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

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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>
This commit is contained in:
Helge Deller 2023-08-19 00:53:28 +02:00
parent 9f5ba4b3e1
commit 3033cd4307
4 changed files with 22 additions and 68 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

17
arch/parisc/Kconfig
View file

@ -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

14
arch/parisc/kernel/process.c
View file

@ -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;
}

54
arch/parisc/kernel/sys_parisc.c
View file

@ -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)

5
mm/util.c
View file

@ -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;