158 lines
4.2 KiB
C
158 lines
4.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_PGALLOC_H
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#define _ASM_PGALLOC_H
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#include <linux/gfp.h>
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#include <linux/mm.h>
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#include <linux/threads.h>
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#include <asm/processor.h>
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#include <asm/fixmap.h>
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#include <asm/cache.h>
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/* Allocate the top level pgd (page directory)
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*
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* Here (for 64 bit kernels) we implement a Hybrid L2/L3 scheme: we
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* allocate the first pmd adjacent to the pgd. This means that we can
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* subtract a constant offset to get to it. The pmd and pgd sizes are
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* arranged so that a single pmd covers 4GB (giving a full 64-bit
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* process access to 8TB) so our lookups are effectively L2 for the
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* first 4GB of the kernel (i.e. for all ILP32 processes and all the
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* kernel for machines with under 4GB of memory) */
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static inline pgd_t *pgd_alloc(struct mm_struct *mm)
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{
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pgd_t *pgd = (pgd_t *)__get_free_pages(GFP_KERNEL,
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PGD_ALLOC_ORDER);
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pgd_t *actual_pgd = pgd;
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if (likely(pgd != NULL)) {
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memset(pgd, 0, PAGE_SIZE<<PGD_ALLOC_ORDER);
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#if CONFIG_PGTABLE_LEVELS == 3
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actual_pgd += PTRS_PER_PGD;
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/* Populate first pmd with allocated memory. We mark it
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* with PxD_FLAG_ATTACHED as a signal to the system that this
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* pmd entry may not be cleared. */
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__pgd_val_set(*actual_pgd, (PxD_FLAG_PRESENT |
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PxD_FLAG_VALID |
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PxD_FLAG_ATTACHED)
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+ (__u32)(__pa((unsigned long)pgd) >> PxD_VALUE_SHIFT));
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/* The first pmd entry also is marked with PxD_FLAG_ATTACHED as
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* a signal that this pmd may not be freed */
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__pgd_val_set(*pgd, PxD_FLAG_ATTACHED);
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#endif
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}
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return actual_pgd;
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}
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static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
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{
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#if CONFIG_PGTABLE_LEVELS == 3
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pgd -= PTRS_PER_PGD;
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#endif
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free_pages((unsigned long)pgd, PGD_ALLOC_ORDER);
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}
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#if CONFIG_PGTABLE_LEVELS == 3
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/* Three Level Page Table Support for pmd's */
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static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmd)
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{
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__pgd_val_set(*pgd, (PxD_FLAG_PRESENT | PxD_FLAG_VALID) +
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(__u32)(__pa((unsigned long)pmd) >> PxD_VALUE_SHIFT));
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}
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static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
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{
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pmd_t *pmd = (pmd_t *)__get_free_pages(GFP_KERNEL, PMD_ORDER);
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if (pmd)
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memset(pmd, 0, PAGE_SIZE<<PMD_ORDER);
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return pmd;
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}
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static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
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{
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if (pmd_flag(*pmd) & PxD_FLAG_ATTACHED) {
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/*
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* This is the permanent pmd attached to the pgd;
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* cannot free it.
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* Increment the counter to compensate for the decrement
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* done by generic mm code.
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*/
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mm_inc_nr_pmds(mm);
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return;
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}
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free_pages((unsigned long)pmd, PMD_ORDER);
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}
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#else
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/* Two Level Page Table Support for pmd's */
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/*
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* allocating and freeing a pmd is trivial: the 1-entry pmd is
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* inside the pgd, so has no extra memory associated with it.
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*/
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#define pmd_alloc_one(mm, addr) ({ BUG(); ((pmd_t *)2); })
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#define pmd_free(mm, x) do { } while (0)
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#define pgd_populate(mm, pmd, pte) BUG()
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#endif
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static inline void
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pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte)
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{
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#if CONFIG_PGTABLE_LEVELS == 3
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/* preserve the gateway marker if this is the beginning of
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* the permanent pmd */
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if(pmd_flag(*pmd) & PxD_FLAG_ATTACHED)
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__pmd_val_set(*pmd, (PxD_FLAG_PRESENT |
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PxD_FLAG_VALID |
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PxD_FLAG_ATTACHED)
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+ (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT));
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else
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#endif
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__pmd_val_set(*pmd, (PxD_FLAG_PRESENT | PxD_FLAG_VALID)
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+ (__u32)(__pa((unsigned long)pte) >> PxD_VALUE_SHIFT));
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}
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#define pmd_populate(mm, pmd, pte_page) \
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pmd_populate_kernel(mm, pmd, page_address(pte_page))
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#define pmd_pgtable(pmd) pmd_page(pmd)
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static inline pgtable_t
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pte_alloc_one(struct mm_struct *mm, unsigned long address)
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{
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struct page *page = alloc_page(GFP_KERNEL|__GFP_ZERO);
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if (!page)
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return NULL;
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if (!pgtable_page_ctor(page)) {
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__free_page(page);
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return NULL;
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}
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return page;
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}
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static inline pte_t *
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pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr)
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{
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pte_t *pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
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return pte;
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}
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static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
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{
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free_page((unsigned long)pte);
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}
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static inline void pte_free(struct mm_struct *mm, struct page *pte)
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{
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pgtable_page_dtor(pte);
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pte_free_kernel(mm, page_address(pte));
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}
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#define check_pgt_cache() do { } while (0)
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#endif
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