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SubjectRe: [PATCH v5 3/9] RISC-V: Implement late mapping page table allocation functions
On Thu, Aug 13, 2020 at 5:19 AM Atish Patra <atish.patra@wdc.com> wrote:
>
> Currently, page table setup is done during setup_va_final where fixmap can
> be used to create the temporary mappings. The physical frame is allocated
> from memblock_alloc_* functions. However, this won't work if page table
> mapping needs to be created for a different mm context (i.e. efi mm) at
> a later point of time.
>
> Use generic kernel page allocation function & macros for any mapping
> after setup_vm_final.
>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
> arch/riscv/mm/init.c | 130 ++++++++++++++++++++++++++++++++-----------
> 1 file changed, 99 insertions(+), 31 deletions(-)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index b75ebe8e7a92..d238cdc501ee 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -32,6 +32,17 @@ extern char _start[];
> void *dtb_early_va __initdata;
> uintptr_t dtb_early_pa __initdata;
>
> +struct pt_alloc_ops {
> + pte_t *(*get_pte_virt)(phys_addr_t pa);
> + phys_addr_t (*alloc_pte)(uintptr_t va);
> +#ifndef __PAGETABLE_PMD_FOLDED
> + pmd_t *(*get_pmd_virt)(phys_addr_t pa);
> + phys_addr_t (*alloc_pmd)(uintptr_t va);
> +#endif
> +};
> +
> +struct pt_alloc_ops pt_ops;
> +
> static void __init zone_sizes_init(void)
> {
> unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };
> @@ -211,7 +222,6 @@ EXPORT_SYMBOL(pfn_base);
> pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
> pgd_t trampoline_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
> pte_t fixmap_pte[PTRS_PER_PTE] __page_aligned_bss;
> -static bool mmu_enabled;
>
> #define MAX_EARLY_MAPPING_SIZE SZ_128M
>
> @@ -234,27 +244,46 @@ void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot)
> }
> }
>
> -static pte_t *__init get_pte_virt(phys_addr_t pa)
> +static inline pte_t *__init get_pte_virt_early(phys_addr_t pa)
> {
> - if (mmu_enabled) {
> - clear_fixmap(FIX_PTE);
> - return (pte_t *)set_fixmap_offset(FIX_PTE, pa);
> - } else {
> - return (pte_t *)((uintptr_t)pa);
> - }
> + return (pte_t *)((uintptr_t)pa);
> }
>
> -static phys_addr_t __init alloc_pte(uintptr_t va)
> +static inline pte_t *__init get_pte_virt_fixmap(phys_addr_t pa)
> +{
> + clear_fixmap(FIX_PTE);
> + return (pte_t *)set_fixmap_offset(FIX_PTE, pa);
> +}
> +
> +static inline pte_t *get_pte_virt_late(phys_addr_t pa)
> +{
> + return (pte_t *) __va(pa);
> +}
> +
> +static inline phys_addr_t __init alloc_pte_early(uintptr_t va)
> {
> /*
> * We only create PMD or PGD early mappings so we
> * should never reach here with MMU disabled.
> */
> - BUG_ON(!mmu_enabled);
> + BUG();
> +}
>
> +static inline phys_addr_t __init alloc_pte_fixmap(uintptr_t va)
> +{
> return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
> }
>
> +static phys_addr_t alloc_pte_late(uintptr_t va)
> +{
> + unsigned long vaddr;
> +
> + vaddr = __get_free_page(GFP_KERNEL);
> + if (!vaddr || !pgtable_pte_page_ctor(virt_to_page(vaddr)))
> + BUG();
> + return __pa(vaddr);
> +}
> +
> static void __init create_pte_mapping(pte_t *ptep,
> uintptr_t va, phys_addr_t pa,
> phys_addr_t sz, pgprot_t prot)
> @@ -279,28 +308,46 @@ pmd_t fixmap_pmd[PTRS_PER_PMD] __page_aligned_bss;
> #endif
> pmd_t early_pmd[PTRS_PER_PMD * NUM_EARLY_PMDS] __initdata __aligned(PAGE_SIZE);
>
> -static pmd_t *__init get_pmd_virt(phys_addr_t pa)
> +static pmd_t *__init get_pmd_virt_early(phys_addr_t pa)
> {
> - if (mmu_enabled) {
> - clear_fixmap(FIX_PMD);
> - return (pmd_t *)set_fixmap_offset(FIX_PMD, pa);
> - } else {
> - return (pmd_t *)((uintptr_t)pa);
> - }
> + /* Before MMU is enabled */
> + return (pmd_t *)((uintptr_t)pa);
> }
>
> -static phys_addr_t __init alloc_pmd(uintptr_t va)
> +static pmd_t *__init get_pmd_virt_fixmap(phys_addr_t pa)
> {
> - uintptr_t pmd_num;
> + clear_fixmap(FIX_PMD);
> + return (pmd_t *)set_fixmap_offset(FIX_PMD, pa);
> +}
> +
> +static pmd_t *get_pmd_virt_late(phys_addr_t pa)
> +{
> + return (pmd_t *) __va(pa);
