提交 7a0eedee 编写于 作者: A Aneesh Kumar K.V 提交者: Michael Ellerman

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: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
上级 177ba7c6
......@@ -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:
......
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