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Subject[RFC V1 01/31] mm/debug_vm_pgtable: Directly use vm_get_page_prot()
Date
Although protection_map[] contains the platform defined page protection map
, vm_get_page_prot() is the right interface to call for page protection for
a given vm_flags. Hence lets use it directly instead. This will also reduce
dependency on protection_map[].

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
mm/debug_vm_pgtable.c | 27 +++++++++++++++------------
1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index a7ac97c76762..07593eb79338 100644
--- 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.
@@ -188,7 +188,7 @@ 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;

@@ -200,7 +200,7 @@ 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.
@@ -323,7 +323,7 @@ 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;

@@ -335,7 +335,7 @@ 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.
@@ -1104,14 +1104,14 @@ 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;
@@ -1246,12 +1246,15 @@ 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 VM_NONE ..[VM_SHARED|READ|WRITE|EXEC].
*/
- for (idx = 0; idx < ARRAY_SIZE(protection_map); idx++) {
+ for (idx = VM_NONE; idx <= (VM_SHARED | VM_READ | VM_WRITE | VM_EXEC); idx++) {
pte_basic_tests(&args, idx);
pmd_basic_tests(&args, idx);
pud_basic_tests(&args, idx);
--
2.25.1
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