x86/ldt: Make all size computations unsigned

ldt->size can never be negative. The helper functions take 'unsigned int'
arguments which are assigned from ldt->size. The related user space
user_desc struct member entry_number is unsigned as well.

But ldt->size itself and a few local variables which are related to
ldt->size are type 'int' which makes no sense whatsoever and results in
typecasts which make the eyes bleed.

Clean it up and convert everything which is related to ldt->size to
unsigned it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>

arch/x86/events/core.c

@@ -2299,7 +2299,7 @@ valid_user_frame(const void __user *fp, unsigned long size)
 static unsigned long get_segment_base(unsigned int segment)
 {
 	struct desc_struct *desc;
-	int idx = segment >> 3;
+	unsigned int idx = segment >> 3;
 
 	if ((segment & SEGMENT_TI_MASK) == SEGMENT_LDT) {
 #ifdef CONFIG_MODIFY_LDT_SYSCALL

arch/x86/include/asm/mmu_context.h

@@ -47,7 +47,7 @@ struct ldt_struct {
 	 * allocations, but it's not worth trying to optimize.
 	 */
 	struct desc_struct *entries;
-	int size;
+	unsigned int size;
 };
 
 /*

arch/x86/kernel/ldt.c

@@ -37,7 +37,7 @@ static void flush_ldt(void *current_mm)
 static struct ldt_struct *alloc_ldt_struct(unsigned int size)
 {
 	struct ldt_struct *new_ldt;
-	int alloc_size;
+	unsigned int alloc_size;
 
 	if (size > LDT_ENTRIES)
 		return NULL;
@@ -207,11 +207,11 @@ static int read_default_ldt(void __user *ptr, unsigned long bytecount)
 static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
 {
 	struct mm_struct *mm = current->mm;
+	struct ldt_struct *new_ldt, *old_ldt;
+	unsigned int oldsize, newsize;
+	struct user_desc ldt_info;
 	struct desc_struct ldt;
 	int error;
-	struct user_desc ldt_info;
-	int oldsize, newsize;
-	struct ldt_struct *new_ldt, *old_ldt;
 
 	error = -EINVAL;
 	if (bytecount != sizeof(ldt_info))
@@ -249,7 +249,7 @@ static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
 
 	old_ldt = mm->context.ldt;
 	oldsize = old_ldt ? old_ldt->size : 0;
-	newsize = max((int)(ldt_info.entry_number + 1), oldsize);
+	newsize = max(ldt_info.entry_number + 1, oldsize);
 
 	error = -ENOMEM;
 	new_ldt = alloc_ldt_struct(newsize);