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61a6bd83ab
This reverts commit1f40a46cf4. It turned out that this patch is not sufficient to enable PTI on 32 bit systems with legacy 2-level page-tables. In this paging mode the huge-page PTEs are in the top-level page-table directory, where also the mirroring to the user-space page-table happens. So every huge PTE exits twice, in the kernel and in the user page-table. That means that accessed/dirty bits need to be fetched from two PTEs in this mode to be safe, but this is not trivial to implement because it needs changes to generic code just for the sake of enabling PTI with 32-bit legacy paging. As all systems that need PTI should support PAE anyway, remove support for PTI when 32-bit legacy paging is used. Fixes:7757d607c6('x86/pti: Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32') Reported-by: Meelis Roos <mroos@linux.ee> Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: hpa@zytor.com Cc: linux-mm@kvack.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Link: https://lkml.kernel.org/r/1536922754-31379-1-git-send-email-joro@8bytes.org
115 lines
2.7 KiB
C
115 lines
2.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_PGTABLE_2LEVEL_H
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#define _ASM_X86_PGTABLE_2LEVEL_H
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#define pte_ERROR(e) \
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pr_err("%s:%d: bad pte %08lx\n", __FILE__, __LINE__, (e).pte_low)
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#define pgd_ERROR(e) \
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pr_err("%s:%d: bad pgd %08lx\n", __FILE__, __LINE__, pgd_val(e))
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/*
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* Certain architectures need to do special things when PTEs
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* within a page table are directly modified. Thus, the following
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* hook is made available.
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*/
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static inline void native_set_pte(pte_t *ptep , pte_t pte)
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{
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*ptep = pte;
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}
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static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd)
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{
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*pmdp = pmd;
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}
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static inline void native_set_pud(pud_t *pudp, pud_t pud)
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{
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}
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static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte)
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{
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native_set_pte(ptep, pte);
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}
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static inline void native_pmd_clear(pmd_t *pmdp)
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{
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native_set_pmd(pmdp, __pmd(0));
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}
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static inline void native_pud_clear(pud_t *pudp)
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{
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}
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static inline void native_pte_clear(struct mm_struct *mm,
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unsigned long addr, pte_t *xp)
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{
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*xp = native_make_pte(0);
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}
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#ifdef CONFIG_SMP
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static inline pte_t native_ptep_get_and_clear(pte_t *xp)
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{
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return __pte(xchg(&xp->pte_low, 0));
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}
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#else
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#define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp)
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#endif
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#ifdef CONFIG_SMP
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static inline pmd_t native_pmdp_get_and_clear(pmd_t *xp)
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{
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return __pmd(xchg((pmdval_t *)xp, 0));
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}
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#else
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#define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp)
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#endif
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#ifdef CONFIG_SMP
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static inline pud_t native_pudp_get_and_clear(pud_t *xp)
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{
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return __pud(xchg((pudval_t *)xp, 0));
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}
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#else
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#define native_pudp_get_and_clear(xp) native_local_pudp_get_and_clear(xp)
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#endif
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/* Bit manipulation helper on pte/pgoff entry */
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static inline unsigned long pte_bitop(unsigned long value, unsigned int rightshift,
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unsigned long mask, unsigned int leftshift)
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{
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return ((value >> rightshift) & mask) << leftshift;
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}
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/* Encode and de-code a swap entry */
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#define SWP_TYPE_BITS 5
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#define SWP_OFFSET_SHIFT (_PAGE_BIT_PROTNONE + 1)
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#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > SWP_TYPE_BITS)
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#define __swp_type(x) (((x).val >> (_PAGE_BIT_PRESENT + 1)) \
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& ((1U << SWP_TYPE_BITS) - 1))
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#define __swp_offset(x) ((x).val >> SWP_OFFSET_SHIFT)
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#define __swp_entry(type, offset) ((swp_entry_t) { \
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((type) << (_PAGE_BIT_PRESENT + 1)) \
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| ((offset) << SWP_OFFSET_SHIFT) })
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#define __pte_to_swp_entry(pte) ((swp_entry_t) { (pte).pte_low })
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#define __swp_entry_to_pte(x) ((pte_t) { .pte = (x).val })
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/* No inverted PFNs on 2 level page tables */
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static inline u64 protnone_mask(u64 val)
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{
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return 0;
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}
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static inline u64 flip_protnone_guard(u64 oldval, u64 val, u64 mask)
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{
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return val;
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}
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static inline bool __pte_needs_invert(u64 val)
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{
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return false;
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}
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#endif /* _ASM_X86_PGTABLE_2LEVEL_H */
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