sh: Revert TLB miss fast-path changes that broke PTEA parts.

This ended up causing problems for older parts (particularly ones
using PTEA). Revert this for now, it can be added back in once it's
had some more testing.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

2 files changed, 107 insertions, 181 deletions

diff --git a/arch/sh/kernel/cpu/sh3/entry.S b/arch/sh/kernel/cpu/sh3/entry.S
index 1c520358ba90..c19205b0f2c0 100644
--- a/arch/sh/kernel/cpu/sh3/entry.S
+++ b/arch/sh/kernel/cpu/sh3/entry.S
@@ -13,10 +13,8 @@
 #include <linux/linkage.h>
 #include <asm/asm-offsets.h>
 #include <asm/thread_info.h>
-#include <asm/unistd.h>
 #include <asm/cpu/mmu_context.h>
-#include <asm/pgtable.h>
-#include <asm/page.h>
+#include <asm/unistd.h>
 
 ! NOTE:
 ! GNU as (as of 2.9.1) changes bf/s into bt/s and bra, when the address
@@ -138,14 +136,29 @@ ENTRY(tlb_protection_violation_store)
 
 call_dpf:
         mov.l   1f, r0
-        mov.l   @r0, r6         ! address
+        mov     r5, r8
+        mov.l   @r0, r6
+        mov     r6, r9
+        mov.l   2f, r0
+        sts     pr, r10
+        jsr     @r0
+         mov    r15, r4
+        !
+        tst     r0, r0
+        bf/s    0f
+         lds    r10, pr
+        rts
+         nop
+0:      sti
         mov.l   3f, r0
-
+        mov     r9, r6
+        mov     r8, r5
         jmp     @r0
-         mov    r15, r4         ! regs
+         mov    r15, r4
 
         .align 2
 1:      .long   MMU_TEA
+2:      .long   __do_page_fault
 3:      .long   do_page_fault
 
         .align  2
@@ -332,171 +345,9 @@ general_exception:
 !
 !
 
