cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

hash_4k.c (3687B)

      1/*
      2 * Copyright IBM Corporation, 2015
      3 * Author Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
      4 *
      5 * This program is free software; you can redistribute it and/or modify it
      6 * under the terms of version 2 of the GNU Lesser General Public License
      7 * as published by the Free Software Foundation.
      8 *
      9 * This program is distributed in the hope that it would be useful, but
     10 * WITHOUT ANY WARRANTY; without even the implied warranty of
     11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
     12 *
     13 */
     14
     15#include <linux/mm.h>
     16#include <asm/machdep.h>
     17#include <asm/mmu.h>
     18
     19int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
     20		   pte_t *ptep, unsigned long trap, unsigned long flags,
     21		   int ssize, int subpg_prot)
     22{
     23	real_pte_t rpte;
     24	unsigned long hpte_group;
     25	unsigned long rflags, pa;
     26	unsigned long old_pte, new_pte;
     27	unsigned long vpn, hash, slot;
     28	unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
     29
     30	/*
     31	 * atomically mark the linux large page PTE busy and dirty
     32	 */
     33	do {
     34		pte_t pte = READ_ONCE(*ptep);
     35
     36		old_pte = pte_val(pte);
     37		/* If PTE busy, retry the access */
     38		if (unlikely(old_pte & H_PAGE_BUSY))
     39			return 0;
     40		/* If PTE permissions don't match, take page fault */
     41		if (unlikely(!check_pte_access(access, old_pte)))
     42			return 1;
     43		/*
     44		 * Try to lock the PTE, add ACCESSED and DIRTY if it was
     45		 * a write access. Since this is 4K insert of 64K page size
     46		 * also add H_PAGE_COMBO
     47		 */
     48		new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
     49		if (access & _PAGE_WRITE)
     50			new_pte |= _PAGE_DIRTY;
     51	} while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
     52
     53	/*
     54	 * PP bits. _PAGE_USER is already PP bit 0x2, so we only
     55	 * need to add in 0x1 if it's a read-only user page
     56	 */
     57	rflags = htab_convert_pte_flags(new_pte, flags);
     58	rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
     59
     60	if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
     61	    !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
     62		rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
     63
     64	vpn  = hpt_vpn(ea, vsid, ssize);
     65	if (unlikely(old_pte & H_PAGE_HASHPTE)) {
     66		/*
     67		 * There MIGHT be an HPTE for this pte
     68		 */
     69		unsigned long gslot = pte_get_hash_gslot(vpn, shift, ssize,
     70							 rpte, 0);
     71
     72		if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_4K,
     73					       MMU_PAGE_4K, ssize, flags) == -1)
     74			old_pte &= ~_PAGE_HPTEFLAGS;
     75	}
     76
     77	if (likely(!(old_pte & H_PAGE_HASHPTE))) {
     78
     79		pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
     80		hash = hpt_hash(vpn, shift, ssize);
     81
     82repeat:
     83		hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
     84
     85		/* Insert into the hash table, primary slot */
     86		slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
     87						MMU_PAGE_4K, MMU_PAGE_4K, ssize);
     88		/*
     89		 * Primary is full, try the secondary
     90		 */
     91		if (unlikely(slot == -1)) {
     92			hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
     93			slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
     94							rflags,
     95							HPTE_V_SECONDARY,
     96							MMU_PAGE_4K,
     97							MMU_PAGE_4K, ssize);
     98			if (slot == -1) {
     99				if (mftb() & 0x1)
    100					hpte_group = (hash & htab_hash_mask) *
    101							HPTES_PER_GROUP;
    102				mmu_hash_ops.hpte_remove(hpte_group);
    103				/*
    104				 * FIXME!! Should be try the group from which we removed ?
    105				 */
    106				goto repeat;
    107			}
    108		}
    109		/*
    110		 * Hypervisor failure. Restore old pte and return -1
    111		 * similar to __hash_page_*
    112		 */
    113		if (unlikely(slot == -2)) {
    114			*ptep = __pte(old_pte);
    115			hash_failure_debug(ea, access, vsid, trap, ssize,
    116					   MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
    117			return -1;
    118		}
    119		new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
    120		new_pte |= pte_set_hidx(ptep, rpte, 0, slot, PTRS_PER_PTE);
    121	}
    122	*ptep = __pte(new_pte & ~H_PAGE_BUSY);
    123	return 0;
    124}