diff mbox series

[SRU,B/aws,F/aws,G/aws,H/aws,1/1] arm64: pgtable: Ensure dirty bit is preserved across pte_wrprotect()

Message ID 20201217094233.335411-2-andrea.righi@canonical.com
State New
Headers show
Series arm64: prevent losing page dirty state | expand

Commit Message

Andrea Righi Dec. 17, 2020, 9:42 a.m. UTC 
From: Will Deacon <will@kernel.org>

BugLink: https://bugs.launchpad.net/bugs/1908503

With hardware dirty bit management, calling pte_wrprotect() on a writable,
dirty PTE will lose the dirty state and return a read-only, clean entry.

Move the logic from ptep_set_wrprotect() into pte_wrprotect() to ensure that
the dirty bit is preserved for writable entries, as this is required for
soft-dirty bit management if we enable it in the future.

Cc: <stable@vger.kernel.org>
Fixes: 2f4b829c625e ("arm64: Add support for hardware updates of the access and dirty pte bits")
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20201120143557.6715-3-will@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
(backported from commit ff1712f953e27f0b0718762ec17d0adb15c9fd0b)
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
---
 arch/arm64/include/asm/pgtable.h | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

Comments

Kleber Sacilotto de Souza Dec. 17, 2020, 9:49 a.m. UTC | #1 
On 17.12.20 10:42, Andrea Righi wrote:
> From: Will Deacon <will@kernel.org>
> 
> BugLink: https://bugs.launchpad.net/bugs/1908503
> 
> With hardware dirty bit management, calling pte_wrprotect() on a writable,
> dirty PTE will lose the dirty state and return a read-only, clean entry.
> 
> Move the logic from ptep_set_wrprotect() into pte_wrprotect() to ensure that
> the dirty bit is preserved for writable entries, as this is required for
> soft-dirty bit management if we enable it in the future.
> 
> Cc: <stable@vger.kernel.org>
> Fixes: 2f4b829c625e ("arm64: Add support for hardware updates of the access and dirty pte bits")
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Link: https://lore.kernel.org/r/20201120143557.6715-3-will@kernel.org
> Signed-off-by: Will Deacon <will@kernel.org>
> (backported from commit ff1712f953e27f0b0718762ec17d0adb15c9fd0b)
> Signed-off-by: Andrea Righi <andrea.righi@canonical.com>

LGTM.

Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

> ---
>   arch/arm64/include/asm/pgtable.h | 27 ++++++++++++++-------------
>   1 file changed, 14 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 41dd4b1f0ccb..32e62b60989c 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -135,13 +135,6 @@ static inline pte_t set_pte_bit(pte_t pte, pgprot_t prot)
>   	return pte;
>   }
>   
> -static inline pte_t pte_wrprotect(pte_t pte)
> -{
> -	pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
> -	pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
> -	return pte;
> -}
> -
>   static inline pte_t pte_mkwrite(pte_t pte)
>   {
>   	pte = set_pte_bit(pte, __pgprot(PTE_WRITE));
> @@ -167,6 +160,20 @@ static inline pte_t pte_mkdirty(pte_t pte)
>   	return pte;
>   }
>   
> +static inline pte_t pte_wrprotect(pte_t pte)
> +{
> +	/*
> +	 * If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
> +	 * clear), set the PTE_DIRTY bit.
> +	 */
> +	if (pte_hw_dirty(pte))
> +		pte = pte_mkdirty(pte);
> +
> +	pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
> +	pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
> +	return pte;
> +}
> +
>   static inline pte_t pte_mkold(pte_t pte)
>   {
>   	return clear_pte_bit(pte, __pgprot(PTE_AF));
> @@ -782,12 +789,6 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
>   	pte = READ_ONCE(*ptep);
>   	do {
>   		old_pte = pte;
> -		/*
> -		 * If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
> -		 * clear), set the PTE_DIRTY bit.
> -		 */
> -		if (pte_hw_dirty(pte))
> -			pte = pte_mkdirty(pte);
>   		pte = pte_wrprotect(pte);
>   		pte_val(pte) = cmpxchg_relaxed(&pte_val(*ptep),
>   					       pte_val(old_pte), pte_val(pte));
>
Kamal Mostafa Dec. 17, 2020, 4:40 p.m. UTC | #2 
LGTM -- thanks, Andrea.
 
