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>

7 files changed, 21 insertions, 33 deletions

diff --git a/arch/s390/include/asm/mman.h b/arch/s390/include/asm/mman.h
index b55a59e1d134..b79813d9cf68 100644
--- a/arch/s390/include/asm/mman.h
+++ b/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__ */
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index cc101f9371cb..60d395fdc864 100644
--- a/arch/s390/include/asm/processor.h
+++ b/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
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index fd6cd05bb6a7..28983836c0f7 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/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)
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index ffb55c935eda..7f6db1e6c048 100644
--- a/arch/s390/mm/gmap.c
+++ b/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;
diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c
index 18d4107e10ee..b7b779c40a5b 100644
--- a/arch/s390/mm/gup.c
+++ b/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
diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c
index 50618614881f..eed233ce59dd 100644
--- a/arch/s390/mm/mmap.c
+++ b/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)
diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c
index 2776bad61094..f502cbe657af 100644
--- a/arch/s390/mm/pgalloc.c
+++ b/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)