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// SPDX-License-Identifier: GPL-2.0-only
// Copyright 2023 Google LLC
// Author: Ard Biesheuvel <ardb@google.com>
#include <linux/types.h>
#include <linux/sizes.h>
#include <asm/memory.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include "pi.h"
/**
* map_range - Map a contiguous range of physical pages into virtual memory
*
* @pte: Address of physical pointer to array of pages to
* allocate page tables from
* @start: Virtual address of the start of the range
* @end: Virtual address of the end of the range (exclusive)
* @pa: Physical address of the start of the range
* @prot: Access permissions of the range
* @level: Translation level for the mapping
* @tbl: The level @level page table to create the mappings in
* @may_use_cont: Whether the use of the contiguous attribute is allowed
* @va_offset: Offset between a physical page and its current mapping
* in the VA space
*/
void __init map_range(u64 *pte, u64 start, u64 end, u64 pa, pgprot_t prot,
int level, pte_t *tbl, bool may_use_cont, u64 va_offset)
{
u64 cmask = (level == 3) ? CONT_PTE_SIZE - 1 : U64_MAX;
u64 protval = pgprot_val(prot) & ~PTE_TYPE_MASK;
int lshift = (3 - level) * (PAGE_SHIFT - 3);
u64 lmask = (PAGE_SIZE << lshift) - 1;
start &= PAGE_MASK;
pa &= PAGE_MASK;
/* Advance tbl to the entry that covers start */
tbl += (start >> (lshift + PAGE_SHIFT)) % PTRS_PER_PTE;
/*
* Set the right block/page bits for this level unless we are
* clearing the mapping
*/
if (protval)
protval |= (level < 3) ? PMD_TYPE_SECT : PTE_TYPE_PAGE;
while (start < end) {
u64 next = min((start | lmask) + 1, PAGE_ALIGN(end));
if (level < 3 && (start | next | pa) & lmask) {
/*
* This chunk needs a finer grained mapping. Create a
* table mapping if necessary and recurse.
*/
if (pte_none(*tbl)) {
*tbl = __pte(__phys_to_pte_val(*pte) |
PMD_TYPE_TABLE | PMD_TABLE_UXN);
*pte += PTRS_PER_PTE * sizeof(pte_t);
}
map_range(pte, start, next, pa, prot, level + 1,
(pte_t *)(__pte_to_phys(*tbl) + va_offset),
may_use_cont, va_offset);
} else {
/*
* Start a contiguous range if start and pa are
* suitably aligned
*/
if (((start | pa) & cmask) == 0 && may_use_cont)
protval |= PTE_CONT;
/*
* Clear the contiguous attribute if the remaining
* range does not cover a contiguous block
*/
if ((end & ~cmask) <= start)
protval &= ~PTE_CONT;
/* Put down a block or page mapping */
*tbl = __pte(__phys_to_pte_val(pa) | protval);
}
pa += next - start;
start = next;
tbl++;
}
}
asmlinkage u64 __init create_init_idmap(pgd_t *pg_dir, pteval_t clrmask)
{
u64 ptep = (u64)pg_dir + PAGE_SIZE;
pgprot_t text_prot = PAGE_KERNEL_ROX;
pgprot_t data_prot = PAGE_KERNEL;
pgprot_val(text_prot) &= ~clrmask;
pgprot_val(data_prot) &= ~clrmask;
map_range(&ptep, (u64)_stext, (u64)__initdata_begin, (u64)_stext,
text_prot, IDMAP_ROOT_LEVEL, (pte_t *)pg_dir, false, 0);
map_range(&ptep, (u64)__initdata_begin, (u64)_end, (u64)__initdata_begin,
data_prot, IDMAP_ROOT_LEVEL, (pte_t *)pg_dir, false, 0);
return ptep;
}
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