| Message ID | 1529077646-2848-2-git-send-email-Dave.Martin@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Jun 15, 2018 at 04:47:23PM +0100, Dave P Martin wrote: > From: Mark Rutland <mark.rutland@arm.com> > > Currently we have a couple of helpers to manipulate bits in particular > sysregs: > > * config_sctlr_el1(u32 clear, u32 set) > > * change_cpacr(u64 val, u64 mask) > > The parameters of these differ in naming convention, order, and size, > which is unfortunate. They also differ slightly in behaviour, as > change_cpacr() skips the sysreg write if the bits are unchanged, which > is a useful optimization when sysreg writes are expensive. > > Before we gain more yet another sysreg manipulation function, let's > unify these with a common helper, providing a consistent order for > clear/set operands, and the write skipping behaviour from > change_cpacr(). Code will be migrated to the new helper in subsequent > patches. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Reviewed-by: Dave Martin <dave.martin@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Marc Zyngier <marc.zyngier@arm.com> Since you are submitting this patch, it should have your signed-off-by as well. Other than that: Acked-by: Catalin Marinas <catalin.marinas@arm.com>
On Fri, Jun 15, 2018 at 05:21:25PM +0100, Catalin Marinas wrote: > On Fri, Jun 15, 2018 at 04:47:23PM +0100, Dave P Martin wrote: > > From: Mark Rutland <mark.rutland@arm.com> > > > > Currently we have a couple of helpers to manipulate bits in particular > > sysregs: > > > > * config_sctlr_el1(u32 clear, u32 set) > > > > * change_cpacr(u64 val, u64 mask) > > > > The parameters of these differ in naming convention, order, and size, > > which is unfortunate. They also differ slightly in behaviour, as > > change_cpacr() skips the sysreg write if the bits are unchanged, which > > is a useful optimization when sysreg writes are expensive. > > > > Before we gain more yet another sysreg manipulation function, let's > > unify these with a common helper, providing a consistent order for > > clear/set operands, and the write skipping behaviour from > > change_cpacr(). Code will be migrated to the new helper in subsequent > > patches. > > > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > > Reviewed-by: Dave Martin <dave.martin@arm.com> > > Cc: Catalin Marinas <catalin.marinas@arm.com> > > Cc: Marc Zyngier <marc.zyngier@arm.com> > > Since you are submitting this patch, it should have your signed-off-by > as well. Other than that: > > Acked-by: Catalin Marinas <catalin.marinas@arm.com> Oops, added locally. I had considered this optional if the patch was unmodified from the original author, but I guess I at least applied it on a different base. In any case, I can see why it would be considered mandatory. Cheers ---Dave
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index 6171178..a8f8481 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -728,6 +728,17 @@ asm( asm volatile("msr_s " __stringify(r) ", %x0" : : "rZ" (__val)); \ } while (0) +/* + * Modify bits in a sysreg. Bits in the clear mask are zeroed, then bits in the + * set mask are set. Other bits are left as-is. + */ +#define sysreg_clear_set(sysreg, clear, set) do { \ + u64 __scs_val = read_sysreg(sysreg); \ + u64 __scs_new = (__scs_val & ~(u64)(clear)) | (set); \ + if (__scs_new != __scs_val) \ + write_sysreg(__scs_new, sysreg); \ +} while (0) + static inline void config_sctlr_el1(u32 clear, u32 set) { u32 val;