On Thu, 2015-10-29 at 11:43 +1100, Anton Blanchard wrote:
> mtmsrd_isync() will do an mtmsrd followed by an isync on older
> processors. On newer processors we avoid the isync via a feature fixup.
The isync is needed specifically when enabling/disable FP etc... right
?
I'd like to make the name a bit clearer. Maybe something like
set_msr_fpvec() or maybe you can come up with something even better, ie
use a name that represents what it's for rather than what it does.
> Signed-off-by: Anton Blanchard <an...@samba.org>
> ---
> arch/powerpc/include/asm/reg.h | 8 ++++++++
> arch/powerpc/kernel/process.c | 30 ++++++++++++++++++++++--------
> 2 files changed, 30 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
> index a908ada..987dac0 100644
> --- a/arch/powerpc/include/asm/reg.h
> +++ b/arch/powerpc/include/asm/reg.h
> @@ -1193,12 +1193,20 @@
> #define __mtmsrd(v, l) asm volatile("mtmsrd %0," __stringify(l) \
> : : "r" (v) : "memory")
> #define mtmsr(v) __mtmsrd((v), 0)
> +#define __MTMSR "mtmsrd"
> #else
> #define mtmsr(v) asm volatile("mtmsr %0" : \
> : "r" ((unsigned long)(v)) \
> : "memory")
> +#define __MTMSR "mtmsr"
> #endif
>
> +static inline void mtmsr_isync(unsigned long val)
> +{
> + asm volatile(__MTMSR " %0; " ASM_FTR_IFCLR("isync", "nop", %1) : :
> + "r" (val), "i" (CPU_FTR_ARCH_206) : "memory");
> +}
> +
> #define mfspr(rn) ({unsigned long rval; \
> asm volatile("mfspr %0," __stringify(rn) \
> : "=r" (rval)); rval;})
> diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
> index ef64219..5bf8ec2 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -130,7 +130,10 @@ void enable_kernel_fp(void)
> check_if_tm_restore_required(current);
> giveup_fpu(current);
> } else {
> - giveup_fpu(NULL); /* just enables FP for kernel */
> + u64 oldmsr = mfmsr();
> +
> + if (!(oldmsr & MSR_FP))
> + mtmsr_isync(oldmsr | MSR_FP);
> }
> }
> EXPORT_SYMBOL(enable_kernel_fp);
> @@ -144,7 +147,10 @@ void enable_kernel_altivec(void)
> check_if_tm_restore_required(current);
> giveup_altivec(current);
> } else {
> - giveup_altivec_notask();
> + u64 oldmsr = mfmsr();
> +
> + if (!(oldmsr & MSR_VEC))
> + mtmsr_isync(oldmsr | MSR_VEC);
> }
> }
> EXPORT_SYMBOL(enable_kernel_altivec);
> @@ -173,10 +179,14 @@ void enable_kernel_vsx(void)
> {
> WARN_ON(preemptible());
>
> - if (current->thread.regs && (current->thread.regs->msr & MSR_VSX))
> + if (current->thread.regs && (current->thread.regs->msr & MSR_VSX)) {
> giveup_vsx(current);
> - else
> - giveup_vsx(NULL); /* just enable vsx for kernel - force */
> + } else {
> + u64 oldmsr = mfmsr();
> +
> + if (!(oldmsr & MSR_VSX))
> + mtmsr_isync(oldmsr | MSR_VSX);
> + }
> }
> EXPORT_SYMBOL(enable_kernel_vsx);
>
> @@ -209,10 +219,14 @@ void enable_kernel_spe(void)
> {
> WARN_ON(preemptible());
>
> - if (current->thread.regs && (current->thread.regs->msr & MSR_SPE))
> + if (current->thread.regs && (current->thread.regs->msr & MSR_SPE)) {
> giveup_spe(current);
> - else
> - giveup_spe(NULL); /* just enable SPE for kernel - force */
> + } else {
> + u64 oldmsr = mfmsr();
> +
> + if (!(oldmsr & MSR_SPE))
> + mtmsr_isync(oldmsr | MSR_SPE);
> + }
> }
> EXPORT_SYMBOL(enable_kernel_spe);
>
