x86, bitops: remove use of "sbb" to return CF

Use SETC instead of SBB to return the value of CF from assembly. Using
SETcc enables uniformity with other flags-returning pieces of assembly
code.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1465414726-197858-2-git-send-email-hpa@linux.intel.com
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h
index 7766d1c..b2b797d 100644 (file)
--- a/arch/x86/include/asm/bitops.h
+++ b/arch/x86/include/asm/bitops.h
@@ -230,11 +230,11 @@ test_and_set_bit_lock(long nr, volatile unsigned long *addr)
  */
 static __always_inline int __test_and_set_bit(long nr, volatile unsigned long *addr)
 {
-       int oldbit;
+       unsigned char oldbit;
 
        asm("bts %2,%1\n\t"
-           "sbb %0,%0"
-           : "=r" (oldbit), ADDR
+           "setc %0"
+           : "=qm" (oldbit), ADDR
            : "Ir" (nr));
        return oldbit;
 }
@@ -270,11 +270,11 @@ static __always_inline int test_and_clear_bit(long nr, volatile unsigned long *a
  */
 static __always_inline int __test_and_clear_bit(long nr, volatile unsigned long *addr)
 {
-       int oldbit;
+       unsigned char oldbit;
 
        asm volatile("btr %2,%1\n\t"
-                    "sbb %0,%0"
-                    : "=r" (oldbit), ADDR
+                    "setc %0"
+                    : "=qm" (oldbit), ADDR
                     : "Ir" (nr));
        return oldbit;
 }
@@ -282,11 +282,11 @@ static __always_inline int __test_and_clear_bit(long nr, volatile unsigned long
 /* WARNING: non atomic and it can be reordered! */
 static __always_inline int __test_and_change_bit(long nr, volatile unsigned long *addr)
 {
-       int oldbit;
+       unsigned char oldbit;
 
        asm volatile("btc %2,%1\n\t"
-                    "sbb %0,%0"
-                    : "=r" (oldbit), ADDR
+                    "setc %0"
+                    : "=qm" (oldbit), ADDR
                     : "Ir" (nr) : "memory");
 
        return oldbit;
@@ -313,11 +313,11 @@ static __always_inline int constant_test_bit(long nr, const volatile unsigned lo
 
 static __always_inline int variable_test_bit(long nr, volatile const unsigned long *addr)
 {
-       int oldbit;
+       unsigned char oldbit;
 
        asm volatile("bt %2,%1\n\t"
-                    "sbb %0,%0"
-                    : "=r" (oldbit)
+                    "setc %0"
+                    : "=qm" (oldbit)
                     : "m" (*(unsigned long *)addr), "Ir" (nr));
 
        return oldbit;

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index e0ba66c..65039e9 100644 (file)
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -510,9 +510,9 @@ do {                                                                        \
 /* This is not atomic against other CPUs -- CPU preemption needs to be off */
 #define x86_test_and_clear_bit_percpu(bit, var)                                \
 ({                                                                     \
-       int old__;                                                      \
-       asm volatile("btr %2,"__percpu_arg(1)"\n\tsbbl %0,%0"           \
-                    : "=r" (old__), "+m" (var)                         \
+       unsigned char old__;                                            \
+       asm volatile("btr %2,"__percpu_arg(1)"\n\tsetc %0"              \
+                    : "=qm" (old__), "+m" (var)                        \
                     : "dIr" (bit));                                    \
        old__;                                                          \
 })
@@ -532,11 +532,11 @@ static __always_inline int x86_this_cpu_constant_test_bit(unsigned int nr,
 static inline int x86_this_cpu_variable_test_bit(int nr,
                         const unsigned long __percpu *addr)
 {
-       int oldbit;
+       unsigned char oldbit;
 
        asm volatile("bt "__percpu_arg(2)",%1\n\t"
-                       "sbb %0,%0"
-                       : "=r" (oldbit)
+                       "setc %0"
+                       : "=qm" (oldbit)
                        : "m" (*(unsigned long *)addr), "Ir" (nr));
 
        return oldbit;

diff --git a/arch/x86/include/asm/signal.h b/arch/x86/include/asm/signal.h
index 2138c9a..dd1e7d6 100644 (file)
--- a/arch/x86/include/asm/signal.h
+++ b/arch/x86/include/asm/signal.h
@@ -81,9 +81,9 @@ static inline int __const_sigismember(sigset_t *set, int _sig)
 
 static inline int __gen_sigismember(sigset_t *set, int _sig)
 {
-       int ret;
-       asm("btl %2,%1\n\tsbbl %0,%0"
-           : "=r"(ret) : "m"(*set), "Ir"(_sig-1) : "cc");
+       unsigned char ret;
+       asm("btl %2,%1\n\tsetc %0"
+           : "=qm"(ret) : "m"(*set), "Ir"(_sig-1) : "cc");
        return ret;
 }
 

diff --git a/arch/x86/include/asm/sync_bitops.h b/arch/x86/include/asm/sync_bitops.h
index f28a24b..cbf8847 100644 (file)
--- a/arch/x86/include/asm/sync_bitops.h
+++ b/arch/x86/include/asm/sync_bitops.h
@@ -79,10 +79,10 @@ static inline void sync_change_bit(long nr, volatile unsigned long *addr)
  */
 static inline int sync_test_and_set_bit(long nr, volatile unsigned long *addr)
 {
-       int oldbit;
+       unsigned char oldbit;
 
-       asm volatile("lock; bts %2,%1\n\tsbbl %0,%0"
-                    : "=r" (oldbit), "+m" (ADDR)
+       asm volatile("lock; bts %2,%1\n\tsetc %0"
+                    : "=qm" (oldbit), "+m" (ADDR)
                     : "Ir" (nr) : "memory");
        return oldbit;
 }
@@ -97,10 +97,10 @@ static inline int sync_test_and_set_bit(long nr, volatile unsigned long *addr)
  */
 static inline int sync_test_and_clear_bit(long nr, volatile unsigned long *addr)
 {
-       int oldbit;
+       unsigned char oldbit;
 
-       asm volatile("lock; btr %2,%1\n\tsbbl %0,%0"
-                    : "=r" (oldbit), "+m" (ADDR)
+       asm volatile("lock; btr %2,%1\n\tsetc %0"
+                    : "=qm" (oldbit), "+m" (ADDR)
                     : "Ir" (nr) : "memory");
        return oldbit;
 }
@@ -115,10 +115,10 @@ static inline int sync_test_and_clear_bit(long nr, volatile unsigned long *addr)
  */
 static inline int sync_test_and_change_bit(long nr, volatile unsigned long *addr)
 {
-       int oldbit;
+       unsigned char oldbit;
 
-       asm volatile("lock; btc %2,%1\n\tsbbl %0,%0"
-                    : "=r" (oldbit), "+m" (ADDR)
+       asm volatile("lock; btc %2,%1\n\tsetc %0"
+                    : "=qm" (oldbit), "+m" (ADDR)
                     : "Ir" (nr) : "memory");
        return oldbit;
 }

diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index 3dce1ca..01f30e5 100644 (file)
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -440,10 +440,7 @@ static inline unsigned long get_vflags(struct kernel_vm86_regs *regs)
 
 static inline int is_revectored(int nr, struct revectored_struct *bitmap)
 {
-       __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
-               :"=r" (nr)
-               :"m" (*bitmap), "r" (nr));
-       return nr;
+       return test_bit(nr, bitmap->__map);
 }
 
 #define val_byte(val, n) (((__u8 *)&val)[n])