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// SPDX-License-Identifier: GPL-2.0
/*
* Helper routines for building identity mapping page tables. This is
* included by both the compressed kernel and the regular kernel.
*/
static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page,
unsigned long addr, unsigned long end)
{
addr &= PMD_MASK;
for (; addr < end; addr += PMD_SIZE) {
pmd_t *pmd = pmd_page + pmd_index(addr);
if (pmd_present(*pmd))
continue;
set_pmd(pmd, __pmd((addr - info->offset) | info->page_flag));
}
}
static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
unsigned long addr, unsigned long end)
{
unsigned long next;
for (; addr < end; addr = next) {
pud_t *pud = pud_page + pud_index(addr);
pmd_t *pmd;
bool use_gbpage;
next = (addr & PUD_MASK) + PUD_SIZE;
if (next > end)
next = end;
/* if this is already a gbpage, this portion is already mapped */
if (pud_large(*pud))
continue;
/* Is using a gbpage allowed? */
use_gbpage = info->direct_gbpages;
/* Don't use gbpage if it maps more than the requested region. */
/* at the begining: */
use_gbpage &= ((addr & ~PUD_MASK) == 0);
/* ... or at the end: */
use_gbpage &= ((next & ~PUD_MASK) == 0);
/* Never overwrite existing mappings */
use_gbpage &= !pud_present(*pud);
if (use_gbpage) {
pud_t pudval;
pudval = __pud((addr - info->offset) | info->page_flag);
set_pud(pud, pudval);
continue;
}
if (pud_present(*pud)) {
pmd = pmd_offset(pud, 0);
ident_pmd_init(info, pmd, addr, next);
continue;
}
pmd = (pmd_t *)info->alloc_pgt_page(info->context);
if (!pmd)
return -ENOMEM;
ident_pmd_init(info, pmd, addr, next);
set_pud(pud, __pud(__pa(pmd) | info->kernpg_flag));
}
return 0;
}
static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page,
unsigned long addr, unsigned long end)
{
unsigned long next;
int result;
for (; addr < end; addr = next) {
p4d_t *p4d = p4d_page + p4d_index(addr);
pud_t *pud;
next = (addr & P4D_MASK) + P4D_SIZE;
if (next > end)
next = end;
if (p4d_present(*p4d)) {
pud = pud_offset(p4d, 0);
result = ident_pud_init(info, pud, addr, next);
if (result)
return result;
continue;
}
pud = (pud_t *)info->alloc_pgt_page(info->context);
if (!pud)
return -ENOMEM;
result = ident_pud_init(info, pud, addr, next);
if (result)
return result;
set_p4d(p4d, __p4d(__pa(pud) | info->kernpg_flag));
}
return 0;
}
int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
unsigned long pstart, unsigned long pend)
{
unsigned long addr = pstart + info->offset;
unsigned long end = pend + info->offset;
unsigned long next;
int result;
/* Set the default pagetable flags if not supplied */
if (!info->kernpg_flag)
info->kernpg_flag = _KERNPG_TABLE;
/* Filter out unsupported __PAGE_KERNEL_* bits: */
info->kernpg_flag &= __default_kernel_pte_mask;
for (; addr < end; addr = next) {
pgd_t *pgd = pgd_page + pgd_index(addr);
p4d_t *p4d;
next = (addr & PGDIR_MASK) + PGDIR_SIZE;
if (next > end)
next = end;
if (pgd_present(*pgd)) {
p4d = p4d_offset(pgd, 0);
result = ident_p4d_init(info, p4d, addr, next);
if (result)
return result;
continue;
}
p4d = (p4d_t *)info->alloc_pgt_page(info->context);
if (!p4d)
return -ENOMEM;
result = ident_p4d_init(info, p4d, addr, next);
if (result)
return result;
if (pgtable_l5_enabled()) {
set_pgd(pgd, __pgd(__pa(p4d) | info->kernpg_flag));
} else {
/*
* With p4d folded, pgd is equal to p4d.
* The pgd entry has to point to the pud page table in this case.
*/
pud_t *pud = pud_offset(p4d, 0);
set_pgd(pgd, __pgd(__pa(pud) | info->kernpg_flag));
}
}
return 0;
}
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