arm64: hibernate: add trans_pgd public functions

trans_pgd_create_copy() and trans_pgd_map_page() are going to be
the basis for new shared code that handles page tables for cases
which are between kernels: kexec, and hibernate.

Note: Eventually, get_safe_page() will be moved into a function pointer
passed via argument, but for now keep it as is.

Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: James Morse <james.morse@arm.com>
[will: Keep these functions static until kexec needs them]
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index ce60bce..590963c 100644 (file)
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -182,39 +182,15 @@ int arch_hibernation_header_restore(void *addr)
 }
 EXPORT_SYMBOL(arch_hibernation_header_restore);
 
-/*
- * Copies length bytes, starting at src_start into an new page,
- * perform cache maintentance, then maps it at the specified address low
- * address as executable.
- *
- * This is used by hibernate to copy the code it needs to execute when
- * overwriting the kernel text. This function generates a new set of page
- * tables, which it loads into ttbr0.
- *
- * Length is provided as we probably only want 4K of data, even on a 64K
- * page system.
- */
-static int create_safe_exec_page(void *src_start, size_t length,
-                                unsigned long dst_addr,
-                                phys_addr_t *phys_dst_addr)
+static int trans_pgd_map_page(pgd_t *trans_pgd, void *page,
+                      unsigned long dst_addr,
+                      pgprot_t pgprot)
 {
-       void *page = (void *)get_safe_page(GFP_ATOMIC);
-       pgd_t *trans_pgd;
        pgd_t *pgdp;
        pud_t *pudp;
        pmd_t *pmdp;
        pte_t *ptep;
 
-       if (!page)
-               return -ENOMEM;
-
-       memcpy(page, src_start, length);
-       __flush_icache_range((unsigned long)page, (unsigned long)page + length);
-
-       trans_pgd = (void *)get_safe_page(GFP_ATOMIC);
-       if (!trans_pgd)
-               return -ENOMEM;
-
        pgdp = pgd_offset_raw(trans_pgd, dst_addr);
        if (pgd_none(READ_ONCE(*pgdp))) {
                pudp = (void *)get_safe_page(GFP_ATOMIC);
@@ -242,6 +218,44 @@ static int create_safe_exec_page(void *src_start, size_t length,
        ptep = pte_offset_kernel(pmdp, dst_addr);
        set_pte(ptep, pfn_pte(virt_to_pfn(page), PAGE_KERNEL_EXEC));
 
+       return 0;
+}
+
+/*
+ * Copies length bytes, starting at src_start into an new page,
+ * perform cache maintenance, then maps it at the specified address low
+ * address as executable.
+ *
+ * This is used by hibernate to copy the code it needs to execute when
+ * overwriting the kernel text. This function generates a new set of page
+ * tables, which it loads into ttbr0.
+ *
+ * Length is provided as we probably only want 4K of data, even on a 64K
+ * page system.
+ */
+static int create_safe_exec_page(void *src_start, size_t length,
+                                unsigned long dst_addr,
+                                phys_addr_t *phys_dst_addr)
+{
+       void *page = (void *)get_safe_page(GFP_ATOMIC);
+       pgd_t *trans_pgd;
+       int rc;
+
+       if (!page)
+               return -ENOMEM;
+
+       memcpy(page, src_start, length);
+       __flush_icache_range((unsigned long)page, (unsigned long)page + length);
+
+       trans_pgd = (void *)get_safe_page(GFP_ATOMIC);
+       if (!trans_pgd)
+               return -ENOMEM;
+
+       rc = trans_pgd_map_page(trans_pgd, page, dst_addr,
+                               PAGE_KERNEL_EXEC);
+       if (rc)
+               return rc;
+
        /*
         * Load our new page tables. A strict BBM approach requires that we
         * ensure that TLBs are free of any entries that may overlap with the
@@ -462,6 +476,24 @@ static int copy_page_tables(pgd_t *dst_pgdp, unsigned long start,
        return 0;
 }
 
+static int trans_pgd_create_copy(pgd_t **dst_pgdp, unsigned long start,
+                         unsigned long end)
+{
+       int rc;
+       pgd_t *trans_pgd = (pgd_t *)get_safe_page(GFP_ATOMIC);
+
+       if (!trans_pgd) {
+               pr_err("Failed to allocate memory for temporary page tables.\n");
+               return -ENOMEM;
+       }
+
+       rc = copy_page_tables(trans_pgd, start, end);
+       if (!rc)
+               *dst_pgdp = trans_pgd;
+
+       return rc;
+}
+
 /*
  * Setup then Resume from the hibernate image using swsusp_arch_suspend_exit().
  *
@@ -483,12 +515,7 @@ int swsusp_arch_resume(void)
         * Create a second copy of just the linear map, and use this when
         * restoring.
         */
-       tmp_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
-       if (!tmp_pg_dir) {
-               pr_err("Failed to allocate memory for temporary page tables.\n");
-               return -ENOMEM;
-       }
-       rc = copy_page_tables(tmp_pg_dir, PAGE_OFFSET, PAGE_END);
+       rc = trans_pgd_create_copy(&tmp_pg_dir, PAGE_OFFSET, PAGE_END);
        if (rc)
                return rc;