-/* gas doesn't flag impossible values for mov #immediate as an error */
-#if (_PAGE_PRESENT >> 2) > 0x7f
-#error cannot load PAGE_PRESENT as an immediate
-#endif
-#if _PAGE_DIRTY > 0x7f
-#error cannot load PAGE_DIRTY as an immediate
-#endif
-#if (_PAGE_PRESENT << 2) != _PAGE_ACCESSED
-#error cannot derive PAGE_ACCESSED from PAGE_PRESENT
-#endif
-
-#if defined(CONFIG_CPU_SH4)
-#define ldmmupteh(r)    mov.l   8f, r
-#else
-#define ldmmupteh(r)    mov     #MMU_PTEH, r
-#endif
-
         .balign         1024,0,1024
 tlb_miss:
-#ifdef COUNT_EXCEPTIONS
-        ! Increment the counts
-        mov.l   9f, k1
-        mov.l   @k1, k2
-        add     #1, k2
-        mov.l   k2, @k1
-#endif
-
-        ! k0 scratch
-        ! k1 pgd and pte pointers
-        ! k2 faulting address
-        ! k3 pgd and pte index masks
-        ! k4 shift
-
-        ! Load up the pgd entry (k1)
-
-        ldmmupteh(k0)                   !  9 LS (latency=2)     MMU_PTEH
-
-        mov.w   4f, k3                  !  8 LS (latency=2)     (PTRS_PER_PGD-1) << 2
-        mov     #-(PGDIR_SHIFT-2), k4   !  6 EX
-
-        mov.l   @(MMU_TEA-MMU_PTEH,k0), k2      ! 18 LS (latency=2)
-
-        mov.l   @(MMU_TTB-MMU_PTEH,k0), k1      ! 18 LS (latency=2)
-
-        mov     k2, k0                  !   5 MT (latency=0)
-        shld    k4, k0                  !  99 EX
-
-        and     k3, k0                  !  78 EX
-
-        mov.l   @(k0, k1), k1           !  21 LS (latency=2)
-        mov     #-(PAGE_SHIFT-2), k4    !   6 EX
-
-        ! Load up the pte entry (k2)
-
-        mov     k2, k0                  !   5 MT (latency=0)
-        shld    k4, k0                  !  99 EX
-
-        tst     k1, k1                  !  86 MT
-
-        bt      20f                     ! 110 BR
-
-        mov.w   3f, k3                  !  8 LS (latency=2)     (PTRS_PER_PTE-1) << 2
-        and     k3, k0                  !  78 EX
-        mov.w   5f, k4                  !   8 LS (latency=2)    _PAGE_PRESENT
-
-        mov.l   @(k0, k1), k2           !  21 LS (latency=2)
-        add     k0, k1                  !  49 EX
-
-#ifdef CONFIG_CPU_HAS_PTEA
-        ! Test the entry for present and _PAGE_ACCESSED
-
-        mov     #-28, k3                !   6 EX
-        mov     k2, k0                  !   5 MT (latency=0)
-
-        tst     k4, k2                  !  68 MT
-        shld    k3, k0                  !  99 EX
-
-        bt      20f                     ! 110 BR
-
-        ! Set PTEA register
-        ! MMU_PTEA = ((pteval >> 28) & 0xe) | (pteval & 0x1)
-        !
-        ! k0=pte>>28, k1=pte*, k2=pte, k3=<unused>, k4=_PAGE_PRESENT
-
-        and     #0xe, k0                !  79 EX
-
-        mov     k0, k3                  !   5 MT (latency=0)
-        mov     k2, k0                  !   5 MT (latency=0)
-
-        and     #1, k0                  !  79 EX
-
-        or      k0, k3                  !  82 EX
-
-        ldmmupteh(k0)                   !   9 LS (latency=2)
-        shll2   k4                      ! 101 EX                _PAGE_ACCESSED
-
-        tst     k4, k2                  !  68 MT
-
-        mov.l   k3, @(MMU_PTEA-MMU_PTEH,k0)     ! 27 LS
-
-        mov.l   7f, k3                  !   9 LS (latency=2)    _PAGE_FLAGS_HARDWARE_MASK
-
-        ! k0=MMU_PTEH, k1=pte*, k2=pte, k3=_PAGE_FLAGS_HARDWARE, k4=_PAGE_ACCESSED
-#else
-
-        ! Test the entry for present and _PAGE_ACCESSED
-
-        mov.l   7f, k3                  !   9 LS (latency=2)    _PAGE_FLAGS_HARDWARE_MASK
-        tst     k4, k2                  !  68 MT
-
-        shll2   k4                      ! 101 EX                _PAGE_ACCESSED
-        ldmmupteh(k0)                   !   9 LS (latency=2)
-
-        bt      20f                     ! 110 BR
-        tst     k4, k2                  !  68 MT
-
-        ! k0=MMU_PTEH, k1=pte*, k2=pte, k3=_PAGE_FLAGS_HARDWARE, k4=_PAGE_ACCESSED
-
-#endif
-
-        ! Set up the entry
-
-        and     k2, k3                  !  78 EX
-        bt/s    10f                     ! 108 BR
-
-         mov.l  k3, @(MMU_PTEL-MMU_PTEH,k0)     ! 27 LS
-
-        ldtlb                           ! 128 CO
-
-        ! At least one instruction between ldtlb and rte
-        nop                             ! 119 NOP
-
-        rte                             ! 126 CO
-
-         nop                            ! 119 NOP
-
-
-10:     or      k4, k2                  !  82 EX
-
-        ldtlb                           ! 128 CO
-
-        ! At least one instruction between ldtlb and rte
-        mov.l   k2, @k1                 !  27 LS
-
-        rte                             ! 126 CO
-
-        ! Note we cannot execute mov here, because it is executed after
-        ! restoring SSR, so would be executed in user space.
-         nop                            ! 119 NOP
-
-
-        .align 5
-        ! Once cache line if possible...
-1:      .long   swapper_pg_dir
-3:      .short  (PTRS_PER_PTE-1) << 2
-4:      .short  (PTRS_PER_PGD-1) << 2
-5:      .long   _PAGE_PRESENT
-7:      .long   _PAGE_FLAGS_HARDWARE_MASK
-8:      .long   MMU_PTEH
-#ifdef COUNT_EXCEPTIONS
-9:      .long   exception_count_miss
-#endif
-
-        ! Either pgd or pte not present
-20:     mov.l   1f, k2
+        mov.l   1f, k2
         mov.l   4f, k3
         bra     handle_exception
          mov.l  @k2, k2
@@ -647,15 +498,6 @@ skip_save:
         bf      interrupt_exception
         shlr2   r8
         shlr    r8
-
-#ifdef COUNT_EXCEPTIONS
-        mov.l   5f, r9
-        add     r8, r9
-        mov.l   @r9, r10
-        add     #1, r10
-        mov.l   r10, @r9
-#endif
-
         mov.l   4f, r9
         add     r8, r9
         mov.l   @r9, r9
@@ -669,9 +511,6 @@ skip_save:
 2:      .long   0x000080f0      ! FD=1, IMASK=15
 3:      .long   0xcfffffff      ! RB=0, BL=0
 4:      .long   exception_handling_table
-#ifdef COUNT_EXCEPTIONS
-5:      .long   exception_count_table
-#endif
 
