109,6 @@ wincaps wincap_8 __attribute__((section (".cygwin_dll_common"), shared)) = {
   has_gaa_largeaddress_bug:false,
   has_broken_alloc_console:true,
   has_console_logon_sid:true,
-  wow64_has_secondary_stack:false,
   has_program_compatibility_assistant:true,
   has_pipe_reject_remote_clients:true,
   terminate_thread_frees_stack:true,
@@ -135,7 +130,6 @@ wincaps wincap_10 __attribute__((section (".cygwin_dll_common"), shared)) = {
   has_gaa_largeaddress_bug:false,
   has_broken_alloc_console:true,
   has_console_logon_sid:true,
-  wow64_has_secondary_stack:false,
   has_program_compatibility_assistant:true,
   has_pipe_reject_remote_clients:true,
   terminate_thread_frees_stack:true,
@@ -157,7 +151,6 @@ wincaps wincap_10_1511 __attribute__((section (".cygwin_dll_common"), shared)) =
   has_gaa_largeaddress_bug:false,
   has_broken_alloc_console:true,
   has_console_logon_sid:true,
-  wow64_has_secondary_stack:false,
   has_program_compatibility_assistant:true,
   has_pipe_reject_remote_clients:true,
   terminate_thread_frees_stack:true,
@@ -248,7 +241,6 @@ wincapc::init ()
 #endif
     {
       ((wincaps *)caps)->needs_count_in_si_lpres2 = false;
-      ((wincaps *)caps)->wow64_has_secondary_stack = false;
       ((wincaps *)caps)->has_gaa_largeaddress_bug = false;
       ((wincaps *)caps)->has_broken_prefetchvm = false;
     }
diff --git a/winsup/cygwin/wincap.h b/winsup/cygwin/wincap.h
index bdbb0f2..7d7dbc7 100644
--- a/winsup/cygwin/wincap.h
+++ b/winsup/cygwin/wincap.h
@@ -18,7 +18,6 @@ struct wincaps
   unsigned has_gaa_largeaddress_bug			: 1;
   unsigned has_broken_alloc_console			: 1;
   unsigned has_console_logon_sid			: 1;
-  unsigned wow64_has_secondary_stack			: 1;
   unsigned has_program_compatibility_assistant		: 1;
   unsigned has_pipe_reject_remote_clients		: 1;
   unsigned terminate_thread_frees_stack			: 1;
@@ -65,7 +64,6 @@ public:
   bool	IMPLEMENT (has_gaa_largeaddress_bug)
   bool	IMPLEMENT (has_broken_alloc_console)
   bool	IMPLEMENT (has_console_logon_sid)
-  bool	IMPLEMENT (wow64_has_secondary_stack)
   bool	IMPLEMENT (has_program_compatibility_assistant)
   bool	IMPLEMENT (has_pipe_reject_remote_clients)
   bool	IMPLEMENT (terminate_thread_frees_stack)
diff --git a/winsup/cygwin/wow64.cc b/winsup/cygwin/wow64.cc
deleted file mode 100644
index 95651a8..0000000
--- a/winsup/cygwin/wow64.cc
+++ /dev/null
@@ -1,213 +0,0 @@
-/* wow64.cc
-
-This file is part of Cygwin.
-
-This software is a copyrighted work licensed under the terms of the
-Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
-details. */
-
-#ifndef __x86_64__
-/* WOW64 only plays a role in the 32 bit version.  Don't use any of this
-   in the 64 bit version. */
-
-#include "winsup.h"
-#include "cygtls.h"
-#include "ntdll.h"
-#include <sys/param.h>
-
-#define PTR_ADD(p,o)	((PVOID)((PBYTE)(p)+(o)))
-
-bool NO_COPY wow64_needs_stack_adjustment = false;
-
-static void
-wow64_eval_expected_main_stack (PVOID &allocbase, PVOID &stackbase)
-{
-  PIMAGE_DOS_HEADER dosheader;
-  PIMAGE_NT_HEADERS ntheader;
-  SIZE_T size;
-
-  dosheader = (PIMAGE_DOS_HEADER) GetModuleHandle (NULL);
-  ntheader = (PIMAGE_NT_HEADERS) ((PBYTE) dosheader + dosheader->e_lfanew);
-  /* The main thread stack is expected to be located at 0x30000, which is the
-     case for all observed NT systems up to Server 2003 R2, unless the
-     stacksize requested by the StackReserve field in the PE/COFF header is
-     so big that the stack doesn't fit in the area between 0x30000 and the
-     start of the image.  In case of a conflict, the OS allocates the stack
-     right after the image.
