diff mbox series

[v3,07/11] arm: Use generic mmap top-down layout

Message ID 20190417052247.17809-8-alex@ghiti.fr (mailing list archive)
State Superseded
Headers show
Series Provide generic top-down mmap layout functions | expand

Commit Message

Alexandre Ghiti April 17, 2019, 5:22 a.m. UTC
arm uses a top-down mmap layout by default that exactly fits the generic
functions, so get rid of arch specific code and use the generic version
by selecting ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
---
 arch/arm/Kconfig                 |  1 +
 arch/arm/include/asm/processor.h |  2 --
 arch/arm/mm/mmap.c               | 62 --------------------------------
 3 files changed, 1 insertion(+), 64 deletions(-)

Comments

Kees Cook April 18, 2019, 5:28 a.m. UTC | #1
On Wed, Apr 17, 2019 at 12:30 AM Alexandre Ghiti <alex@ghiti.fr> wrote:
>
> arm uses a top-down mmap layout by default that exactly fits the generic
> functions, so get rid of arch specific code and use the generic version
> by selecting ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT.
>
> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>

Acked-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  arch/arm/Kconfig                 |  1 +
>  arch/arm/include/asm/processor.h |  2 --
>  arch/arm/mm/mmap.c               | 62 --------------------------------
>  3 files changed, 1 insertion(+), 64 deletions(-)
>
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 850b4805e2d1..f8f603da181f 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -28,6 +28,7 @@ config ARM
>         select ARCH_SUPPORTS_ATOMIC_RMW
>         select ARCH_USE_BUILTIN_BSWAP
>         select ARCH_USE_CMPXCHG_LOCKREF
> +       select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
>         select ARCH_WANT_IPC_PARSE_VERSION
>         select BUILDTIME_EXTABLE_SORT if MMU
>         select CLONE_BACKWARDS
> diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
> index 57fe73ea0f72..944ef1fb1237 100644
> --- a/arch/arm/include/asm/processor.h
> +++ b/arch/arm/include/asm/processor.h
> @@ -143,8 +143,6 @@ static inline void prefetchw(const void *ptr)
>  #endif
>  #endif
>
> -#define HAVE_ARCH_PICK_MMAP_LAYOUT
> -
>  #endif
>
>  #endif /* __ASM_ARM_PROCESSOR_H */
> diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
> index 0b94b674aa91..b8d912ac9e61 100644
> --- a/arch/arm/mm/mmap.c
> +++ b/arch/arm/mm/mmap.c
> @@ -17,43 +17,6 @@
>         ((((addr)+SHMLBA-1)&~(SHMLBA-1)) +      \
>          (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
>
> -/* gap between mmap and stack */
> -#define MIN_GAP                (128*1024*1024UL)
> -#define MAX_GAP                ((STACK_TOP)/6*5)
> -#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))
> -
> -static int mmap_is_legacy(struct rlimit *rlim_stack)
> -{
> -       if (current->personality & ADDR_COMPAT_LAYOUT)
> -               return 1;
> -
> -       if (rlim_stack->rlim_cur == RLIM_INFINITY)
> -               return 1;
> -
> -       return sysctl_legacy_va_layout;
> -}
> -
> -static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
> -{
> -       unsigned long gap = rlim_stack->rlim_cur;
> -       unsigned long pad = stack_guard_gap;
> -
> -       /* Account for stack randomization if necessary */
> -       if (current->flags & PF_RANDOMIZE)
> -               pad += (STACK_RND_MASK << PAGE_SHIFT);
> -
> -       /* Values close to RLIM_INFINITY can overflow. */
> -       if (gap + pad > gap)
> -               gap += pad;
> -
> -       if (gap < MIN_GAP)
> -               gap = MIN_GAP;
> -       else if (gap > MAX_GAP)
> -               gap = MAX_GAP;
> -
> -       return PAGE_ALIGN(STACK_TOP - gap - rnd);
> -}
> -
>  /*
>   * We need to ensure that shared mappings are correctly aligned to
>   * avoid aliasing issues with VIPT caches.  We need to ensure that
> @@ -181,31 +144,6 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
>         return addr;
>  }
>
> -unsigned long arch_mmap_rnd(void)
> -{
> -       unsigned long rnd;
> -
> -       rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
> -
> -       return rnd << PAGE_SHIFT;
> -}
> -
> -void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
> -{
> -       unsigned long random_factor = 0UL;
> -
> -       if (current->flags & PF_RANDOMIZE)
> -               random_factor = arch_mmap_rnd();
> -
> -       if (mmap_is_legacy(rlim_stack)) {
> -               mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
> -               mm->get_unmapped_area = arch_get_unmapped_area;
> -       } else {
> -               mm->mmap_base = mmap_base(random_factor, rlim_stack);
> -               mm->get_unmapped_area = arch_get_unmapped_area_topdown;
> -       }
> -}
> -
>  /*
>   * You really shouldn't be using read() or write() on /dev/mem.  This
>   * might go away in the future.
> --
> 2.20.1
>
Alexandre Ghiti April 18, 2019, 6:06 a.m. UTC | #2
On 4/18/19 1:28 AM, Kees Cook wrote:
> On Wed, Apr 17, 2019 at 12:30 AM Alexandre Ghiti <alex@ghiti.fr> wrote:
>> arm uses a top-down mmap layout by default that exactly fits the generic
>> functions, so get rid of arch specific code and use the generic version
>> by selecting ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT.
>>
>> Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
> Acked-by: Kees Cook <keescook@chromium.org>


