MMCR0_PMXE
#define MMCR0_USER_MASK (MMCR0_FC | MMCR0_PMXE | MMCR0_PMAO)
mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~(MMCR0_PMXE|MMCR0_PMAO));
mtspr(SPRN_MMCR0, mfspr(SPRN_MMCR0) & ~MMCR0_PMXE);
MMCR0_PMXE | MMCR0_FC56);
cpuhw->mmcr.mmcr0 |= MMCR0_PMXE | MMCR0_FCECE;
cpuhw->mmcr.mmcr0 &= ~(MMCR0_PMXE | MMCR0_FCECE);
current->thread.mmcr0 |= MMCR0_PMXE;
if (!(current->thread.mmcr0 & MMCR0_PMXE))
mmcr0 &= ~MMCR0_PMXE;
mtspr(SPRN_MMCR0, MMCR0_PMXE | MMCR0_PMCjCE | MMCR0_PMAO);