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    Subject[PATCH v5 09/10] mm: add a user_virt_to_phys symbol
    Date
    We need someting like this for testing XPFO. Since it's architecture
    specific, putting it in the test code is slightly awkward, so let's make it
    an arch-specific symbol and export it for use in LKDTM.

    Signed-off-by: Tycho Andersen <tycho@docker.com>
    Tested-by: Marco Benatto <marco.antonio.780@gmail.com>
    ---
    arch/arm64/mm/xpfo.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++
    arch/x86/mm/xpfo.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++
    include/linux/xpfo.h | 4 ++++
    3 files changed, 112 insertions(+)

    diff --git a/arch/arm64/mm/xpfo.c b/arch/arm64/mm/xpfo.c
    index c4deb2b720cf..a221799a9242 100644
    --- a/arch/arm64/mm/xpfo.c
    +++ b/arch/arm64/mm/xpfo.c
    @@ -107,3 +107,54 @@ inline void xpfo_dma_map_unmap_area(bool map, const void *addr, size_t size,

    local_irq_restore(flags);
    }
    +
    +/* Convert a user space virtual address to a physical address.
    + * Shamelessly copied from slow_virt_to_phys() and lookup_address() in
    + * arch/x86/mm/pageattr.c
    + */
    +phys_addr_t user_virt_to_phys(unsigned long addr)
    +{
    + phys_addr_t phys_addr;
    + unsigned long offset;
    + pgd_t *pgd;
    + p4d_t *p4d;
    + pud_t *pud;
    + pmd_t *pmd;
    + pte_t *pte;
    +
    + pgd = pgd_offset(current->mm, addr);
    + if (pgd_none(*pgd))
    + return 0;
    +
    + p4d = p4d_offset(pgd, addr);
    + if (p4d_none(*p4d))
    + return 0;
    +
    + pud = pud_offset(p4d, addr);
    + if (pud_none(*pud))
    + return 0;
    +
    + if (pud_sect(*pud) || !pud_present(*pud)) {
    + phys_addr = (unsigned long)pud_pfn(*pud) << PAGE_SHIFT;
    + offset = addr & ~PUD_MASK;
    + goto out;
    + }
    +
    + pmd = pmd_offset(pud, addr);
    + if (pmd_none(*pmd))
    + return 0;
    +
    + if (pmd_sect(*pmd) || !pmd_present(*pmd)) {
    + phys_addr = (unsigned long)pmd_pfn(*pmd) << PAGE_SHIFT;
    + offset = addr & ~PMD_MASK;
    + goto out;
    + }
    +
    + pte = pte_offset_kernel(pmd, addr);
    + phys_addr = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT;
    + offset = addr & ~PAGE_MASK;
    +
    +out:
    + return (phys_addr_t)(phys_addr | offset);
    +}
    +EXPORT_SYMBOL(user_virt_to_phys);
    diff --git a/arch/x86/mm/xpfo.c b/arch/x86/mm/xpfo.c
    index 3635b37f2fc5..a1344f27406c 100644
    --- a/arch/x86/mm/xpfo.c
    +++ b/arch/x86/mm/xpfo.c
    @@ -94,3 +94,60 @@ inline void xpfo_flush_kernel_page(struct page *page, int order)

    flush_tlb_kernel_range(kaddr, kaddr + (1 << order) * size);
    }
    +
    +/* Convert a user space virtual address to a physical address.
    + * Shamelessly copied from slow_virt_to_phys() and lookup_address() in
    + * arch/x86/mm/pageattr.c
    + */
    +phys_addr_t user_virt_to_phys(unsigned long addr)
    +{
    + phys_addr_t phys_addr;
    + unsigned long offset;
    + pgd_t *pgd;
    + p4d_t *p4d;
    + pud_t *pud;
    + pmd_t *pmd;
    + pte_t *pte;
    +
    + pgd = pgd_offset(current->mm, addr);
    + if (pgd_none(*pgd))
    + return 0;
    +
    + p4d = p4d_offset(pgd, addr);
    + if (p4d_none(*p4d))
    + return 0;
    +
    + if (p4d_large(*p4d) || !p4d_present(*p4d)) {
    + phys_addr = (unsigned long)p4d_pfn(*p4d) << PAGE_SHIFT;
    + offset = addr & ~P4D_MASK;
    + goto out;
    + }
    +
    + pud = pud_offset(p4d, addr);
    + if (pud_none(*pud))
    + return 0;
    +
    + if (pud_large(*pud) || !pud_present(*pud)) {
    + phys_addr = (unsigned long)pud_pfn(*pud) << PAGE_SHIFT;
    + offset = addr & ~PUD_MASK;
    + goto out;
    + }
    +
    + pmd = pmd_offset(pud, addr);
    + if (pmd_none(*pmd))
    + return 0;
    +
    + if (pmd_large(*pmd) || !pmd_present(*pmd)) {
    + phys_addr = (unsigned long)pmd_pfn(*pmd) << PAGE_SHIFT;
    + offset = addr & ~PMD_MASK;
    + goto out;
    + }
    +
    + pte = pte_offset_kernel(pmd, addr);
    + phys_addr = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT;
    + offset = addr & ~PAGE_MASK;
    +
    +out:
    + return (phys_addr_t)(phys_addr | offset);
    +}
    +EXPORT_SYMBOL(user_virt_to_phys);
    diff --git a/include/linux/xpfo.h b/include/linux/xpfo.h
    index 6b61f7b820f4..449cd8dbf064 100644
    --- a/include/linux/xpfo.h
    +++ b/include/linux/xpfo.h
    @@ -16,6 +16,8 @@

    #ifdef CONFIG_XPFO

    +#include <linux/types.h>
    +
    extern struct page_ext_operations page_xpfo_ops;

    void set_kpte(void *kaddr, struct page *page, pgprot_t prot);
    @@ -29,6 +31,8 @@ void xpfo_free_pages(struct page *page, int order);

    bool xpfo_page_is_unmapped(struct page *page);

    +extern phys_addr_t user_virt_to_phys(unsigned long addr);
    +
    #else /* !CONFIG_XPFO */

    static inline void xpfo_kmap(void *kaddr, struct page *page) { }
    --
    2.11.0
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