[v1,1/2] x86/power/64: Support unaligned addresses for temporary mapping
diff mbox

Message ID 1470071280-78706-2-git-send-email-thgarnie@google.com
State New
Headers show

Commit Message

Thomas Garnier Aug. 1, 2016, 5:07 p.m. UTC
Correctly setup the temporary mapping for hibernation. Previous
implementation assumed the address was aligned on the PGD level. With
KASLR memory randomization enabled, the address is randomized on the PUD
level. This change supports unaligned address up to PMD.

Signed-off-by: Thomas Garnier <thgarnie@google.com>
---
 arch/x86/mm/ident_map.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

Comments

Rafael J. Wysocki Aug. 2, 2016, 12:36 a.m. UTC | #1
On Monday, August 01, 2016 10:07:59 AM Thomas Garnier wrote:
> Correctly setup the temporary mapping for hibernation. Previous
> implementation assumed the address was aligned on the PGD level. With
> KASLR memory randomization enabled, the address is randomized on the PUD
> level. This change supports unaligned address up to PMD.
> 
> Signed-off-by: Thomas Garnier <thgarnie@google.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

This code is shared with kexec AFAICS, so it likely is better to push it
through tip rather than through the PM tree.

> ---
>  arch/x86/mm/ident_map.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
> index ec21796..ea1ebf1 100644
> --- a/arch/x86/mm/ident_map.c
> +++ b/arch/x86/mm/ident_map.c
> @@ -3,15 +3,16 @@
>   * included by both the compressed kernel and the regular kernel.
>   */
>  
> -static void ident_pmd_init(unsigned long pmd_flag, pmd_t *pmd_page,
> +static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page,
>  			   unsigned long addr, unsigned long end)
>  {
> -	addr &= PMD_MASK;
> -	for (; addr < end; addr += PMD_SIZE) {
> -		pmd_t *pmd = pmd_page + pmd_index(addr);
> +	int off = info->kernel_mapping ? pmd_index(__PAGE_OFFSET) : 0;
> +
> +	for (addr &= PMD_MASK; addr < end; addr += PMD_SIZE) {
> +		pmd_t *pmd = pmd_page + pmd_index(addr) + off;
>  
>  		if (!pmd_present(*pmd))
> -			set_pmd(pmd, __pmd(addr | pmd_flag));
> +			set_pmd(pmd, __pmd(addr | info->pmd_flag));
>  	}
>  }
>  
> @@ -19,9 +20,10 @@ static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
>  			  unsigned long addr, unsigned long end)
>  {
>  	unsigned long next;
> +	int off = info->kernel_mapping ? pud_index(__PAGE_OFFSET) : 0;
>  
>  	for (; addr < end; addr = next) {
> -		pud_t *pud = pud_page + pud_index(addr);
> +		pud_t *pud = pud_page + pud_index(addr) + off;
>  		pmd_t *pmd;
>  
>  		next = (addr & PUD_MASK) + PUD_SIZE;
> @@ -30,13 +32,13 @@ static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
>  
>  		if (pud_present(*pud)) {
>  			pmd = pmd_offset(pud, 0);
> -			ident_pmd_init(info->pmd_flag, pmd, addr, next);
> +			ident_pmd_init(info, pmd, addr, next);
>  			continue;
>  		}
>  		pmd = (pmd_t *)info->alloc_pgt_page(info->context);
>  		if (!pmd)
>  			return -ENOMEM;
> -		ident_pmd_init(info->pmd_flag, pmd, addr, next);
> +		ident_pmd_init(info, pmd, addr, next);
>  		set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
>  	}
>  
>
Yinghai Lu Aug. 2, 2016, 5:36 p.m. UTC | #2
On Mon, Aug 1, 2016 at 10:07 AM, Thomas Garnier <thgarnie@google.com> wrote:
> Correctly setup the temporary mapping for hibernation. Previous
> implementation assumed the address was aligned on the PGD level. With
> KASLR memory randomization enabled, the address is randomized on the PUD
> level. This change supports unaligned address up to PMD.
>
> Signed-off-by: Thomas Garnier <thgarnie@google.com>
> ---
>  arch/x86/mm/ident_map.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
> index ec21796..ea1ebf1 100644
> --- a/arch/x86/mm/ident_map.c
> +++ b/arch/x86/mm/ident_map.c
> @@ -3,15 +3,16 @@
>   * included by both the compressed kernel and the regular kernel.
>   */
>
> -static void ident_pmd_init(unsigned long pmd_flag, pmd_t *pmd_page,
> +static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page,
>                            unsigned long addr, unsigned long end)
>  {
> -       addr &= PMD_MASK;
> -       for (; addr < end; addr += PMD_SIZE) {
> -               pmd_t *pmd = pmd_page + pmd_index(addr);
> +       int off = info->kernel_mapping ? pmd_index(__PAGE_OFFSET) : 0;
> +
> +       for (addr &= PMD_MASK; addr < end; addr += PMD_SIZE) {
> +               pmd_t *pmd = pmd_page + pmd_index(addr) + off;
>
>                 if (!pmd_present(*pmd))
> -                       set_pmd(pmd, __pmd(addr | pmd_flag));
> +                       set_pmd(pmd, __pmd(addr | info->pmd_flag));
>         }
>  }
>
> @@ -19,9 +20,10 @@ static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
>                           unsigned long addr, unsigned long end)
>  {
>         unsigned long next;
> +       int off = info->kernel_mapping ? pud_index(__PAGE_OFFSET) : 0;
>
>         for (; addr < end; addr = next) {
> -               pud_t *pud = pud_page + pud_index(addr);
> +               pud_t *pud = pud_page + pud_index(addr) + off;
>                 pmd_t *pmd;
>
>                 next = (addr & PUD_MASK) + PUD_SIZE;

