mm: mmap: Allow for "high" userspace addresses
This patch adds support for "high" userspace addresses that are optionally supported on the system and have to be requested via a hint mechanism ("high" addr parameter to mmap). Architectures such as powerpc and x86 achieve this by making changes to their architectural versions of arch_get_unmapped_* functions. However, on arm64 we use the generic versions of these functions. Rather than duplicate the generic arch_get_unmapped_* implementations for arm64, this patch instead introduces two architectural helper macros and applies them to arch_get_unmapped_*: arch_get_mmap_end(addr) - get mmap upper limit depending on addr hint arch_get_mmap_base(addr, base) - get mmap_base depending on addr hint If these macros are not defined in architectural code then they default to (TASK_SIZE) and (base) so should not introduce any behavioural changes to architectures that do not define them. Signed-off-by: Steve Capper <steve.capper@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
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6e8830674e
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1 changed files with 18 additions and 7 deletions
25
mm/mmap.c
25
mm/mmap.c
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@ -2066,6 +2066,15 @@ found_highest:
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return gap_end;
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}
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#ifndef arch_get_mmap_end
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#define arch_get_mmap_end(addr) (TASK_SIZE)
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#endif
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#ifndef arch_get_mmap_base
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#define arch_get_mmap_base(addr, base) (base)
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#endif
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/* Get an address range which is currently unmapped.
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* For shmat() with addr=0.
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*
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@ -2085,8 +2094,9 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma, *prev;
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struct vm_unmapped_area_info info;
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const unsigned long mmap_end = arch_get_mmap_end(addr);
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if (len > TASK_SIZE - mmap_min_addr)
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if (len > mmap_end - mmap_min_addr)
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return -ENOMEM;
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if (flags & MAP_FIXED)
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@ -2095,7 +2105,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
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if (addr) {
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addr = PAGE_ALIGN(addr);
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vma = find_vma_prev(mm, addr, &prev);
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if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
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if (mmap_end - len >= addr && addr >= mmap_min_addr &&
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(!vma || addr + len <= vm_start_gap(vma)) &&
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(!prev || addr >= vm_end_gap(prev)))
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return addr;
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@ -2104,7 +2114,7 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
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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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info.high_limit = mmap_end;
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info.align_mask = 0;
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return vm_unmapped_area(&info);
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}
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@ -2124,9 +2134,10 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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struct mm_struct *mm = current->mm;
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unsigned long addr = addr0;
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struct vm_unmapped_area_info info;
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const unsigned long mmap_end = arch_get_mmap_end(addr);
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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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if (len > mmap_end - mmap_min_addr)
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return -ENOMEM;
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if (flags & MAP_FIXED)
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@ -2136,7 +2147,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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if (addr) {
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addr = PAGE_ALIGN(addr);
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vma = find_vma_prev(mm, addr, &prev);
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if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
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if (mmap_end - len >= addr && addr >= mmap_min_addr &&
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(!vma || addr + len <= vm_start_gap(vma)) &&
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(!prev || addr >= vm_end_gap(prev)))
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return addr;
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@ -2145,7 +2156,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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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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info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
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info.align_mask = 0;
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addr = vm_unmapped_area(&info);
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@ -2159,7 +2170,7 @@ arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
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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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info.high_limit = mmap_end;
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addr = vm_unmapped_area(&info);
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}
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