On Tue, Jul 24, 2018 at 11:29:45AM +0530, Bharat Bhushan wrote: > E200 have TLB1 only and it does not have TLB0. > So TLB1 are used for mapping kernel and user-space both. > TLB miss handler for E200 does not consider skipping TLBs > used for kernel mapping. This patch ensures that we skip > tlb1 entries used for kernel mapping (tlbcam_index).
How much more is needed to get e200 working? What was this tested on? > Signed-off-by: Bharat Bhushan <bharat.bhus...@nxp.com> > --- > arch/powerpc/kernel/head_fsl_booke.S | 20 ++++++++++++++++++-- > 1 file changed, 18 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/kernel/head_fsl_booke.S > b/arch/powerpc/kernel/head_fsl_booke.S > index bf4c602..951fb96 100644 > --- a/arch/powerpc/kernel/head_fsl_booke.S > +++ b/arch/powerpc/kernel/head_fsl_booke.S > @@ -801,12 +801,28 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_BIG_PHYS) > /* Round robin TLB1 entries assignment */ > mfspr r12, SPRN_MAS0 > > + /* Get first free tlbcam entry */ > + lis r11, tlbcam_index@ha > + lwz r11, tlbcam_index@l(r11) The existing handler already loads tlbcam_index and uses that when wrapping. What specifically is causing that to not work (perhaps it's just a matter of initializing NV when tlbcam_index changes?), and why does this patch leave that code in place? > + > + /* Extract MAS0(NV) */ > + andi. r13, r12, 0xfff > + cmpw 0, r13, r11 > + blt 0, 5f > + b 6f > +5: Why these two instructions instead of "bge 6f"? If it's for branch prediction, does e200 pay attention to static hints? If it doesn't, you could move the wrap code out-of-line. > + /* When NV is less than first free tlbcam entry, use first free > + * tlbcam entry for ESEL and set NV */ > + rlwimi r12, r11, 16, 4, 15 > + addi r11, r11, 1 > + rlwimi r12, r11, 0, 20, 31 > + b 7f The 4-argument form of rlwimi is easier to read. BTW, The TLB miss handler would be simpler/faster if you reserve the upper entries rather than the lower entries. Then you would just have one value to check (instead of using TLB1CFG[NENTRY]) to see if you wrap back to zero. -Scott
