Le 24/10/2022 à 02:35, Rohan McLure a écrit :
> Prior to this commit, pud_pfn was implemented with BUILD_BUG as the inline
> function for 64-bit Book3S systems but is never included, as its
> invocations in generic code are guarded by calls to pud_devmap which return
> zero on such systems. A future patch will provide support for page table
> checks, the generic code for which depends on a pud_pfn stub being
> implemented, even while the patch will not interact with puds directly.
>
> Remove the 64-bit Book3S stub and define pud_pfn to warn on all
> platforms. pud_pfn may be defined properly on a per-platform basis
> should it grow real usages in future.
>
> Signed-off-by: Rohan McLure <rmcl...@linux.ibm.com>
> ---
> V2: Remove conditional BUILD_BUG and BUG. Instead warn on usage.
> ---
> arch/powerpc/include/asm/book3s/64/pgtable.h | 10 ----------
> arch/powerpc/include/asm/pgtable.h | 14 ++++++++++++++
> 2 files changed, 14 insertions(+), 10 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h
> b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index 486902aff040..f9aefa492df0 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -1413,16 +1413,6 @@ static inline int pgd_devmap(pgd_t pgd)
> }
> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>
> -static inline int pud_pfn(pud_t pud)
> -{
> - /*
> - * Currently all calls to pud_pfn() are gated around a pud_devmap()
> - * check so this should never be used. If it grows another user we
> - * want to know about it.
> - */
> - BUILD_BUG();
> - return 0;
> -}
> #define __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION
> pte_t ptep_modify_prot_start(struct vm_area_struct *, unsigned long, pte_t
> *);
> void ptep_modify_prot_commit(struct vm_area_struct *, unsigned long,
> diff --git a/arch/powerpc/include/asm/pgtable.h
> b/arch/powerpc/include/asm/pgtable.h
> index 33f4bf8d22b0..36956fb440e1 100644
> --- a/arch/powerpc/include/asm/pgtable.h
> +++ b/arch/powerpc/include/asm/pgtable.h
> @@ -158,6 +158,20 @@ struct seq_file;
> void arch_report_meminfo(struct seq_file *m);
> #endif /* CONFIG_PPC64 */
>
> +/*
> + * Currently only consumed by page_table_check_pud_{set,clear}. Since clears
> + * and sets to page table entries at any level are done through
> + * page_table_check_pte_{set,clear}, provide stub implementation.
> + */
> +#ifndef pud_pfn
> +#define pud_pfn pud_pfn
> +static inline int pud_pfn(pud_t pud)
> +{
> + WARN(1, "pud: platform does not use pud entries directly");
Would a WARN_ONCE() be enough ?
> + return 0;
> +}
> +#endif
> +
> #endif /* __ASSEMBLY__ */
>
> #endif /* _ASM_POWERPC_PGTABLE_H */
