Re: [PATCH v2 2/8] riscv: mm: Change attribute from __init to __meminit for page functions

[Alexandre Ghiti <alexghiti@rivosinc.com>]

On Tue, May 14, 2024 at 4:05 PM Björn Töpel <bjorn@kernel.org> wrote:
>
> From: Björn Töpel <bjorn@rivosinc.com>
>
> Prepare for memory hotplugging support by changing from __init to
> __meminit for the page table functions that are used by the upcoming
> architecture specific callbacks.
>
> Changing the __init attribute to __meminit, avoids that the functions
> are removed after init. The __meminit attribute makes sure the
> functions are kept in the kernel text post init, but only if memory
> hotplugging is enabled for the build.
>
> Also, make sure that the altmap parameter is properly passed on to
> vmemmap_populate_hugepages().
>
> Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
> ---
>  arch/riscv/include/asm/mmu.h     |  4 +--
>  arch/riscv/include/asm/pgtable.h |  2 +-
>  arch/riscv/mm/init.c             | 58 ++++++++++++++------------------
>  3 files changed, 29 insertions(+), 35 deletions(-)
>
> diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h
> index 60be458e94da..c09c3c79f496 100644
> --- a/arch/riscv/include/asm/mmu.h
> +++ b/arch/riscv/include/asm/mmu.h
> @@ -28,8 +28,8 @@ typedef struct {
>  #endif
>  } mm_context_t;
>
> -void __init create_pgd_mapping(pgd_t *pgdp, uintptr_t va, phys_addr_t pa,
> -                              phys_addr_t sz, pgprot_t prot);
> +void __meminit create_pgd_mapping(pgd_t *pgdp, uintptr_t va, phys_addr_t pa, phys_addr_t sz,
> +                                 pgprot_t prot);
>  #endif /* __ASSEMBLY__ */
>
>  #endif /* _ASM_RISCV_MMU_H */
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 58fd7b70b903..7933f493db71 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -162,7 +162,7 @@ struct pt_alloc_ops {
>  #endif
>  };
>
> -extern struct pt_alloc_ops pt_ops __initdata;
> +extern struct pt_alloc_ops pt_ops __meminitdata;
>
>  #ifdef CONFIG_MMU
>  /* Number of PGD entries that a user-mode program can use */
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 5b8cdfafb52a..c969427eab88 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -295,7 +295,7 @@ static void __init setup_bootmem(void)
>  }
>
>  #ifdef CONFIG_MMU
> -struct pt_alloc_ops pt_ops __initdata;
> +struct pt_alloc_ops pt_ops __meminitdata;
>
>  pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
>  pgd_t trampoline_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
> @@ -357,7 +357,7 @@ static inline pte_t *__init get_pte_virt_fixmap(phys_addr_t pa)
>         return (pte_t *)set_fixmap_offset(FIX_PTE, pa);
>  }
>
> -static inline pte_t *__init get_pte_virt_late(phys_addr_t pa)
> +static inline pte_t *__meminit get_pte_virt_late(phys_addr_t pa)
>  {
>         return (pte_t *) __va(pa);
>  }
> @@ -376,7 +376,7 @@ static inline phys_addr_t __init alloc_pte_fixmap(uintptr_t va)
>         return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>  }
>
> -static phys_addr_t __init alloc_pte_late(uintptr_t va)
> +static phys_addr_t __meminit alloc_pte_late(uintptr_t va)
>  {
>         struct ptdesc *ptdesc = pagetable_alloc(GFP_KERNEL & ~__GFP_HIGHMEM, 0);
>
> @@ -384,9 +384,8 @@ static phys_addr_t __init alloc_pte_late(uintptr_t va)
>         return __pa((pte_t *)ptdesc_address(ptdesc));
>  }
>
