[S390] System z large page support.

This adds hugetlbfs support on System z, using both hardware large page
support if available and software large page emulation on older hardware.
Shared (large) page tables are implemented in software emulation mode,
by using page->index of the first tail page from a compound large page
to store page table information.

Signed-off-by: Gerald Schaefer <geraldsc@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 48 insertions, 7 deletions

diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c
index 3ffc0211dc8..97bce6c9757 100644
--- a/arch/s390/mm/vmem.c
+++ b/arch/s390/mm/vmem.c
@@ -10,10 +10,12 @@
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/list.h>
+#include <linux/hugetlb.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
 #include <asm/setup.h>
 #include <asm/tlbflush.h>
+#include <asm/sections.h>
 
 static DEFINE_MUTEX(vmem_mutex);
 
@@ -113,7 +115,7 @@ static pte_t __init_refok *vmem_pte_alloc(void)
 /*
  * Add a physical memory range to the 1:1 mapping.
  */
-static int vmem_add_range(unsigned long start, unsigned long size)
+static int vmem_add_range(unsigned long start, unsigned long size, int ro)
 {
 	unsigned long address;
 	pgd_t *pg_dir;
@@ -140,7 +142,19 @@ static int vmem_add_range(unsigned long start, unsigned long size)
 			pud_populate_kernel(&init_mm, pu_dir, pm_dir);
 		}
 
+		pte = mk_pte_phys(address, __pgprot(ro ? _PAGE_RO : 0));
 		pm_dir = pmd_offset(pu_dir, address);
+
+#ifdef __s390x__
+		if (MACHINE_HAS_HPAGE && !(address & ~HPAGE_MASK) &&
+		    (address + HPAGE_SIZE <= start + size) &&
+		    (address >= HPAGE_SIZE)) {
+			pte_val(pte) |= _SEGMENT_ENTRY_LARGE;
+			pmd_val(*pm_dir) = pte_val(pte);
+			address += HPAGE_SIZE - PAGE_SIZE;
+			continue;
+		}
+#endif
 		if (pmd_none(*pm_dir)) {
 			pt_dir = vmem_pte_alloc();
 			if (!pt_dir)
@@ -149,7 +163,6 @@ static int vmem_add_range(unsigned long start, unsigned long size)
 		}
 
 		pt_dir = pte_offset_kernel(pm_dir, address);
-		pte = pfn_pte(address >> PAGE_SHIFT, PAGE_KERNEL);
 		*pt_dir = pte;
 	}
 	ret = 0;
@@ -180,6 +193,13 @@ static void vmem_remove_range(unsigned long start, unsigned long size)
 		pm_dir = pmd_offset(pu_dir, address);
 		if (pmd_none(*pm_dir))
 			continue;
+
+		if (pmd_huge(*pm_dir)) {
+			pmd_clear_kernel(pm_dir);
+			address += HPAGE_SIZE - PAGE_SIZE;
+			continue;
+		}
+
 		pt_dir = pte_offset_kernel(pm_dir, address);
 		*pt_dir = pte;
 	}
@@ -248,14 +268,14 @@ out:
 	return ret;
 }
 
-static int vmem_add_mem(unsigned long start, unsigned long size)
+static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
 {
 	int ret;
 
 	ret = vmem_add_mem_map(start, size);
 	if (ret)
 		return ret;
-	return vmem_add_range(start, size);
+	return vmem_add_range(start, size, ro);
 }
 
 /*
@@ -338,7 +358,7 @@ int add_shared_memory(unsigned long start, unsigned long size)
 	if (ret)
 		goto out_free;
 
-	ret = vmem_add_mem(start, size);
+	ret = vmem_add_mem(start, size, 0);
 	if (ret)
 		goto out_remove;
 
@@ -374,14 +394,35 @@ out:
  */
 void __init vmem_map_init(void)
 {
+	unsigned long ro_start, ro_end;
+	unsigned long start, end;
 	int i;
 
 	INIT_LIST_HEAD(&init_mm.context.crst_list);
 	INIT_LIST_HEAD(&init_mm.context.pgtable_list);
 	init_mm.context.noexec = 0;
 	NODE_DATA(0)->node_mem_map = VMEM_MAP;
-	for (i = 0; i < MEMORY_CHUNKS && memory_chunk[i].size > 0; i++)
-		vmem_add_mem(memory_chunk[i].addr, memory_chunk[i].size);
+	ro_start = ((unsigned long)&_stext) & PAGE_MASK;
+	ro_end = PFN_ALIGN((unsigned long)&_eshared);
+	for (i = 0; i < MEMORY_CHUNKS && memory_chunk[i].size > 0; i++) {
+		start = memory_chunk[i].addr;
+		end = memory_chunk[i].addr + memory_chunk[i].size;
+		if (start >= ro_end || end <= ro_start)
+			vmem_add_mem(start, end - start, 0);
+		else if (start >= ro_start && end <= ro_end)
+			vmem_add_mem(start, end - start, 1);
+		else if (start >= ro_start) {
+			vmem_add_mem(start, ro_end - start, 1);
+			vmem_add_mem(ro_end, end - ro_end, 0);
+		} else if (end < ro_end) {
+			vmem_add_mem(start, ro_start - start, 0);
+			vmem_add_mem(ro_start, end - ro_start, 1);
+		} else {
+			vmem_add_mem(start, ro_start - start, 0);
+			vmem_add_mem(ro_start, ro_end - ro_start, 1);
+			vmem_add_mem(ro_end, end - ro_end, 0);
+		}
+	}
 }
 
 /*