[PATCH v4 0/4] riscv, mm: detect svnapot cpu support at runtime

[Conor.Dooley at microchip.com]

On 22/08/2022 16:34, panqinglin2020 at iscas.ac.cn wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> From: Qinglin Pan <panqinglin2020 at iscas.ac.cn>

Hey Qingling,
Apologies for yet another mail - but I built allmodconfig
with CONFIG_SVNAPOT=y and got a build error:

  CC      arch/riscv/kernel/asm-offsets.s
In file included from /stuff/linux/arch/riscv/include/asm/tlbflush.h:12,
                 from /stuff/linux/arch/riscv/include/asm/pgtable.h:108,
                 from /stuff/linux/include/linux/pgtable.h:6,
                 from /stuff/linux/include/linux/mm.h:29,
                 from /stuff/linux/arch/riscv/kernel/asm-offsets.c:10:
/stuff/linux/arch/riscv/include/asm/pgtable.h: In function 'pte_pfn':
/stuff/linux/arch/riscv/include/asm/pgtable.h:299:35: error: '_PAGE_NAPOT_SHIFT' undeclared (first use in this function)
  299 |         ALT_SVNAPOT_PTE_PFN(_val, _PAGE_NAPOT_SHIFT,
      |                                   ^~~~~~~~~~~~~~~~~
/stuff/linux/arch/riscv/include/asm/errata_list.h:165:23: note: in definition of macro 'ALT_SVNAPOT_PTE_PFN'
  165 |                   "i"(_napot_shift))
      |                       ^~~~~~~~~~~~
/stuff/linux/arch/riscv/include/asm/pgtable.h:299:35: note: each undeclared identifier is reported only once for each function it appears in
  299 |         ALT_SVNAPOT_PTE_PFN(_val, _PAGE_NAPOT_SHIFT,
      |                                   ^~~~~~~~~~~~~~~~~
/stuff/linux/arch/riscv/include/asm/errata_list.h:165:23: note: in definition of macro 'ALT_SVNAPOT_PTE_PFN'
  165 |                   "i"(_napot_shift))
      |                       ^~~~~~~~~~~~
In file included from /stuff/linux/include/linux/mm.h:29,
                 from /stuff/linux/arch/riscv/kernel/asm-offsets.c:10:
/stuff/linux/include/linux/pgtable.h: At top level:
/stuff/linux/include/linux/pgtable.h:1457:20: error: redefinition of 'p4d_clear_huge'
 1457 | static inline void p4d_clear_huge(p4d_t *p4d) { }
      |                    ^~~~~~~~~~~~~~
In file included from /stuff/linux/include/linux/pgtable.h:6,
                 from /stuff/linux/include/linux/mm.h:29,
                 from /stuff/linux/arch/riscv/kernel/asm-offsets.c:10:
/stuff/linux/arch/riscv/include/asm/pgtable.h:763:20: note: previous definition of 'p4d_clear_huge' with type 'void(p4d_t *)'
  763 | static inline void p4d_clear_huge(p4d_t *p4d) { }
      |                    ^~~~~~~~~~~~~~
make[3]: *** [/stuff/linux/scripts/Makefile.build:117: arch/riscv/kernel/asm-offsets.s] Error 1
make[2]: *** [/stuff/linux/Makefile:1205: prepare0] Error 2
make[2]: Leaving directory '/stuff/brsdk/work/linux'
make[1]: *** [Makefile:222: __sub-make] Error 2
make[1]: Leaving directory '/stuff/linux'
make: *** [Makefile:179: allmodconfig] Error 2

> 
> Svnapot is a RISC-V extension for marking contiguous 4K pages as a non-4K
> page. This patch set is for using Svnapot in Linux Kernel's boot process
> and hugetlb fs.
> 
> This patchset adds a Kconfig item for using Svnapot in
> "Platform type"->"Svnapot support". Its default value is off, and people can set
> it on if they allow kernel to detect Svnapot hardware support and leverage it.
> 
> Tested on:
>   - qemu rv64 with "Svnapot support" off and svnapot=true.
>   - qemu rv64 with "Svnapot support" on and svnapot=true.
>   - qemu rv64 with "Svnapot support" off and svnapot=false.
>   - qemu rv64 with "Svnapot support" on and svnapot=false.
> 
> Changes in v2:
>   - detect Svnapot hardware support at boot time.
> Changes in v3:
>   - do linear mapping again if has_svnapot
> Changes in v4:
>   - fix some errors/warns reported by checkpatch.pl, thanks @Conor
> 
> Qinglin Pan (4):
>   mm: modify pte format for Svnapot
>   mm: support Svnapot in physical page linear-mapping
>   mm: support Svnapot in hugetlb page
>   mm: support Svnapot in huge vmap
> 
>  arch/riscv/Kconfig                   |  10 +-
>  arch/riscv/include/asm/errata_list.h |  24 ++-
>  arch/riscv/include/asm/hugetlb.h     |  30 +++-
>  arch/riscv/include/asm/hwcap.h       |   1 +
>  arch/riscv/include/asm/mmu.h         |   1 +
>  arch/riscv/include/asm/page.h        |   2 +-
>  arch/riscv/include/asm/pgtable-64.h  |  14 ++
>  arch/riscv/include/asm/pgtable.h     |  70 +++++++-
>  arch/riscv/include/asm/vmalloc.h     |  22 +++
>  arch/riscv/kernel/cpu.c              |   1 +
>  arch/riscv/kernel/cpufeature.c       |  18 ++
>  arch/riscv/kernel/setup.c            |  11 +-
>  arch/riscv/mm/hugetlbpage.c          | 250 ++++++++++++++++++++++++++-
>  arch/riscv/mm/init.c                 |  47 +++--
>  14 files changed, 477 insertions(+), 24 deletions(-)
> 
> --
> 2.35.1
> 
> 
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