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