[POWERPC] Use 1TB segments

This makes the kernel use 1TB segments for all kernel mappings and for
user addresses of 1TB and above, on machines which support them
(currently POWER5+, POWER6 and PA6T).

We detect that the machine supports 1TB segments by looking at the
ibm,processor-segment-sizes property in the device tree.

We don't currently use 1TB segments for user addresses < 1T, since
that would effectively prevent 32-bit processes from using huge pages
unless we also had a way to revert to using 256MB segments.  That
would be possible but would involve extra complications (such as
keeping track of which segment size was used when HPTEs were inserted)
and is not addressed here.

Parts of this patch were originally written by Ben Herrenschmidt.

Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 83 insertions, 31 deletions

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index d525f2eba313..611ad084b7e7 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -93,6 +93,8 @@ int mmu_linear_psize = MMU_PAGE_4K;
 int mmu_virtual_psize = MMU_PAGE_4K;
 int mmu_vmalloc_psize = MMU_PAGE_4K;
 int mmu_io_psize = MMU_PAGE_4K;
+int mmu_kernel_ssize = MMU_SEGSIZE_256M;
+int mmu_highuser_ssize = MMU_SEGSIZE_256M;
 #ifdef CONFIG_HUGETLB_PAGE
 int mmu_huge_psize = MMU_PAGE_16M;
 unsigned int HPAGE_SHIFT;
@@ -145,7 +147,8 @@ struct mmu_psize_def mmu_psize_defaults_gp[] = {
 
 
 int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
-		      unsigned long pstart, unsigned long mode, int psize)
+		      unsigned long pstart, unsigned long mode,
+		      int psize, int ssize)
 {
 	unsigned long vaddr, paddr;
 	unsigned int step, shift;
@@ -158,8 +161,8 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
 	for (vaddr = vstart, paddr = pstart; vaddr < vend;
 	     vaddr += step, paddr += step) {
 		unsigned long hash, hpteg;
-		unsigned long vsid = get_kernel_vsid(vaddr);
-		unsigned long va = (vsid << 28) | (vaddr & 0x0fffffff);
+		unsigned long vsid = get_kernel_vsid(vaddr, ssize);
+		unsigned long va = hpt_va(vaddr, vsid, ssize);
 
 		tmp_mode = mode;
 		
@@ -167,14 +170,14 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
 		if (!in_kernel_text(vaddr))
 			tmp_mode = mode | HPTE_R_N;
 
-		hash = hpt_hash(va, shift);
+		hash = hpt_hash(va, shift, ssize);
 		hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);
 
 		DBG("htab_bolt_mapping: calling %p\n", ppc_md.hpte_insert);
 
 		BUG_ON(!ppc_md.hpte_insert);
 		ret = ppc_md.hpte_insert(hpteg, va, paddr,
-				tmp_mode, HPTE_V_BOLTED, psize);
+				tmp_mode, HPTE_V_BOLTED, psize, ssize);
 
 		if (ret < 0)
 			break;
@@ -186,6 +189,37 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
 	return ret < 0 ? ret : 0;
 }
 
+static int __init htab_dt_scan_seg_sizes(unsigned long node,
+					 const char *uname, int depth,
+					 void *data)
+{
+	char *type = of_get_flat_dt_prop(node, "device_type", NULL);
+	u32 *prop;
+	unsigned long size = 0;
+
+	/* We are scanning "cpu" nodes only */
+	if (type == NULL || strcmp(type, "cpu") != 0)
+		return 0;
+
+	prop = (u32 *)of_get_flat_dt_prop(node, "ibm,processor-segment-sizes",
+					  &size);
+	if (prop == NULL)
+		return 0;
+	for (; size >= 4; size -= 4, ++prop) {
+		if (prop[0] == 40) {
+			DBG("1T segment support detected\n");
+			cur_cpu_spec->cpu_features |= CPU_FTR_1T_SEGMENT;
+		}
+		return 1;
+	}
+	return 0;
+}
+
+static void __init htab_init_seg_sizes(void)
+{
+	of_scan_flat_dt(htab_dt_scan_seg_sizes, NULL);
+}
+
 static int __init htab_dt_scan_page_sizes(unsigned long node,
 					  const char *uname, int depth,
 					  void *data)
@@ -265,7 +299,6 @@ static int __init htab_dt_scan_page_sizes(unsigned long node,
 	return 0;
 }
 
-
 static void __init htab_init_page_sizes(void)
 {
 	int rc;
@@ -398,7 +431,7 @@ void create_section_mapping(unsigned long start, unsigned long end)
 {
 		BUG_ON(htab_bolt_mapping(start, end, __pa(start),
 			_PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_COHERENT | PP_RWXX,
-			mmu_linear_psize));
+			mmu_linear_psize, mmu_kernel_ssize));
 }
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
@@ -449,9 +482,18 @@ void __init htab_initialize(void)
 
