s390/mm: make TASK_SIZE independent from the number of page table levels

The TASK_SIZE for a process should be maximum possible size of the address
space, 2GB for a 31-bit process and 8PB for a 64-bit process. The number
of page table levels required for a given memory layout is a consequence
of the mapped memory areas and their location.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/mman.h

@@ -8,8 +8,4 @@
 
 #include <uapi/asm/mman.h>
 
-#ifndef __ASSEMBLY__
-int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags);
-#define arch_mmap_check(addr, len, flags) s390_mmap_check(addr, len, flags)
-#endif
 #endif /* __S390_MMAN_H__ */

arch/s390/include/asm/processor.h

@@ -91,14 +91,15 @@ extern void execve_tail(void);
  * User space process size: 2GB for 31 bit, 4TB or 8PT for 64 bit.
  */
 
-#define TASK_SIZE_OF(tsk)	((tsk)->mm ? \
-				 (tsk)->mm->context.asce_limit : TASK_MAX_SIZE)
+#define TASK_SIZE_OF(tsk)	(test_tsk_thread_flag(tsk, TIF_31BIT) ? \
+					(1UL << 31) : (1UL << 53))
 #define TASK_UNMAPPED_BASE	(test_thread_flag(TIF_31BIT) ? \
 					(1UL << 30) : (1UL << 41))
 #define TASK_SIZE		TASK_SIZE_OF(current)
-#define TASK_MAX_SIZE		(1UL << 53)
+#define TASK_SIZE_MAX		(1UL << 53)
 
-#define STACK_TOP		(1UL << (test_thread_flag(TIF_31BIT) ? 31:42))
+#define STACK_TOP		(test_thread_flag(TIF_31BIT) ? \
+					(1UL << 31) : (1UL << 42))
 #define STACK_TOP_MAX		(1UL << 42)
 
 #define HAVE_ARCH_PICK_MMAP_LAYOUT

arch/s390/kvm/kvm-s390.c

@@ -1512,9 +1512,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 		kvm->arch.mem_limit = KVM_S390_NO_MEM_LIMIT;
 	} else {
 		if (sclp.hamax == U64_MAX)
-			kvm->arch.mem_limit = TASK_MAX_SIZE;
+			kvm->arch.mem_limit = TASK_SIZE_MAX;
 		else
-			kvm->arch.mem_limit = min_t(unsigned long, TASK_MAX_SIZE,
+			kvm->arch.mem_limit = min_t(unsigned long, TASK_SIZE_MAX,
 						    sclp.hamax + 1);
 		kvm->arch.gmap = gmap_create(current->mm, kvm->arch.mem_limit - 1);
 		if (!kvm->arch.gmap)

arch/s390/mm/gmap.c

@@ -431,7 +431,7 @@ int gmap_map_segment(struct gmap *gmap, unsigned long from,
 	if ((from | to | len) & (PMD_SIZE - 1))
 		return -EINVAL;
 	if (len == 0 || from + len < from || to + len < to ||
-	    from + len - 1 > TASK_MAX_SIZE || to + len - 1 > gmap->asce_end)
+	    from + len - 1 > TASK_SIZE_MAX || to + len - 1 > gmap->asce_end)
 		return -EINVAL;
 
 	flush = 0;

arch/s390/mm/gup.c

@@ -211,7 +211,7 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
 	addr = start;
 	len = (unsigned long) nr_pages << PAGE_SHIFT;
 	end = start + len;
-	if ((end <= start) || (end > TASK_SIZE))
+	if ((end <= start) || (end > mm->context.asce_limit))
 		return 0;
 	/*
 	 * local_irq_save() doesn't prevent pagetable teardown, but does

arch/s390/mm/mmap.c

@@ -90,7 +90,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	struct vm_area_struct *vma;
 	struct vm_unmapped_area_info info;
 
