ARC: mm: Improve Duplicate PD Fault handler

 - Move the verbosity knob from .data to .bss by using inverted logic
 - No need to readout PD1 descriptor
 - clip the non pfn bits of PD0 to avoid clipping inside the loop

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

diff --git a/arch/arc/mm/tlb.c b/arch/arc/mm/tlb.c
index 2a30c91f7977fdc0e27024cae6f8b28527071ada..5dcae21dd8dc1f5f54f601e57d52120894dcbb94 100644 (file)
--- a/arch/arc/mm/tlb.c
+++ b/arch/arc/mm/tlb.c
@@ -856,15 +856,15 @@ void arc_mmu_init(void)
  *      the duplicate one.
  * -Knob to be verbose abt it.(TODO: hook them up to debugfs)
  */
-volatile int dup_pd_verbose = 1;/* Be slient abt it or complain (default) */
+volatile int dup_pd_silent; /* Be slient abt it or complain (default) */
 
 void do_tlb_overlap_fault(unsigned long cause, unsigned long address,
                          struct pt_regs *regs)
 {
-       int set, way, n;
-       unsigned long flags, is_valid;
        struct cpuinfo_arc_mmu *mmu = &cpuinfo_arc700[smp_processor_id()].mmu;
-       unsigned int pd0[mmu->ways], pd1[mmu->ways];
+       unsigned int pd0[mmu->ways];
+       unsigned long flags;
+       int set;
 
        local_irq_save(flags);
 
@@ -874,14 +874,16 @@ void do_tlb_overlap_fault(unsigned long cause, unsigned long address,
        /* loop thru all sets of TLB */
        for (set = 0; set < mmu->sets; set++) {
 
+               int is_valid, way;
+
                /* read out all the ways of current set */
                for (way = 0, is_valid = 0; way < mmu->ways; way++) {
                        write_aux_reg(ARC_REG_TLBINDEX,
                                          SET_WAY_TO_IDX(mmu, set, way));
                        write_aux_reg(ARC_REG_TLBCOMMAND, TLBRead);
                        pd0[way] = read_aux_reg(ARC_REG_TLBPD0);
-                       pd1[way] = read_aux_reg(ARC_REG_TLBPD1);
                        is_valid |= pd0[way] & _PAGE_PRESENT;
+                       pd0[way] &= PAGE_MASK;
                }
 
                /* If all the WAYS in SET are empty, skip to next SET */
@@ -890,30 +892,28 @@ void do_tlb_overlap_fault(unsigned long cause, unsigned long address,
 
                /* Scan the set for duplicate ways: needs a nested loop */
                for (way = 0; way < mmu->ways - 1; way++) {
+
+                       int n;
+
                        if (!pd0[way])
                                continue;
 
                        for (n = way + 1; n < mmu->ways; n++) {
-                               if ((pd0[way] & PAGE_MASK) ==
-                                   (pd0[n] & PAGE_MASK)) {
-
-                                       if (dup_pd_verbose) {
-                                               pr_info("Duplicate PD's @"
-                                                       "[%d:%d]/[%d:%d]\n",
-                                                    set, way, set, n);
-                                               pr_info("TLBPD0[%u]: %08x\n",
-                                                    way, pd0[way]);
-                                       }
-
-                                       /*
-                                        * clear entry @way and not @n. This is
-                                        * critical to our optimised loop
-                                        */
-                                       pd0[way] = pd1[way] = 0;
-                                       write_aux_reg(ARC_REG_TLBINDEX,
+                               if (pd0[way] != pd0[n])
+                                       continue;
+
+                               if (!dup_pd_silent)
+                                       pr_info("Dup TLB PD0 %08x @ set %d ways %d,%d\n",
+                                               pd0[way], set, way, n);
+
+                               /*
+                                * clear entry @way and not @n.
+                                * This is critical to our optimised loop
+                                */
+                               pd0[way] = 0;
+                               write_aux_reg(ARC_REG_TLBINDEX,
                                                SET_WAY_TO_IDX(mmu, set, way));
-                                       __tlb_entry_erase();
-                               }
+                               __tlb_entry_erase();
                        }
                }
        }