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x86/mm: Introduce kernel_ident_mapping_free()

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The helper complements kernel_ident_mapping_init(): it frees the identity
mapping that was previously allocated. It will be used in the error path to free
a partially allocated mapping or if the mapping is no longer needed.

The caller provides a struct x86_mapping_info with the free_pgd_page() callback
hooked up and the pgd_t to free.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Kai Huang <kai.huang@intel.com>
Tested-by: Tao Liu <ltao@redhat.com>
Link: https://lore.kernel.org/r/20240614095904.1345461-18-kirill.shutemov@linux.intel.com
This commit is contained in:
Kirill A. Shutemov 2024-06-14 12:59:02 +03:00 committed by Borislav Petkov (AMD)
parent 26ba7353ca
commit d88e7b3e35
2 changed files with 76 additions and 0 deletions
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3
arch/x86/include/asm/init.h
View File

@ -6,6 +6,7 @@
struct x86_mapping_info {
void *(*alloc_pgt_page)(void *); /* allocate buf for page table */
void (*free_pgt_page)(void *, void *); /* free buf for page table */
void *context; /* context for alloc_pgt_page */
unsigned long page_flag; /* page flag for PMD or PUD entry */
unsigned long offset; /* ident mapping offset */
@ -16,4 +17,6 @@ struct x86_mapping_info {
int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
unsigned long pstart, unsigned long pend);
void kernel_ident_mapping_free(struct x86_mapping_info *info, pgd_t *pgd);
#endif /* _ASM_X86_INIT_H */

73
arch/x86/mm/ident_map.c
View File

@ -4,6 +4,79 @@
* included by both the compressed kernel and the regular kernel.
*/
static void free_pte(struct x86_mapping_info *info, pmd_t *pmd)
{
pte_t *pte = pte_offset_kernel(pmd, 0);
info->free_pgt_page(pte, info->context);
}
static void free_pmd(struct x86_mapping_info *info, pud_t *pud)
{
pmd_t *pmd = pmd_offset(pud, 0);
int i;
for (i = 0; i < PTRS_PER_PMD; i++) {
if (!pmd_present(pmd[i]))
continue;
if (pmd_leaf(pmd[i]))
continue;
free_pte(info, &pmd[i]);
}
info->free_pgt_page(pmd, info->context);
}
static void free_pud(struct x86_mapping_info *info, p4d_t *p4d)
{
pud_t *pud = pud_offset(p4d, 0);
int i;
for (i = 0; i < PTRS_PER_PUD; i++) {
if (!pud_present(pud[i]))
continue;
if (pud_leaf(pud[i]))
continue;
free_pmd(info, &pud[i]);
}
info->free_pgt_page(pud, info->context);
}
static void free_p4d(struct x86_mapping_info *info, pgd_t *pgd)
{
p4d_t *p4d = p4d_offset(pgd, 0);
int i;
for (i = 0; i < PTRS_PER_P4D; i++) {
if (!p4d_present(p4d[i]))
continue;
free_pud(info, &p4d[i]);
}
if (pgtable_l5_enabled())
info->free_pgt_page(p4d, info->context);
}
void kernel_ident_mapping_free(struct x86_mapping_info *info, pgd_t *pgd)
{
int i;
for (i = 0; i < PTRS_PER_PGD; i++) {
if (!pgd_present(pgd[i]))
continue;
free_p4d(info, &pgd[i]);
}
info->free_pgt_page(pgd, info->context);
}
static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page,
unsigned long addr, unsigned long end)
{