-	if (len > TASK_SIZE - mmap_min_addr)
+	if (len > mm->context.asce_limit - mmap_min_addr)
 		return -ENOMEM;
 
 	if (flags & MAP_FIXED)
@@ -99,7 +99,8 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma(mm, addr);
-		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+		if (mm->context.asce_limit - len >= addr &&
+		    addr >= mmap_min_addr &&
 		    (!vma || addr + len <= vma->vm_start))
 			return addr;
 	}
@@ -107,7 +108,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	info.flags = 0;
 	info.length = len;
 	info.low_limit = mm->mmap_base;
-	info.high_limit = TASK_SIZE;
+	info.high_limit = mm->context.asce_limit;
 	if (filp || (flags & MAP_SHARED))
 		info.align_mask = MMAP_ALIGN_MASK << PAGE_SHIFT;
 	else
@@ -127,7 +128,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	struct vm_unmapped_area_info info;
 
 	/* requested length too big for entire address space */
-	if (len > TASK_SIZE - mmap_min_addr)
+	if (len > mm->context.asce_limit - mmap_min_addr)
 		return -ENOMEM;
 
 	if (flags & MAP_FIXED)
@@ -137,7 +138,8 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma(mm, addr);
-		if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
+		if (mm->context.asce_limit - len >= addr &&
+		    addr >= mmap_min_addr &&
 				(!vma || addr + len <= vma->vm_start))
 			return addr;
 	}
@@ -163,24 +165,13 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 		VM_BUG_ON(addr != -ENOMEM);
 		info.flags = 0;
 		info.low_limit = TASK_UNMAPPED_BASE;
-		info.high_limit = TASK_SIZE;
+		info.high_limit = mm->context.asce_limit;
 		addr = vm_unmapped_area(&info);
 	}
 
 	return addr;
 }
 
-int s390_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
-{
-	if (is_compat_task() || TASK_SIZE >= TASK_MAX_SIZE)
-		return 0;
-	if (!(flags & MAP_FIXED))
-		addr = 0;
-	if ((addr + len) >= TASK_SIZE)
-		return crst_table_upgrade(current->mm);
-	return 0;
-}
-
 static unsigned long
 s390_get_unmapped_area(struct file *filp, unsigned long addr,
 		unsigned long len, unsigned long pgoff, unsigned long flags)
@@ -192,7 +183,8 @@ s390_get_unmapped_area(struct file *filp, unsigned long addr,
 	area = arch_get_unmapped_area(filp, addr, len, pgoff, flags);
 	if (!(area & ~PAGE_MASK))
 		return area;
-	if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < TASK_MAX_SIZE) {
+	if (area == -ENOMEM && !is_compat_task() &&
+	    current->mm->context.asce_limit < TASK_SIZE_MAX) {
 		/* Upgrade the page table to 4 levels and retry. */
 		rc = crst_table_upgrade(mm);
 		if (rc)
@@ -214,7 +206,8 @@ s390_get_unmapped_area_topdown(struct file *filp, const unsigned long addr,
 	area = arch_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
 	if (!(area & ~PAGE_MASK))
 		return area;
-	if (area == -ENOMEM && !is_compat_task() && TASK_SIZE < TASK_MAX_SIZE) {
+	if (area == -ENOMEM && !is_compat_task() &&
+	    current->mm->context.asce_limit < TASK_SIZE_MAX) {
 		/* Upgrade the page table to 4 levels and retry. */
 		rc = crst_table_upgrade(mm);
 		if (rc)

arch/s390/mm/pgalloc.c

@@ -95,7 +95,6 @@ int crst_table_upgrade(struct mm_struct *mm)
 	mm->context.asce_limit = 1UL << 53;
 	mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
 			   _ASCE_USER_BITS | _ASCE_TYPE_REGION2;
-	mm->task_size = mm->context.asce_limit;
 	spin_unlock_bh(&mm->page_table_lock);
 
 	on_each_cpu(__crst_table_upgrade, mm, 0);
@@ -119,7 +118,6 @@ void crst_table_downgrade(struct mm_struct *mm)
 	mm->context.asce_limit = 1UL << 31;
 	mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
 			   _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT;
-	mm->task_size = mm->context.asce_limit;
 	crst_table_free(mm, (unsigned long *) pgd);
 
 	if (current->active_mm == mm)