ARC: MMUv4 preps/3 - Abstract out TLB Insert/Delete

This reorganizes the current TLB operations into psuedo-ops to better
pair with MMUv4's native Insert/Delete operations

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

2 files changed, 56 insertions, 40 deletions

diff --git a/arch/arc/include/asm/mmu.h b/arch/arc/include/asm/mmu.h
index 7c03fe61759c..d14da3d02fbc 100644
--- a/arch/arc/include/asm/mmu.h
+++ b/arch/arc/include/asm/mmu.h
@@ -32,6 +32,8 @@
 /* Error code if probe fails */
 #define TLB_LKUP_ERR            0x80000000
 
+#define TLB_DUP_ERR     (TLB_LKUP_ERR | 0x00000001)
+
 /* TLB Commands */
 #define TLBWrite    0x1
 #define TLBRead     0x2
diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c
index 85a8716e6028..f58d5f62bccc 100644
--- a/arch/arc/mm/tlb.c
+++ b/arch/arc/mm/tlb.c
@@ -52,6 +52,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/bug.h>
 #include <asm/arcregs.h>
 #include <asm/setup.h>
 #include <asm/mmu_context.h>
@@ -109,38 +110,41 @@ struct mm_struct *asid_mm_map[NUM_ASID + 1];
 
 /*
  * Utility Routine to erase a J-TLB entry
- * The procedure is to look it up in the MMU. If found, ERASE it by
- *  issuing a TlbWrite CMD with PD0 = PD1 = 0
+ * Caller needs to setup Index Reg (manually or via getIndex)
  */
-
-static void __tlb_entry_erase(void)
+static inline void __tlb_entry_erase(void)
 {
         write_aux_reg(ARC_REG_TLBPD1, 0);
         write_aux_reg(ARC_REG_TLBPD0, 0);
         write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
 }
 
-static void tlb_entry_erase(unsigned int vaddr_n_asid)
+static inline unsigned int tlb_entry_lkup(unsigned long vaddr_n_asid)
 {
         unsigned int idx;
 
-        /* Locate the TLB entry for this vaddr + ASID */
         write_aux_reg(ARC_REG_TLBPD0, vaddr_n_asid);
+
         write_aux_reg(ARC_REG_TLBCOMMAND, TLBProbe);
         idx = read_aux_reg(ARC_REG_TLBINDEX);
 
+        return idx;
+}
+
+static void tlb_entry_erase(unsigned int vaddr_n_asid)
+{
+        unsigned int idx;
+
+        /* Locate the TLB entry for this vaddr + ASID */
+        idx = tlb_entry_lkup(vaddr_n_asid);
+
         /* No error means entry found, zero it out */
         if (likely(!(idx & TLB_LKUP_ERR))) {
                 __tlb_entry_erase();
-        } else {                /* Some sort of Error */
-
+        } else {
                 /* Duplicate entry error */
-                if (idx & 0x1) {
-                        /* TODO we need to handle this case too */
-                        pr_emerg("unhandled Duplicate flush for %x\n",
-                               vaddr_n_asid);
-                }
-                /* else entry not found so nothing to do */
+                WARN(idx == TLB_DUP_ERR, "Probe returned Dup PD for %x\n",
+                                           vaddr_n_asid);
         }
 }
 
@@ -159,7 +163,7 @@ static void utlb_invalidate(void)
 {
 #if (CONFIG_ARC_MMU_VER >= 2)
 
-#if (CONFIG_ARC_MMU_VER < 3)
+#if (CONFIG_ARC_MMU_VER == 2)
         /* MMU v2 introduced the uTLB Flush command.
          * There was however an obscure hardware bug, where uTLB flush would
          * fail when a prior probe for J-TLB (both totally unrelated) would
@@ -182,6 +186,36 @@ static void utlb_invalidate(void)
 
 }
 
+static void tlb_entry_insert(unsigned int pd0, unsigned int pd1)
+{
+        unsigned int idx;
+
+        /*
+         * First verify if entry for this vaddr+ASID already exists
+         * This also sets up PD0 (vaddr, ASID..) for final commit
+         */
+        idx = tlb_entry_lkup(pd0);
+
+        /*
+         * If Not already present get a free slot from MMU.
+         * Otherwise, Probe would have located the entry and set INDEX Reg
+         * with existing location. This will cause Write CMD to over-write
+         * existing entry with new PD0 and PD1
+         */
+        if (likely(idx & TLB_LKUP_ERR))
+                write_aux_reg(ARC_REG_TLBCOMMAND, TLBGetIndex);
+
+        /* setup the other half of TLB entry (pfn, rwx..) */
+        write_aux_reg(ARC_REG_TLBPD1, pd1);
+
+        /*
+         * Commit the Entry to MMU
+         * It doesnt sound safe to use the TLBWriteNI cmd here
+         * which doesn't flush uTLBs. I'd rather be safe than sorry.
+         */
+        write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
+}
+
 /*
  * Un-conditionally (without lookup) erase the entire MMU contents
  */
@@ -341,7 +375,8 @@ void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
 void create_tlb(struct vm_area_struct *vma, unsigned long address, pte_t *ptep)
 {
         unsigned long flags;
-        unsigned int idx, asid_or_sasid, rwx;
+        unsigned int asid_or_sasid, rwx;
+        unsigned long pd0, pd1;
 
         /*
          * create_tlb() assumes that current->mm == vma->mm, since
@@ -385,8 +420,7 @@ void create_tlb(struct vm_area_struct *vma, unsigned long address, pte_t *ptep)
         /* ASID for this task */
         asid_or_sasid = read_aux_reg(ARC_REG_PID) & 0xff;
 
-        write_aux_reg(ARC_REG_TLBPD0, address | asid_or_sasid |
-                                      (pte_val(*ptep) & PTE_BITS_IN_PD0));
+        pd0 = address | asid_or_sasid | (pte_val(*ptep) & PTE_BITS_IN_PD0);
 
         /*
          * ARC MMU provides fully orthogonal access bits for K/U mode,
@@ -402,29 +436,9 @@ void create_tlb(struct vm_area_struct *vma, unsigned long address, pte_t *ptep)
         else
                 rwx |= (rwx << 3);      /* r w x => Kr Kw Kx Ur Uw Ux */
 
-        /* Load remaining info in PD1 (Page Frame Addr and Kx/Kw/Kr Flags) */
-        write_aux_reg(ARC_REG_TLBPD1,
-                      rwx | (pte_val(*ptep) & PTE_BITS_NON_RWX_IN_PD1));
-
-        /* First verify if entry for this vaddr+ASID already exists */
-        write_aux_reg(ARC_REG_TLBCOMMAND, TLBProbe);
-        idx = read_aux_reg(ARC_REG_TLBINDEX);
-
-        /*
-         * If Not already present get a free slot from MMU.
-         * Otherwise, Probe would have located the entry and set INDEX Reg
-         * with existing location. This will cause Write CMD to over-write
-         * existing entry with new PD0 and PD1
-         */
-        if (likely(idx & TLB_LKUP_ERR))
-                write_aux_reg(ARC_REG_TLBCOMMAND, TLBGetIndex);
+        pd1 = rwx | (pte_val(*ptep) & PTE_BITS_NON_RWX_IN_PD1);
 
-        /*
-         * Commit the Entry to MMU
-         * It doesnt sound safe to use the TLBWriteNI cmd here
-         * which doesn't flush uTLBs. I'd rather be safe than sorry.
-         */
-        write_aux_reg(ARC_REG_TLBCOMMAND, TLBWrite);
+        tlb_entry_insert(pd0, pd1);
 
         local_irq_restore(flags);
 }