> +}
>
> - if (mmu_enabled)
> - return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
> +static phys_addr_t __init alloc_pmd_early(uintptr_t va)
> +{
> + uintptr_t pmd_num;
>
> pmd_num = (va - PAGE_OFFSET) >> PGDIR_SHIFT;
> BUG_ON(pmd_num >= NUM_EARLY_PMDS);
> return (uintptr_t)&early_pmd[pmd_num * PTRS_PER_PMD];
> }
>
> +static phys_addr_t __init alloc_pmd_fixmap(uintptr_t va)
> +{
> + return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
> +}
> +
> +static phys_addr_t alloc_pmd_late(uintptr_t va)
> +{
> + unsigned long vaddr;
> +
> + vaddr = __get_free_page(GFP_KERNEL);
> + BUG_ON(!vaddr);
> + return __pa(vaddr);
> +}
> +
> static void __init create_pmd_mapping(pmd_t *pmdp,
> uintptr_t va, phys_addr_t pa,
> phys_addr_t sz, pgprot_t prot)
> @@ -316,28 +363,28 @@ static void __init create_pmd_mapping(pmd_t *pmdp,
> }
>
> if (pmd_none(pmdp[pmd_idx])) {
> - pte_phys = alloc_pte(va);
> + pte_phys = pt_ops.alloc_pte(va);
> pmdp[pmd_idx] = pfn_pmd(PFN_DOWN(pte_phys), PAGE_TABLE);
> - ptep = get_pte_virt(pte_phys);
> + ptep = pt_ops.get_pte_virt(pte_phys);
> memset(ptep, 0, PAGE_SIZE);
> } else {
> pte_phys = PFN_PHYS(_pmd_pfn(pmdp[pmd_idx]));
> - ptep = get_pte_virt(pte_phys);
> + ptep = pt_ops.get_pte_virt(pte_phys);
> }
>
> create_pte_mapping(ptep, va, pa, sz, prot);
> }
>
> #define pgd_next_t pmd_t
> -#define alloc_pgd_next(__va) alloc_pmd(__va)
> -#define get_pgd_next_virt(__pa) get_pmd_virt(__pa)
> +#define alloc_pgd_next(__va) pt_ops.alloc_pmd(__va)
> +#define get_pgd_next_virt(__pa) pt_ops.get_pmd_virt(__pa)
> #define create_pgd_next_mapping(__nextp, __va, __pa, __sz, __prot) \
> create_pmd_mapping(__nextp, __va, __pa, __sz, __prot)
> #define fixmap_pgd_next fixmap_pmd
> #else
> #define pgd_next_t pte_t
> -#define alloc_pgd_next(__va) alloc_pte(__va)
> -#define get_pgd_next_virt(__pa) get_pte_virt(__pa)
> +#define alloc_pgd_next(__va) pt_ops.alloc_pte(__va)
> +#define get_pgd_next_virt(__pa) pt_ops.get_pte_virt(__pa)
> #define create_pgd_next_mapping(__nextp, __va, __pa, __sz, __prot) \
> create_pte_mapping(__nextp, __va, __pa, __sz, __prot)
> #define fixmap_pgd_next fixmap_pte
> @@ -421,6 +468,12 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
> BUG_ON((load_pa % map_size) != 0);
> BUG_ON(load_sz > MAX_EARLY_MAPPING_SIZE);
>
> + pt_ops.alloc_pte = alloc_pte_early;
> + pt_ops.get_pte_virt = get_pte_virt_early;
> +#ifndef __PAGETABLE_PMD_FOLDED
> + pt_ops.alloc_pmd = alloc_pmd_early;
> + pt_ops.get_pmd_virt = get_pmd_virt_early;
> +#endif
> /* Setup early PGD for fixmap */
> create_pgd_mapping(early_pg_dir, FIXADDR_START,
> (uintptr_t)fixmap_pgd_next, PGDIR_SIZE, PAGE_TABLE);
> @@ -497,9 +550,16 @@ static void __init setup_vm_final(void)
> phys_addr_t pa, start, end;
> struct memblock_region *reg;
>
> - /* Set mmu_enabled flag */
> - mmu_enabled = true;
> -
> + /**
> + * MMU is enabled at this point. But page table setup is not complete yet.
> + * fixmap page table alloc functions should be used at this point
> + */
> + pt_ops.alloc_pte = alloc_pte_fixmap;
> + pt_ops.get_pte_virt = get_pte_virt_fixmap;
> +#ifndef __PAGETABLE_PMD_FOLDED
> + pt_ops.alloc_pmd = alloc_pmd_fixmap;
> + pt_ops.get_pmd_virt = get_pmd_virt_fixmap;
> +#endif
> /* Setup swapper PGD for fixmap */
> create_pgd_mapping(swapper_pg_dir, FIXADDR_START,
> __pa_symbol(fixmap_pgd_next),
> @@ -533,6 +593,14 @@ static void __init setup_vm_final(void)
> /* Move to swapper page table */
> csr_write(CSR_SATP, PFN_DOWN(__pa_symbol(swapper_pg_dir)) | SATP_MODE);
> local_flush_tlb_all();
> +
> + /* generic page allocation functions must be used to setup page table */
> + pt_ops.alloc_pte = alloc_pte_late;
> + pt_ops.get_pte_virt = get_pte_virt_late;
> +#ifndef __PAGETABLE_PMD_FOLDED
> + pt_ops.alloc_pmd = alloc_pmd_late;
> + pt_ops.get_pmd_virt = get_pmd_virt_late;
> +#endif
> }
> #else
> asmlinkage void __init setup_vm(uintptr_t dtb_pa)
> --
> 2.24.0
>

Looks good to me.

Reviewed-by: Anup Patel <anup@brainfault.org>

Regards,
Anup

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