Is there any chance for (pud_index(addr) + off) or (pmd_index(addr) + off)
bigger than 512?

Looks like we need to change the loop from phys address to virtual
address instead.
to avoid the overflow.

Thanks

Yinghai
Thomas Garnier Aug. 2, 2016, 5:48 p.m. UTC | #3
On Tue, Aug 2, 2016 at 10:36 AM, Yinghai Lu <yinghai@kernel.org> wrote:
> On Mon, Aug 1, 2016 at 10:07 AM, Thomas Garnier <thgarnie@google.com> wrote:
>> Correctly setup the temporary mapping for hibernation. Previous
>> implementation assumed the address was aligned on the PGD level. With
>> KASLR memory randomization enabled, the address is randomized on the PUD
>> level. This change supports unaligned address up to PMD.
>>
>> Signed-off-by: Thomas Garnier <thgarnie@google.com>
>> ---
>>  arch/x86/mm/ident_map.c | 18 ++++++++++--------
>>  1 file changed, 10 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
>> index ec21796..ea1ebf1 100644
>> --- a/arch/x86/mm/ident_map.c
>> +++ b/arch/x86/mm/ident_map.c
>> @@ -3,15 +3,16 @@
>>   * included by both the compressed kernel and the regular kernel.
>>   */
>>
>> -static void ident_pmd_init(unsigned long pmd_flag, pmd_t *pmd_page,
>> +static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page,
>>                            unsigned long addr, unsigned long end)
>>  {
>> -       addr &= PMD_MASK;
>> -       for (; addr < end; addr += PMD_SIZE) {
>> -               pmd_t *pmd = pmd_page + pmd_index(addr);
>> +       int off = info->kernel_mapping ? pmd_index(__PAGE_OFFSET) : 0;
>> +
>> +       for (addr &= PMD_MASK; addr < end; addr += PMD_SIZE) {
>> +               pmd_t *pmd = pmd_page + pmd_index(addr) + off;
>>
>>                 if (!pmd_present(*pmd))
>> -                       set_pmd(pmd, __pmd(addr | pmd_flag));
>> +                       set_pmd(pmd, __pmd(addr | info->pmd_flag));
>>         }
>>  }
>>
>> @@ -19,9 +20,10 @@ static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
>>                           unsigned long addr, unsigned long end)
>>  {
>>         unsigned long next;
>> +       int off = info->kernel_mapping ? pud_index(__PAGE_OFFSET) : 0;
>>
>>         for (; addr < end; addr = next) {
>> -               pud_t *pud = pud_page + pud_index(addr);
>> +               pud_t *pud = pud_page + pud_index(addr) + off;
>>                 pmd_t *pmd;
>>
>>                 next = (addr & PUD_MASK) + PUD_SIZE;
>
> Is there any chance for (pud_index(addr) + off) or (pmd_index(addr) + off)
> bigger than 512?
>
> Looks like we need to change the loop from phys address to virtual
> address instead.
> to avoid the overflow.
>

