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Diffstat (limited to 'arch/mips/mm/mmap.c')
| -rw-r--r-- | arch/mips/mm/mmap.c | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c new file mode 100644 index 000000000..233033f99 --- /dev/null +++ b/arch/mips/mm/mmap.c @@ -0,0 +1,223 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 2011 Wind River Systems, + * written by Ralf Baechle <ralf@linux-mips.org> + */ +#include <linux/compiler.h> +#include <linux/elf-randomize.h> +#include <linux/errno.h> +#include <linux/mm.h> +#include <linux/mman.h> +#include <linux/export.h> +#include <linux/personality.h> +#include <linux/random.h> +#include <linux/sched/signal.h> +#include <linux/sched/mm.h> + +unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */ +EXPORT_SYMBOL(shm_align_mask); + +/* gap between mmap and stack */ +#define MIN_GAP (128*1024*1024UL) +#define MAX_GAP ((TASK_SIZE)/6*5) +#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) + +static int mmap_is_legacy(struct rlimit *rlim_stack) +{ + if (current->personality & ADDR_COMPAT_LAYOUT) + return 1; + + if (rlim_stack->rlim_cur == RLIM_INFINITY) + return 1; + + return sysctl_legacy_va_layout; +} + +static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) +{ + unsigned long gap = rlim_stack->rlim_cur; + unsigned long pad = stack_guard_gap; + + /* Account for stack randomization if necessary */ + if (current->flags & PF_RANDOMIZE) + pad += (STACK_RND_MASK << PAGE_SHIFT); + + /* Values close to RLIM_INFINITY can overflow. */ + if (gap + pad > gap) + gap += pad; + + if (gap < MIN_GAP) + gap = MIN_GAP; + else if (gap > MAX_GAP) + gap = MAX_GAP; + + return PAGE_ALIGN(TASK_SIZE - gap - rnd); +} + +#define COLOUR_ALIGN(addr, pgoff) \ + ((((addr) + shm_align_mask) & ~shm_align_mask) + \ + (((pgoff) << PAGE_SHIFT) & shm_align_mask)) + +enum mmap_allocation_direction {UP, DOWN}; + +static unsigned long arch_get_unmapped_area_common(struct file *filp, + unsigned long addr0, unsigned long len, unsigned long pgoff, + unsigned long flags, enum mmap_allocation_direction dir) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + unsigned long addr = addr0; + int do_color_align; + struct vm_unmapped_area_info info; + + if (unlikely(len > TASK_SIZE)) + return -ENOMEM; + + if (flags & MAP_FIXED) { + /* Even MAP_FIXED mappings must reside within TASK_SIZE */ + if (TASK_SIZE - len < addr) + return -EINVAL; + + /* + * We do not accept a shared mapping if it would violate + * cache aliasing constraints. + */ + if ((flags & MAP_SHARED) && + ((addr - (pgoff << PAGE_SHIFT)) & shm_align_mask)) + return -EINVAL; + return addr; + } + + do_color_align = 0; + if (filp || (flags & MAP_SHARED)) + do_color_align = 1; + + /* requesting a specific address */ + if (addr) { + if (do_color_align) + addr = COLOUR_ALIGN(addr, pgoff); + else + addr = PAGE_ALIGN(addr); + + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && + (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + + info.length = len; + info.align_mask = do_color_align ? (PAGE_MASK & shm_align_mask) : 0; + info.align_offset = pgoff << PAGE_SHIFT; + + if (dir == DOWN) { + info.flags = VM_UNMAPPED_AREA_TOPDOWN; + info.low_limit = PAGE_SIZE; + info.high_limit = mm->mmap_base; + addr = vm_unmapped_area(&info); + + if (!(addr & ~PAGE_MASK)) + return addr; + + /* + * A failed mmap() very likely causes application failure, + * so fall back to the bottom-up function here. This scenario + * can happen with large stack limits and large mmap() + * allocations. + */ + } + + info.flags = 0; + info.low_limit = mm->mmap_base; + info.high_limit = TASK_SIZE; + return vm_unmapped_area(&info); +} + +unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0, + unsigned long len, unsigned long pgoff, unsigned long flags) +{ + return arch_get_unmapped_area_common(filp, + addr0, len, pgoff, flags, UP); +} + +/* + * There is no need to export this but sched.h declares the function as + * extern so making it static here results in an error. + */ +unsigned long arch_get_unmapped_area_topdown(struct file *filp, + unsigned long addr0, unsigned long len, unsigned long pgoff, + unsigned long flags) +{ + return arch_get_unmapped_area_common(filp, + addr0, len, pgoff, flags, DOWN); +} + +unsigned long arch_mmap_rnd(void) +{ + unsigned long rnd; + +#ifdef CONFIG_COMPAT + if (TASK_IS_32BIT_ADDR) + rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); + else +#endif /* CONFIG_COMPAT */ + rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); + + return rnd << PAGE_SHIFT; +} + +void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) +{ + unsigned long random_factor = 0UL; + + if (current->flags & PF_RANDOMIZE) + random_factor = arch_mmap_rnd(); + + if (mmap_is_legacy(rlim_stack)) { + mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; + mm->get_unmapped_area = arch_get_unmapped_area; + } else { + mm->mmap_base = mmap_base(random_factor, rlim_stack); + mm->get_unmapped_area = arch_get_unmapped_area_topdown; + } +} + +static inline unsigned long brk_rnd(void) +{ + unsigned long rnd = get_random_long(); + + rnd = rnd << PAGE_SHIFT; + /* 8MB for 32bit, 256MB for 64bit */ + if (TASK_IS_32BIT_ADDR) + rnd = rnd & 0x7ffffful; + else + rnd = rnd & 0xffffffful; + + return rnd; +} + +unsigned long arch_randomize_brk(struct mm_struct *mm) +{ + unsigned long base = mm->brk; + unsigned long ret; + + ret = PAGE_ALIGN(base + brk_rnd()); + + if (ret < mm->brk) + return mm->brk; + + return ret; +} + +int __virt_addr_valid(const volatile void *kaddr) +{ + unsigned long vaddr = (unsigned long)kaddr; + + if ((vaddr < PAGE_OFFSET) || (vaddr >= MAP_BASE)) + return 0; + + return pfn_valid(PFN_DOWN(virt_to_phys(kaddr))); +} +EXPORT_SYMBOL_GPL(__virt_addr_valid); |