[PATCH 0/1] PPC32: fix ptrace() access to FPU registers

[Daniel Axtens]

Andreas Schwab <schwab at linux-m68k.org> writes:

> On Jun 18 2019, Radu Rendec <radu.rendec at gmail.com> wrote:
>
>> Since you already have a working setup, it would be nice if you could
>> add a printk to arch_ptrace() to print the address and confirm what I
>> believe happens (by reading the gdb source code).
>
> A ppc32 ptrace syscall goes through compat_arch_ptrace.


Ah right, and that (in ptrace32.c) contains code that will work:


			/*
			 * the user space code considers the floating point
			 * to be an array of unsigned int (32 bits) - the
			 * index passed in is based on this assumption.
			 */
			tmp = ((unsigned int *)child->thread.fp_state.fpr)
				[FPRINDEX(index)];

FPRINDEX is defined above to deal with the various manipulations you
need to do.

Radu: I think we want to copy that working code back into ptrace.c. The
challenge will be unpicking the awful mess of ifdefs in ptrace.c and
making it somewhat more comprehensible.

Regards,
Daniel

>
> Andreas.
>
> -- 
> Andreas Schwab, schwab at linux-m68k.org
> GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
> "And now for something completely different."