> -static void __init create_pte_mapping(pte_t *ptep,
> -                                     uintptr_t va, phys_addr_t pa,
> -                                     phys_addr_t sz, pgprot_t prot)
> +static void __meminit create_pte_mapping(pte_t *ptep, uintptr_t va, phys_addr_t pa, phys_addr_t sz,
> +                                        pgprot_t prot)
>  {
>         uintptr_t pte_idx = pte_index(va);
>
> @@ -440,7 +439,7 @@ static pmd_t *__init get_pmd_virt_fixmap(phys_addr_t pa)
>         return (pmd_t *)set_fixmap_offset(FIX_PMD, pa);
>  }
>
> -static pmd_t *__init get_pmd_virt_late(phys_addr_t pa)
> +static pmd_t *__meminit get_pmd_virt_late(phys_addr_t pa)
>  {
>         return (pmd_t *) __va(pa);
>  }
> @@ -457,7 +456,7 @@ static phys_addr_t __init alloc_pmd_fixmap(uintptr_t va)
>         return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>  }
>
> -static phys_addr_t __init alloc_pmd_late(uintptr_t va)
> +static phys_addr_t __meminit alloc_pmd_late(uintptr_t va)
>  {
>         struct ptdesc *ptdesc = pagetable_alloc(GFP_KERNEL & ~__GFP_HIGHMEM, 0);
>
> @@ -465,9 +464,9 @@ static phys_addr_t __init alloc_pmd_late(uintptr_t va)
>         return __pa((pmd_t *)ptdesc_address(ptdesc));
>  }
>
> -static void __init create_pmd_mapping(pmd_t *pmdp,
> -                                     uintptr_t va, phys_addr_t pa,
> -                                     phys_addr_t sz, pgprot_t prot)
> +static void __meminit create_pmd_mapping(pmd_t *pmdp,
> +                                        uintptr_t va, phys_addr_t pa,
> +                                        phys_addr_t sz, pgprot_t prot)
>  {
>         pte_t *ptep;
>         phys_addr_t pte_phys;
> @@ -503,7 +502,7 @@ static pud_t *__init get_pud_virt_fixmap(phys_addr_t pa)
>         return (pud_t *)set_fixmap_offset(FIX_PUD, pa);
>  }
>
> -static pud_t *__init get_pud_virt_late(phys_addr_t pa)
> +static pud_t *__meminit get_pud_virt_late(phys_addr_t pa)
>  {
>         return (pud_t *)__va(pa);
>  }
> @@ -521,7 +520,7 @@ static phys_addr_t __init alloc_pud_fixmap(uintptr_t va)
>         return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>  }
>
> -static phys_addr_t alloc_pud_late(uintptr_t va)
> +static phys_addr_t __meminit alloc_pud_late(uintptr_t va)
>  {
>         unsigned long vaddr;
>
> @@ -541,7 +540,7 @@ static p4d_t *__init get_p4d_virt_fixmap(phys_addr_t pa)
>         return (p4d_t *)set_fixmap_offset(FIX_P4D, pa);
>  }
>
> -static p4d_t *__init get_p4d_virt_late(phys_addr_t pa)
> +static p4d_t *__meminit get_p4d_virt_late(phys_addr_t pa)
>  {
>         return (p4d_t *)__va(pa);
>  }
> @@ -559,7 +558,7 @@ static phys_addr_t __init alloc_p4d_fixmap(uintptr_t va)
>         return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
>  }
>
> -static phys_addr_t alloc_p4d_late(uintptr_t va)
> +static phys_addr_t __meminit alloc_p4d_late(uintptr_t va)
>  {
>         unsigned long vaddr;
>
> @@ -568,9 +567,8 @@ static phys_addr_t alloc_p4d_late(uintptr_t va)
>         return __pa(vaddr);
>  }
>
> -static void __init create_pud_mapping(pud_t *pudp,
> -                                     uintptr_t va, phys_addr_t pa,
> -                                     phys_addr_t sz, pgprot_t prot)
> +static void __meminit create_pud_mapping(pud_t *pudp, uintptr_t va, phys_addr_t pa, phys_addr_t sz,
> +                                        pgprot_t prot)
