949a05d034
On Thu, 2012-11-01 at 16:45 -0700, Michel Lespinasse wrote: > Looking at the arch/parisc/kernel/sys_parisc.c implementation of > get_shared_area(), I do have a concern though. The function basically > ignores the pgoff argument, so that if one creates a shared mapping of > pages 0-N of a file, and then a separate shared mapping of pages 1-N > of that same file, both will have the same cache offset for their > starting address. > > This looks like this would create obvious aliasing issues. Am I > misreading this ? I can't understand how this could work good enough > to be undetected, so there must be something I'm missing here ??? This turns out to be correct and we need to pay attention to the pgoff as well as the address when creating the virtual address for the area. Fortunately, the bug is rarely triggered as most applications which use pgoff tend to use large values (git being the primary one, and it uses pgoff in multiples of 16MB) which are larger than our cache coherency modulus, so the problem isn't often seen in practise. Reported-by: Michel Lespinasse <walken@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
238 lines
6.9 KiB
C
238 lines
6.9 KiB
C
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/*
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* PARISC specific syscalls
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*
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* Copyright (C) 1999-2003 Matthew Wilcox <willy at parisc-linux.org>
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* Copyright (C) 2000-2003 Paul Bame <bame at parisc-linux.org>
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* Copyright (C) 2001 Thomas Bogendoerfer <tsbogend at parisc-linux.org>
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*
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <asm/uaccess.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/linkage.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/shm.h>
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#include <linux/syscalls.h>
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#include <linux/utsname.h>
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#include <linux/personality.h>
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static unsigned long get_unshared_area(unsigned long addr, unsigned long len)
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{
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struct vm_area_struct *vma;
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addr = PAGE_ALIGN(addr);
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for (vma = find_vma(current->mm, addr); ; vma = vma->vm_next) {
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/* At this point: (!vma || addr < vma->vm_end). */
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if (TASK_SIZE - len < addr)
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return -ENOMEM;
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if (!vma || addr + len <= vma->vm_start)
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return addr;
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addr = vma->vm_end;
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}
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}
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#define DCACHE_ALIGN(addr) (((addr) + (SHMLBA - 1)) &~ (SHMLBA - 1))
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/*
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* We need to know the offset to use. Old scheme was to look for
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* existing mapping and use the same offset. New scheme is to use the
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* address of the kernel data structure as the seed for the offset.
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* We'll see how that works...
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*
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* The mapping is cacheline aligned, so there's no information in the bottom
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* few bits of the address. We're looking for 10 bits (4MB / 4k), so let's
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* drop the bottom 8 bits and use bits 8-17.
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*/
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static int get_offset(struct address_space *mapping)
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{
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int offset = (unsigned long) mapping << (PAGE_SHIFT - 8);
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return offset & 0x3FF000;
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}
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static unsigned long get_shared_area(struct address_space *mapping,
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unsigned long addr, unsigned long len, unsigned long pgoff)
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{
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struct vm_area_struct *vma;
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int offset = mapping ? get_offset(mapping) : 0;
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offset = (offset + (pgoff << PAGE_SHIFT)) & 0x3FF000;
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addr = DCACHE_ALIGN(addr - offset) + offset;
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for (vma = find_vma(current->mm, addr); ; vma = vma->vm_next) {
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/* At this point: (!vma || addr < vma->vm_end). */
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if (TASK_SIZE - len < addr)
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return -ENOMEM;
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if (!vma || addr + len <= vma->vm_start)
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return addr;
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addr = DCACHE_ALIGN(vma->vm_end - offset) + offset;
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if (addr < vma->vm_end) /* handle wraparound */
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return -ENOMEM;
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}
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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, unsigned long flags)
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{
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if (len > TASK_SIZE)
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return -ENOMEM;
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/* Might want to check for cache aliasing issues for MAP_FIXED case
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* like ARM or MIPS ??? --BenH.
