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* dcrt0.cc (_dll_crt0): Rephrase comments. Set $ebp to NULL, as in

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the pthread stack setup.
	* wow64.cc (wow64_revert_to_original_stack): Rephrase some comments.
	Return _tlsbase-16 rather than _main_tls-4 so as not to waste stack.
This commit is contained in:
Corinna Vinschen 2011-12-21 17:19:48 +00:00
parent 40fb18380b
commit f500a700b1
3 changed files with 20 additions and 9 deletions
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7
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,10 @@
2011-12-11 Corinna Vinschen <vinschen@redhat.com>
* dcrt0.cc (_dll_crt0): Rephrase comments. Set $ebp to NULL, as in
the pthread stack setup.
* wow64.cc (wow64_revert_to_original_stack): Rephrase some comments.
Return _tlsbase-16 rather than _main_tls-4 so as not to waste stack.
2011-12-19 Corinna Vinschen <vinschen@redhat.com>
* syscalls.cc (rename): Fix typo in comment. Fix condition to handle

12
winsup/cygwin/dcrt0.cc
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@ -951,19 +951,21 @@ _dll_crt0 ()
description. */
if (wow64_needs_stack_adjustment && !dynamically_loaded)
{
/* Must be static since it's referenced after the stack pointers have
been moved. */
/* Must be static since it's referenced after the stack and frame
pointer registers have been changed. */
static PVOID allocationbase = 0;
/* Check if we just move the stack. See comment in
/* Check if we just move the stack. If so, wow64_revert_to_original_stack
returns a non-NULL, 16 byte aligned address. See comments in
wow64_revert_to_original_stack for the gory details. */
PVOID stackaddr = wow64_revert_to_original_stack (allocationbase);
if (stackaddr)
{
/* 2nd half of the stack move. Set stack pointers to new address. */
/* 2nd half of the stack move. Set stack pointer to new address.
Set frame pointer to 0. */
__asm__ ("\n\
movl %[ADDR], %%esp \n\
movl %%esp, %%ebp \n"
xorl %%ebp, %%ebp \n"
: : [ADDR] "r" (stackaddr));
/* Now we're back on the original stack. Free up space taken by the
former main thread stack and set DeallocationStack correctly. */

10
winsup/cygwin/wow64.cc
View File

@ -128,7 +128,8 @@ wow64_revert_to_original_stack (PVOID &allocationbase)
/* 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. */
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
@ -163,12 +164,13 @@ wow64_revert_to_original_stack (PVOID &allocationbase)
/* 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 address for the stack pointer.
The second half of the stack move is done by the caller _dll_crt0. */
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. */
_tlsbase = (char *) newbase;
_tlstop = (char *) newtop;
_main_tls = &_my_tls;
return PTR_ADD (_main_tls, -4);
return PTR_ADD (_tlsbase, -16);
}
/* Respawn WOW64 process. This is only called if we can't reuse the original