>  {
>         pmd_t *nextp;
>         phys_addr_t next_phys;
> @@ -595,9 +593,8 @@ static void __init create_pud_mapping(pud_t *pudp,
>         create_pmd_mapping(nextp, va, pa, sz, prot);
>  }
>
> -static void __init create_p4d_mapping(p4d_t *p4dp,
> -                                     uintptr_t va, phys_addr_t pa,
> -                                     phys_addr_t sz, pgprot_t prot)
> +static void __meminit create_p4d_mapping(p4d_t *p4dp, uintptr_t va, phys_addr_t pa, phys_addr_t sz,
> +                                        pgprot_t prot)
>  {
>         pud_t *nextp;
>         phys_addr_t next_phys;
> @@ -653,9 +650,8 @@ static void __init create_p4d_mapping(p4d_t *p4dp,
>  #define create_pmd_mapping(__pmdp, __va, __pa, __sz, __prot) do {} while(0)
>  #endif /* __PAGETABLE_PMD_FOLDED */
>
> -void __init create_pgd_mapping(pgd_t *pgdp,
> -                                     uintptr_t va, phys_addr_t pa,
> -                                     phys_addr_t sz, pgprot_t prot)
> +void __meminit create_pgd_mapping(pgd_t *pgdp, uintptr_t va, phys_addr_t pa, phys_addr_t sz,
> +                                 pgprot_t prot)
>  {
>         pgd_next_t *nextp;
>         phys_addr_t next_phys;
> @@ -680,8 +676,7 @@ void __init create_pgd_mapping(pgd_t *pgdp,
>         create_pgd_next_mapping(nextp, va, pa, sz, prot);
>  }
>
> -static uintptr_t __init best_map_size(phys_addr_t pa, uintptr_t va,
> -                                     phys_addr_t size)
> +static uintptr_t __meminit best_map_size(phys_addr_t pa, uintptr_t va, phys_addr_t size)
>  {
>         if (pgtable_l5_enabled &&
>             !(pa & (P4D_SIZE - 1)) && !(va & (P4D_SIZE - 1)) && size >= P4D_SIZE)
> @@ -714,7 +709,7 @@ asmlinkage void __init __copy_data(void)
>  #endif
>
>  #ifdef CONFIG_STRICT_KERNEL_RWX
> -static __init pgprot_t pgprot_from_va(uintptr_t va)
> +static __meminit pgprot_t pgprot_from_va(uintptr_t va)
>  {
>         if (is_va_kernel_text(va))
>                 return PAGE_KERNEL_READ_EXEC;
> @@ -739,7 +734,7 @@ void mark_rodata_ro(void)
>                                   set_memory_ro);
>  }
>  #else
> -static __init pgprot_t pgprot_from_va(uintptr_t va)
> +static __meminit pgprot_t pgprot_from_va(uintptr_t va)
>  {
>         if (IS_ENABLED(CONFIG_64BIT) && !is_kernel_mapping(va))
>                 return PAGE_KERNEL;
> @@ -1231,9 +1226,8 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>         pt_ops_set_fixmap();
>  }
>
> -static void __init create_linear_mapping_range(phys_addr_t start,
> -                                              phys_addr_t end,
> -                                              uintptr_t fixed_map_size)
> +static void __meminit create_linear_mapping_range(phys_addr_t start, phys_addr_t end,
> +                                                 uintptr_t fixed_map_size)
>  {
>         phys_addr_t pa;
>         uintptr_t va, map_size;
> @@ -1435,7 +1429,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>          * memory hotplug, we are not able to update all the page tables with
>          * the new PMDs.
>          */
> -       return vmemmap_populate_hugepages(start, end, node, NULL);
> +       return vmemmap_populate_hugepages(start, end, node, altmap);

Is this a fix? Does this deserve to be split into another patch then?

>  }
>  #endif
>
> --
> 2.40.1
>