Thanks !


>
> -Kees
>
>> ---
>>   arch/arm/Kconfig                 |  1 +
>>   arch/arm/include/asm/processor.h |  2 --
>>   arch/arm/mm/mmap.c               | 62 --------------------------------
>>   3 files changed, 1 insertion(+), 64 deletions(-)
>>
>> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
>> index 850b4805e2d1..f8f603da181f 100644
>> --- a/arch/arm/Kconfig
>> +++ b/arch/arm/Kconfig
>> @@ -28,6 +28,7 @@ config ARM
>>          select ARCH_SUPPORTS_ATOMIC_RMW
>>          select ARCH_USE_BUILTIN_BSWAP
>>          select ARCH_USE_CMPXCHG_LOCKREF
>> +       select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
>>          select ARCH_WANT_IPC_PARSE_VERSION
>>          select BUILDTIME_EXTABLE_SORT if MMU
>>          select CLONE_BACKWARDS
>> diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
>> index 57fe73ea0f72..944ef1fb1237 100644
>> --- a/arch/arm/include/asm/processor.h
>> +++ b/arch/arm/include/asm/processor.h
>> @@ -143,8 +143,6 @@ static inline void prefetchw(const void *ptr)
>>   #endif
>>   #endif
>>
>> -#define HAVE_ARCH_PICK_MMAP_LAYOUT
>> -
>>   #endif
>>
>>   #endif /* __ASM_ARM_PROCESSOR_H */
>> diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
>> index 0b94b674aa91..b8d912ac9e61 100644
>> --- a/arch/arm/mm/mmap.c
>> +++ b/arch/arm/mm/mmap.c
>> @@ -17,43 +17,6 @@
>>          ((((addr)+SHMLBA-1)&~(SHMLBA-1)) +      \
>>           (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
>>
>> -/* gap between mmap and stack */
>> -#define MIN_GAP                (128*1024*1024UL)
>> -#define MAX_GAP                ((STACK_TOP)/6*5)
>> -#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))
>> -
>> -static int mmap_is_legacy(struct rlimit *rlim_stack)
>> -{
>> -       if (current->personality & ADDR_COMPAT_LAYOUT)
>> -               return 1;
>> -
>> -       if (rlim_stack->rlim_cur == RLIM_INFINITY)
>> -               return 1;
>> -
>> -       return sysctl_legacy_va_layout;
>> -}
>> -
>> -static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
>> -{
>> -       unsigned long gap = rlim_stack->rlim_cur;
>> -       unsigned long pad = stack_guard_gap;
>> -
>> -       /* Account for stack randomization if necessary */
>> -       if (current->flags & PF_RANDOMIZE)
>> -               pad += (STACK_RND_MASK << PAGE_SHIFT);
>> -
>> -       /* Values close to RLIM_INFINITY can overflow. */
>> -       if (gap + pad > gap)
>> -               gap += pad;
>> -
>> -       if (gap < MIN_GAP)
>> -               gap = MIN_GAP;
>> -       else if (gap > MAX_GAP)
>> -               gap = MAX_GAP;
>> -
>> -       return PAGE_ALIGN(STACK_TOP - gap - rnd);
>> -}
>> -
>>   /*
>>    * We need to ensure that shared mappings are correctly aligned to
>>    * avoid aliasing issues with VIPT caches.  We need to ensure that
>> @@ -181,31 +144,6 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
>>          return addr;
>>   }
>>
>> -unsigned long arch_mmap_rnd(void)
>> -{
>> -       unsigned long rnd;
>> -
>> -       rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
>> -
>> -       return rnd << PAGE_SHIFT;
>> -}
>> -
>> -void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
>> -{
>> -       unsigned long random_factor = 0UL;
>> -
>> -       if (current->flags & PF_RANDOMIZE)
>> -               random_factor = arch_mmap_rnd();
>> -
>> -       if (mmap_is_legacy(rlim_stack)) {
>> -               mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
>> -               mm->get_unmapped_area = arch_get_unmapped_area;
>> -       } else {
>> -               mm->mmap_base = mmap_base(random_factor, rlim_stack);
>> -               mm->get_unmapped_area = arch_get_unmapped_area_topdown;
>> -       }
>> -}
>> -
>>   /*
>>    * You really shouldn't be using read() or write() on /dev/mem.  This
>>    * might go away in the future.
>> --
>> 2.20.1
>>
>
diff mbox series