-     Sidenote: While post-2K3 32 bit systems continue to have the default
-     main thread stack address located at 0x30000, the default main thread
-     stack address on Vista/2008 64 bit is 0x80000 and on W7/2K8R2 64 bit
-     it is 0x90000.  However, this is no problem because the system sticks
-     to that address for all WOW64 processes, not only for the first one
-     started from a 64 bit parent. */
-  allocbase = (PVOID) 0x30000;
-  /* Stack size.  The OS always rounds the size up to allocation granularity
-     and it never allocates less than 256K. */
-  size = roundup2 (ntheader->OptionalHeader.SizeOfStackReserve,
-		   wincap.allocation_granularity ());
-  if (size < 256 * 1024)
-    size = 256 * 1024;
-  /* If the stack doesn't fit in the area before the image, it's allocated
-     right after the image, rounded up to allocation granularity boundary. */
-  if (PTR_ADD (allocbase, size) > (PVOID) ntheader->OptionalHeader.ImageBase)
-    allocbase = PTR_ADD (ntheader->OptionalHeader.ImageBase,
-			 ntheader->OptionalHeader.SizeOfImage);
-  allocbase = (PVOID) roundup2 ((uintptr_t) allocbase,
-				wincap.allocation_granularity ());
-  stackbase = PTR_ADD (allocbase, size);
-  debug_printf ("expected allocbase: %p, stackbase: %p", allocbase, stackbase);
-}
-
-bool
-wow64_test_for_64bit_parent ()
-{
-  /* On Windows XP 64 and 2003 64 there's a problem with processes running
-     under WOW64.  The first process started from a 64 bit process has its
-     main thread stack not where it should be.  Rather, it uses another
-     stack while the original stack is used for other purposes.
-     The problem is, the child has its stack in the usual spot again, thus
-     we have to "alloc_stack_hard_way".  However, this fails in almost all
-     cases because the stack slot of the parent process is taken by something
-     else in the child process.
-     What we do here is to check if the current stack is the expected main
-     thread stack and if not, if we really have been started from a 64 bit
-     process here.  If so, we note this fact in wow64_needs_stack_adjustment
-     so we can workaround the stack problem in _dll_crt0.  See there for how
-     we go along. */
-  NTSTATUS ret;
-  PROCESS_BASIC_INFORMATION pbi;
-  HANDLE parent;
-  PVOID allocbase, stackbase;
-
-  ULONG_PTR wow64 = TRUE;   /* Opt on the safe side. */
-
-  /* First check if the current stack is where it belongs.  If so, we don't
-     have to do anything special.  This is the case on Vista and later. */
-  wow64_eval_expected_main_stack (allocbase, stackbase);
-  if (&wow64 >= (PULONG_PTR) allocbase && &wow64 < (PULONG_PTR) stackbase)
-    return false;
-
-  /* Check if the parent is a native 64 bit process.  Unfortunately there's
-     no simpler way to retrieve the parent process in NT, as far as I know.
-     Hints welcome. */
-  ret = NtQueryInformationProcess (NtCurrentProcess (),
-				   ProcessBasicInformation,
-				   &pbi, sizeof pbi, NULL);
-  if (NT_SUCCESS (ret)
-      && (parent = OpenProcess (PROCESS_QUERY_INFORMATION,
-				FALSE,
-				(DWORD) pbi.InheritedFromUniqueProcessId)))
-    {
-      NtQueryInformationProcess (parent, ProcessWow64Information,
-				 &wow64, sizeof wow64, NULL);
-      CloseHandle (parent);
-    }
-  return !wow64;
-}
-
-PVOID
-wow64_revert_to_original_stack (PVOID &allocationbase)
-{
-  /* Test if the original stack exists and has been set up as usual.  Even
-     though the stack of the WOW64 process is at an unusual address, it appears
-     that the "normal" stack has been created as usual.  It's partially in use
-     by the 32->64 bit transition layer of the OS to help along the WOW64
-     process, but it's otherwise mostly unused. */
-  MEMORY_BASIC_INFORMATION mbi;
-  PVOID stackbase;
-
-  wow64_eval_expected_main_stack (allocationbase, stackbase);
-
-  /* The stack is allocated in a single call, so the entire stack has the
-     same AllocationBase.  At the start we expect a reserved region big
-     enough still to host as the main stack. The OS apparently reserves
-     always at least 256K for the main thread stack.  We err on the side
-     of caution so we test here for a reserved region of at least 256K.
-     That should be enough (knock on wood). */
-  VirtualQuery (allocationbase, &mbi, sizeof mbi);
-  if (mbi.State != MEM_RESERVE || mbi.RegionSize < 256 * 1024)
-    return NULL;
-
-  /* Next we expect a guard page.  We fetch the size of the guard area to
-     see how big it is.  Apparently the guard area on 64 bit systems spans
-     2 pages, only for the main thread for some reason.  We better keep it
-     that way. */
-  PVOID addr = PTR_ADD (mbi.BaseAddress, mbi.RegionSize);
-  VirtualQuery (addr, &mbi, sizeof mbi);
-  if (mbi.AllocationBase != allocationbase
-      || mbi.State != MEM_COMMIT
-      || !(mbi.Protect & PAGE_GUARD))
-    return NULL;
-  PVOID guardaddr = mbi.BaseAddress;
-  SIZE_T guardsize = mbi.RegionSize;
-
-  /* Next we expect a committed R/W region, the in-use area of that stack.
