[PATCH v6 10/11] mm: add a user_virt_to_phys symbol

Tycho Andersen
2017-09-07T17:37:16Z

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.

v6: * add a definition of user_virt_to_phys in the !CONFIG_XPFO case

CC: linux-arm-kernel@lists.infradead.org
CC: x86@kernel.org
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 | 5 +++++
3 files changed, 113 insertions(+)

diff --git a/arch/arm64/mm/xpfo.c b/arch/arm64/mm/xpfo.c
index 342a9ccb93c1..94a667d94e15 100644
--- a/arch/arm64/mm/xpfo.c
+++ b/arch/arm64/mm/xpfo.c
@@ -74,3 +74,54 @@ void xpfo_dma_map_unmap_area(bool map, const void *addr, size_t size,

xpfo_temp_unmap(addr, size, mapping, sizeof(mapping[0]) * num_pages);
}
+
+/* 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 6794d6724ab5..d24cf2c600e8 100644
--- a/arch/x86/mm/xpfo.c
+++ b/arch/x86/mm/xpfo.c
@@ -112,3 +112,60 @@ inline void xpfo_flush_kernel_tlb(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 1693af1a0293..be72da5fba26 100644
--- a/include/linux/xpfo.h
+++ b/include/linux/xpfo.h
@@ -19,6 +19,7 @@
#ifdef CONFIG_XPFO

#include <linux/dma-mapping.h>
+#include <linux/types.h>

extern struct page_ext_operations page_xpfo_ops;

@@ -45,6 +46,8 @@ void xpfo_temp_unmap(const void *addr, size_t size, void **mapping,

bool xpfo_enabled(void);

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

static inline void xpfo_kmap(void *kaddr, struct page *page) { }
@@ -69,6 +72,8 @@ static inline void xpfo_temp_unmap(const void *addr, size_t size,

static inline bool xpfo_enabled(void) { return false; }

+static inline phys_addr_t user_virt_to_phys(unsigned long addr) { return 0; }
+
#endif /* CONFIG_XPFO */

#endif /* _LINUX_XPFO_H */
--
2.11.0