PROBLEM: ptrace access to syscall page of 32 bit process on x86_64 fails

PROBLEM: ptrace access to syscall page of 32 bit process on x86_64 fails

[James Cownie]

Running Suse 9.1 on an Opteron 242 uniprocessor,

Using gdb (or TotalView) to debug a 32 bit process ptrace calls which
try to access the system call page at 0xffffe000 fail.

When run on a 32 bit x86 ptrace can successfully access the system call
page.

To reproduce simply use gdb on a -m32 program, set a breakpoint, run to
it and then try to "print *(0xffffe000)"

The relevant ptrace call (a PEEKDATA), return with errno 5 (EIO).

Details of the machine :-

Linux amd64 2.6.5-7.108-default #1 Wed Aug 25 13:34:40 UTC 2004 x86_64 x86_64 x86_64 GNU/Linux
 
Gnu C                  3.3.3
Gnu make               3.80
binutils               2.15.90.0.1.1
util-linux             2.12
mount                  2.12
module-init-tools      3.0-pre10
e2fsprogs              1.34
jfsutils               1.1.5
xfsprogs               2.6.3
quota-tools            3.11.
PPP                    2.4.2
nfs-utils              1.0.6
Linux C Library        06 01:50 /lib64/tls/libc.so.6
Dynamic linker (ldd)   2.3.3
Linux C++ Library      5.0.5
Procps                 3.2.1
Net-tools              1.60
Kbd                    1.12
Sh-utils               5.2.1

Modules Loaded         usbserial parport_pc lp parport nfsd exportfs joydev sg
                       st sr_mod floppy ehci_hcd uhci_hcd evdev
                       snd_seq_oss snd_seq_midi_event snd_seq
                       snd_pcm_oss snd_mixer_oss snd_ioctl32 ipv6
                       freq_table thermal processor fan button battery
                       ac snd_via82xx snd_pcm snd_timer snd_ac97_codec
                       snd_page_alloc gameport snd_mpu401_uart
                       snd_rawmidi snd_seq_device snd soundcore usbcore
                       tg3 binfmt_misc subfs dm_mod reiserfs sym53c8xx
                       sd_mod scsi_mod

-- 
-- Jim
--
James Cownie	<jcownie@etnus.com>
Etnus, LLC.     +44 117 9071438
http://www.etnus.com