On Wed, 13 Jul 2016 15:10:49 +0530 "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com> wrote:
> We also handle fault with proper stack initialized. This enable us to > callout to C in fault handling routines. We don't do this for kernel > mapping, because of the possibility of taking recursive fault if > kernel stack in not yet mapped by an slb entry. > > This enable us to handle Power9 slb fault better. We will add bolted > entries for the entire kernel mapping in segment table and user slb > entries we take fault and insert on demand. With translation on, we > should be able to access segment table from fault handler. What does this cost on P8? Is that a problem? Might need to do feature bits. > Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.vnet.ibm.com> > --- > arch/powerpc/kernel/exceptions-64s.S | 55 > ++++++++++++++++++++++++++++++++---- > arch/powerpc/mm/slb.c | 11 ++++++++ 2 files changed, > 61 insertions(+), 5 deletions(-) > > diff --git a/arch/powerpc/kernel/exceptions-64s.S > b/arch/powerpc/kernel/exceptions-64s.S index > 2747e901fb99..2132bf55573c 100644 --- > a/arch/powerpc/kernel/exceptions-64s.S +++ > b/arch/powerpc/kernel/exceptions-64s.S @@ -794,7 +794,7 @@ > data_access_slb_relon_pSeries: mfspr r3,SPRN_DAR > mfspr r12,SPRN_SRR1 > #ifndef CONFIG_RELOCATABLE > - b slb_miss_realmode > + b handle_slb_miss_relon > #else > /* > * We can't just use a direct branch to slb_miss_realmode > @@ -803,7 +803,7 @@ data_access_slb_relon_pSeries: > */ > mfctr r11 > ld r10,PACAKBASE(r13) > - LOAD_HANDLER(r10, slb_miss_realmode) > + LOAD_HANDLER(r10, handle_slb_miss_relon) > mtctr r10 > bctr > #endif > @@ -819,11 +819,11 @@ instruction_access_slb_relon_pSeries: > mfspr r3,SPRN_SRR0 /* SRR0 is faulting > address */ mfspr r12,SPRN_SRR1 > #ifndef CONFIG_RELOCATABLE > - b slb_miss_realmode > + b handle_slb_miss_relon > #else > mfctr r11 > ld r10,PACAKBASE(r13) > - LOAD_HANDLER(r10, slb_miss_realmode) > + LOAD_HANDLER(r10, handle_slb_miss_relon) > mtctr r10 > bctr > #endif > @@ -961,7 +961,23 @@ h_data_storage_common: > bl unknown_exception > b ret_from_except > > +/* r3 point to DAR */ > .align 7 > + .globl slb_miss_user > +slb_miss_user: > + std r3,PACA_EXSLB+EX_DAR(r13) > + /* Restore r3 as expected by PROLOG_COMMON below */ > + ld r3,PACA_EXSLB+EX_R3(r13) > + EXCEPTION_PROLOG_COMMON(0x380, PACA_EXSLB) > + RECONCILE_IRQ_STATE(r10, r11) > + ld r4,PACA_EXSLB+EX_DAR(r13) > + li r5,0x380 > + std r4,_DAR(r1) > + addi r3,r1,STACK_FRAME_OVERHEAD > + bl handle_slb_miss > + b ret_from_except_lite > + > + .align 7 > .globl instruction_access_common > instruction_access_common: > EXCEPTION_PROLOG_COMMON(0x400, PACA_EXGEN) > @@ -1379,11 +1395,17 @@ unrecover_mce: > * We assume we aren't going to take any exceptions during this > procedure. */ > slb_miss_realmode: > - mflr r10 > #ifdef CONFIG_RELOCATABLE > mtctr r11 > #endif > + /* > + * Handle user slb miss with translation enabled > + */ > + cmpdi r3,0 > + bge 3f > > +slb_miss_kernel: > + mflr r10 > stw r9,PACA_EXSLB+EX_CCR(r13) /* save CR in > exc. frame */ std r10,PACA_EXSLB+EX_LR(r13) /* save LR > */ > @@ -1429,6 +1451,29 @@ > ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_TYPE_RADIX) mtspr > SPRN_SRR1,r10 rfid > b . > +3: > + /* > + * Enable IR/DR and handle the fault > + */ > + EXCEPTION_PROLOG_PSERIES_1(slb_miss_user, EXC_STD) > + /* > + * handler with relocation on > + */ > +handle_slb_miss_relon: > +#ifdef CONFIG_RELOCATABLE > + mtctr r11 > +#endif This is turning into a bit of spaghetti. I think it can be improved though. I have a patch that I think can save a few instructions in the relocatable case for SLB miss. I think that may give enough space inline to branch to the correct handler. I should submit it soon. > + /* > + * Handle user slb miss with stack initialized. > + */ > + cmpdi r3,0 > + bge 4f > + /* > + * go back to slb_miss_realmode > + */ Are these comments adding much? I think if the names of some of the labels was improved, you might find they're not necessary. Some existing labels like slb_miss_realmode don't help too much either. That handler runs in real and virtual mode, and now the realmode exception can go elsewhere too. > + b slb_miss_kernel blt slb_miss_kernel? > +4: > + EXCEPTION_RELON_PROLOG_PSERIES_1(slb_miss_user, EXC_STD) _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
