diff mbox series

[1/2] arm64/hugetlb: Use ptep_get() to get the pte value of a huge page

Message ID 6aabddaf4cae5ae2205c3a7df9b9e15dbd61b641.1652180088.git.baolin.wang@linux.alibaba.com (mailing list archive)
State New
Headers show
Series Implement arm64 specific huge_ptep_get() | expand

Commit Message

Baolin Wang May 10, 2022, 11:12 a.m. UTC 
The original huge_ptep_get() on ARM64 is just a wrapper of ptep_get(),
which will not take into account any contig-PTEs dirty and access bits.
Meanwhile we will implement a new ARM64-specific huge_ptep_get()
interface in following patch, which will take into account any contig-PTEs
dirty and access bits and only be allowed to pass the head pte of
a contig-PTE/PMD size page.

Thus change to use ptep_get() to get the pte value of a huge page as
a preparation.

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
 arch/arm64/mm/hugetlbpage.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Muchun Song May 10, 2022, 3:55 p.m. UTC | #1 
On Tue, May 10, 2022 at 07:12:52PM +0800, Baolin Wang wrote:
> The original huge_ptep_get() on ARM64 is just a wrapper of ptep_get(),
> which will not take into account any contig-PTEs dirty and access bits.
> Meanwhile we will implement a new ARM64-specific huge_ptep_get()
> interface in following patch, which will take into account any contig-PTEs
> dirty and access bits and only be allowed to pass the head pte of
> a contig-PTE/PMD size page.

IIUC, the huge_ptep_get() you have implemented in patch 2 could
handle non-head pte. It'll return the original pte without potential
AD bit. I admit it is more efficeent to use ptep_get() directly,
but the judgement here should be updated.

With this update.

Reviewed-by: Muchun Song <songmuchun@bytedance.com>

Thanks.
 
> Thus change to use ptep_get() to get the pte value of a huge page as
> a preparation.
> 
> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> ---
>  arch/arm64/mm/hugetlbpage.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index ca8e65c..be5e2f3 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -172,7 +172,7 @@ static pte_t get_clear_flush(struct mm_struct *mm,
>  			     unsigned long pgsize,
>  			     unsigned long ncontig)
>  {
> -	pte_t orig_pte = huge_ptep_get(ptep);
> +	pte_t orig_pte = ptep_get(ptep);
>  	bool valid = pte_valid(orig_pte);
>  	unsigned long i, saddr = addr;
>  
> @@ -385,7 +385,7 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
>  {
>  	int ncontig;
>  	size_t pgsize;
> -	pte_t orig_pte = huge_ptep_get(ptep);
> +	pte_t orig_pte = ptep_get(ptep);
>  
>  	if (!pte_cont(orig_pte))
>  		return ptep_get_and_clear(mm, addr, ptep);
> @@ -408,11 +408,11 @@ static int __cont_access_flags_changed(pte_t *ptep, pte_t pte, int ncontig)
>  {
>  	int i;
>  
> -	if (pte_write(pte) != pte_write(huge_ptep_get(ptep)))
> +	if (pte_write(pte) != pte_write(ptep_get(ptep)))
>  		return 1;
>  
>  	for (i = 0; i < ncontig; i++) {
> -		pte_t orig_pte = huge_ptep_get(ptep + i);
> +		pte_t orig_pte = ptep_get(ptep + i);
>  
>  		if (pte_dirty(pte) != pte_dirty(orig_pte))
>  			return 1;
> -- 
> 1.8.3.1
> 
>
Baolin Wang May 11, 2022, 1:24 a.m. UTC | #2 
On 5/10/2022 11:55 PM, Muchun Song wrote:
> On Tue, May 10, 2022 at 07:12:52PM +0800, Baolin Wang wrote:
>> The original huge_ptep_get() on ARM64 is just a wrapper of ptep_get(),
>> which will not take into account any contig-PTEs dirty and access bits.
>> Meanwhile we will implement a new ARM64-specific huge_ptep_get()
>> interface in following patch, which will take into account any contig-PTEs
>> dirty and access bits and only be allowed to pass the head pte of
>> a contig-PTE/PMD size page.
> 
> IIUC, the huge_ptep_get() you have implemented in patch 2 could
> handle non-head pte. It'll return the original pte without potential
> AD bit. I admit it is more efficeent to use ptep_get() directly,
> but the judgement here should be updated.

Ah, right. I missed the 'ncontig' will be 0 if a non-head pte passed. 
Will update the commit message in next version. Thanks for reviewing.

> 
> With this update.
> 
> Reviewed-by: Muchun Song <songmuchun@bytedance.com>
diff mbox series

Patch

diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index ca8e65c..be5e2f3 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -172,7 +172,7 @@  static pte_t get_clear_flush(struct mm_struct *mm,
 			     unsigned long pgsize,
 			     unsigned long ncontig)
 {
-	pte_t orig_pte = huge_ptep_get(ptep);
+	pte_t orig_pte = ptep_get(ptep);
 	bool valid = pte_valid(orig_pte);
 	unsigned long i, saddr = addr;
 
@@ -385,7 +385,7 @@  pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 {
 	int ncontig;
 	size_t pgsize;
-	pte_t orig_pte = huge_ptep_get(ptep);
+	pte_t orig_pte = ptep_get(ptep);
 
 	if (!pte_cont(orig_pte))
 		return ptep_get_and_clear(mm, addr, ptep);
@@ -408,11 +408,11 @@  static int __cont_access_flags_changed(pte_t *ptep, pte_t pte, int ncontig)
 {
 	int i;
 
-	if (pte_write(pte) != pte_write(huge_ptep_get(ptep)))
+	if (pte_write(pte) != pte_write(ptep_get(ptep)))
 		return 1;
 
 	for (i = 0; i < ncontig; i++) {
-		pte_t orig_pte = huge_ptep_get(ptep + i);
+		pte_t orig_pte = ptep_get(ptep + i);
 
 		if (pte_dirty(pte) != pte_dirty(orig_pte))
 			return 1;