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SubjectRe: [PATCH v2 00/10] Independent per-CPU data section for nVHE
On Wed, Sep 16, 2020 at 01:24:12PM +0100, David Brazdil wrote:
> > I was also wondering about another approach - using the PERCPU_SECTION macro
> > unchanged in the hyp linker script. It would lay out a single .data..percpu and
> > we would then prefix it with .hyp and the symbols with __kvm_nvhe_ as with
> > everything else. WDYT? Haven't tried that yet, could be a naive idea.
>
> Seems to work. Can't use PERCPU_SECTION directly because then we couldn't
> rename it in the same linker script, but if we just unwrap that one layer
> we can use PERCPU_INPUT. No global macro changes needed.
>
> Let me know what you think.
>
> ------8<------
> diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
> index 5904a4de9f40..9e6bf21268f1 100644
> --- a/arch/arm64/kernel/vmlinux.lds.S
> +++ b/arch/arm64/kernel/vmlinux.lds.S
> @@ -195,11 +195,9 @@ SECTIONS
> PERCPU_SECTION(L1_CACHE_BYTES)
>
> /* KVM nVHE per-cpu section */
> - #undef PERCPU_SECTION_NAME
> - #undef PERCPU_SYMBOL_NAME
> - #define PERCPU_SECTION_NAME(suffix) CONCAT3(.hyp, PERCPU_SECTION_BASE_NAME, suffix)
> - #define PERCPU_SYMBOL_NAME(name) __kvm_nvhe_ ## name
> - PERCPU_SECTION(L1_CACHE_BYTES)
> + . = ALIGN(PAGE_SIZE);
> + .hyp.data..percpu : { *(.hyp.data..percpu) }
> + . = ALIGN(PAGE_SIZE);
>
> .rela.dyn : ALIGN(8) {
> *(.rela .rela*)
> diff --git a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
> index 7d8c3fa004f4..1d8e4f7edc29 100644
> --- a/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
> +++ b/arch/arm64/kvm/hyp/nvhe/hyp.lds.S
> @@ -4,6 +4,10 @@
> * Written by David Brazdil <dbrazdil@google.com>
> */
>
> +#include <asm-generic/vmlinux.lds.h>
> +#include <asm/cache.h>
> +#include <asm/memory.h>
> +
> /*
> * Defines an ELF hyp section from input section @NAME and its subsections.
> */
> @@ -11,9 +15,9 @@
>
> SECTIONS {
> HYP_SECTION(.text)
> - HYP_SECTION(.data..percpu)
> - HYP_SECTION(.data..percpu..first)
> - HYP_SECTION(.data..percpu..page_aligned)
> - HYP_SECTION(.data..percpu..read_mostly)
> - HYP_SECTION(.data..percpu..shared_aligned)
> +
> + .hyp..data..percpu : {

Too many '.'s here?

> + __per_cpu_load = .;

I don't think we need this symbol.

Otherwise, idea looks good to me. Can you respin like this, but also
incorporating some of the cleanup in the diff I posted, please?

Will

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