| Message ID | 87394ij3aa.fsf@skywalker.in.ibm.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Mon, Jul 23, 2012 at 01:51:49PM +0530, Aneesh Kumar K.V wrote: > Paul Mackerras <paulus@samba.org> writes: > > > On Mon, Jul 09, 2012 at 06:43:39PM +0530, Aneesh Kumar K.V wrote: > >> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> > >> > >> Increase the number of valid VSID bits in slbmte instruction. > >> We will use the new bits when we increase valid VSID bits. > >> > >> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> > >> --- > >> arch/powerpc/mm/slb_low.S | 4 ++-- > >> 1 file changed, 2 insertions(+), 2 deletions(-) > >> > >> diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S > >> index c355af6..c1fc81c 100644 > >> --- a/arch/powerpc/mm/slb_low.S > >> +++ b/arch/powerpc/mm/slb_low.S > >> @@ -226,7 +226,7 @@ _GLOBAL(slb_allocate_user) > >> */ > >> slb_finish_load: > >> ASM_VSID_SCRAMBLE(r10,r9,256M) > >> - rldimi r11,r10,SLB_VSID_SHIFT,16 /* combine VSID and flags */ > >> + rldimi r11,r10,SLB_VSID_SHIFT,2 /* combine VSID and flags */ > > > > You can't do that without either changing ASM_VSID_SCRAMBLE or masking > > the VSID it generates to 36 bits, since the logic in ASM_VSID_SCRAMBLE > > can leave non-zero bits in the high 28 bits of the result. Similarly > > for the 1T case. > > > > How about change ASM_VSID_SCRAMBLE to clear the high bits ? That would > also make it close to vsid_scramble() One more instruction in a hot path - I'd rather not. How about changing the rldimi instruction to: rldimi r11,r10,SLB_VSID_SHIFT,(64-SLB_VSID_SHIFT-VSID_BITS_256M) and similarly for the 1T case. That will give the proper masking when you change VSID_BITS_256M. Paul.
Paul Mackerras <paulus@samba.org> writes: > On Mon, Jul 23, 2012 at 01:51:49PM +0530, Aneesh Kumar K.V wrote: >> Paul Mackerras <paulus@samba.org> writes: >> >> > On Mon, Jul 09, 2012 at 06:43:39PM +0530, Aneesh Kumar K.V wrote: >> >> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> >> >> >> >> Increase the number of valid VSID bits in slbmte instruction. >> >> We will use the new bits when we increase valid VSID bits. >> >> >> >> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> >> >> --- >> >> arch/powerpc/mm/slb_low.S | 4 ++-- >> >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> >> >> diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S >> >> index c355af6..c1fc81c 100644 >> >> --- a/arch/powerpc/mm/slb_low.S >> >> +++ b/arch/powerpc/mm/slb_low.S >> >> @@ -226,7 +226,7 @@ _GLOBAL(slb_allocate_user) >> >> */ >> >> slb_finish_load: >> >> ASM_VSID_SCRAMBLE(r10,r9,256M) >> >> - rldimi r11,r10,SLB_VSID_SHIFT,16 /* combine VSID and flags */ >> >> + rldimi r11,r10,SLB_VSID_SHIFT,2 /* combine VSID and flags */ >> > >> > You can't do that without either changing ASM_VSID_SCRAMBLE or masking >> > the VSID it generates to 36 bits, since the logic in ASM_VSID_SCRAMBLE >> > can leave non-zero bits in the high 28 bits of the result. Similarly >> > for the 1T case. >> > >> >> How about change ASM_VSID_SCRAMBLE to clear the high bits ? That would >> also make it close to vsid_scramble() > > One more instruction in a hot path - I'd rather not. How about > changing the rldimi instruction to: > rldimi r11,r10,SLB_VSID_SHIFT,(64-SLB_VSID_SHIFT-VSID_BITS_256M) > > and similarly for the 1T case. That will give the proper masking > when you change VSID_BITS_256M. > This is better. I have made this change. -aneesh
diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h index d24d484..173bb34 100644 --- a/arch/powerpc/include/asm/mmu-hash64.h +++ b/arch/powerpc/include/asm/mmu-hash64.h @@ -420,7 +420,8 @@ extern void slb_set_size(u16 size); * cases the answer is the low 36 bits of (r3 + ((r3+1) >> 36))*/\ addi rx,rt,1; \ srdi rx,rx,VSID_BITS_##size; /* extract 2^VSID_BITS bit */ \ - add rt,rt,rx + add rt,rt,rx; \ + clrldi rt,rt,(64 - VSID_BITS_##size); /* 4 bits per slice and we have one slice per 1TB */ #if 0 /* We can't directly include pgtable.h hence this hack */