Reduce KVA pressure on OEA64 systems running in bridge mode by mapping

UMA segments at their physical addresses instead of into KVA. This emulates
the direct mapping behavior of OEA32 in an ad-hoc way. To make this work
properly required sharing the entire kernel PMAP with Open Firmware, so
ofw_pmap is transformed into a stub on 64-bit CPUs.

Also implement some more tweaks to get more mileage out of our limited
amount of KVA, principally by extending KVA into segment 16 until the
beginning of the first OFW mapping.

Reported by:	linimon

1 files changed, 28 insertions, 48 deletions

diff --git a/sys/powerpc/aim/mmu_oea64.c b/sys/powerpc/aim/mmu_oea64.c
index db41275..c86bc8a 100644
--- a/sys/powerpc/aim/mmu_oea64.c
+++ b/sys/powerpc/aim/mmu_oea64.c
@@ -297,9 +297,6 @@ struct	pvo_head moea64_pvo_unmanaged =
 uma_zone_t	moea64_upvo_zone; /* zone for pvo entries for unmanaged pages */
 uma_zone_t	moea64_mpvo_zone; /* zone for pvo entries for managed pages */
 
-vm_offset_t	pvo_allocator_start;
-vm_offset_t	pvo_allocator_end;
-
 #define	BPVO_POOL_SIZE	327680
 static struct	pvo_entry *moea64_bpvo_pool;
 static int	moea64_bpvo_pool_index = 0;
@@ -699,6 +696,7 @@ moea64_add_ofw_mappings(mmu_t mmup, phandle_t mmu, size_t sz)
 	struct ofw_map	translations[sz/sizeof(struct ofw_map)];
 	register_t	msr;
 	vm_offset_t	off;
+	vm_paddr_t	pa_base;
 	int		i, ofw_mappings;
 
 	bzero(translations, sz);
@@ -720,33 +718,18 @@ moea64_add_ofw_mappings(mmu_t mmup, phandle_t mmu, size_t sz)
 		if (translations[i].om_pa_hi)
 			panic("OFW translations above 32-bit boundary!");
 
+		pa_base = translations[i].om_pa_lo;
+
 		/* Now enter the pages for this mapping */
 
-		/*
-		 * Lock the ofw pmap. pmap_kenter(), which we use for the
-		 * pages the kernel also needs, does its own locking.
-		 */
-		PMAP_LOCK(&ofw_pmap); 
 		DISABLE_TRANS(msr);
 		for (off = 0; off < translations[i].om_len; off += PAGE_SIZE) {
-			struct vm_page m;
-
-			/* Map low memory mappings into the kernel pmap, too.
-			 * These are typically mappings made by the loader,
-			 * so we need them if we want to keep executing. */
-
-			if (translations[i].om_va + off < SEGMENT_LENGTH)
-				moea64_kenter(mmup, translations[i].om_va + off,
-				    translations[i].om_va + off);
-
-			m.phys_addr = translations[i].om_pa_lo + off;
-			moea64_enter_locked(&ofw_pmap,
-			    translations[i].om_va + off, &m, VM_PROT_ALL, 1);
+			moea64_kenter(mmup, translations[i].om_va + off,
+			    pa_base + off);
 
 			ofw_mappings++;
 		}
 		ENABLE_TRANS(msr);
-		PMAP_UNLOCK(&ofw_pmap);
 	}
 }
 
@@ -926,8 +909,8 @@ moea64_bridge_bootstrap(mmu_t mmup, vm_offset_t kernelstart, vm_offset_t kernele
 	     */
 
 	    moea64_pinit(mmup, &ofw_pmap);
-	    ofw_pmap.pm_sr[KERNEL_SR] = kernel_pmap->pm_sr[KERNEL_SR];
-	    ofw_pmap.pm_sr[KERNEL2_SR] = kernel_pmap->pm_sr[KERNEL2_SR];
+	    for (i = 0; i < 16; i++)
+		ofw_pmap.pm_sr[i] = kernel_pmap->pm_sr[i];
 
 	    if ((chosen = OF_finddevice("/chosen")) == -1)
 		panic("moea64_bootstrap: can't find /chosen");
@@ -965,15 +948,20 @@ moea64_bridge_bootstrap(mmu_t mmup, vm_offset_t kernelstart, vm_offset_t kernele
 	 * Set the start and end of kva.
 	 */
 	virtual_avail = VM_MIN_KERNEL_ADDRESS;
-	virtual_end = VM_MAX_KERNEL_ADDRESS;
+	virtual_end = VM_MAX_SAFE_KERNEL_ADDRESS; 
 