 	DBG(" -> htab_initialize()\n");
 
+	/* Initialize segment sizes */
+	htab_init_seg_sizes();
+
 	/* Initialize page sizes */
 	htab_init_page_sizes();
 
+	if (cpu_has_feature(CPU_FTR_1T_SEGMENT)) {
+		mmu_kernel_ssize = MMU_SEGSIZE_1T;
+		mmu_highuser_ssize = MMU_SEGSIZE_1T;
+		printk(KERN_INFO "Using 1TB segments\n");
+	}
+
 	/*
 	 * Calculate the required size of the htab.  We want the number of
 	 * PTEGs to equal one half the number of real pages.
@@ -523,18 +565,20 @@ void __init htab_initialize(void)
 			if (base != dart_tablebase)
 				BUG_ON(htab_bolt_mapping(base, dart_tablebase,
 							__pa(base), mode_rw,
-							mmu_linear_psize));
+							mmu_linear_psize,
+							mmu_kernel_ssize));
 			if ((base + size) > dart_table_end)
 				BUG_ON(htab_bolt_mapping(dart_tablebase+16*MB,
 							base + size,
 							__pa(dart_table_end),
 							 mode_rw,
-							 mmu_linear_psize));
+							 mmu_linear_psize,
+							 mmu_kernel_ssize));
 			continue;
 		}
 #endif /* CONFIG_U3_DART */
 		BUG_ON(htab_bolt_mapping(base, base + size, __pa(base),
-					mode_rw, mmu_linear_psize));
+				mode_rw, mmu_linear_psize, mmu_kernel_ssize));
        }
 
 	/*
@@ -553,7 +597,7 @@ void __init htab_initialize(void)
 
 		BUG_ON(htab_bolt_mapping(tce_alloc_start, tce_alloc_end,
 					 __pa(tce_alloc_start), mode_rw,
-					 mmu_linear_psize));
+					 mmu_linear_psize, mmu_kernel_ssize));
 	}
 
 	htab_finish_init();
@@ -621,7 +665,7 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
 	pte_t *ptep;
 	cpumask_t tmp;
 	int rc, user_region = 0, local = 0;
-	int psize;
+	int psize, ssize;
 
 	DBG_LOW("hash_page(ea=%016lx, access=%lx, trap=%lx\n",
 		ea, access, trap);
@@ -640,20 +684,22 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
 			DBG_LOW(" user region with no mm !\n");
 			return 1;
 		}
-		vsid = get_vsid(mm->context.id, ea);
 #ifdef CONFIG_PPC_MM_SLICES
 		psize = get_slice_psize(mm, ea);
 #else
 		psize = mm->context.user_psize;
 #endif
+		ssize = user_segment_size(ea);
+		vsid = get_vsid(mm->context.id, ea, ssize);
 		break;
 	case VMALLOC_REGION_ID:
 		mm = &init_mm;
-		vsid = get_kernel_vsid(ea);
+		vsid = get_kernel_vsid(ea, mmu_kernel_ssize);
 		if (ea < VMALLOC_END)
 			psize = mmu_vmalloc_psize;
 		else
 			psize = mmu_io_psize;
+		ssize = mmu_kernel_ssize;
 		break;
 	default:
 		/* Not a valid range
@@ -758,10 +804,10 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
 
 #ifdef CONFIG_PPC_HAS_HASH_64K
 	if (psize == MMU_PAGE_64K)
-		rc = __hash_page_64K(ea, access, vsid, ptep, trap, local);
+		rc = __hash_page_64K(ea, access, vsid, ptep, trap, local, ssize);
 	else
 #endif /* CONFIG_PPC_HAS_HASH_64K */
-		rc = __hash_page_4K(ea, access, vsid, ptep, trap, local);
+		rc = __hash_page_4K(ea, access, vsid, ptep, trap, local, ssize);
 
 #ifndef CONFIG_PPC_64K_PAGES
 	DBG_LOW(" o-pte: %016lx\n", pte_val(*ptep));
@@ -783,6 +829,7 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
 	cpumask_t mask;
 	unsigned long flags;
 	int local = 0;
+	int ssize;
 
 	BUG_ON(REGION_ID(ea) != USER_REGION_ID);
 
@@ -815,7 +862,8 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
 #endif /* CONFIG_PPC_64K_PAGES */
 
 	/* Get VSID */
-	vsid = get_vsid(mm->context.id, ea);
+	ssize = user_segment_size(ea);
+	vsid = get_vsid(mm->context.id, ea, ssize);
 
