On Wed, Jun 05, 2019 at 04:17:35PM -0700, Palmer Dabbelt wrote: > REG_S ra, TASK_THREAD_RA_RA(a3) > + /* > + * The Linux ABI allows programs to depend on load reservations being > + * broken on context switches, but the ISA doesn't require that the > + * hardware ever breaks a load reservation. The only way to break a > + * load reservation is with a store conditional, so we emit one here. > + * Since nothing ever takes a load reservation on TASK_THREAD_RA_RA we > + * know this will always fail, but just to be on the safe side this > + * writes the same value that was unconditionally written by the > + * previous instruction. > + */ > +#if (TASK_THREAD_RA_RA != 0)
I don't think this check works as intended. TASK_THREAD_RA_RA is a parameterized macro, thus the above would never evaluate to 0. The error message also is rather odd while we're at it. > +#if (__riscv_xlen == 64) > + sc.d x0, ra, 0(a3) > +#else > + sc.w x0, ra, 0(a3) > +#endif I'd rather add an macro ala REG_S to asm.h and distinguish between the xlen variants there: #define REG_SC __REG_SEL(sc.d, sc.w)
