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RISC-V: Implement late mapping page table allocation functions
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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>
Reviewed-by: Anup Patel <anup@brainfault.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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Atish Patra authored and Palmer Dabbelt committed Oct 2, 2020
1 parent 6262f66 commit e8dcb61
Showing 1 changed file with 99 additions and 31 deletions.
130 changes: 99 additions & 31 deletions arch/riscv/mm/init.c
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,15 @@ 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
};

static void __init zone_sizes_init(void)
{
unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };
Expand Down Expand Up @@ -203,6 +212,8 @@ void __init setup_bootmem(void)
}

#ifdef CONFIG_MMU
static struct pt_alloc_ops pt_ops;

unsigned long va_pa_offset;
EXPORT_SYMBOL(va_pa_offset);
unsigned long pfn_base;
Expand All @@ -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

Expand All @@ -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)
Expand All @@ -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)
Expand All @@ -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
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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),
Expand Down Expand Up @@ -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)
Expand Down

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