 interrupt_exception:
         mov.l   1f, r9
diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 716ebf568af2..fa5d7f0b9f18 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -17,6 +17,7 @@
 #include <linux/kprobes.h>
 #include <asm/system.h>
 #include <asm/mmu_context.h>
+#include <asm/tlbflush.h>
 #include <asm/kgdb.h>
 
 extern void die(const char *,struct pt_regs *,long);
@@ -224,3 +225,89 @@ do_sigbus:
         if (!user_mode(regs))
                 goto no_context;
 }
+
+#ifdef CONFIG_SH_STORE_QUEUES
+/*
+ * This is a special case for the SH-4 store queues, as pages for this
+ * space still need to be faulted in before it's possible to flush the
+ * store queue cache for writeout to the remapped region.
+ */
+#define P3_ADDR_MAX             (P4SEG_STORE_QUE + 0x04000000)
+#else
+#define P3_ADDR_MAX             P4SEG
+#endif
+
+/*
+ * Called with interrupts disabled.
+ */
+asmlinkage int __kprobes __do_page_fault(struct pt_regs *regs,
+                                         unsigned long writeaccess,
+                                         unsigned long address)
+{
+        pgd_t *pgd;
+        pud_t *pud;
+        pmd_t *pmd;
+        pte_t *pte;
+        pte_t entry;
+        struct mm_struct *mm = current->mm;
+        spinlock_t *ptl;
+        int ret = 1;
+
+#ifdef CONFIG_SH_KGDB
+        if (kgdb_nofault && kgdb_bus_err_hook)
+                kgdb_bus_err_hook();
+#endif
+
+        /*
+         * We don't take page faults for P1, P2, and parts of P4, these
+         * are always mapped, whether it be due to legacy behaviour in
+         * 29-bit mode, or due to PMB configuration in 32-bit mode.
+         */
+        if (address >= P3SEG && address < P3_ADDR_MAX) {
+                pgd = pgd_offset_k(address);
+                mm = NULL;
+        } else {
+                if (unlikely(address >= TASK_SIZE || !mm))
+                        return 1;
+
+                pgd = pgd_offset(mm, address);
+        }
+
+        pud = pud_offset(pgd, address);
+        if (pud_none_or_clear_bad(pud))
+                return 1;
+        pmd = pmd_offset(pud, address);
+        if (pmd_none_or_clear_bad(pmd))
+                return 1;
+
+        if (mm)
+                pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+        else
+                pte = pte_offset_kernel(pmd, address);
+
+        entry = *pte;
+        if (unlikely(pte_none(entry) || pte_not_present(entry)))
+                goto unlock;
+        if (unlikely(writeaccess && !pte_write(entry)))
+                goto unlock;
+
+        if (writeaccess)
+                entry = pte_mkdirty(entry);
+        entry = pte_mkyoung(entry);
+
+#ifdef CONFIG_CPU_SH4
+        /*
+         * ITLB is not affected by "ldtlb" instruction.
+         * So, we need to flush the entry by ourselves.
+         */
+        local_flush_tlb_one(get_asid(), address & PAGE_MASK);
+#endif
+
+        set_pte(pte, entry);
+        update_mmu_cache(NULL, address, entry);
+        ret = 0;
+unlock:
+        if (mm)
+                pte_unmap_unlock(pte, ptl);
+        return ret;
+}