cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ident_map.c (3372B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Helper routines for building identity mapping page tables. This is
      4 * included by both the compressed kernel and the regular kernel.
      5 */
      6
      7static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page,
      8			   unsigned long addr, unsigned long end)
      9{
     10	addr &= PMD_MASK;
     11	for (; addr < end; addr += PMD_SIZE) {
     12		pmd_t *pmd = pmd_page + pmd_index(addr);
     13
     14		if (pmd_present(*pmd))
     15			continue;
     16
     17		set_pmd(pmd, __pmd((addr - info->offset) | info->page_flag));
     18	}
     19}
     20
     21static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
     22			  unsigned long addr, unsigned long end)
     23{
     24	unsigned long next;
     25
     26	for (; addr < end; addr = next) {
     27		pud_t *pud = pud_page + pud_index(addr);
     28		pmd_t *pmd;
     29
     30		next = (addr & PUD_MASK) + PUD_SIZE;
     31		if (next > end)
     32			next = end;
     33
     34		if (info->direct_gbpages) {
     35			pud_t pudval;
     36
     37			if (pud_present(*pud))
     38				continue;
     39
     40			addr &= PUD_MASK;
     41			pudval = __pud((addr - info->offset) | info->page_flag);
     42			set_pud(pud, pudval);
     43			continue;
     44		}
     45
     46		if (pud_present(*pud)) {
     47			pmd = pmd_offset(pud, 0);
     48			ident_pmd_init(info, pmd, addr, next);
     49			continue;
     50		}
     51		pmd = (pmd_t *)info->alloc_pgt_page(info->context);
     52		if (!pmd)
     53			return -ENOMEM;
     54		ident_pmd_init(info, pmd, addr, next);
     55		set_pud(pud, __pud(__pa(pmd) | info->kernpg_flag));
     56	}
     57
     58	return 0;
     59}
     60
     61static int ident_p4d_init(struct x86_mapping_info *info, p4d_t *p4d_page,
     62			  unsigned long addr, unsigned long end)
     63{
     64	unsigned long next;
     65	int result;
     66
     67	for (; addr < end; addr = next) {
     68		p4d_t *p4d = p4d_page + p4d_index(addr);
     69		pud_t *pud;
     70
     71		next = (addr & P4D_MASK) + P4D_SIZE;
     72		if (next > end)
     73			next = end;
     74
     75		if (p4d_present(*p4d)) {
     76			pud = pud_offset(p4d, 0);
     77			result = ident_pud_init(info, pud, addr, next);
     78			if (result)
     79				return result;
     80
     81			continue;
     82		}
     83		pud = (pud_t *)info->alloc_pgt_page(info->context);
     84		if (!pud)
     85			return -ENOMEM;
     86
     87		result = ident_pud_init(info, pud, addr, next);
     88		if (result)
     89			return result;
     90
     91		set_p4d(p4d, __p4d(__pa(pud) | info->kernpg_flag));
     92	}
     93
     94	return 0;
     95}
     96
     97int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page,
     98			      unsigned long pstart, unsigned long pend)
     99{
    100	unsigned long addr = pstart + info->offset;
    101	unsigned long end = pend + info->offset;
    102	unsigned long next;
    103	int result;
    104
    105	/* Set the default pagetable flags if not supplied */
    106	if (!info->kernpg_flag)
    107		info->kernpg_flag = _KERNPG_TABLE;
    108
    109	/* Filter out unsupported __PAGE_KERNEL_* bits: */
    110	info->kernpg_flag &= __default_kernel_pte_mask;
    111
    112	for (; addr < end; addr = next) {
    113		pgd_t *pgd = pgd_page + pgd_index(addr);
    114		p4d_t *p4d;
    115
    116		next = (addr & PGDIR_MASK) + PGDIR_SIZE;
    117		if (next > end)
    118			next = end;
    119
    120		if (pgd_present(*pgd)) {
    121			p4d = p4d_offset(pgd, 0);
    122			result = ident_p4d_init(info, p4d, addr, next);
    123			if (result)
    124				return result;
    125			continue;
    126		}
    127
    128		p4d = (p4d_t *)info->alloc_pgt_page(info->context);
    129		if (!p4d)
    130			return -ENOMEM;
    131		result = ident_p4d_init(info, p4d, addr, next);
    132		if (result)
    133			return result;
    134		if (pgtable_l5_enabled()) {
    135			set_pgd(pgd, __pgd(__pa(p4d) | info->kernpg_flag));
    136		} else {
    137			/*
    138			 * With p4d folded, pgd is equal to p4d.
    139			 * The pgd entry has to point to the pud page table in this case.
    140			 */
    141			pud_t *pud = pud_offset(p4d, 0);
    142			set_pgd(pgd, __pgd(__pa(pud) | info->kernpg_flag));
    143		}
    144	}
    145
    146	return 0;
    147}