That's a good point. I will take a look at it.

> Thanks
>
> Yinghai
Yinghai Lu Aug. 2, 2016, 6:01 p.m. UTC | #4
On Mon, Aug 1, 2016 at 5:36 PM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> On Monday, August 01, 2016 10:07:59 AM Thomas Garnier wrote:
>> Correctly setup the temporary mapping for hibernation. Previous
>> implementation assumed the address was aligned on the PGD level. With
>> KASLR memory randomization enabled, the address is randomized on the PUD
>> level. This change supports unaligned address up to PMD.
>
> This code is shared with kexec AFAICS, so it likely is better to push it
> through tip rather than through the PM tree.

Only calling path via arch/x86/power/hibernate_64.c have
   kernel_mapping = true;
other two paths: arch/x86/boot/compressed/pagetable.c and
arch/x86/kernel/machine_kexec_64.c
all have kernel_mapping as false.

maybe that path need simplified kernel_physical_mapping_init() instead?

Thanks

Yinghai

Patch
diff mbox

diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
index ec21796..ea1ebf1 100644
--- a/arch/x86/mm/ident_map.c
+++ b/arch/x86/mm/ident_map.c
@@ -3,15 +3,16 @@ 
  * included by both the compressed kernel and the regular kernel.
  */
 
-static void ident_pmd_init(unsigned long pmd_flag, pmd_t *pmd_page,
+static void ident_pmd_init(struct x86_mapping_info *info, pmd_t *pmd_page,
 			   unsigned long addr, unsigned long end)
 {
-	addr &= PMD_MASK;
-	for (; addr < end; addr += PMD_SIZE) {
-		pmd_t *pmd = pmd_page + pmd_index(addr);
+	int off = info->kernel_mapping ? pmd_index(__PAGE_OFFSET) : 0;
+
+	for (addr &= PMD_MASK; addr < end; addr += PMD_SIZE) {
+		pmd_t *pmd = pmd_page + pmd_index(addr) + off;
 
 		if (!pmd_present(*pmd))
-			set_pmd(pmd, __pmd(addr | pmd_flag));
+			set_pmd(pmd, __pmd(addr | info->pmd_flag));
 	}
 }
 
@@ -19,9 +20,10 @@  static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
 			  unsigned long addr, unsigned long end)
 {
 	unsigned long next;
+	int off = info->kernel_mapping ? pud_index(__PAGE_OFFSET) : 0;
 
 	for (; addr < end; addr = next) {
-		pud_t *pud = pud_page + pud_index(addr);
+		pud_t *pud = pud_page + pud_index(addr) + off;
 		pmd_t *pmd;
 
 		next = (addr & PUD_MASK) + PUD_SIZE;
@@ -30,13 +32,13 @@  static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
 
 		if (pud_present(*pud)) {
 			pmd = pmd_offset(pud, 0);
-			ident_pmd_init(info->pmd_flag, pmd, addr, next);
+			ident_pmd_init(info, pmd, addr, next);
 			continue;
 		}
 		pmd = (pmd_t *)info->alloc_pgt_page(info->context);
 		if (!pmd)
 			return -ENOMEM;
-		ident_pmd_init(info->pmd_flag, pmd, addr, next);
+		ident_pmd_init(info, pmd, addr, next);
 		set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
 	}