From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/powerpc/mm/mmap.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 103 insertions(+) create mode 100644 arch/powerpc/mm/mmap.c (limited to 'arch/powerpc/mm/mmap.c') diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c new file mode 100644 index 000000000..0f0502e12 --- /dev/null +++ b/arch/powerpc/mm/mmap.c @@ -0,0 +1,103 @@ +/* + * 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 + */ + +#include +#include +#include +#include + +/* + * Top of mmap area (just below the process stack). + * + * Leave at least a ~128 MB hole on 32bit applications. + * + * On 64bit applications we randomise the stack by 1GB so we need to + * space our mmap start address by a further 1GB, otherwise there is a + * chance the mmap area will end up closer to the stack than our ulimit + * requires. + */ +#define MIN_GAP32 (128*1024*1024) +#define MIN_GAP64 ((128 + 1024)*1024*1024UL) +#define MIN_GAP ((is_32bit_task()) ? MIN_GAP32 : MIN_GAP64) +#define MAX_GAP (TASK_SIZE/6*5) + +static inline int mmap_is_legacy(void) +{ + if (current->personality & ADDR_COMPAT_LAYOUT) + return 1; + + if (rlimit(RLIMIT_STACK) == RLIM_INFINITY) + return 1; + + return sysctl_legacy_va_layout; +} + +unsigned long arch_mmap_rnd(void) +{ + unsigned long rnd; + + /* 8MB for 32bit, 1GB for 64bit */ + if (is_32bit_task()) + rnd = (unsigned long)get_random_int() % (1<<(23-PAGE_SHIFT)); + else + rnd = (unsigned long)get_random_int() % (1<<(30-PAGE_SHIFT)); + + return rnd << PAGE_SHIFT; +} + +static inline unsigned long mmap_base(unsigned long rnd) +{ + unsigned long gap = rlimit(RLIMIT_STACK); + + if (gap < MIN_GAP) + gap = MIN_GAP; + else if (gap > MAX_GAP) + gap = MAX_GAP; + + return PAGE_ALIGN(TASK_SIZE - 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) +{ + 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()) { + mm->mmap_base = TASK_UNMAPPED_BASE; + mm->get_unmapped_area = arch_get_unmapped_area; + } else { + mm->mmap_base = mmap_base(random_factor); + mm->get_unmapped_area = arch_get_unmapped_area_topdown; + } +} -- cgit v1.2.3-54-g00ecf