On May 7, 2020 4:34:22 AM PDT, Peter Zijlstra peterz@infradead.org wrote:
On Tue, May 05, 2020 at 11:07:24AM -0700, hpa@zytor.com wrote:
On May 5, 2020 10:44:22 AM PDT, Nick Desaulniers
ndesaulniers@google.com wrote:
@@ -54,7 +54,7 @@ arch_set_bit(long nr, volatile unsigned long
*addr)
if (__builtin_constant_p(nr)) { asm volatile(LOCK_PREFIX "orb %1,%0" : CONST_MASK_ADDR(nr, addr)
: "iq" (CONST_MASK(nr) & 0xff)
: "iq" ((u8)(CONST_MASK(nr) & 0xff)) : "memory");@@ -74,7 +74,7 @@ arch_clear_bit(long nr, volatile unsigned long
*addr)
if (__builtin_constant_p(nr)) { asm volatile(LOCK_PREFIX "andb %1,%0" : CONST_MASK_ADDR(nr, addr)
: "iq" (CONST_MASK(nr) ^ 0xff));
: "iq" ((u8)(CONST_MASK(nr) ^ 0xff)));Drop & 0xff and change ^ 0xff to ~.
But then we're back to sparse being unhappy, no? The thing with ~ is that it will set high bits which will be truncated, which makes sparse sad.
In that case, sparse is just broken.