Acked-by: Kamal Mostafa <kamal@canonical.com>

 -Kamal

On Thu, Dec 17, 2020 at 10:42:33AM +0100, Andrea Righi wrote:
> From: Will Deacon <will@kernel.org>
> 
> BugLink: https://bugs.launchpad.net/bugs/1908503
> 
> With hardware dirty bit management, calling pte_wrprotect() on a writable,
> dirty PTE will lose the dirty state and return a read-only, clean entry.
> 
> Move the logic from ptep_set_wrprotect() into pte_wrprotect() to ensure that
> the dirty bit is preserved for writable entries, as this is required for
> soft-dirty bit management if we enable it in the future.
> 
> Cc: <stable@vger.kernel.org>
> Fixes: 2f4b829c625e ("arm64: Add support for hardware updates of the access and dirty pte bits")
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Link: https://lore.kernel.org/r/20201120143557.6715-3-will@kernel.org
> Signed-off-by: Will Deacon <will@kernel.org>
> (backported from commit ff1712f953e27f0b0718762ec17d0adb15c9fd0b)
> Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
> ---
>  arch/arm64/include/asm/pgtable.h | 27 ++++++++++++++-------------
>  1 file changed, 14 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 41dd4b1f0ccb..32e62b60989c 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -135,13 +135,6 @@ static inline pte_t set_pte_bit(pte_t pte, pgprot_t prot)
>  	return pte;
>  }
>  
> -static inline pte_t pte_wrprotect(pte_t pte)
> -{
> -	pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
> -	pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
> -	return pte;
> -}
> -
>  static inline pte_t pte_mkwrite(pte_t pte)
>  {
>  	pte = set_pte_bit(pte, __pgprot(PTE_WRITE));
> @@ -167,6 +160,20 @@ static inline pte_t pte_mkdirty(pte_t pte)
>  	return pte;
>  }
>  
> +static inline pte_t pte_wrprotect(pte_t pte)
> +{
> +	/*
> +	 * If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
> +	 * clear), set the PTE_DIRTY bit.
> +	 */
> +	if (pte_hw_dirty(pte))
> +		pte = pte_mkdirty(pte);
> +
> +	pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
> +	pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
> +	return pte;
> +}
> +
>  static inline pte_t pte_mkold(pte_t pte)
>  {
>  	return clear_pte_bit(pte, __pgprot(PTE_AF));
> @@ -782,12 +789,6 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
>  	pte = READ_ONCE(*ptep);
>  	do {
>  		old_pte = pte;
> -		/*
> -		 * If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
> -		 * clear), set the PTE_DIRTY bit.
> -		 */
> -		if (pte_hw_dirty(pte))
> -			pte = pte_mkdirty(pte);
>  		pte = pte_wrprotect(pte);
>  		pte_val(pte) = cmpxchg_relaxed(&pte_val(*ptep),
>  					       pte_val(old_pte), pte_val(pte));
> -- 
> 2.29.2
> 
> 
> -- 
> kernel-team mailing list
> kernel-team@lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team
Ian May Dec. 17, 2020, 7:15 p.m. UTC | #3 
Applied to:
  bionic/linux-aws
  focal/linux-aws
  groovy/linux-aws

