svn commit: r360690 - head/sys/arm64/arm64

[Mark Johnston]

Author: markj
Date: Wed May  6 15:01:06 2020
New Revision: 360690
URL: https://svnweb.freebsd.org/changeset/base/360690

Log:
  Simplify arm64's pmap_bootstrap() a bit.
  
  locore constructs an L2 page mapping the kernel and preloaded data
  starting a KERNBASE (the same as VM_MIN_KERNEL_ADDRESS on arm64).
  initarm() and pmap_bootstrap() use the preloaded metadata to
  tell it where it can start allocating from.
  
  pmap_bootstrap() currently iterates over the L2 page to find the last
  valid entry, but doesn't do anything with the result.  Remove the loop
  and zap some now-unused local variables.
  
  MFC after:	2 weeks
  Sponsored by:	Juniper Networks, Klara Inc.
  Differential Revision:	https://reviews.freebsd.org/D24559

Modified:
  head/sys/arm64/arm64/pmap.c

Modified: head/sys/arm64/arm64/pmap.c
==============================================================================
--- head/sys/arm64/arm64/pmap.c	Wed May  6 11:40:32 2020	(r360689)
+++ head/sys/arm64/arm64/pmap.c	Wed May  6 15:01:06 2020	(r360690)
@@ -831,9 +831,7 @@ void
 pmap_bootstrap(vm_offset_t l0pt, vm_offset_t l1pt, vm_paddr_t kernstart,
     vm_size_t kernlen)
 {
-	u_int l1_slot, l2_slot;
-	pt_entry_t *l2;
-	vm_offset_t va, freemempos;
+	vm_offset_t freemempos;
 	vm_offset_t dpcpu, msgbufpv;
 	vm_paddr_t start_pa, pa, min_pa;
 	uint64_t kern_delta;
@@ -867,7 +865,7 @@ pmap_bootstrap(vm_offset_t l0pt, vm_offset_t l1pt, vm_
 	 * Find the minimum physical address. physmap is sorted,
 	 * but may contain empty ranges.
 	 */
-	for (i = 0; i < (physmap_idx * 2); i += 2) {
+	for (i = 0; i < physmap_idx * 2; i += 2) {
 		if (physmap[i] == physmap[i + 1])
 			continue;
 		if (physmap[i] <= min_pa)
@@ -880,38 +878,14 @@ pmap_bootstrap(vm_offset_t l0pt, vm_offset_t l1pt, vm_
 	/* Create a direct map region early so we can use it for pa -> va */
 	freemempos = pmap_bootstrap_dmap(l1pt, min_pa, freemempos);
 
-	va = KERNBASE;
 	start_pa = pa = KERNBASE - kern_delta;
 
 	/*
-	 * Read the page table to find out what is already mapped.
-	 * This assumes we have mapped a block of memory from KERNBASE
-	 * using a single L1 entry.
+	 * Create the l2 tables up to VM_MAX_KERNEL_ADDRESS.  We assume that the
+	 * loader allocated the first and only l2 page table page used to map
+	 * the kernel, preloaded files and module metadata.
 	 */
-	l2 = pmap_early_page_idx(l1pt, KERNBASE, &l1_slot, &l2_slot);
-
-	/* Sanity check the index, KERNBASE should be the first VA */
-	KASSERT(l2_slot == 0, ("The L2 index is non-zero"));
-
-	/* Find how many pages we have mapped */
-	for (; l2_slot < Ln_ENTRIES; l2_slot++) {
-		if ((l2[l2_slot] & ATTR_DESCR_MASK) == 0)
-			break;
-
-		/* Check locore used L2 blocks */
-		KASSERT((l2[l2_slot] & ATTR_DESCR_MASK) == L2_BLOCK,
-		    ("Invalid bootstrap L2 table"));
-		KASSERT((l2[l2_slot] & ~ATTR_MASK) == pa,
-		    ("Incorrect PA in L2 table"));
-
-		va += L2_SIZE;
-		pa += L2_SIZE;
-	}
-
-	va = roundup2(va, L1_SIZE);
-
-	/* Create the l2 tables up to VM_MAX_KERNEL_ADDRESS */
-	freemempos = pmap_bootstrap_l2(l1pt, va, freemempos);
+	freemempos = pmap_bootstrap_l2(l1pt, KERNBASE + L1_SIZE, freemempos);
 	/* And the l3 tables for the early devmap */
 	freemempos = pmap_bootstrap_l3(l1pt,
 	    VM_MAX_KERNEL_ADDRESS - (PMAP_MAPDEV_EARLY_SIZE), freemempos);