x86, asm: use bool for bitops and other assembly outputs
The gcc people have confirmed that using "bool" when combined with
inline assembly always is treated as a byte-sized operand that can be
assumed to be 0 or 1, which is exactly what the SET instruction
emits. Change the output types and intermediate variables of as many
operations as practical to "bool".
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1465414726-197858-3-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/percpu.h b/arch/x86/include/asm/percpu.h
index 65039e9..184d7f3 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -510,14 +510,14 @@
/* This is not atomic against other CPUs -- CPU preemption needs to be off */
#define x86_test_and_clear_bit_percpu(bit, var) \
({ \
- unsigned char old__; \
+ bool old__; \
asm volatile("btr %2,"__percpu_arg(1)"\n\tsetc %0" \
: "=qm" (old__), "+m" (var) \
: "dIr" (bit)); \
old__; \
})
-static __always_inline int x86_this_cpu_constant_test_bit(unsigned int nr,
+static __always_inline bool x86_this_cpu_constant_test_bit(unsigned int nr,
const unsigned long __percpu *addr)
{
unsigned long __percpu *a = (unsigned long *)addr + nr / BITS_PER_LONG;
@@ -529,10 +529,10 @@
#endif
}
-static inline int x86_this_cpu_variable_test_bit(int nr,
+static inline bool x86_this_cpu_variable_test_bit(int nr,
const unsigned long __percpu *addr)
{
- unsigned char oldbit;
+ bool oldbit;
asm volatile("bt "__percpu_arg(2)",%1\n\t"
"setc %0"