[SPARC64]: Fix boot failures on SunBlade-150

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>

5 files changed, 92 insertions, 113 deletions

diff --git a/arch/sparc64/kernel/dtlb_base.S b/arch/sparc64/kernel/dtlb_base.S
index 702d349c1e88..6528786840c0 100644
--- a/arch/sparc64/kernel/dtlb_base.S
+++ b/arch/sparc64/kernel/dtlb_base.S
@@ -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:
@@ -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:
@@ -106,8 +103,7 @@ longpath:
         nop
         nop
         nop
-        CREATE_VPTE_NOP
+        nop
 
 #undef CREATE_VPTE_OFFSET1
 #undef CREATE_VPTE_OFFSET2
-#undef CREATE_VPTE_NOP
diff --git a/arch/sparc64/kernel/dtlb_prot.S b/arch/sparc64/kernel/dtlb_prot.S
index d848bb7374bb..e0a920162604 100644
--- a/arch/sparc64/kernel/dtlb_prot.S
+++ b/arch/sparc64/kernel/dtlb_prot.S
@@ -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
diff --git a/arch/sparc64/kernel/head.S b/arch/sparc64/kernel/head.S
index 4c942f71184d..b49dcd4504b0 100644
--- a/arch/sparc64/kernel/head.S
+++ b/arch/sparc64/kernel/head.S
@@ -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.      */
@@ -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
 
@@ -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
@@ -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
diff --git a/arch/sparc64/kernel/itlb_base.S b/arch/sparc64/kernel/itlb_base.S
index b5e32dfa4fbc..4951ff8f6877 100644
--- a/arch/sparc64/kernel/itlb_base.S
+++ b/arch/sparc64/kernel/itlb_base.S
@@ -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 */
 
 
@@ -36,6 +34,7 @@
  */
 
 /* 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
@@ -43,41 +42,38 @@
 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
diff --git a/arch/sparc64/kernel/ktlb.S b/arch/sparc64/kernel/ktlb.S
index 7796b37f478c..d9244d3c9f73 100644
--- a/arch/sparc64/kernel/ktlb.S
+++ b/arch/sparc64/kernel/ktlb.S
@@ -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 */
@@ -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