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x86/pti: Enable global pages for shared areas
The entry/exit text and cpu_entry_area are mapped into userspace and the kernel. But, they are not _PAGE_GLOBAL. This creates unnecessary TLB misses. Add the _PAGE_GLOBAL flag for these areas. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kees Cook <keescook@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nadav Amit <namit@vmware.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205515.2977EE7D@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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parent
639d6aafe4
commit
0f561fce4d
2 changed files with 35 additions and 2 deletions
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@ -27,8 +27,20 @@ EXPORT_SYMBOL(get_cpu_entry_area);
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void cea_set_pte(void *cea_vaddr, phys_addr_t pa, pgprot_t flags)
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{
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unsigned long va = (unsigned long) cea_vaddr;
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pte_t pte = pfn_pte(pa >> PAGE_SHIFT, flags);
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set_pte_vaddr(va, pfn_pte(pa >> PAGE_SHIFT, flags));
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/*
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* The cpu_entry_area is shared between the user and kernel
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* page tables. All of its ptes can safely be global.
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* _PAGE_GLOBAL gets reused to help indicate PROT_NONE for
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* non-present PTEs, so be careful not to set it in that
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* case to avoid confusion.
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*/
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if (boot_cpu_has(X86_FEATURE_PGE) &&
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(pgprot_val(flags) & _PAGE_PRESENT))
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pte = pte_set_flags(pte, _PAGE_GLOBAL);
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set_pte_vaddr(va, pte);
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}
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static void __init
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@ -299,6 +299,27 @@ pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear)
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if (WARN_ON(!target_pmd))
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return;
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/*
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* Only clone present PMDs. This ensures only setting
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* _PAGE_GLOBAL on present PMDs. This should only be
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* called on well-known addresses anyway, so a non-
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* present PMD would be a surprise.
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*/
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if (WARN_ON(!(pmd_flags(*pmd) & _PAGE_PRESENT)))
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return;
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/*
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* Setting 'target_pmd' below creates a mapping in both
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* the user and kernel page tables. It is effectively
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* global, so set it as global in both copies. Note:
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* the X86_FEATURE_PGE check is not _required_ because
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* the CPU ignores _PAGE_GLOBAL when PGE is not
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* supported. The check keeps consistentency with
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* code that only set this bit when supported.
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*/
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if (boot_cpu_has(X86_FEATURE_PGE))
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*pmd = pmd_set_flags(*pmd, _PAGE_GLOBAL);
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/*
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* Copy the PMD. That is, the kernelmode and usermode
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* tables will share the last-level page tables of this
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@ -348,7 +369,7 @@ static void __init pti_clone_entry_text(void)
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{
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pti_clone_pmds((unsigned long) __entry_text_start,
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(unsigned long) __irqentry_text_end,
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_PAGE_RW | _PAGE_GLOBAL);
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_PAGE_RW);
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}
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/*
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