Thanks,
Ian

On 2020-12-17 10:42:33 , Andrea Righi wrote:
> From: Will Deacon <will@kernel.org>
> 
> BugLink: https://bugs.launchpad.net/bugs/1908503
> 
> With hardware dirty bit management, calling pte_wrprotect() on a writable,
> dirty PTE will lose the dirty state and return a read-only, clean entry.
> 
> Move the logic from ptep_set_wrprotect() into pte_wrprotect() to ensure that
> the dirty bit is preserved for writable entries, as this is required for
> soft-dirty bit management if we enable it in the future.
> 
> Cc: <stable@vger.kernel.org>
> Fixes: 2f4b829c625e ("arm64: Add support for hardware updates of the access and dirty pte bits")
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Link: https://lore.kernel.org/r/20201120143557.6715-3-will@kernel.org
> Signed-off-by: Will Deacon <will@kernel.org>
> (backported from commit ff1712f953e27f0b0718762ec17d0adb15c9fd0b)
> Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
> ---
>  arch/arm64/include/asm/pgtable.h | 27 ++++++++++++++-------------
>  1 file changed, 14 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 41dd4b1f0ccb..32e62b60989c 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -135,13 +135,6 @@ static inline pte_t set_pte_bit(pte_t pte, pgprot_t prot)
>  	return pte;
>  }
>  
> -static inline pte_t pte_wrprotect(pte_t pte)
> -{
> -	pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
> -	pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
> -	return pte;
> -}
> -
>  static inline pte_t pte_mkwrite(pte_t pte)
>  {
>  	pte = set_pte_bit(pte, __pgprot(PTE_WRITE));
> @@ -167,6 +160,20 @@ static inline pte_t pte_mkdirty(pte_t pte)
>  	return pte;
>  }
>  
> +static inline pte_t pte_wrprotect(pte_t pte)
> +{
> +	/*
> +	 * If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
> +	 * clear), set the PTE_DIRTY bit.
> +	 */
> +	if (pte_hw_dirty(pte))
> +		pte = pte_mkdirty(pte);
> +
> +	pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
> +	pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
> +	return pte;
> +}
> +
>  static inline pte_t pte_mkold(pte_t pte)
>  {
>  	return clear_pte_bit(pte, __pgprot(PTE_AF));
> @@ -782,12 +789,6 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
>  	pte = READ_ONCE(*ptep);
>  	do {
>  		old_pte = pte;
> -		/*
> -		 * If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
> -		 * clear), set the PTE_DIRTY bit.
> -		 */
> -		if (pte_hw_dirty(pte))
> -			pte = pte_mkdirty(pte);
>  		pte = pte_wrprotect(pte);
>  		pte_val(pte) = cmpxchg_relaxed(&pte_val(*ptep),
>  					       pte_val(old_pte), pte_val(pte));
> -- 
> 2.29.2
> 
> 
> -- 
> kernel-team mailing list
> kernel-team@lists.ubuntu.com
> https://lists.ubuntu.com/mailman/listinfo/kernel-team
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 41dd4b1f0ccb..32e62b60989c 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -135,13 +135,6 @@  static inline pte_t set_pte_bit(pte_t pte, pgprot_t prot)
 	return pte;
 }
 
-static inline pte_t pte_wrprotect(pte_t pte)
-{
-	pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
-	pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
-	return pte;
-}
-
 static inline pte_t pte_mkwrite(pte_t pte)
 {
 	pte = set_pte_bit(pte, __pgprot(PTE_WRITE));
@@ -167,6 +160,20 @@  static inline pte_t pte_mkdirty(pte_t pte)
 	return pte;
 }
 
+static inline pte_t pte_wrprotect(pte_t pte)
+{
+	/*
+	 * If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
+	 * clear), set the PTE_DIRTY bit.
+	 */
+	if (pte_hw_dirty(pte))
+		pte = pte_mkdirty(pte);
+
+	pte = clear_pte_bit(pte, __pgprot(PTE_WRITE));
+	pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
+	return pte;
+}
+
 static inline pte_t pte_mkold(pte_t pte)
 {
 	return clear_pte_bit(pte, __pgprot(PTE_AF));
@@ -782,12 +789,6 @@  static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
 	pte = READ_ONCE(*ptep);
 	do {
 		old_pte = pte;
-		/*
-		 * If hardware-dirty (PTE_WRITE/DBM bit set and PTE_RDONLY
-		 * clear), set the PTE_DIRTY bit.
-		 */
-		if (pte_hw_dirty(pte))
-			pte = pte_mkdirty(pte);
 		pte = pte_wrprotect(pte);
 		pte_val(pte) = cmpxchg_relaxed(&pte_val(*ptep),
 					       pte_val(old_pte), pte_val(pte));