[PATCH 3/3] MIPS: Do not call flush_tlb_all when setting pmd entry

Bibo Mao
2020-06-24T09:26:49Z

Function set_pmd_at is to set pmd entry, if tlb entry need to
be flushed, there exists pmdp_huge_clear_flush alike function
before set_pmd_at is called. So it is not necessary to call
flush_tlb_all in this function.

In these scenarios, tlb for the pmd range needs to be flushed:
1. privilege degrade such as wrprotect is set on the pmd entry
2. pmd entry is cleared
3. there is exception if set_pmd_at is issued by dup_mmap, since
flush_tlb_mm is called for parent process, it is not necessary
to flush tlb in function copy_huge_pmd.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
---
arch/mips/mm/pgtable-32.c | 1 -
arch/mips/mm/pgtable-64.c | 1 -
2 files changed, 2 deletions(-)

diff --git a/arch/mips/mm/pgtable-32.c b/arch/mips/mm/pgtable-32.c
index bd4b065..61891af 100644
--- a/arch/mips/mm/pgtable-32.c
+++ b/arch/mips/mm/pgtable-32.c
@@ -45,7 +45,6 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
pmd_t *pmdp, pmd_t pmd)
{
*pmdp = pmd;
- flush_tlb_all();
}
#endif /* defined(CONFIG_TRANSPARENT_HUGEPAGE) */

diff --git a/arch/mips/mm/pgtable-64.c b/arch/mips/mm/pgtable-64.c
index 183ff9f..7536f78 100644
--- a/arch/mips/mm/pgtable-64.c
+++ b/arch/mips/mm/pgtable-64.c
@@ -100,7 +100,6 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr,
pmd_t *pmdp, pmd_t pmd)
{
*pmdp = pmd;
- flush_tlb_all();
}

void __init pagetable_init(void)
--
1.8.3.1