On Wed, 20 Jun 2018, Chang S. Bae wrote:
> CPU number initialization in vDSO is now a bit cleaned up by
> the new helper functions. The helper functions will take
> care of combing CPU and node number and reading each from
s/combing/combining/ please
> the combined value.
>
> Suggested-by: Andy Lutomirski <l...@kernel.org>
> Signed-off-by: Chang S. Bae <chang.seok....@intel.com>
> Cc: H. Peter Anvin <h...@zytor.com>
> Cc: Andi Kleen <a...@linux.intel.com>
> Cc: Dave Hansen <dave.han...@linux.intel.com>
> Cc: Thomas Gleixner <t...@linutronix.de>
> Cc: Ingo Molnar <mi...@kernel.org>
> Acked-by: Andy Lutomirski <l...@kernel.org>
> ---
> arch/x86/entry/vdso/vgetcpu.c | 4 ++--
> arch/x86/entry/vdso/vma.c | 16 ++++++++--------
> arch/x86/include/asm/segment.h | 28 ++++++++++++++++++++++++++++
> arch/x86/include/asm/vgtod.h | 2 --
> 4 files changed, 38 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/entry/vdso/vgetcpu.c b/arch/x86/entry/vdso/vgetcpu.c
> index 8ec3d1f..3284069 100644
> --- a/arch/x86/entry/vdso/vgetcpu.c
> +++ b/arch/x86/entry/vdso/vgetcpu.c
> @@ -18,9 +18,9 @@ __vdso_getcpu(unsigned *cpu, unsigned *node, struct
> getcpu_cache *unused)
> p = __getcpu();
While we are touching this, can we please as a first step change __getcpu()
to something else? I've tripped over this several times in the past and
confused it with a (nonexisting) variant of get_cpu().
>
> if (cpu)
> - *cpu = p & VGETCPU_CPU_MASK;
> + *cpu = lsl_tscp_to_cpu(p);
>
> if (node)
> - *node = p >> 12;
> + *node = lsl_tscp_to_node(p);
Are these new helpers going to be used at some other place than this? If
not, then there is really no point at all. Then just go and make this:
__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
{
vdso_read_cpu_and_node(cpu, node);
return 0;
}
> diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
> index 833e229..1fc93da 100644
> --- a/arch/x86/entry/vdso/vma.c
> +++ b/arch/x86/entry/vdso/vma.c
> @@ -340,19 +340,19 @@ static void vgetcpu_cpu_init(void *arg)
> int cpu = smp_processor_id();
> struct desc_struct d = { };
> unsigned long node = 0;
> + unsigned long cpu_number = 0;
That's hardly a CPU number. It's encoded CPU and node information.
> #ifdef CONFIG_NUMA
> node = cpu_to_node(cpu);
> #endif
While at it please get rid of the ifdeffery. If CONFIG_NUMA=n then
cpu_to_node(cpu) resolves to (0).
> + cpu_number = make_lsl_tscp(cpu, node);
So the whole thing can be reduced to:
u64 cpudata = vdso_encode_cpu_and_node(cpu, cpu_to_node(cpu));
Or some other sensible function name.
Thanks,
tglx
