amap: panic -> KASSERT

[Martin Pieuchot]

Convert various "if (x) panic()" idioms into "KASSERT(!x)".  The panic
message isn't helping for such sanity checks and this help reducing the
diff with NetBSD.

ok?

Index: uvm/uvm_amap.c
===================================================================
RCS file: /cvs/src/sys/uvm/uvm_amap.c,v
retrieving revision 1.83
diff -u -p -r1.83 uvm_amap.c
--- uvm/uvm_amap.c      22 Sep 2020 14:31:08 -0000      1.83
+++ uvm/uvm_amap.c      24 Sep 2020 09:47:54 -0000
@@ -1019,9 +1019,7 @@ amap_lookup(struct vm_aref *aref, vaddr_
 
        AMAP_B2SLOT(slot, offset);
        slot += aref->ar_pageoff;
-
-       if (slot >= amap->am_nslot)
-               panic("amap_lookup: offset out of range");
+       KASSERT(slot < amap->am_nslot);
 
        chunk = amap_chunk_get(amap, slot, 0, PR_NOWAIT);
        if (chunk == NULL)
@@ -1046,8 +1044,7 @@ amap_lookups(struct vm_aref *aref, vaddr
        AMAP_B2SLOT(slot, offset);
        slot += aref->ar_pageoff;
 
-       if ((slot + (npages - 1)) >= amap->am_nslot)
-               panic("amap_lookups: offset out of range");
+       KASSERT((slot + (npages - 1)) < amap->am_nslot);
 
        for (i = 0, lcv = slot; lcv < slot + npages; i += n, lcv += n) {
                n = UVM_AMAP_CHUNK - UVM_AMAP_SLOTIDX(lcv);
@@ -1078,9 +1075,7 @@ amap_populate(struct vm_aref *aref, vadd
 
        AMAP_B2SLOT(slot, offset);
        slot += aref->ar_pageoff;
-
-       if (slot >= amap->am_nslot)
-               panic("amap_populate: offset out of range");
+       KASSERT(slot < amap->am_nslot);
 
        chunk = amap_chunk_get(amap, slot, 1, PR_WAITOK);
        KASSERT(chunk != NULL);
@@ -1101,9 +1096,8 @@ amap_add(struct vm_aref *aref, vaddr_t o
 
        AMAP_B2SLOT(slot, offset);
        slot += aref->ar_pageoff;
+       KASSERT(slot < amap->am_nslot);
 
-       if (slot >= amap->am_nslot)
-               panic("amap_add: offset out of range");
        chunk = amap_chunk_get(amap, slot, 1, PR_NOWAIT);
        if (chunk == NULL)
                return 1;
@@ -1144,9 +1138,7 @@ amap_unadd(struct vm_aref *aref, vaddr_t
 
        AMAP_B2SLOT(slot, offset);
        slot += aref->ar_pageoff;
-
-       if (slot >= amap->am_nslot)
-               panic("amap_unadd: offset out of range");
+       KASSERT(slot < amap->am_nslot);
        chunk = amap_chunk_get(amap, slot, 0, PR_NOWAIT);
        if (chunk == NULL)
                panic("amap_unadd: chunk for slot %d not present", slot);