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[SPARC64]: Fix boot failures on SunBlade-150
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The sequence to move over to the Linux trap tables from
the firmware ones needs to be more air tight.  It turns
out that to be %100 safe we do need to be able to translate
OBP mappings in our TLB miss handlers early.

In order not to eat up a lot of kernel image memory with
static page tables, just use the translations array in
the OBP TLB miss handlers.  That solves the bulk of the
problem.

Furthermore, to make sure the OBP TLB miss path will work
even before the fixed MMU globals are loaded, explicitly
load %g1 to TLB_SFSR at the beginning of the i-TLB and
d-TLB miss handlers.

To ease the OBP TLB miss walking of the prom_trans[] array,
we sort it then delete all of the non-OBP entries in there
(for example, there are entries for the kernel image itself
which we're not interested in at all).

We also save about 32K of kernel image size with this change.
Not a bad side effect :-)

There are still some reasons why trampoline.S can't use the
setup_trap_table() yet.  The most noteworthy are:

1) OBP boots secondary processors with non-bias'd stack for
   some reason.  This is easily fixed by using a small bootup
   stack in the kernel image explicitly for this purpose.

2) Doing a firmware call via the normal C call prom_set_trap_table()
   goes through the whole OBP enter/exit sequence that saves and
   restores OBP and Linux kernel state in the MMUs.  This path
   unfortunately does a "flush %g6" while loading up the OBP locked
   TLB entries for the firmware call.

   If we setup the %g6 in the trampoline.S code properly, that
   is in the PAGE_OFFSET linear mapping, but we're not on the
   kernel trap table yet so those addresses won't translate properly.

   One idea is to do a by-hand firmware call like we do in the
   early bootup code and elsewhere here in trampoline.S  But this
   fails as well, as aparently the secondary processors are not
   booted with OBP's special locked TLB entries loaded.  These
   are necessary for the firwmare to processes TLB misses correctly
   up until the point where we take over the trap table.

This does need to be resolved at some point.

Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller committed Oct 12, 2005
1 parent d8e998c commit c9c1083
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Showing 6 changed files with 166 additions and 226 deletions.
14 changes: 5 additions & 9 deletions arch/sparc64/kernel/dtlb_base.S
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Original file line number Diff line number Diff line change
Expand Up @@ -53,19 +53,18 @@
* be guaranteed to be 0 ... mmu_context.h does guarantee this
* by only using 10 bits in the hwcontext value.
*/
#define CREATE_VPTE_OFFSET1(r1, r2)
#define CREATE_VPTE_OFFSET1(r1, r2) nop
#define CREATE_VPTE_OFFSET2(r1, r2) \
srax r1, 10, r2
#define CREATE_VPTE_NOP nop
#else
#define CREATE_VPTE_OFFSET1(r1, r2) \
srax r1, PAGE_SHIFT, r2
#define CREATE_VPTE_OFFSET2(r1, r2) \
sllx r2, 3, r2
#define CREATE_VPTE_NOP
#endif

/* DTLB ** ICACHE line 1: Quick user TLB misses */
mov TLB_SFSR, %g1
ldxa [%g1 + %g1] ASI_DMMU, %g4 ! Get TAG_ACCESS
andcc %g4, TAG_CONTEXT_BITS, %g0 ! From Nucleus?
from_tl1_trap:
Expand All @@ -74,18 +73,16 @@ from_tl1_trap:
be,pn %xcc, kvmap ! Yep, special processing
CREATE_VPTE_OFFSET2(%g4, %g6) ! Create VPTE offset
cmp %g5, 4 ! Last trap level?
be,pn %xcc, longpath ! Yep, cannot risk VPTE miss
nop ! delay slot

/* DTLB ** ICACHE line 2: User finish + quick kernel TLB misses */
be,pn %xcc, longpath ! Yep, cannot risk VPTE miss
nop ! delay slot
ldxa [%g3 + %g6] ASI_S, %g5 ! Load VPTE
1: brgez,pn %g5, longpath ! Invalid, branch out
nop ! Delay-slot
9: stxa %g5, [%g0] ASI_DTLB_DATA_IN ! Reload TLB
retry ! Trap return
nop
nop
nop

/* DTLB ** ICACHE line 3: winfixups+real_faults */
longpath:
Expand All @@ -106,8 +103,7 @@ longpath:
nop
nop
nop
CREATE_VPTE_NOP
nop