Patch

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 850b4805e2d1..f8f603da181f 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -28,6 +28,7 @@  config ARM
 	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_CMPXCHG_LOCKREF
+	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select BUILDTIME_EXTABLE_SORT if MMU
 	select CLONE_BACKWARDS
diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
index 57fe73ea0f72..944ef1fb1237 100644
--- a/arch/arm/include/asm/processor.h
+++ b/arch/arm/include/asm/processor.h
@@ -143,8 +143,6 @@  static inline void prefetchw(const void *ptr)
 #endif
 #endif
 
-#define HAVE_ARCH_PICK_MMAP_LAYOUT
-
 #endif
 
 #endif /* __ASM_ARM_PROCESSOR_H */
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 0b94b674aa91..b8d912ac9e61 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -17,43 +17,6 @@ 
 	((((addr)+SHMLBA-1)&~(SHMLBA-1)) +	\
 	 (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
 
-/* gap between mmap and stack */
-#define MIN_GAP		(128*1024*1024UL)
-#define MAX_GAP		((STACK_TOP)/6*5)
-#define STACK_RND_MASK	(0x7ff >> (PAGE_SHIFT - 12))
-
-static int mmap_is_legacy(struct rlimit *rlim_stack)
-{
-	if (current->personality & ADDR_COMPAT_LAYOUT)
-		return 1;
-
-	if (rlim_stack->rlim_cur == RLIM_INFINITY)
-		return 1;
-
-	return sysctl_legacy_va_layout;
-}
-
-static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack)
-{
-	unsigned long gap = rlim_stack->rlim_cur;
-	unsigned long pad = stack_guard_gap;
-
-	/* Account for stack randomization if necessary */
-	if (current->flags & PF_RANDOMIZE)
-		pad += (STACK_RND_MASK << PAGE_SHIFT);
-
-	/* Values close to RLIM_INFINITY can overflow. */
-	if (gap + pad > gap)
-		gap += pad;
-
-	if (gap < MIN_GAP)
-		gap = MIN_GAP;
-	else if (gap > MAX_GAP)
-		gap = MAX_GAP;
-
-	return PAGE_ALIGN(STACK_TOP - gap - rnd);
-}
-
 /*
  * We need to ensure that shared mappings are correctly aligned to
  * avoid aliasing issues with VIPT caches.  We need to ensure that
@@ -181,31 +144,6 @@  arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 	return addr;
 }
 
-unsigned long arch_mmap_rnd(void)
-{
-	unsigned long rnd;
-
-	rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
-
-	return rnd << PAGE_SHIFT;
-}
-
-void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
-{
-	unsigned long random_factor = 0UL;
-
-	if (current->flags & PF_RANDOMIZE)
-		random_factor = arch_mmap_rnd();
-
-	if (mmap_is_legacy(rlim_stack)) {
-		mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
-		mm->get_unmapped_area = arch_get_unmapped_area;
-	} else {
-		mm->mmap_base = mmap_base(random_factor, rlim_stack);
-		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
-	}
-}
-
 /*
  * You really shouldn't be using read() or write() on /dev/mem.  This
  * might go away in the future.