diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2007-10-11 11:13:49 +0200 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2007-10-11 11:13:49 +0200 |
commit | 0b690a40d30ff6924953888d43ab8e90d401fcc7 (patch) | |
tree | 2b29aca6502753da3b38857cf59339a3cf645010 /arch/i386/mm/mmap_32.c | |
parent | afb5ce0671f8b14f15525fd3e952b4a989c94a6b (diff) |
i386: prepare shared mm/mmap.c
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/i386/mm/mmap_32.c')
-rw-r--r-- | arch/i386/mm/mmap_32.c | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/arch/i386/mm/mmap_32.c b/arch/i386/mm/mmap_32.c new file mode 100644 index 00000000000..552e0847375 --- /dev/null +++ b/arch/i386/mm/mmap_32.c @@ -0,0 +1,77 @@ +/* + * linux/arch/i386/mm/mmap.c + * + * flexible mmap layout support + * + * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina. + * All Rights Reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + * + * Started by Ingo Molnar <mingo@elte.hu> + */ + +#include <linux/personality.h> +#include <linux/mm.h> +#include <linux/random.h> +#include <linux/sched.h> + +/* + * Top of mmap area (just below the process stack). + * + * Leave an at least ~128 MB hole. + */ +#define MIN_GAP (128*1024*1024) +#define MAX_GAP (TASK_SIZE/6*5) + +static inline unsigned long mmap_base(struct mm_struct *mm) +{ + unsigned long gap = current->signal->rlim[RLIMIT_STACK].rlim_cur; + unsigned long random_factor = 0; + + if (current->flags & PF_RANDOMIZE) + random_factor = get_random_int() % (1024*1024); + + if (gap < MIN_GAP) + gap = MIN_GAP; + else if (gap > MAX_GAP) + gap = MAX_GAP; + + return PAGE_ALIGN(TASK_SIZE - gap - random_factor); +} + +/* + * 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) +{ + /* + * Fall back to the standard layout if the personality + * bit is set, or if the expected stack growth is unlimited: + */ + if (sysctl_legacy_va_layout || + (current->personality & ADDR_COMPAT_LAYOUT) || + current->signal->rlim[RLIMIT_STACK].rlim_cur == RLIM_INFINITY) { + mm->mmap_base = TASK_UNMAPPED_BASE; + mm->get_unmapped_area = arch_get_unmapped_area; + mm->unmap_area = arch_unmap_area; + } else { + mm->mmap_base = mmap_base(mm); + mm->get_unmapped_area = arch_get_unmapped_area_topdown; + mm->unmap_area = arch_unmap_area_topdown; + } +} |