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Diffstat (limited to '')
| -rw-r--r-- | arch/powerpc/mm/mmap.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c new file mode 100644 index 000000000..ae683fdc7 --- /dev/null +++ b/arch/powerpc/mm/mmap.c @@ -0,0 +1,228 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * flexible mmap layout support + * + * Copyright 2003-2004 Red Hat Inc., Durham, North Carolina. + * All Rights Reserved. + * + * Started by Ingo Molnar <mingo@elte.hu> + */ + +#include <linux/personality.h> +#include <linux/mm.h> +#include <linux/random.h> +#include <linux/sched/signal.h> +#include <linux/sched/mm.h> +#include <linux/elf-randomize.h> +#include <linux/security.h> +#include <linux/mman.h> + +/* + * Top of mmap area (just below the process stack). + * + * Leave at least a ~128 MB hole. + */ +#define MIN_GAP (128*1024*1024) +#define MAX_GAP (TASK_SIZE/6*5) + +static inline 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; +} + +unsigned long arch_mmap_rnd(void) +{ + unsigned long shift, rnd; + + shift = mmap_rnd_bits; +#ifdef CONFIG_COMPAT + if (is_32bit_task()) + shift = mmap_rnd_compat_bits; +#endif + rnd = get_random_long() % (1ul << shift); + + return rnd << PAGE_SHIFT; +} + +static inline unsigned long stack_maxrandom_size(void) +{ + if (!(current->flags & PF_RANDOMIZE)) + return 0; + + /* 8MB for 32bit, 1GB for 64bit */ + if (is_32bit_task()) + return (1<<23); + else + return (1<<30); +} + +static inline unsigned long mmap_base(unsigned long rnd, + struct rlimit *rlim_stack) +{ + unsigned long gap = rlim_stack->rlim_cur; + unsigned long pad = stack_maxrandom_size() + stack_guard_gap; + + /* 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(DEFAULT_MAP_WINDOW - gap - rnd); +} + +#ifdef CONFIG_PPC_RADIX_MMU +/* + * Same function as generic code used only for radix, because we don't need to overload + * the generic one. But we will have to duplicate, because hash select + * HAVE_ARCH_UNMAPPED_AREA + */ +static unsigned long +radix__arch_get_unmapped_area(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, + unsigned long flags) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + int fixed = (flags & MAP_FIXED); + unsigned long high_limit; + struct vm_unmapped_area_info info; + + high_limit = DEFAULT_MAP_WINDOW; + if (addr >= high_limit || (fixed && (addr + len > high_limit))) + high_limit = TASK_SIZE; + + if (len > high_limit) + return -ENOMEM; + + if (fixed) { + if (addr > high_limit - len) + return -ENOMEM; + return addr; + } + + if (addr) { + addr = PAGE_ALIGN(addr); + vma = find_vma(mm, addr); + if (high_limit - len >= addr && addr >= mmap_min_addr && + (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + + info.flags = 0; + info.length = len; + info.low_limit = mm->mmap_base; + info.high_limit = high_limit; + info.align_mask = 0; + + return vm_unmapped_area(&info); +} + +static unsigned long +radix__arch_get_unmapped_area_topdown(struct file *filp, + const unsigned long addr0, + const unsigned long len, + const unsigned long pgoff, + const unsigned long flags) +{ + struct vm_area_struct *vma; + struct mm_struct *mm = current->mm; + unsigned long addr = addr0; + int fixed = (flags & MAP_FIXED); + unsigned long high_limit; + struct vm_unmapped_area_info info; + + high_limit = DEFAULT_MAP_WINDOW; + if (addr >= high_limit || (fixed && (addr + len > high_limit))) + high_limit = TASK_SIZE; + + if (len > high_limit) + return -ENOMEM; + + if (fixed) { + if (addr > high_limit - len) + return -ENOMEM; + return addr; + } + + if (addr) { + addr = PAGE_ALIGN(addr); + vma = find_vma(mm, addr); + if (high_limit - len >= addr && addr >= mmap_min_addr && + (!vma || addr + len <= vm_start_gap(vma))) + return addr; + } + + info.flags = VM_UNMAPPED_AREA_TOPDOWN; + info.length = len; + info.low_limit = max(PAGE_SIZE, mmap_min_addr); + info.high_limit = mm->mmap_base + (high_limit - DEFAULT_MAP_WINDOW); + info.align_mask = 0; + + addr = vm_unmapped_area(&info); + if (!(addr & ~PAGE_MASK)) + return addr; + VM_BUG_ON(addr != -ENOMEM); + + /* + * 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. + */ + return radix__arch_get_unmapped_area(filp, addr0, len, pgoff, flags); +} + +static void radix__arch_pick_mmap_layout(struct mm_struct *mm, + unsigned long random_factor, + struct rlimit *rlim_stack) +{ + if (mmap_is_legacy(rlim_stack)) { + mm->mmap_base = TASK_UNMAPPED_BASE; + mm->get_unmapped_area = radix__arch_get_unmapped_area; + } else { + mm->mmap_base = mmap_base(random_factor, rlim_stack); + mm->get_unmapped_area = radix__arch_get_unmapped_area_topdown; + } +} +#else +/* dummy */ +extern void radix__arch_pick_mmap_layout(struct mm_struct *mm, + unsigned long random_factor, + struct rlimit *rlim_stack); +#endif +/* + * 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) +{ + unsigned long random_factor = 0UL; + + if (current->flags & PF_RANDOMIZE) + random_factor = arch_mmap_rnd(); + + if (radix_enabled()) + return radix__arch_pick_mmap_layout(mm, random_factor, + rlim_stack); + /* + * Fall back to the standard layout if the personality + * bit is set, or if the expected stack growth is unlimited: + */ + if (mmap_is_legacy(rlim_stack)) { + mm->mmap_base = TASK_UNMAPPED_BASE; + 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; + } +} |