Gdbserver syscall clobber

Bill Gatliff bgat at
Fri Jul 27 02:28:48 EST 2007

Daniel Jacobowitz wrote:
> Look around do_signal:
>                         regs->nip -= 4; /* Back up & retry system call */
> If your kernel has corrupted the register containing the syscall
> number at this point, that would explain your problem.  It will then
> do the wrong syscall.  I guess PPC only backs up one instruction.

Found the code in do_signal, right where you said it would be.  I threw 
in a printk or two to see what's up when an ERESTARTSYS is detected, and 
started getting OOPSes all over the place.  Apparently that's not a good 
place for printk.  :)

Before I go on, can anyone confirm that gdbserver and/or strace _ever_ 
worked with circa 2.4.16 PPC kernels?


Bill Gatliff
bgat at

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