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ace7fab7a6
A recent patch changed the format of a swap PTE.
The comment explaining the format of the swap PTE is wrong about
the bits used for the swap type field. Amusingly, the ASCII art
and the patch description are correct, but the comment itself
is wrong.
As I was looking at this, I also noticed that the
SWP_OFFSET_FIRST_BIT has an off-by-one error. This does not
really hurt anything. It just wasted a bit of space in the PTE,
giving us 2^59 bytes of addressable space in our swapfiles
instead of 2^60. But, it doesn't match with the comments, and it
wastes a bit of space, so fix it.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Fixes: 00839ee3b2 ("x86/mm: Move swap offset/type up in PTE to work around erratum")
Link: http://lkml.kernel.org/r/20160810172325.E56AD7DA@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
198 lines
5.1 KiB
C
198 lines
5.1 KiB
C
#ifndef _ASM_X86_PGTABLE_64_H
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#define _ASM_X86_PGTABLE_64_H
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#include <linux/const.h>
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#include <asm/pgtable_64_types.h>
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#ifndef __ASSEMBLY__
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/*
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* This file contains the functions and defines necessary to modify and use
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* the x86-64 page table tree.
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*/
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#include <asm/processor.h>
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#include <linux/bitops.h>
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#include <linux/threads.h>
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extern pud_t level3_kernel_pgt[512];
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extern pud_t level3_ident_pgt[512];
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extern pmd_t level2_kernel_pgt[512];
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extern pmd_t level2_fixmap_pgt[512];
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extern pmd_t level2_ident_pgt[512];
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extern pte_t level1_fixmap_pgt[512];
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extern pgd_t init_level4_pgt[];
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#define swapper_pg_dir init_level4_pgt
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extern void paging_init(void);
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#define pte_ERROR(e) \
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pr_err("%s:%d: bad pte %p(%016lx)\n", \
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__FILE__, __LINE__, &(e), pte_val(e))
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#define pmd_ERROR(e) \
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pr_err("%s:%d: bad pmd %p(%016lx)\n", \
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__FILE__, __LINE__, &(e), pmd_val(e))
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#define pud_ERROR(e) \
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pr_err("%s:%d: bad pud %p(%016lx)\n", \
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__FILE__, __LINE__, &(e), pud_val(e))
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#define pgd_ERROR(e) \
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pr_err("%s:%d: bad pgd %p(%016lx)\n", \
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__FILE__, __LINE__, &(e), pgd_val(e))
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struct mm_struct;
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void set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t new_pte);
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static inline void native_pte_clear(struct mm_struct *mm, unsigned long addr,
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pte_t *ptep)
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{
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*ptep = native_make_pte(0);
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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_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_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_pmd_clear(pmd_t *pmd)
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{
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native_set_pmd(pmd, native_make_pmd(0));
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}
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static inline pte_t native_ptep_get_and_clear(pte_t *xp)
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{
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#ifdef CONFIG_SMP
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return native_make_pte(xchg(&xp->pte, 0));
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#else
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/* native_local_ptep_get_and_clear,
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but duplicated because of cyclic dependency */
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pte_t ret = *xp;
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native_pte_clear(NULL, 0, xp);
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return ret;
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#endif
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}
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static inline pmd_t native_pmdp_get_and_clear(pmd_t *xp)
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{
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#ifdef CONFIG_SMP
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return native_make_pmd(xchg(&xp->pmd, 0));
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#else
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/* native_local_pmdp_get_and_clear,
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but duplicated because of cyclic dependency */
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pmd_t ret = *xp;
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native_pmd_clear(xp);
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return ret;
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#endif
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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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*pudp = pud;
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}
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static inline void native_pud_clear(pud_t *pud)
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{
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native_set_pud(pud, native_make_pud(0));
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}
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static inline void native_set_pgd(pgd_t *pgdp, pgd_t pgd)
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{
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*pgdp = pgd;
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}
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static inline void native_pgd_clear(pgd_t *pgd)
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{
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native_set_pgd(pgd, native_make_pgd(0));
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}
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extern void sync_global_pgds(unsigned long start, unsigned long end,
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int removed);
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/*
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* Conversion functions: convert a page and protection to a page entry,
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* and a page entry and page directory to the page they refer to.
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*/
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/*
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* Level 4 access.
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*/
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static inline int pgd_large(pgd_t pgd) { return 0; }
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#define mk_kernel_pgd(address) __pgd((address) | _KERNPG_TABLE)
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/* PUD - Level3 access */
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/* PMD - Level 2 access */
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/* PTE - Level 1 access. */
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/* x86-64 always has all page tables mapped. */
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#define pte_offset_map(dir, address) pte_offset_kernel((dir), (address))
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#define pte_unmap(pte) ((void)(pte))/* NOP */
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/*
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* Encode and de-code a swap entry
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*
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* | ... | 11| 10| 9|8|7|6|5| 4| 3|2|1|0| <- bit number
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* | ... |SW3|SW2|SW1|G|L|D|A|CD|WT|U|W|P| <- bit names
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* | OFFSET (14->63) | TYPE (9-13) |0|X|X|X| X| X|X|X|0| <- swp entry
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*
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* G (8) is aliased and used as a PROT_NONE indicator for
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* !present ptes. We need to start storing swap entries above
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* there. We also need to avoid using A and D because of an
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* erratum where they can be incorrectly set by hardware on
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* non-present PTEs.
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*/
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#define SWP_TYPE_FIRST_BIT (_PAGE_BIT_PROTNONE + 1)
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#define SWP_TYPE_BITS 5
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/* Place the offset above the type: */
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#define SWP_OFFSET_FIRST_BIT (SWP_TYPE_FIRST_BIT + SWP_TYPE_BITS)
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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 >> (SWP_TYPE_FIRST_BIT)) \
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& ((1U << SWP_TYPE_BITS) - 1))
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#define __swp_offset(x) ((x).val >> SWP_OFFSET_FIRST_BIT)
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#define __swp_entry(type, offset) ((swp_entry_t) { \
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((type) << (SWP_TYPE_FIRST_BIT)) \
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| ((offset) << SWP_OFFSET_FIRST_BIT) })
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#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val((pte)) })
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#define __swp_entry_to_pte(x) ((pte_t) { .pte = (x).val })
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extern int kern_addr_valid(unsigned long addr);
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extern void cleanup_highmap(void);
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#define HAVE_ARCH_UNMAPPED_AREA
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#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
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#define pgtable_cache_init() do { } while (0)
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#define check_pgt_cache() do { } while (0)
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#define PAGE_AGP PAGE_KERNEL_NOCACHE
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#define HAVE_PAGE_AGP 1
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/* fs/proc/kcore.c */
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#define kc_vaddr_to_offset(v) ((v) & __VIRTUAL_MASK)
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#define kc_offset_to_vaddr(o) ((o) | ~__VIRTUAL_MASK)
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#define __HAVE_ARCH_PTE_SAME
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#define vmemmap ((struct page *)VMEMMAP_START)
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extern void init_extra_mapping_uc(unsigned long phys, unsigned long size);
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extern void init_extra_mapping_wb(unsigned long phys, unsigned long size);
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#endif /* !__ASSEMBLY__ */
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#endif /* _ASM_X86_PGTABLE_64_H */
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