mm/debug_vm_pgtable: drop protection_map[] usage

Patch series "mm: protection_map[] cleanups".

This patch (of 2):

Although protection_map[] contains the platform defined page protection
map for a given vm_flags combination, vm_get_page_prot() is the right
interface to use.  This will also reduce dependency on protection_map[]
which is going to be dropped off completely later on.

Link: https://lkml.kernel.org/r/20220404031840.588321-1-anshuman.khandual@arm.com
Link: https://lkml.kernel.org/r/20220404031840.588321-2-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index db2abd9..30fd11a 100644 (file)
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -93,7 +93,7 @@ struct pgtable_debug_args {
 
 static void __init pte_basic_tests(struct pgtable_debug_args *args, int idx)
 {
-       pgprot_t prot = protection_map[idx];
+       pgprot_t prot = vm_get_page_prot(idx);
        pte_t pte = pfn_pte(args->fixed_pte_pfn, prot);
        unsigned long val = idx, *ptr = &val;
 
@@ -101,7 +101,7 @@ static void __init pte_basic_tests(struct pgtable_debug_args *args, int idx)
 
        /*
         * This test needs to be executed after the given page table entry
-        * is created with pfn_pte() to make sure that protection_map[idx]
+        * is created with pfn_pte() to make sure that vm_get_page_prot(idx)
         * does not have the dirty bit enabled from the beginning. This is
         * important for platforms like arm64 where (!PTE_RDONLY) indicate
         * dirty bit being set.
@@ -190,7 +190,7 @@ static void __init pte_savedwrite_tests(struct pgtable_debug_args *args)
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx)
 {
-       pgprot_t prot = protection_map[idx];
+       pgprot_t prot = vm_get_page_prot(idx);
        unsigned long val = idx, *ptr = &val;
        pmd_t pmd;
 
@@ -202,7 +202,7 @@ static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx)
 
        /*
         * This test needs to be executed after the given page table entry
-        * is created with pfn_pmd() to make sure that protection_map[idx]
+        * is created with pfn_pmd() to make sure that vm_get_page_prot(idx)
         * does not have the dirty bit enabled from the beginning. This is
         * important for platforms like arm64 where (!PTE_RDONLY) indicate
         * dirty bit being set.
@@ -325,7 +325,7 @@ static void __init pmd_savedwrite_tests(struct pgtable_debug_args *args)
 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx)
 {
-       pgprot_t prot = protection_map[idx];
+       pgprot_t prot = vm_get_page_prot(idx);
        unsigned long val = idx, *ptr = &val;
        pud_t pud;
 
@@ -337,7 +337,7 @@ static void __init pud_basic_tests(struct pgtable_debug_args *args, int idx)
 
        /*
         * This test needs to be executed after the given page table entry
-        * is created with pfn_pud() to make sure that protection_map[idx]
+        * is created with pfn_pud() to make sure that vm_get_page_prot(idx)
         * does not have the dirty bit enabled from the beginning. This is
         * important for platforms like arm64 where (!PTE_RDONLY) indicate
         * dirty bit being set.
@@ -1106,14 +1106,14 @@ static int __init init_args(struct pgtable_debug_args *args)
        /*
         * Initialize the debugging data.
         *
-        * protection_map[0] (or even protection_map[8]) will help create
-        * page table entries with PROT_NONE permission as required for
-        * pxx_protnone_tests().
+        * vm_get_page_prot(VM_NONE) or vm_get_page_prot(VM_SHARED|VM_NONE)
+        * will help create page table entries with PROT_NONE permission as
+        * required for pxx_protnone_tests().
         */
        memset(args, 0, sizeof(*args));
        args->vaddr              = get_random_vaddr();
        args->page_prot          = vm_get_page_prot(VMFLAGS);
-       args->page_prot_none     = protection_map[0];
+       args->page_prot_none     = vm_get_page_prot(VM_NONE);
        args->is_contiguous_page = false;
        args->pud_pfn            = ULONG_MAX;
        args->pmd_pfn            = ULONG_MAX;
@@ -1248,12 +1248,19 @@ static int __init debug_vm_pgtable(void)
                return ret;
 
        /*
-        * Iterate over the protection_map[] to make sure that all
+        * Iterate over each possible vm_flags to make sure that all
         * the basic page table transformation validations just hold
         * true irrespective of the starting protection value for a
         * given page table entry.
+        *
+        * Protection based vm_flags combinatins are always linear
+        * and increasing i.e starting from VM_NONE and going upto
+        * (VM_SHARED | READ | WRITE | EXEC).
         */
-       for (idx = 0; idx < ARRAY_SIZE(protection_map); idx++) {
+#define VM_FLAGS_START (VM_NONE)
+#define VM_FLAGS_END   (VM_SHARED | VM_EXEC | VM_WRITE | VM_READ)
+
+       for (idx = VM_FLAGS_START; idx <= VM_FLAGS_END; idx++) {
                pte_basic_tests(&args, idx);
                pmd_basic_tests(&args, idx);
                pud_basic_tests(&args, idx);