 	/* Hash doesn't like irqs */
 	local_irq_save(flags);
@@ -828,28 +876,29 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
 	/* Hash it in */
 #ifdef CONFIG_PPC_HAS_HASH_64K
 	if (mm->context.user_psize == MMU_PAGE_64K)
-		__hash_page_64K(ea, access, vsid, ptep, trap, local);
+		__hash_page_64K(ea, access, vsid, ptep, trap, local, ssize);
 	else
 #endif /* CONFIG_PPC_HAS_HASH_64K */
-		__hash_page_4K(ea, access, vsid, ptep, trap, local);
+		__hash_page_4K(ea, access, vsid, ptep, trap, local, ssize);
 
 	local_irq_restore(flags);
 }
 
-void flush_hash_page(unsigned long va, real_pte_t pte, int psize, int local)
+void flush_hash_page(unsigned long va, real_pte_t pte, int psize, int ssize,
+		     int local)
 {
 	unsigned long hash, index, shift, hidx, slot;
 
 	DBG_LOW("flush_hash_page(va=%016x)\n", va);
 	pte_iterate_hashed_subpages(pte, psize, va, index, shift) {
-		hash = hpt_hash(va, shift);
+		hash = hpt_hash(va, shift, ssize);
 		hidx = __rpte_to_hidx(pte, index);
 		if (hidx & _PTEIDX_SECONDARY)
 			hash = ~hash;
 		slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 		slot += hidx & _PTEIDX_GROUP_IX;
 		DBG_LOW(" sub %d: hash=%x, hidx=%x\n", index, slot, hidx);
-		ppc_md.hpte_invalidate(slot, va, psize, local);
+		ppc_md.hpte_invalidate(slot, va, psize, ssize, local);
 	} pte_iterate_hashed_end();
 }
 
@@ -864,7 +913,7 @@ void flush_hash_range(unsigned long number, int local)
 
 		for (i = 0; i < number; i++)
 			flush_hash_page(batch->vaddr[i], batch->pte[i],
-					batch->psize, local);
+					batch->psize, batch->ssize, local);
 	}
 }
 
@@ -890,17 +939,19 @@ void low_hash_fault(struct pt_regs *regs, unsigned long address)
 #ifdef CONFIG_DEBUG_PAGEALLOC
 static void kernel_map_linear_page(unsigned long vaddr, unsigned long lmi)
 {
-	unsigned long hash, hpteg, vsid = get_kernel_vsid(vaddr);
-	unsigned long va = (vsid << 28) | (vaddr & 0x0fffffff);
+	unsigned long hash, hpteg;
+	unsigned long vsid = get_kernel_vsid(vaddr, mmu_kernel_ssize);
+	unsigned long va = hpt_va(vaddr, vsid, mmu_kernel_ssize);
 	unsigned long mode = _PAGE_ACCESSED | _PAGE_DIRTY |
 		_PAGE_COHERENT | PP_RWXX | HPTE_R_N;
 	int ret;
 
-	hash = hpt_hash(va, PAGE_SHIFT);
+	hash = hpt_hash(va, PAGE_SHIFT, mmu_kernel_ssize);
 	hpteg = ((hash & htab_hash_mask) * HPTES_PER_GROUP);
 
 	ret = ppc_md.hpte_insert(hpteg, va, __pa(vaddr),
-				 mode, HPTE_V_BOLTED, mmu_linear_psize);
+				 mode, HPTE_V_BOLTED,
+				 mmu_linear_psize, mmu_kernel_ssize);
 	BUG_ON (ret < 0);
 	spin_lock(&linear_map_hash_lock);
 	BUG_ON(linear_map_hash_slots[lmi] & 0x80);
@@ -910,10 +961,11 @@ static void kernel_map_linear_page(unsigned long vaddr, unsigned long lmi)
 
 static void kernel_unmap_linear_page(unsigned long vaddr, unsigned long lmi)
 {
-	unsigned long hash, hidx, slot, vsid = get_kernel_vsid(vaddr);
-	unsigned long va = (vsid << 28) | (vaddr & 0x0fffffff);
+	unsigned long hash, hidx, slot;
+	unsigned long vsid = get_kernel_vsid(vaddr, mmu_kernel_ssize);
+	unsigned long va = hpt_va(vaddr, vsid, mmu_kernel_ssize);
 
-	hash = hpt_hash(va, PAGE_SHIFT);
+	hash = hpt_hash(va, PAGE_SHIFT, mmu_kernel_ssize);
 	spin_lock(&linear_map_hash_lock);
 	BUG_ON(!(linear_map_hash_slots[lmi] & 0x80));
 	hidx = linear_map_hash_slots[lmi] & 0x7f;
@@ -923,7 +975,7 @@ static void kernel_unmap_linear_page(unsigned long vaddr, unsigned long lmi)
 		hash = ~hash;
 	slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 	slot += hidx & _PTEIDX_GROUP_IX;
-	ppc_md.hpte_invalidate(slot, va, mmu_linear_psize, 0);
+	ppc_md.hpte_invalidate(slot, va, mmu_linear_psize, mmu_kernel_ssize, 0);
 }
 
 void kernel_map_pages(struct page *page, int numpages, int enable)