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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/i386/mm/mmap.c
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/i386/mm/mmap.c')
-rw-r--r--arch/i386/mm/mmap.c76
1 files changed, 76 insertions, 0 deletions
diff --git a/arch/i386/mm/mmap.c b/arch/i386/mm/mmap.c
new file mode 100644
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+++ b/arch/i386/mm/mmap.c
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+/*
+ * 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>
+
+/*
+ * 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;
+ }
+}