#undef CREATE_VPTE_OFFSET1
#undef CREATE_VPTE_OFFSET2
#undef CREATE_VPTE_NOP
12 changes: 6 additions & 6 deletions arch/sparc64/kernel/dtlb_prot.S
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Original file line number Diff line number Diff line change
Expand Up @@ -14,14 +14,14 @@
*/

/* PROT ** ICACHE line 1: User DTLB protection trap */
stxa %g0, [%g1] ASI_DMMU ! Clear SFSR FaultValid bit
membar #Sync ! Synchronize ASI stores
rdpr %pstate, %g5 ! Move into alternate globals
mov TLB_SFSR, %g1
stxa %g0, [%g1] ASI_DMMU ! Clear FaultValid bit
membar #Sync ! Synchronize stores
rdpr %pstate, %g5 ! Move into alt-globals
wrpr %g5, PSTATE_AG|PSTATE_MG, %pstate
rdpr %tl, %g1 ! Need to do a winfixup?
rdpr %tl, %g1 ! Need a winfixup?
cmp %g1, 1 ! Trap level >1?
mov TLB_TAG_ACCESS, %g4 ! Prepare reload of vaddr
nop
mov TLB_TAG_ACCESS, %g4 ! For reload of vaddr

/* PROT ** ICACHE line 2: More real fault processing */
bgu,pn %xcc, winfix_trampoline ! Yes, perform winfixup
Expand Down
61 changes: 26 additions & 35 deletions arch/sparc64/kernel/head.S
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Original file line number Diff line number Diff line change
Expand Up @@ -28,19 +28,14 @@
#include <asm/mmu.h>

/* This section from from _start to sparc64_boot_end should fit into
* 0x0000.0000.0040.4000 to 0x0000.0000.0040.8000 and will be sharing space
* with bootup_user_stack, which is from 0x0000.0000.0040.4000 to
* 0x0000.0000.0040.6000 and empty_bad_page, which is from
* 0x0000.0000.0040.6000 to 0x0000.0000.0040.8000.
* 0x0000000000404000 to 0x0000000000408000.
*/

.text
.globl start, _start, stext, _stext
_start:
start:
_stext:
stext:
bootup_user_stack:
! 0x0000000000404000
b sparc64_boot
flushw /* Flush register file. */
Expand Down Expand Up @@ -392,31 +387,30 @@ tlb_fixup_done:
* former does use this code, the latter does not yet due
* to some complexities. That should be fixed up at some
* point.
*
* There used to be enormous complexity wrt. transferring
* over from the firwmare's trap table to the Linux kernel's.
* For example, there was a chicken & egg problem wrt. building
* the OBP page tables, yet needing to be on the Linux kernel
* trap table (to translate PAGE_OFFSET addresses) in order to
* do that.
*
* We now handle OBP tlb misses differently, via linear lookups
* into the prom_trans[] array. So that specific problem no
* longer exists. Yet, unfortunately there are still some issues
* preventing trampoline.S from using this code... ho hum.
*/
.globl setup_trap_table
setup_trap_table:
save %sp, -192, %sp

/* Force interrupts to be disabled. Transferring over to
* the Linux trap table is a very delicate operation.
* Until we are actually on the Linux trap table, we cannot
* get the PAGE_OFFSET linear mappings translated. We need
* that mapping to be setup in order to initialize the firmware
* page tables.
*
* So there is this window of time, from the return from
* prom_set_trap_table() until inherit_prom_mappings_post()
* (in arch/sparc64/mm/init.c) completes, during which no
* firmware address space accesses can be made.
*/
/* Force interrupts to be disabled. */
rdpr %pstate, %o1
andn %o1, PSTATE_IE, %o1
wrpr %o1, 0x0, %pstate
wrpr %g0, 15, %pil

/* Ok, now make the final valid firmware call to jump over
* to the Linux trap table.
*/
/* Make the firmware call to jump over to the Linux trap table. */
call prom_set_trap_table
sethi %hi(sparc64_ttable_tl0), %o0

Expand Down Expand Up @@ -540,15 +534,21 @@ setup_tba: /* i0 = is_starfire */

ret
restore
sparc64_boot_end:

#include "systbls.S"
#include "ktlb.S"
#include "etrap.S"
#include "rtrap.S"
#include "winfixup.S"
#include "entry.S"

