| Message ID | OF18595787.9140CED3-ONC1257815.003BD10E-C1257815.003C1BD5@transmode.se (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Tue, 11 Jan 2011 11:56:32 +0100 Joakim Tjernlund <joakim.tjernlund@transmode.se> wrote: > Joakim Tjernlund/Transmode wrote on 2011/01/11 09:12:44: > > > > Willy Tarreau <w@1wt.eu> wrote on 2011/01/11 07:09:26: > > > > > > Hi Joakim, > > > > > > On Mon, Jan 10, 2011 at 10:37:46PM +0100, Joakim Tjernlund wrote: > > > > This is a backport from 2.6 which I did to overcome 8xx CPU > > > > bugs. 8xx does not update the DAR register when taking a TLB > > > > error caused by dcbX and icbi insns which makes it very > > > > tricky to use these insns. Also the dcbst wrongly sets the > > > > the store bit when faulting into DTLB error. > > > > A few more bugs very found during development. > > > > > > > > I know 2.4 is in strict maintenance mode and 8xx is obsolete > > > > but as it is still in use I wanted 8xx to age with grace. > > > > > > Thank you very much for taking care of this, that's very much appreciated. > > > I'll look at this ASAP. Just a quick question in order to be certain, did > > > you have the opportunity to test all of these changes on real hardware ? > > > I tested these on real 8xx HW but I used an older 2.4 linux as we haven't > > moved forward on 2.4 for quite some time. > > The affected files were almost identical though. Would be great if > > Scott could give them a spin on 8xx with current 2.4. Is ep88xc (the board I have easily available to test) supported in mainline 2.4? I don't see a platform file, defconfig, or bootwrapper code that obviously covers it. Is there anyone out there actually using 8xx on top-of-tree mainline 2.4 who can test it? > BTW, it occurred to me that the following 8xx quirk is best > done in 8xx code: > > From c1985a3b8b16d96ddce5ef90d5a15e70fb8a2aec Mon Sep 17 00:00:00 2001 > From: Joakim Tjernlund <Joakim.Tjernlund@transmode.se> > Date: Tue, 11 Jan 2011 11:24:22 +0100 > Subject: [PATCH] 8xx: Move invalidation of non present TLBs > > 8xx does not invalidate ~PRESENT TLBs, move the workaround > in mm/fault.c here to keep 8xx quirks localized. > > Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se> > --- > arch/ppc/kernel/head_8xx.S | 12 ++++++++++-- > arch/ppc/mm/fault.c | 7 ------- > 2 files changed, 10 insertions(+), 9 deletions(-) > > diff --git a/arch/ppc/kernel/head_8xx.S b/arch/ppc/kernel/head_8xx.S > index 75acaa0..24b206c 100644 > --- a/arch/ppc/kernel/head_8xx.S > +++ b/arch/ppc/kernel/head_8xx.S > @@ -221,7 +221,11 @@ DataAccess: > mr r5,r20 > mfspr r4,DAR > stw r4,_DAR(r21) > - li r20,0x00f0 > + /* invalidate ~PRESENT TLBs, 8xx MMU don't do this */ > + andis. r20,r5,0x4000 > + beq+ 1f > + tlbie r4 > +1: li r20,0x00f > mtspr DAR,r20 /* Tag DAR */ > addi r3,r1,STACK_FRAME_OVERHEAD > li r20,MSR_KERNEL > @@ -238,7 +242,11 @@ InstructionAccess: > addi r3,r1,STACK_FRAME_OVERHEAD > mr r4,r22 > mr r5,r23 > - li r20,MSR_KERNEL > + /* invalidate ~PRESENT TLBs, 8xx MMU don't do this */ > + andis. r20,r5,0x4000 > + beq+ 1f > + tlbie r4 > +1: li r20,MSR_KERNEL > rlwimi r20,r23,0,16,16 /* copy EE bit from saved MSR */ > FINISH_EXCEPTION(do_page_fault) > > diff --git a/arch/ppc/mm/fault.c b/arch/ppc/mm/fault.c > index 874005a..8819fb1 100644 > --- a/arch/ppc/mm/fault.c > +++ b/arch/ppc/mm/fault.c > @@ -116,13 +116,6 @@ void do_page_fault(struct pt_regs *regs, unsigned long address, > else > is_write = error_code & 0x02000000; > #endif /* CONFIG_4xx || CONFIG_BOOKE */ > -#if defined(CONFIG_8xx) > - /* 8xx does no invalidate TLBs that are ~PRESENT, > - * do it here. > - */ > - if (error_code & 0x40000000) > - _tlbie(address); > -#endif > #if defined(CONFIG_XMON) || defined(CONFIG_KGDB) > if (debugger_fault_handler && regs->trap == 0x300) { > debugger_fault_handler(regs); > -- > 1.7.3.4 > > Scott, what do you think of this? Is it safe to call tlbie in this context? I'd guess so (I assume the concern is MMU translation being off?), but I don't have any particular knowledge about this. I'd be checking the same manual that you have. :-) -Scott