-     This is just a sanity check. */
-  addr = PTR_ADD (mbi.BaseAddress, mbi.RegionSize);
-  VirtualQuery (addr, &mbi, sizeof mbi);
-  if (mbi.AllocationBase != allocationbase
-      || PTR_ADD (mbi.BaseAddress, mbi.RegionSize) != stackbase
-      || mbi.State != MEM_COMMIT
-      || mbi.Protect != PAGE_READWRITE)
-    return NULL;
-
-  /* The original stack is used by the OS.  Leave enough space for the OS
-     to be happy (another 64K) and constitute a second stack within the so
-     far reserved stack area. */
-  PVOID newbase = PTR_ADD (guardaddr, -wincap.allocation_granularity ());
-  PVOID newtop = PTR_ADD (newbase, -wincap.allocation_granularity ());
-  guardaddr = PTR_ADD (newtop, -guardsize);
-  if (!VirtualAlloc (newtop, wincap.allocation_granularity (),
-		     MEM_COMMIT, PAGE_READWRITE))
-    return NULL;
-  if (!VirtualAlloc (guardaddr, guardsize, MEM_COMMIT,
-		     PAGE_READWRITE | PAGE_GUARD))
-    return NULL;
-
-  /* We're going to reuse the original stack.  Yay, no more respawn!
-     Set the StackBase and StackLimit values in the TEB, set _main_tls
-     accordingly, and return the new, 16 byte aligned address for the
-     stack pointer.  The second half of the stack move is done by the
-     caller _dll_crt0. */
-  NtCurrentTeb ()->Tib.StackBase = (char *) newbase;
-  NtCurrentTeb ()->Tib.StackLimit = (char *) newtop;
-  _main_tls = &_my_tls;
-  return PTR_ADD (NtCurrentTeb ()->Tib.StackBase, -16);
-}
-
-/* Respawn WOW64 process. This is only called if we can't reuse the original
-   stack.  See comment in wow64_revert_to_original_stack for details.  See
-   _dll_crt0 for the call of this function.
-
-   Historical note:
-
-   Originally we just always respawned, right from dll_entry.  This stopped
-   working with Cygwin 1.7.10 on Windows 2003 R2 64.  Starting with Cygwin
-   1.7.10 we don't link against advapi32.dll anymore.  However, any process
-   linked against advapi32, directly or indirectly, failed to respawn when
-   trying respawning during DLL_PROCESS_ATTACH initialization.  In that
-   case CreateProcessW returns with ERROR_ACCESS_DENIED for some reason. */
-void
-wow64_respawn_process ()
-{
-  PROCESS_INFORMATION pi;
-  STARTUPINFOW si;
-  DWORD ret = 0;
-
-  GetStartupInfoW (&si);
-  if (!CreateProcessW (global_progname, GetCommandLineW (), NULL, NULL, TRUE,
-		       CREATE_DEFAULT_ERROR_MODE
-		       | GetPriorityClass (GetCurrentProcess ()),
-		       NULL, NULL, &si, &pi))
-    api_fatal ("Failed to create process <%W> <%W>, %E",
-	       global_progname, GetCommandLineW ());
-  CloseHandle (pi.hThread);
-  if (WaitForSingleObject (pi.hProcess, INFINITE) == WAIT_FAILED)
-    api_fatal ("Waiting for process %u failed, %E", pi.dwProcessId);
-  GetExitCodeProcess (pi.hProcess, &ret);
-  CloseHandle (pi.hProcess);
-  TerminateProcess (GetCurrentProcess (), ret);
-  ExitProcess (ret);
-}
-
-#endif /* !__x86_64__ */
diff --git a/winsup/cygwin/wow64.h b/winsup/cygwin/wow64.h
deleted file mode 100644
index b1271bf..0000000
--- a/winsup/cygwin/wow64.h
+++ /dev/null
@@ -1,19 +0,0 @@
-/* wow64.h
-
-This file is part of Cygwin.
-
-This software is a copyrighted work licensed under the terms of the
-Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
-details. */
-
-#ifndef __x86_64__
-/* WOW64 only plays a role in the 32 bit version.  Don't use any of this
-   in the 64 bit version. */
-
-extern bool NO_COPY wow64_needs_stack_adjustment;
-
-extern bool wow64_test_for_64bit_parent ();
-extern PVOID wow64_revert_to_original_stack (PVOID &allocationbase);
-extern void wow64_respawn_process () __attribute__ ((noreturn));
-
-#endif /* !__x86_64__ */