 	/*
-	 * Allocate some stupid buffer regions.
+	 * Figure out how far we can extend virtual_end into segment 16
+	 * without running into existing mappings. Segment 16 is guaranteed
+	 * to contain neither RAM nor devices (at least on Apple hardware),
+	 * but will generally contain some OFW mappings we should not
+	 * step on.
 	 */
 
-	pvo_allocator_start = virtual_avail;
-	virtual_avail += SEGMENT_LENGTH/4;
-	pvo_allocator_end = virtual_avail;
+	PMAP_LOCK(kernel_pmap);
+	while (moea64_pvo_find_va(kernel_pmap, virtual_end+1, NULL) == NULL)
+		virtual_end += PAGE_SIZE;
+	PMAP_UNLOCK(kernel_pmap);
 
 	/*
 	 * Allocate some things for page zeroing
@@ -1014,26 +1002,20 @@ moea64_bridge_bootstrap(mmu_t mmup, vm_offset_t kernelstart, vm_offset_t kernele
 	 * Allocate virtual address space for the message buffer.
 	 */
 	pa = msgbuf_phys = moea64_bootstrap_alloc(MSGBUF_SIZE, PAGE_SIZE);
-	msgbufp = (struct msgbuf *)virtual_avail;
-	va = virtual_avail;
-	virtual_avail += round_page(MSGBUF_SIZE);
-	while (va < virtual_avail) {
-		moea64_kenter(mmup, va, pa);
+	msgbufp = (struct msgbuf *)msgbuf_phys;
+	while (pa - msgbuf_phys < MSGBUF_SIZE) {
+		moea64_kenter(mmup, pa, pa);
 		pa += PAGE_SIZE;
-		va += PAGE_SIZE;
 	}
 
 	/*
 	 * Allocate virtual address space for the dynamic percpu area.
 	 */
 	pa = moea64_bootstrap_alloc(DPCPU_SIZE, PAGE_SIZE);
-	dpcpu = (void *)virtual_avail;
-	va = virtual_avail;
-	virtual_avail += DPCPU_SIZE;
-	while (va < virtual_avail) {
-		moea64_kenter(mmup, va, pa);
+	dpcpu = (void *)pa;
+	while (pa - (vm_offset_t)dpcpu < DPCPU_SIZE) {
+		moea64_kenter(mmup, pa, pa);
 		pa += PAGE_SIZE;
-		va += PAGE_SIZE;
 	}
 	dpcpu_init(dpcpu, 0);
 }
@@ -1412,14 +1394,10 @@ moea64_uma_page_alloc(uma_zone_t zone, int bytes, u_int8_t *flags, int wait)
                         break;
         }
 
-	va = pvo_allocator_start;
-	pvo_allocator_start += PAGE_SIZE;
-
-	if (pvo_allocator_start >= pvo_allocator_end)
-		panic("Ran out of PVO allocator buffer space!");
+	va = VM_PAGE_TO_PHYS(m);
 
 	moea64_pvo_enter(kernel_pmap, moea64_upvo_zone,
-	    &moea64_pvo_kunmanaged, va,  VM_PAGE_TO_PHYS(m), LPTE_M, 
+	    &moea64_pvo_kunmanaged, va, VM_PAGE_TO_PHYS(m), LPTE_M,
 	    PVO_WIRED | PVO_BOOTSTRAP);
 
 	if (needed_lock)
@@ -1557,10 +1535,12 @@ moea64_kenter(mmu_t mmu, vm_offset_t va, vm_offset_t pa)
 	uint64_t	pte_lo;
 	int		error;	
 
+#if 0
 	if (!pmap_bootstrapped) {
-		if (va >= VM_MIN_KERNEL_ADDRESS && va < VM_MAX_KERNEL_ADDRESS)
+		if (va >= VM_MIN_KERNEL_ADDRESS && va < virtual_end)
 			panic("Trying to enter an address in KVA -- %#x!\n",pa);
 	}
+#endif
 
 	pte_lo = moea64_calc_wimg(pa);