Re: [PATCH v4 04/14] arm64, mm: Move generic mmap layout functions to mm
On Sun, May 26, 2019 at 09:47:36AM -0400, Alexandre Ghiti wrote: > arm64 handles top-down mmap layout in a way that can be easily reused > by other architectures, so make it available in mm. > It then introduces a new config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT > that can be set by other architectures to benefit from those functions. > Note that this new config depends on MMU being enabled, if selected > without MMU support, a warning will be thrown. > > Suggested-by: Christoph Hellwig > Signed-off-by: Alexandre Ghiti > Reviewed-by: Christoph Hellwig Acked-by: Catalin Marinas
Re: [PATCH v4 04/14] arm64, mm: Move generic mmap layout functions to mm
On Sun, May 26, 2019 at 09:47:36AM -0400, Alexandre Ghiti wrote:
> arm64 handles top-down mmap layout in a way that can be easily reused
> by other architectures, so make it available in mm.
> It then introduces a new config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
> that can be set by other architectures to benefit from those functions.
> Note that this new config depends on MMU being enabled, if selected
> without MMU support, a warning will be thrown.
>
> Suggested-by: Christoph Hellwig
> Signed-off-by: Alexandre Ghiti
> Reviewed-by: Christoph Hellwig
Acked-by: Kees Cook
-Kees
> ---
> arch/Kconfig | 10
> arch/arm64/Kconfig | 1 +
> arch/arm64/include/asm/processor.h | 2 -
> arch/arm64/mm/mmap.c | 76 -
> kernel/sysctl.c| 6 ++-
> mm/util.c | 78 +-
> 6 files changed, 92 insertions(+), 81 deletions(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index c47b328eada0..df3ab04270fa 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -701,6 +701,16 @@ config HAVE_ARCH_COMPAT_MMAP_BASES
> and vice-versa 32-bit applications to call 64-bit mmap().
> Required for applications doing different bitness syscalls.
>
> +# This allows to use a set of generic functions to determine mmap base
> +# address by giving priority to top-down scheme only if the process
> +# is not in legacy mode (compat task, unlimited stack size or
> +# sysctl_legacy_va_layout).
> +# Architecture that selects this option can provide its own version of:
> +# - STACK_RND_MASK
> +config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
> + bool
> + depends on MMU
> +
> config HAVE_COPY_THREAD_TLS
> bool
> help
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 4780eb7af842..3d754c19c11e 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -69,6 +69,7 @@ config ARM64
> select ARCH_SUPPORTS_INT128 if GCC_VERSION >= 5 || CC_IS_CLANG
> select ARCH_SUPPORTS_NUMA_BALANCING
> select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
> + select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
> select ARCH_WANT_FRAME_POINTERS
> select ARCH_HAS_UBSAN_SANITIZE_ALL
> select ARM_AMBA
> diff --git a/arch/arm64/include/asm/processor.h
> b/arch/arm64/include/asm/processor.h
> index fcd0e691b1ea..3bd818edf319 100644
> --- a/arch/arm64/include/asm/processor.h
> +++ b/arch/arm64/include/asm/processor.h
> @@ -282,8 +282,6 @@ static inline void spin_lock_prefetch(const void *ptr)
>"nop") : : "p" (ptr));
> }
>
> -#define HAVE_ARCH_PICK_MMAP_LAYOUT
> -
> #endif
>
> extern unsigned long __ro_after_init signal_minsigstksz; /* sigframe size */
> diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
> index ac89686c4af8..c74224421216 100644
> --- a/arch/arm64/mm/mmap.c
> +++ b/arch/arm64/mm/mmap.c
> @@ -31,82 +31,6 @@
>
> #include
>
> -/*
> - * Leave enough space between the mmap area and the stack to honour ulimit in
> - * the face of randomisation.
