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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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712fa5f294
Factor out check_asce_limit() function and fix few style defects in arch_get_unmapped_area() family of functions. Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> [heiko.carstens@de.ibm.com: small coding style changes] Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
192 lines
4.7 KiB
C
192 lines
4.7 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* flexible mmap layout support
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*
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* Copyright 2003-2004 Red Hat Inc., Durham, North Carolina.
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* All Rights Reserved.
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*
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* Started by Ingo Molnar <mingo@elte.hu>
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*/
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#include <linux/elf-randomize.h>
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#include <linux/personality.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/mm.h>
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#include <linux/random.h>
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#include <linux/compat.h>
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#include <linux/security.h>
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#include <asm/pgalloc.h>
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#include <asm/elf.h>
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static unsigned long stack_maxrandom_size(void)
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{
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if (!(current->flags & PF_RANDOMIZE))
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return 0;
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return STACK_RND_MASK << PAGE_SHIFT;
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}
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static inline int mmap_is_legacy(struct rlimit *rlim_stack)
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{
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if (current->personality & ADDR_COMPAT_LAYOUT)
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return 1;
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if (rlim_stack->rlim_cur == RLIM_INFINITY)
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return 1;
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return sysctl_legacy_va_layout;
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}
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unsigned long arch_mmap_rnd(void)
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{
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return (get_random_int() & MMAP_RND_MASK) << PAGE_SHIFT;
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}
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static unsigned long mmap_base_legacy(unsigned long rnd)
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{
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return TASK_UNMAPPED_BASE + rnd;
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}
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static inline unsigned long mmap_base(unsigned long rnd,
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struct rlimit *rlim_stack)
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{
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unsigned long gap = rlim_stack->rlim_cur;
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unsigned long pad = stack_maxrandom_size() + stack_guard_gap;
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unsigned long gap_min, gap_max;
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/* Values close to RLIM_INFINITY can overflow. */
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if (gap + pad > gap)
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gap += pad;
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/*
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* Top of mmap area (just below the process stack).
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* Leave at least a ~32 MB hole.
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*/
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gap_min = 32 * 1024 * 1024UL;
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gap_max = (STACK_TOP / 6) * 5;
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if (gap < gap_min)
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gap = gap_min;
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else if (gap > gap_max)
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gap = gap_max;
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return PAGE_ALIGN(STACK_TOP - gap - rnd);
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}
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unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
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unsigned long len, unsigned long pgoff,
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unsigned long flags)
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{
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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struct vm_unmapped_area_info info;
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if (len > TASK_SIZE - mmap_min_addr)
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return -ENOMEM;
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if (flags & MAP_FIXED)
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goto check_asce_limit;
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if (addr) {
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addr = PAGE_ALIGN(addr);
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
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(!vma || addr + len <= vm_start_gap(vma)))
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goto check_asce_limit;
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}
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info.flags = 0;
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info.length = len;
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info.low_limit = mm->mmap_base;
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info.high_limit = TASK_SIZE;
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if (filp || (flags & MAP_SHARED))
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info.align_mask = MMAP_ALIGN_MASK << PAGE_SHIFT;
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else
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info.align_mask = 0;
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info.align_offset = pgoff << PAGE_SHIFT;
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addr = vm_unmapped_area(&info);
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if (offset_in_page(addr))
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return addr;
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check_asce_limit:
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return check_asce_limit(mm, addr, len);
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}
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unsigned long arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
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unsigned long len, unsigned long pgoff,
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unsigned long flags)
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{
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struct vm_area_struct *vma;
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struct mm_struct *mm = current->mm;
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struct vm_unmapped_area_info info;
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/* requested length too big for entire address space */
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if (len > TASK_SIZE - mmap_min_addr)
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return -ENOMEM;
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if (flags & MAP_FIXED)
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goto check_asce_limit;
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/* requesting a specific address */
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if (addr) {
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addr = PAGE_ALIGN(addr);
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vma = find_vma(mm, addr);
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if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
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(!vma || addr + len <= vm_start_gap(vma)))
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goto check_asce_limit;
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}
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info.flags = VM_UNMAPPED_AREA_TOPDOWN;
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info.length = len;
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info.low_limit = max(PAGE_SIZE, mmap_min_addr);
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info.high_limit = mm->mmap_base;
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if (filp || (flags & MAP_SHARED))
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info.align_mask = MMAP_ALIGN_MASK << PAGE_SHIFT;
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else
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info.align_mask = 0;
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info.align_offset = pgoff << PAGE_SHIFT;
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addr = vm_unmapped_area(&info);
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/*
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* A failed mmap() very likely causes application failure,
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* so fall back to the bottom-up function here. This scenario
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* can happen with large stack limits and large mmap()
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* allocations.
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*/
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if (offset_in_page(addr)) {
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VM_BUG_ON(addr != -ENOMEM);
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info.flags = 0;
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info.low_limit = TASK_UNMAPPED_BASE;
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info.high_limit = TASK_SIZE;
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addr = vm_unmapped_area(&info);
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if (offset_in_page(addr))
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return addr;
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}
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check_asce_limit:
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return check_asce_limit(mm, addr, len);
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}
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/*
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* This function, called very early during the creation of a new
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* process VM image, sets up which VM layout function to use:
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*/
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void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
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{
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unsigned long random_factor = 0UL;
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if (current->flags & PF_RANDOMIZE)
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random_factor = arch_mmap_rnd();
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/*
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* Fall back to the standard layout if the personality
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* bit is set, or if the expected stack growth is unlimited:
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*/
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if (mmap_is_legacy(rlim_stack)) {
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mm->mmap_base = mmap_base_legacy(random_factor);
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mm->get_unmapped_area = arch_get_unmapped_area;
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} else {
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mm->mmap_base = mmap_base(random_factor, rlim_stack);
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mm->get_unmapped_area = arch_get_unmapped_area_topdown;
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}
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}
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