parisc: Use generic mmap top-down layout and brk randomization

parisc uses a top-down 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.

Note that on parisc the stack always grows up and a "unlimited stack"
simply means that the value as defined in CONFIG_STACK_MAX_DEFAULT_SIZE_MB
should be used. So RLIM_INFINITY is not an indicator to use the legacy
memory layout.

Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 4cb46d5..3a257bc 100644 (file)
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -49,6 +49,9 @@ config PARISC
        select TTY # Needed for pdc_cons.c
        select HAS_IOPORT if PCI || EISA
        select HAVE_DEBUG_STACKOVERFLOW
+       select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
+       select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
+       select HAVE_ARCH_MMAP_RND_BITS
        select HAVE_ARCH_AUDITSYSCALL
        select HAVE_ARCH_HASH
        select HAVE_ARCH_JUMP_LABEL
@@ -124,6 +127,20 @@ config TIME_LOW_RES
        depends on SMP
        default y
 
+config ARCH_MMAP_RND_BITS_MIN
+       default 18 if 64BIT
+       default 8
+
+config ARCH_MMAP_RND_COMPAT_BITS_MIN
+       default 8
+
+config ARCH_MMAP_RND_BITS_MAX
+       default 24 if 64BIT
+       default 17
+
+config ARCH_MMAP_RND_COMPAT_BITS_MAX
+       default 17
+
 # unless you want to implement ACPI on PA-RISC ... ;-)
 config PM
        bool

diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index 62f9b14..ed93bd8 100644 (file)
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -278,17 +278,3 @@ __get_wchan(struct task_struct *p)
        } while (count++ < MAX_UNWIND_ENTRIES);
        return 0;
 }
-
-static inline unsigned long brk_rnd(void)
-{
-       return (get_random_u32() & BRK_RND_MASK) << PAGE_SHIFT;
-}
-
-unsigned long arch_randomize_brk(struct mm_struct *mm)
-{
-       unsigned long ret = PAGE_ALIGN(mm->brk + brk_rnd());
-
-       if (ret < mm->brk)
-               return mm->brk;
-       return ret;
-}

diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c
index 9915062..ab896ef 100644 (file)
--- a/arch/parisc/kernel/sys_parisc.c
+++ b/arch/parisc/kernel/sys_parisc.c
@@ -161,7 +161,7 @@ static unsigned long arch_get_unmapped_area_common(struct file *filp,
        }
 
        info.flags = 0;
-       info.low_limit = mm->mmap_legacy_base;
+       info.low_limit = mm->mmap_base;
        info.high_limit = mmap_upper_limit(NULL);
        return vm_unmapped_area(&info);
 }
@@ -181,58 +181,6 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp,
                        addr, len, pgoff, flags, DOWN);
 }
 
-static int mmap_is_legacy(void)
-{
-       if (current->personality & ADDR_COMPAT_LAYOUT)
-               return 1;
-
-       /* parisc stack always grows up - so a unlimited stack should
-        * not be an indicator to use the legacy memory layout.
-        * if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
-        *      return 1;
-        */
-
-       return sysctl_legacy_va_layout;
-}
-
-static unsigned long mmap_rnd(void)
-{
-       unsigned long rnd = 0;
-
-       if (current->flags & PF_RANDOMIZE)
-               rnd = get_random_u32() & MMAP_RND_MASK;
-
-       return rnd << PAGE_SHIFT;
-}
-
-unsigned long arch_mmap_rnd(void)
-{
-       return (get_random_u32() & MMAP_RND_MASK) << PAGE_SHIFT;
-}
-
-static unsigned long mmap_legacy_base(void)
-{
-       return TASK_UNMAPPED_BASE + mmap_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)
-{
-       mm->mmap_legacy_base = mmap_legacy_base();
-       mm->mmap_base = mmap_upper_limit(rlim_stack);
-
-       if (mmap_is_legacy()) {
-               mm->mmap_base = mm->mmap_legacy_base;
-               mm->get_unmapped_area = arch_get_unmapped_area;
-       } else {
-               mm->get_unmapped_area = arch_get_unmapped_area_topdown;
-       }
-}
-
-
 asmlinkage unsigned long sys_mmap2(unsigned long addr, unsigned long len,
        unsigned long prot, unsigned long flags, unsigned long fd,
        unsigned long pgoff)

diff --git a/mm/util.c b/mm/util.c
index dd12b95..8810206 100644 (file)
--- a/mm/util.c
+++ b/mm/util.c
@@ -396,7 +396,10 @@ static int mmap_is_legacy(struct rlimit *rlim_stack)
        if (current->personality & ADDR_COMPAT_LAYOUT)
                return 1;
 
-       if (rlim_stack->rlim_cur == RLIM_INFINITY)
+       /* On parisc the stack always grows up - so a unlimited stack should
+        * not be an indicator to use the legacy memory layout. */
+       if (rlim_stack->rlim_cur == RLIM_INFINITY &&
+               !IS_ENABLED(CONFIG_STACK_GROWSUP))
                return 1;
 
        return sysctl_legacy_va_layout;