/*
* The following skips make sure the trap table in ttable.S is aligned
* The following skip makes sure the trap table in ttable.S is aligned
* on a 32K boundary as required by the v9 specs for TBA register.
*/
sparc64_boot_end:
.skip 0x2000 + _start - sparc64_boot_end
bootup_user_stack_end:
.skip 0x2000
1:
.skip 0x4000 + _start - 1b

#ifdef CONFIG_SBUS
/* This is just a hack to fool make depend config.h discovering
Expand All @@ -560,15 +560,6 @@ bootup_user_stack_end:
! 0x0000000000408000

#include "ttable.S"
#include "systbls.S"
#include "ktlb.S"
#include "etrap.S"
#include "rtrap.S"
#include "winfixup.S"
#include "entry.S"

/* This is just anal retentiveness on my part... */
.align 16384

.data
.align 8
Expand Down
26 changes: 11 additions & 15 deletions arch/sparc64/kernel/itlb_base.S
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Original file line number Diff line number Diff line change
Expand Up @@ -15,14 +15,12 @@
*/
#define CREATE_VPTE_OFFSET1(r1, r2) \
srax r1, 10, r2
#define CREATE_VPTE_OFFSET2(r1, r2)
#define CREATE_VPTE_NOP nop
#define CREATE_VPTE_OFFSET2(r1, r2) nop
#else /* PAGE_SHIFT */
#define CREATE_VPTE_OFFSET1(r1, r2) \
srax r1, PAGE_SHIFT, r2
#define CREATE_VPTE_OFFSET2(r1, r2) \
sllx r2, 3, r2
#define CREATE_VPTE_NOP
#endif /* PAGE_SHIFT */


Expand All @@ -36,48 +34,46 @@
*/

/* ITLB ** ICACHE line 1: Quick user TLB misses */
mov TLB_SFSR, %g1
ldxa [%g1 + %g1] ASI_IMMU, %g4 ! Get TAG_ACCESS
CREATE_VPTE_OFFSET1(%g4, %g6) ! Create VPTE offset
CREATE_VPTE_OFFSET2(%g4, %g6) ! Create VPTE offset
ldxa [%g3 + %g6] ASI_P, %g5 ! Load VPTE
1: brgez,pn %g5, 3f ! Not valid, branch out
sethi %hi(_PAGE_EXEC), %g4 ! Delay-slot
andcc %g5, %g4, %g0 ! Executable?

/* ITLB ** ICACHE line 2: Real faults */
be,pn %xcc, 3f ! Nope, branch.
nop ! Delay-slot
2: stxa %g5, [%g0] ASI_ITLB_DATA_IN ! Load PTE into TLB
retry ! Trap return
3: rdpr %pstate, %g4 ! Move into alternate globals

/* ITLB ** ICACHE line 2: Real faults */
3: rdpr %pstate, %g4 ! Move into alt-globals
wrpr %g4, PSTATE_AG|PSTATE_MG, %pstate
rdpr %tpc, %g5 ! And load faulting VA
mov FAULT_CODE_ITLB, %g4 ! It was read from ITLB
sparc64_realfault_common: ! Called by TL0 dtlb_miss too

/* ITLB ** ICACHE line 3: Finish faults */
sparc64_realfault_common: ! Called by dtlb_miss
stb %g4, [%g6 + TI_FAULT_CODE]
stx %g5, [%g6 + TI_FAULT_ADDR]
ba,pt %xcc, etrap ! Save state
1: rd %pc, %g7 ! ...
nop

/* ITLB ** ICACHE line 3: Finish faults + window fixups */
call do_sparc64_fault ! Call fault handler
add %sp, PTREGS_OFF, %o0! Compute pt_regs arg
ba,pt %xcc, rtrap_clr_l6 ! Restore cpu state
nop

/* ITLB ** ICACHE line 4: Window fixups */
winfix_trampoline:
rdpr %tpc, %g3 ! Prepare winfixup TNPC
or %g3, 0x7c, %g3 ! Compute offset to branch
or %g3, 0x7c, %g3 ! Compute branch offset
wrpr %g3, %tnpc ! Write it into TNPC
done ! Do it to it