> - */
> -#define MIN_GAP (SZ_128M)
> -#define MAX_GAP (STACK_TOP/6*5)
> -
> -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;
> -}
> -
> -unsigned long arch_mmap_rnd(void)
> -{
> - unsigned long rnd;
> -
> -#ifdef CONFIG_COMPAT
> - if (is_compat_task())
> - rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
> - else
> -#endif
> - rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
> - return rnd << PAGE_SHIFT;
> -}
> -
> -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);
> -}
> -
> -/*
> - * This function, called very early during the creation of a new process VM
> - * image, sets up which VM layout function to use:
> - */
> -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();
> -
> - /*
> - * Fall back to the standard layout if the personality bit is set, or
> - * if the expected stack growth is unlimited:
> - */
> -
[PATCH v4 04/14] arm64, mm: Move generic mmap layout functions to mm
arm64 handles top-down mmap layout in a way that can be easily reused
by other architectures, so make it available in mm.
It then introduces a new config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
that can be set by other architectures to benefit from those functions.
Note that this new config depends on MMU being enabled, if selected
without MMU support, a warning will be thrown.
Suggested-by: Christoph Hellwig
Signed-off-by: Alexandre Ghiti
Reviewed-by: Christoph Hellwig
---
arch/Kconfig | 10
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/processor.h | 2 -
arch/arm64/mm/mmap.c | 76 -
kernel/sysctl.c| 6 ++-
mm/util.c | 78 +-
6 files changed, 92 insertions(+), 81 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index c47b328eada0..df3ab04270fa 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -701,6 +701,16 @@ config HAVE_ARCH_COMPAT_MMAP_BASES
and vice-versa 32-bit applications to call 64-bit mmap().
Required for applications doing different bitness syscalls.
+# This allows to use a set of generic functions to determine mmap base
+# address by giving priority to top-down scheme only if the process
+# is not in legacy mode (compat task, unlimited stack size or
+# sysctl_legacy_va_layout).
+# Architecture that selects this option can provide its own version of:
+# - STACK_RND_MASK
+config ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
+ bool
+ depends on MMU
+
config HAVE_COPY_THREAD_TLS
bool
help
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 4780eb7af842..3d754c19c11e 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -69,6 +69,7 @@ config ARM64
select ARCH_SUPPORTS_INT128 if GCC_VERSION >= 5 || CC_IS_CLANG
select ARCH_SUPPORTS_NUMA_BALANCING
select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
+ select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
select ARCH_WANT_FRAME_POINTERS
select ARCH_HAS_UBSAN_SANITIZE_ALL
select ARM_AMBA
diff --git a/arch/arm64/include/asm/processor.h
b/arch/arm64/include/asm/processor.h
index fcd0e691b1ea..3bd818edf319 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -282,8 +282,6 @@ static inline void spin_lock_prefetch(const void *ptr)
"nop") : : "p" (ptr));
}
-#define HAVE_ARCH_PICK_MMAP_LAYOUT
-
#endif
extern unsigned long __ro_after_init signal_minsigstksz; /* sigframe size */
diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
index ac89686c4af8..c74224421216 100644
--- a/arch/arm64/mm/mmap.c
+++ b/arch/arm64/mm/mmap.c
@@ -31,82 +31,6 @@
#include
-/*
- * Leave enough space between the mmap area and the stack to honour ulimit in
- * the face of randomisation.
- */
-#define MIN_GAP (SZ_128M)
-#define MAX_GAP(STACK_TOP/6*5)
-
-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;
-}
-
-unsigned long arch_mmap_rnd(void)
-{
- unsigned long rnd;
-
-#ifdef CONFIG_COMPAT
- if (is_compat_task())
- rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1);
- else
-#endif
- rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1);
- return rnd << PAGE_SHIFT;
-}
-
-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);
-}
-
-/*
- * This function, called very early during the creation of a new process VM
- * image, sets up which VM layout function to use:
- */
-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();
-
- /*
-* Fall back to the standard layout if the personality bit is set, or
-* if the expected stack growth is unlimited:
-*/
- 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);
-
