Regression in ptrace (Wine) starting with 2.6.33-rc1

[Michael Stefaniuc <mstefani@redhat.com>]

Hello!

2.6.33-rc1 broke ptrace for Wine, specifically the setting of the debug
registers. This is visible in the Wine ntdll exception tests failing on
2.6.33-rcX while they work just fine in 2.6.32.

A regression test resulted in:
72f674d203cd230426437cdcf7dd6f681dad8b0d is the first bad commit
commit 72f674d203cd230426437cdcf7dd6f681dad8b0d
Author: K.Prasad <prasad@linux.vnet.ibm.com>
Date:   Mon Jun 1 23:45:48 2009 +0530

    hw-breakpoints: modify Ptrace routines to access breakpoint registers

    This patch modifies the ptrace code to use the new wrapper routines
around
the
    debug/breakpoint registers.

    [ Impact: adapt x86 ptrace to the new breakpoint Api ]

    Original-patch-by: Alan Stern <stern@rowland.harvard.edu>
    Signed-off-by: K.Prasad <prasad@linux.vnet.ibm.com>
    Signed-off-by: Maneesh Soni <maneesh@linux.vnet.ibm.com>
    Reviewed-by: Alan Stern <stern@rowland.harvard.edu>
    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

:040000 040000 f72ff4760c3fa1dffcd72494e77bee2c76039505
b60d5fe2088ff635568e800d5759a0b373b5e439 M      arch


The first ntdll exception test in test_exceptions()
http://source.winehq.org/git/wine.git/?a=blob;f=dlls/ntdll/tests/exception.c;h=9149b6961764dec31a0af5cd3b93ab3072703dbb;hb=312e4f6b235a468f8bf764101a5b97cf34dd4143#l594
  run_exception_test(dreg_handler, NULL, &segfault_code,
sizeof(segfault_code),
0);
produces (make exception.ok) the output:
  err:seh:setup_exception_record stack overflow 932 bytes in thread 0009 eip
7bc3c97f esp 00240f8c stack 0x240000-0x241000-0x340000
The stack overflow is detected by the ntdll internal function
setup_exception_record()
http://source.winehq.org/git/wine.git/?a=blob;f=dlls/ntdll/signal_i386.c;h=4eccb61954c43d75144575411313d59405decfc3;hb=312e4f6b235a468f8bf764101a5b97cf34dd4143#l1495
which aborts the thread.
The problem happens on both i386 (Intel Atom CPU) as well as on x86_64
(Intel Q9450); the stack overflow bytes differ though but are always the
same for each box.

All the ntdll exception tests run just fine with 2.6.32 and older
kernels. For a summary of the ntdll exception tests please see
http://test.winehq.org/data/tests/ntdll:exception.html in the Wine
column.

I have opened also http://bugzilla.kernel.org/show_bug.cgi?id=15273 for
this.

thanks
bye
    michael