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    Subject[tip:x86/mm] x86/mm: Add sync_global_pgds() for configuration with 5-level paging
    Commit-ID:  141efad7d7fa4f4abb3a1b19f6a968d1b1f21903
    Gitweb: http://git.kernel.org/tip/141efad7d7fa4f4abb3a1b19f6a968d1b1f21903
    Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    AuthorDate: Tue, 6 Jun 2017 14:31:29 +0300
    Committer: Ingo Molnar <mingo@kernel.org>
    CommitDate: Tue, 13 Jun 2017 08:56:56 +0200

    x86/mm: Add sync_global_pgds() for configuration with 5-level paging

    This basically restores slightly modified version of original
    sync_global_pgds() which we had before folded p4d was introduced.

    The only modification is protection against 'addr' overflow.

    Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Dave Hansen <dave.hansen@intel.com>
    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: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: linux-arch@vger.kernel.org
    Cc: linux-mm@kvack.org
    Link: http://lkml.kernel.org/r/20170606113133.22974-11-kirill.shutemov@linux.intel.com
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    ---
    arch/x86/mm/init_64.c | 39 +++++++++++++++++++++++++++++++++++++++
    1 file changed, 39 insertions(+)

    diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
    index 95651dc..7a9497a 100644
    --- a/arch/x86/mm/init_64.c
    +++ b/arch/x86/mm/init_64.c
    @@ -92,6 +92,44 @@ __setup("noexec32=", nonx32_setup);
    * When memory was added make sure all the processes MM have
    * suitable PGD entries in the local PGD level page.
    */
    +#ifdef CONFIG_X86_5LEVEL
    +void sync_global_pgds(unsigned long start, unsigned long end)
    +{
    + unsigned long addr;
    +
    + for (addr = start; addr <= end; addr = ALIGN(addr + 1, PGDIR_SIZE)) {
    + const pgd_t *pgd_ref = pgd_offset_k(addr);
    + struct page *page;
    +
    + /* Check for overflow */
    + if (addr < start)
    + break;
    +
    + if (pgd_none(*pgd_ref))
    + continue;
    +
    + spin_lock(&pgd_lock);
    + list_for_each_entry(page, &pgd_list, lru) {
    + pgd_t *pgd;
    + spinlock_t *pgt_lock;
    +
    + pgd = (pgd_t *)page_address(page) + pgd_index(addr);
    + /* the pgt_lock only for Xen */
    + pgt_lock = &pgd_page_get_mm(page)->page_table_lock;
    + spin_lock(pgt_lock);
    +
    + if (!pgd_none(*pgd_ref) && !pgd_none(*pgd))
    + BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));
    +
    + if (pgd_none(*pgd))
    + set_pgd(pgd, *pgd_ref);
    +
    + spin_unlock(pgt_lock);
    + }
    + spin_unlock(&pgd_lock);
    + }
    +}
    +#else
    void sync_global_pgds(unsigned long start, unsigned long end)
    {
    unsigned long addr;
    @@ -135,6 +173,7 @@ void sync_global_pgds(unsigned long start, unsigned long end)
    spin_unlock(&pgd_lock);
    }
    }
    +#endif

    /*
    * NOTE: This function is marked __ref because it calls __init function
    \
     
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      Last update: 2017-06-13 12:17    [W:4.138 / U:0.916 seconds]
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