[PATCH V3] mm: debug_vm_pgtable: Don't use __P000 directly

From: guoren
Date: Mon Sep 27 2021 - 02:44:56 EST


From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>

The __Pxxx/__Sxxx macros are only for protection_map[] init. All
usage of them in linux should come from protection_map array.

Because a lot of architectures would re-initilize protection_map[]
array, eg: x86-mem_encrypt, m68k-motorola, mips, arm, sparc.

Using __P000 is not rigorous.

Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>

---
Changes since V3:
- Add Reviewed-by: Anshuman Khandual
- Add Cc: Christoph Hellwig

Changes since V2:
- s/init protection_map[]/protection_map[] init/
- s/Becasue/Because/
- Remove unclear part
- Replace __P000 and __S000 with protection_map[0] and
protection_map[8]
---
mm/debug_vm_pgtable.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index 1403639302e4..228e3954b90c 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -1104,13 +1104,14 @@ static int __init init_args(struct pgtable_debug_args *args)
/*
* Initialize the debugging data.
*
- * __P000 (or even __S000) will help create page table entries with
- * PROT_NONE permission as required for pxx_protnone_tests().
+ * protection_map[0] (or even protection_map[8]) 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 = __P000;
+ args->page_prot_none = protection_map[0];
args->is_contiguous_page = false;
args->pud_pfn = ULONG_MAX;
args->pmd_pfn = ULONG_MAX;
--
2.25.1