powerpc/mm/radix: Use mm->task_size for boundary checking instead of addr_limit

We don't init addr_limit correctly for 32 bit applications. So default to using
mm->task_size for boundary condition checking. We use addr_limit to only control
free space search. This makes sure that we do the right thing with 32 bit
applications.

We should consolidate the usage of TASK_SIZE/mm->task_size and
mm->context.addr_limit later.

This partially reverts commit fbfef9027c (powerpc/mm: Switch some
TASK_SIZE checks to use mm_context addr_limit).

Fixes: fbfef9027c ("powerpc/mm: Switch some TASK_SIZE checks to use mm_context addr_limit")
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/hugetlbpage-radix.c

@@ -55,7 +55,7 @@ radix__hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 
 	if (len & ~huge_page_mask(h))
 		return -EINVAL;
-	if (len > mm->context.addr_limit)
+	if (len > mm->task_size)
 		return -ENOMEM;
 
 	if (flags & MAP_FIXED) {
@@ -67,7 +67,7 @@ radix__hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 	if (addr) {
 		addr = ALIGN(addr, huge_page_size(h));
 		vma = find_vma(mm, addr);
-		if (mm->context.addr_limit - len >= addr &&
+		if (mm->task_size - len >= addr &&
 		    (!vma || addr + len <= vma->vm_start))
 			return addr;
 	}

arch/powerpc/mm/mmap.c

@@ -100,7 +100,7 @@ radix__arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	if (unlikely(addr > mm->context.addr_limit && addr < TASK_SIZE))
 		mm->context.addr_limit = TASK_SIZE;
 
-	if (len > mm->context.addr_limit - mmap_min_addr)
+	if (len > mm->task_size - mmap_min_addr)
 		return -ENOMEM;
 
 	if (flags & MAP_FIXED)
@@ -109,7 +109,7 @@ radix__arch_get_unmapped_area(struct file *filp, unsigned long addr,
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma(mm, addr);
-		if (mm->context.addr_limit - len >= addr && addr >= mmap_min_addr &&
+		if (mm->task_size - len >= addr && addr >= mmap_min_addr &&
 		    (!vma || addr + len <= vma->vm_start))
 			return addr;
 	}
@@ -143,7 +143,7 @@ radix__arch_get_unmapped_area_topdown(struct file *filp,
 		mm->context.addr_limit = TASK_SIZE;
 
 	/* requested length too big for entire address space */
-	if (len > mm->context.addr_limit - mmap_min_addr)
+	if (len > mm->task_size - mmap_min_addr)
 		return -ENOMEM;
 
 	if (flags & MAP_FIXED)
@@ -153,7 +153,7 @@ radix__arch_get_unmapped_area_topdown(struct file *filp,
 	if (addr) {
 		addr = PAGE_ALIGN(addr);
 		vma = find_vma(mm, addr);
-		if (mm->context.addr_limit - len >= addr && addr >= mmap_min_addr &&
+		if (mm->task_size - len >= addr && addr >= mmap_min_addr &&
 				(!vma || addr + len <= vma->vm_start))
 			return addr;
 	}

arch/powerpc/mm/slice.c

@@ -292,8 +292,8 @@ static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
 		 * Check if we need to reduce the range, or if we can
 		 * extend it to cover the next available slice.
 		 */
-		if (addr >= mm->context.addr_limit)
+		if (addr >= high_limit)
-			addr = mm->context.addr_limit;
+			addr = high_limit;
 		else if (slice_scan_available(addr, available, 1, &next_end)) {
 			addr = next_end;
 			goto next_slice;

arch/powerpc/mm/subpage-prot.c

@@ -197,8 +197,8 @@ long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map)
 
 	/* Check parameters */
 	if ((addr & ~PAGE_MASK) || (len & ~PAGE_MASK) ||
-	    addr >= mm->context.addr_limit || len >= mm->context.addr_limit ||
+	    addr >= mm->task_size || len >= mm->task_size ||
-	    addr + len > mm->context.addr_limit)
+	    addr + len > mm->task_size)
 		return -EINVAL;
 
 	if (is_hugepage_only_range(mm, addr, len))