in kernel/ptrace.c [434:465]
static unsigned long get_reg(struct pt_regs *regs, int num)
{
switch (num) {
case RI(gr[0]) ... RI(gr[31]): return regs->gr[num - RI(gr[0])];
case RI(sr[0]) ... RI(sr[7]): return regs->sr[num - RI(sr[0])];
case RI(iasq[0]): return regs->iasq[0];
case RI(iasq[1]): return regs->iasq[1];
case RI(iaoq[0]): return regs->iaoq[0];
case RI(iaoq[1]): return regs->iaoq[1];
case RI(sar): return regs->sar;
case RI(iir): return regs->iir;
case RI(isr): return regs->isr;
case RI(ior): return regs->ior;
case RI(ipsw): return regs->ipsw;
case RI(cr27): return regs->cr27;
case RI(cr0): return mfctl(0);
case RI(cr24): return mfctl(24);
case RI(cr25): return mfctl(25);
case RI(cr26): return mfctl(26);
case RI(cr28): return mfctl(28);
case RI(cr29): return mfctl(29);
case RI(cr30): return mfctl(30);
case RI(cr31): return mfctl(31);
case RI(cr8): return mfctl(8);
case RI(cr9): return mfctl(9);
case RI(cr12): return mfctl(12);
case RI(cr13): return mfctl(13);
case RI(cr10): return mfctl(10);
case RI(cr15): return mfctl(15);
default: return 0;
}
}