/* ITLB ** ICACHE line 4: Unused... */
nop
nop
nop
nop
CREATE_VPTE_NOP

#undef CREATE_VPTE_OFFSET1
#undef CREATE_VPTE_OFFSET2
#undef CREATE_VPTE_NOP
92 changes: 44 additions & 48 deletions arch/sparc64/kernel/ktlb.S
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Original file line number Diff line number Diff line change
Expand Up @@ -58,9 +58,6 @@ vpte_noent:
done

vpte_insn_obp:
sethi %hi(prom_pmd_phys), %g5
ldx [%g5 + %lo(prom_pmd_phys)], %g5

/* Behave as if we are at TL0. */
wrpr %g0, 1, %tl
rdpr %tpc, %g4 /* Find original faulting iaddr */
Expand All @@ -71,58 +68,57 @@ vpte_insn_obp:
mov TLB_SFSR, %g1
stxa %g4, [%g1 + %g1] ASI_IMMU

/* Get PMD offset. */
srlx %g4, 23, %g6
and %g6, 0x7ff, %g6
sllx %g6, 2, %g6

/* Load PMD, is it valid? */
lduwa [%g5 + %g6] ASI_PHYS_USE_EC, %g5
brz,pn %g5, longpath
sllx %g5, 11, %g5

/* Get PTE offset. */
srlx %g4, 13, %g6
and %g6, 0x3ff, %g6
sllx %g6, 3, %g6

/* Load PTE. */
ldxa [%g5 + %g6] ASI_PHYS_USE_EC, %g5
brgez,pn %g5, longpath
nop

/* TLB load and return from trap. */
sethi %hi(prom_trans), %g5
or %g5, %lo(prom_trans), %g5

1: ldx [%g5 + 0x00], %g6 ! base
brz,a,pn %g6, longpath ! no more entries, fail
mov TLB_SFSR, %g1 ! and restore %g1
ldx [%g5 + 0x08], %g1 ! len
add %g6, %g1, %g1 ! end
cmp %g6, %g4
bgu,pt %xcc, 2f
cmp %g4, %g1
bgeu,pt %xcc, 2f
ldx [%g5 + 0x10], %g1 ! PTE

/* TLB load, restore %g1, and return from trap. */
sub %g4, %g6, %g6
add %g1, %g6, %g5
mov TLB_SFSR, %g1
stxa %g5, [%g0] ASI_ITLB_DATA_IN
retry

kvmap_do_obp:
sethi %hi(prom_pmd_phys), %g5
ldx [%g5 + %lo(prom_pmd_phys)], %g5

/* Get PMD offset. */
srlx %g4, 23, %g6
and %g6, 0x7ff, %g6
sllx %g6, 2, %g6

/* Load PMD, is it valid? */
lduwa [%g5 + %g6] ASI_PHYS_USE_EC, %g5
brz,pn %g5, longpath
sllx %g5, 11, %g5

/* Get PTE offset. */
srlx %g4, 13, %g6
and %g6, 0x3ff, %g6
sllx %g6, 3, %g6

/* Load PTE. */
ldxa [%g5 + %g6] ASI_PHYS_USE_EC, %g5
brgez,pn %g5, longpath
nop
2: ba,pt %xcc, 1b
add %g5, (3 * 8), %g5 ! next entry

/* TLB load and return from trap. */
kvmap_do_obp:
sethi %hi(prom_trans), %g5
or %g5, %lo(prom_trans), %g5
srlx %g4, 13, %g4
sllx %g4, 13, %g4

1: ldx [%g5 + 0x00], %g6 ! base
brz,a,pn %g6, longpath ! no more entries, fail
mov TLB_SFSR, %g1 ! and restore %g1
ldx [%g5 + 0x08], %g1 ! len
add %g6, %g1, %g1 ! end
cmp %g6, %g4
bgu,pt %xcc, 2f
cmp %g4, %g1
bgeu,pt %xcc, 2f
ldx [%g5 + 0x10], %g1 ! PTE

/* TLB load, restore %g1, and return from trap. */
sub %g4, %g6, %g6
add %g1, %g6, %g5
mov TLB_SFSR, %g1
stxa %g5, [%g0] ASI_DTLB_DATA_IN
retry

2: ba,pt %xcc, 1b
add %g5, (3 * 8), %g5 ! next entry

/*
* On a first level data miss, check whether this is to the OBP range (note
* that such accesses can be made by prom, as well as by kernel using
Expand Down
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