[PATCH] riscv: mm: Remove the copy operation of pmd

From: hanchuanhua
Date: Thu Jan 27 2022 - 05:06:37 EST


Since all processes share the kernel address space,
we only need to copy pgd in case of a vmalloc page
fault exception, the other levels of page tables are
shared, so the operation of copying pmd is unnecessary.

Signed-off-by: hanchuanhua <hanchuanhua@xxxxxxxx>
---
arch/riscv/mm/fault.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index 4e9efbe..40694f0 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -102,9 +102,9 @@ static inline void bad_area(struct pt_regs *regs, struct mm_struct *mm, int code
static inline void vmalloc_fault(struct pt_regs *regs, int code, unsigned long addr)
{
pgd_t *pgd, *pgd_k;
- pud_t *pud, *pud_k;
- p4d_t *p4d, *p4d_k;
- pmd_t *pmd, *pmd_k;
+ pud_t *pud_k;
+ p4d_t *p4d_k;
+ pmd_t *pmd_k;
pte_t *pte_k;
int index;
unsigned long pfn;
@@ -132,14 +132,12 @@ static inline void vmalloc_fault(struct pt_regs *regs, int code, unsigned long a
}
set_pgd(pgd, *pgd_k);

- p4d = p4d_offset(pgd, addr);
p4d_k = p4d_offset(pgd_k, addr);
if (!p4d_present(*p4d_k)) {
no_context(regs, addr);
return;
}

- pud = pud_offset(p4d, addr);
pud_k = pud_offset(p4d_k, addr);
if (!pud_present(*pud_k)) {
no_context(regs, addr);
@@ -150,13 +148,11 @@ static inline void vmalloc_fault(struct pt_regs *regs, int code, unsigned long a
* Since the vmalloc area is global, it is unnecessary
* to copy individual PTEs
*/
- 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);

/*
* Make sure the actual PTE exists as well to
--
2.7.4

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