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author | Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> | 2016-04-29 23:26:11 +1000 |
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committer | Michael Ellerman <mpe@ellerman.id.au> | 2016-05-11 21:53:47 +1000 |
commit | 7a0eedeedd5d192f64fd4cd46634e409cb7a513b (patch) | |
tree | 393b98499dbfece26e8eaa050c8ed283d50f43f1 /arch/powerpc/mm | |
parent | 177ba7c647f37bc3f31667192059ee794347d79d (diff) | |
download | linux-7a0eedeedd5d192f64fd4cd46634e409cb7a513b.tar.bz2 |
powerpc/mm/radix: Pick the address layout for radix config
Hash needs special get_unmapped_area() handling because of limitations
around base page size, so we have to set HAVE_ARCH_UNMAPPED_AREA.
With radix we don't have such restrictions, so we could use the generic
code. But because we've set HAVE_ARCH_UNMAPPED_AREA (for hash), we have
to re-implement the same logic as the generic code.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/mm')
-rw-r--r-- | arch/powerpc/mm/mmap.c | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/arch/powerpc/mm/mmap.c b/arch/powerpc/mm/mmap.c index 30611f832923..2f1e44362198 100644 --- a/arch/powerpc/mm/mmap.c +++ b/arch/powerpc/mm/mmap.c @@ -27,6 +27,8 @@ #include <linux/random.h> #include <linux/sched.h> #include <linux/elf-randomize.h> +#include <linux/security.h> +#include <linux/mman.h> /* * Top of mmap area (just below the process stack). @@ -79,6 +81,111 @@ static inline unsigned long mmap_base(unsigned long rnd) return PAGE_ALIGN(TASK_SIZE - 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; + struct vm_unmapped_area_info info; + + if (len > TASK_SIZE - mmap_min_addr) + return -ENOMEM; + + if (flags & MAP_FIXED) + return addr; + + if (addr) { + addr = PAGE_ALIGN(addr); + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && + (!vma || addr + len <= vma->vm_start)) + return addr; + } + + info.flags = 0; + info.length = len; + info.low_limit = mm->mmap_base; + info.high_limit = TASK_SIZE; + 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; + struct vm_unmapped_area_info info; + + /* requested length too big for entire address space */ + if (len > TASK_SIZE - mmap_min_addr) + return -ENOMEM; + + if (flags & MAP_FIXED) + return addr; + + /* requesting a specific address */ + if (addr) { + addr = PAGE_ALIGN(addr); + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && + (!vma || addr + len <= vma->vm_start)) + 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; + info.align_mask = 0; + addr = vm_unmapped_area(&info); + + /* + * 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. + */ + if (addr & ~PAGE_MASK) { + VM_BUG_ON(addr != -ENOMEM); + info.flags = 0; + info.low_limit = TASK_UNMAPPED_BASE; + info.high_limit = TASK_SIZE; + addr = vm_unmapped_area(&info); + } + + return addr; +} + +static void radix__arch_pick_mmap_layout(struct mm_struct *mm, + unsigned long random_factor) +{ + if (mmap_is_legacy()) { + mm->mmap_base = TASK_UNMAPPED_BASE; + mm->get_unmapped_area = radix__arch_get_unmapped_area; + } else { + mm->mmap_base = mmap_base(random_factor); + 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); +#endif /* * This function, called very early during the creation of a new * process VM image, sets up which VM layout function to use: @@ -90,6 +197,8 @@ void arch_pick_mmap_layout(struct mm_struct *mm) if (current->flags & PF_RANDOMIZE) random_factor = arch_mmap_rnd(); + if (radix_enabled()) + return radix__arch_pick_mmap_layout(mm, random_factor); /* * Fall back to the standard layout if the personality * bit is set, or if the expected stack growth is unlimited: |