signed math causes generation of costlier instructions such as DIV when
they could be done by barrerl shifter.
Worse part is this is not caught by things like bloat-o-meter since
instruction length / symbols are typically same size.
e.g.
stock (signed math)
__________________
919b4614 <test_taint>:
919b4614: div r2,r0,0x20
^^^
919b4618: add2 r2,0x920f6050,r2
919b4620: ld_s r2,[r2,0]
919b4622: lsr r0,r2,r0
919b4626: j_s.d [blink]
919b4628: bmsk_s r0,r0,0
919b462a: nop_s
(patched) unsigned math
__________________
919b4614 <test_taint>:
919b4614: lsr r2,r0,0x5 @nr/32
^^^
919b4618: add2 r2,0x920f6050,r2
919b4620: ld_s r2,[r2,0]
919b4622: lsr r0,r2,r0 #test_bit()
919b4626: j_s.d [blink]
919b4628: bmsk_s r0,r0,0
919b462a: nop_s
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
* If it's called on the same region of memory simultaneously, the effect
* may be that only one operation succeeds.
*/
* If it's called on the same region of memory simultaneously, the effect
* may be that only one operation succeeds.
*/
-static inline void __set_bit(int nr, volatile unsigned long *addr)
+static inline void __set_bit(unsigned int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
-static inline void __clear_bit(int nr, volatile unsigned long *addr)
+static inline void __clear_bit(unsigned int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
* If it's called on the same region of memory simultaneously, the effect
* may be that only one operation succeeds.
*/
* If it's called on the same region of memory simultaneously, the effect
* may be that only one operation succeeds.
*/
-static inline void __change_bit(int nr, volatile unsigned long *addr)
+static inline void __change_bit(unsigned int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
* If two examples of this operation race, one can appear to succeed
* but actually fail. You must protect multiple accesses with a lock.
*/
* If two examples of this operation race, one can appear to succeed
* but actually fail. You must protect multiple accesses with a lock.
*/
-static inline int __test_and_set_bit(int nr, volatile unsigned long *addr)
+static inline int __test_and_set_bit(unsigned int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
* If two examples of this operation race, one can appear to succeed
* but actually fail. You must protect multiple accesses with a lock.
*/
* If two examples of this operation race, one can appear to succeed
* but actually fail. You must protect multiple accesses with a lock.
*/
-static inline int __test_and_clear_bit(int nr, volatile unsigned long *addr)
+static inline int __test_and_clear_bit(unsigned int nr, volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
{
unsigned long mask = BIT_MASK(nr);
unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
}
/* WARNING: non atomic and it can be reordered! */
}
/* WARNING: non atomic and it can be reordered! */
-static inline int __test_and_change_bit(int nr,
+static inline int __test_and_change_bit(unsigned int nr,
volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
volatile unsigned long *addr)
{
unsigned long mask = BIT_MASK(nr);
* @nr: bit number to test
* @addr: Address to start counting from
*/
* @nr: bit number to test
* @addr: Address to start counting from
*/
-static inline int test_bit(int nr, const volatile unsigned long *addr)
+static inline int test_bit(unsigned int nr, const volatile unsigned long *addr)
{
return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
}
{
return 1UL & (addr[BIT_WORD(nr)] >> (nr & (BITS_PER_LONG-1)));
}