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Subject[PATCH v5 3/9] RISC-V: Implement late mapping page table allocation functions
Date
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
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