[RFC PATCH 14/34] csky: mm: use proper set_pXd() for generic compile-time folded patable in vmalloc_fault()

[Yeoreum Yun]

We want to rework how set_pXd() behaves for generic compile-time
folded page tables by disallowing its use and triggering a
compile-time error when it is used improperly, ensuring that the actual
first-level set_pXd() function is used instead.

Since csky's PGTABLE_LEVELS always is 2, use set_pmd() instead of
set_pgd() to handle vmalloc_fault().

There should be no functional change.

Signed-off-by: Yeoreum Yun <yeoreum....@arm.com>
---
 arch/csky/mm/fault.c | 35 +++++++++++------------------------
 1 file changed, 11 insertions(+), 24 deletions(-)

diff --git a/arch/csky/mm/fault.c b/arch/csky/mm/fault.c
index 7ff4011089850..1467ea963806c 100644
--- a/arch/csky/mm/fault.c
+++ b/arch/csky/mm/fault.c
@@ -114,12 +114,12 @@ static inline void bad_area_nosemaphore(struct pt_regs 
*regs, struct mm_struct *
 
 static inline void vmalloc_fault(struct pt_regs *regs, int code, unsigned long 
addr)
 {
-       pgd_t *pgd, *pgd_k;
-       pud_t *pud, *pud_k;
-       pmd_t *pmd, *pmd_k;
-       pte_t *pte_k;
+       pmd_t *pmdp, *pmdp_k, pmd_k;
+       pte_t *ptep_k;
        int offset;
 
+       BUILD_BUG_ON(CONFIG_PGTABLE_LEVELS != 2);
+
        /* User mode accesses just cause a SIGSEGV */
        if (user_mode(regs)) {
                do_trap(regs, SIGSEGV, code, addr);
@@ -135,32 +135,19 @@ static inline void vmalloc_fault(struct pt_regs *regs, 
int code, unsigned long a
         */
        offset = pgd_index(addr);
 
-       pgd = get_pgd() + offset;
-       pgd_k = init_mm.pgd + offset;
-
-       if (!pgd_present(*pgd_k)) {
-               no_context(regs, addr);
-               return;
-       }
-       set_pgd(pgd, *pgd_k);
+       pmdp = (pmd_t *)(get_pgd() + offset);
+       pmdp_k = (pmd_t *)(init_mm.pgd + offset);
 
-       pud = (pud_t *)pgd;
-       pud_k = (pud_t *)pgd_k;
-       if (!pud_present(*pud_k)) {
+       pmd_k = *pmdp_k;
+       if (!pmd_present(pmd_k)) {
                no_context(regs, addr);
                return;
        }
 
-       pmd = pmd_offset(pud, addr);
-       pmd_k = pmd_offset(pud_k, addr);
-       if (!pmd_present(*pmd_k)) {
-               no_context(regs, addr);
-               return;
-       }
-       set_pmd(pmd, *pmd_k);
+       set_pmd(pmdp, pmd_k);
 
-       pte_k = pte_offset_kernel(pmd_k, addr);
-       if (!pte_present(*pte_k)) {
+       ptep_k = pte_offset_kernel(pmdp_k, addr);
+       if (!pte_present(*ptep_k)) {
                no_context(regs, addr);
                return;
        }
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}