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SubjectRe: [PATCH 0/5] riscv: Use READ_ONCE()/WRITE_ONCE() for pte accesses
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On Mon, 02 Oct 2023 08:10:26 PDT (-0700), alexghiti@rivosinc.com wrote:
> This series is a follow-up for riscv of a recent series from Ryan [1] which
> converts all direct dereferences of pte_t into a ptet_get() access.
>
> The goal here for riscv is to use READ_ONCE()/WRITE_ONCE() for all page
> table entries accesses to avoid any compiler transformation when the
> hardware can concurrently modify the page tables entries (A/D bits for
> example).
>
> I went a bit further and added pud/p4d/pgd_get() helpers as such concurrent
> modifications can happen too at those levels.
>
> [1] https://lore.kernel.org/all/20230612151545.3317766-1-ryan.roberts@arm.com/
>
> Alexandre Ghiti (5):
> riscv: Use WRITE_ONCE() when setting page table entries
> mm: Introduce pudp/p4dp/pgdp_get() functions
> riscv: mm: Only compile pgtable.c if MMU
> riscv: Suffix all page table entry pointers with 'p'
> riscv: Use accessors to page table entries instead of direct
> dereference
>
> arch/riscv/include/asm/kfence.h | 6 +-
> arch/riscv/include/asm/kvm_host.h | 2 +-
> arch/riscv/include/asm/pgalloc.h | 86 ++++++++++----------
> arch/riscv/include/asm/pgtable-64.h | 26 +++---
> arch/riscv/include/asm/pgtable.h | 33 ++------
> arch/riscv/kernel/efi.c | 2 +-
> arch/riscv/kvm/mmu.c | 44 +++++-----
> arch/riscv/mm/Makefile | 3 +-
> arch/riscv/mm/fault.c | 38 ++++-----
> arch/riscv/mm/hugetlbpage.c | 80 +++++++++----------
> arch/riscv/mm/init.c | 30 +++----
> arch/riscv/mm/kasan_init.c | 119 ++++++++++++++--------------
> arch/riscv/mm/pageattr.c | 74 +++++++++--------
> arch/riscv/mm/pgtable.c | 71 +++++++++++------
> include/linux/pgtable.h | 21 +++++
> 15 files changed, 334 insertions(+), 301 deletions(-)

This has some build failures, I was just talking to Alex and he's going
to fix them.

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