Scott Wood <scottwood@freescale.com> wrote on 2011/01/13 21:44:00: > > BTW, it occurred to me that the following 8xx quirk is best > > done in 8xx code: > > > > From c1985a3b8b16d96ddce5ef90d5a15e70fb8a2aec Mon Sep 17 00:00:00 2001 > > From: Joakim Tjernlund <Joakim.Tjernlund@transmode.se> > > Date: Tue, 11 Jan 2011 11:24:22 +0100 > > Subject: [PATCH] 8xx: Move invalidation of non present TLBs > > > > 8xx does not invalidate ~PRESENT TLBs, move the workaround > > in mm/fault.c here to keep 8xx quirks localized. > > > > Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se> > > --- > > arch/ppc/kernel/head_8xx.S | 12 ++++++++++-- > > arch/ppc/mm/fault.c | 7 ------- > > 2 files changed, 10 insertions(+), 9 deletions(-) > > > > diff --git a/arch/ppc/kernel/head_8xx.S b/arch/ppc/kernel/head_8xx.S > > index 75acaa0..24b206c 100644 > > --- a/arch/ppc/kernel/head_8xx.S > > +++ b/arch/ppc/kernel/head_8xx.S > > @@ -221,7 +221,11 @@ DataAccess: > > mr r5,r20 > > mfspr r4,DAR > > stw r4,_DAR(r21) > > - li r20,0x00f0 > > + /* invalidate ~PRESENT TLBs, 8xx MMU don't do this */ > > + andis. r20,r5,0x4000 > > + beq+ 1f > > + tlbie r4 > > +1: li r20,0x00f > > mtspr DAR,r20 /* Tag DAR */ > > addi r3,r1,STACK_FRAME_OVERHEAD > > li r20,MSR_KERNEL > > @@ -238,7 +242,11 @@ InstructionAccess: > > addi r3,r1,STACK_FRAME_OVERHEAD > > mr r4,r22 > > mr r5,r23 > > - li r20,MSR_KERNEL > > + /* invalidate ~PRESENT TLBs, 8xx MMU don't do this */ > > + andis. r20,r5,0x4000 > > + beq+ 1f > > + tlbie r4 > > +1: li r20,MSR_KERNEL > > rlwimi r20,r23,0,16,16 /* copy EE bit from saved MSR */ > > FINISH_EXCEPTION(do_page_fault) > > > > diff --git a/arch/ppc/mm/fault.c b/arch/ppc/mm/fault.c > > index 874005a..8819fb1 100644 > > --- a/arch/ppc/mm/fault.c > > +++ b/arch/ppc/mm/fault.c > > @@ -116,13 +116,6 @@ void do_page_fault(struct pt_regs *regs, unsigned long address, > > else > > is_write = error_code & 0x02000000; > > #endif /* CONFIG_4xx || CONFIG_BOOKE */ > > -#if defined(CONFIG_8xx) > > - /* 8xx does no invalidate TLBs that are ~PRESENT, > > - * do it here. > > - */ > > - if (error_code & 0x40000000) > > - _tlbie(address); > > -#endif > > #if defined(CONFIG_XMON) || defined(CONFIG_KGDB) > > if (debugger_fault_handler && regs->trap == 0x300) { > > debugger_fault_handler(regs); > > -- > > 1.7.3.4 > > > > Scott, what do you think of this? Is it safe to call tlbie in this context? > > I'd guess so (I assume the concern is MMU translation being off?), but I > don't have any particular knowledge about this. I'd be checking the > same manual that you have. :-) I noticed 2.6 uses tlbie in CPU15 errata workaround so it is fine and it is better to invalidate as soon as possible to free up a TLB slot. Runs on my old 2.4 too. Jocke
diff --git a/arch/ppc/kernel/head_8xx.S b/arch/ppc/kernel/head_8xx.S index 75acaa0..24b206c 100644 --- a/arch/ppc/kernel/head_8xx.S +++ b/arch/ppc/kernel/head_8xx.S @@ -221,7 +221,11 @@ DataAccess: mr r5,r20 mfspr r4,DAR stw r4,_DAR(r21) - li r20,0x00f0 + /* invalidate ~PRESENT TLBs, 8xx MMU don't do this */ + andis. r20,r5,0x4000 + beq+ 1f + tlbie r4 +1: li r20,0x00f0 mtspr DAR,r20 /* Tag DAR */ addi r3,r1,STACK_FRAME_OVERHEAD li r20,MSR_KERNEL @@ -238,7 +242,11 @@ InstructionAccess: addi r3,r1,STACK_FRAME_OVERHEAD mr r4,r22 mr r5,r23 - li r20,MSR_KERNEL + /* invalidate ~PRESENT TLBs, 8xx MMU don't do this */ + andis. r20,r5,0x4000 + beq+ 1f + tlbie r4 +1: li r20,MSR_KERNEL rlwimi r20,r23,0,16,16 /* copy EE bit from saved MSR */ FINISH_EXCEPTION(do_page_fault) diff --git a/arch/ppc/mm/fault.c b/arch/ppc/mm/fault.c index 874005a..8819fb1 100644 --- a/arch/ppc/mm/fault.c +++ b/arch/ppc/mm/fault.c @@ -116,13 +116,6 @@ void do_page_fault(struct pt_regs *regs, unsigned long address, else is_write = error_code & 0x02000000; #endif /* CONFIG_4xx || CONFIG_BOOKE */ -#if defined(CONFIG_8xx) - /* 8xx does no invalidate TLBs that are ~PRESENT, - * do it here. - */ - if (error_code & 0x40000000) - _tlbie(address); -#endif #if defined(CONFIG_XMON) || defined(CONFIG_KGDB) if (debugger_fault_handler && regs->trap == 0x300) { debugger_fault_handler(regs);