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*/
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if (flags & MAP_FIXED)
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return addr;
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if (!addr)
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addr = TASK_UNMAPPED_BASE;
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if (filp) {
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addr = get_shared_area(filp->f_mapping, addr, len, pgoff);
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} else if(flags & MAP_SHARED) {
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addr = get_shared_area(NULL, addr, len, pgoff);
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} else {
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addr = get_unshared_area(addr, len);
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}
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return addr;
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}
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asmlinkage unsigned long sys_mmap2(unsigned long addr, unsigned long len,
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unsigned long prot, unsigned long flags, unsigned long fd,
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unsigned long pgoff)
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{
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/* Make sure the shift for mmap2 is constant (12), no matter what PAGE_SIZE
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we have. */
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return sys_mmap_pgoff(addr, len, prot, flags, fd,
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pgoff >> (PAGE_SHIFT - 12));
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}
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asmlinkage unsigned long sys_mmap(unsigned long addr, unsigned long len,
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unsigned long prot, unsigned long flags, unsigned long fd,
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unsigned long offset)
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{
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if (!(offset & ~PAGE_MASK)) {
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return sys_mmap_pgoff(addr, len, prot, flags, fd,
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offset >> PAGE_SHIFT);
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} else {
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return -EINVAL;
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}
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}
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/* Fucking broken ABI */
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#ifdef CONFIG_64BIT
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asmlinkage long parisc_truncate64(const char __user * path,
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unsigned int high, unsigned int low)
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{
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return sys_truncate(path, (long)high << 32 | low);
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}
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asmlinkage long parisc_ftruncate64(unsigned int fd,
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unsigned int high, unsigned int low)
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{
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return sys_ftruncate(fd, (long)high << 32 | low);
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}
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/* stubs for the benefit of the syscall_table since truncate64 and truncate
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* are identical on LP64 */
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asmlinkage long sys_truncate64(const char __user * path, unsigned long length)
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{
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return sys_truncate(path, length);
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}
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asmlinkage long sys_ftruncate64(unsigned int fd, unsigned long length)
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{
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return sys_ftruncate(fd, length);
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}
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asmlinkage long sys_fcntl64(unsigned int fd, unsigned int cmd, unsigned long arg)
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{
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return sys_fcntl(fd, cmd, arg);
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}
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#else
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asmlinkage long parisc_truncate64(const char __user * path,
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unsigned int high, unsigned int low)
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{
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return sys_truncate64(path, (loff_t)high << 32 | low);
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}
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asmlinkage long parisc_ftruncate64(unsigned int fd,
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unsigned int high, unsigned int low)
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{
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return sys_ftruncate64(fd, (loff_t)high << 32 | low);
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}
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#endif
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asmlinkage ssize_t parisc_pread64(unsigned int fd, char __user *buf, size_t count,
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unsigned int high, unsigned int low)
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{
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return sys_pread64(fd, buf, count, (loff_t)high << 32 | low);
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}
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asmlinkage ssize_t parisc_pwrite64(unsigned int fd, const char __user *buf,
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size_t count, unsigned int high, unsigned int low)
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{
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return sys_pwrite64(fd, buf, count, (loff_t)high << 32 | low);
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}
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asmlinkage ssize_t parisc_readahead(int fd, unsigned int high, unsigned int low,
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size_t count)
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{
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return sys_readahead(fd, (loff_t)high << 32 | low, count);
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}
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asmlinkage long parisc_fadvise64_64(int fd,
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unsigned int high_off, unsigned int low_off,
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unsigned int high_len, unsigned int low_len, int advice)
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{
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return sys_fadvise64_64(fd, (loff_t)high_off << 32 | low_off,
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(loff_t)high_len << 32 | low_len, advice);
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}
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asmlinkage long parisc_sync_file_range(int fd,
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u32 hi_off, u32 lo_off, u32 hi_nbytes, u32 lo_nbytes,
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unsigned int flags)
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{
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return sys_sync_file_range(fd, (loff_t)hi_off << 32 | lo_off,
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(loff_t)hi_nbytes << 32 | lo_nbytes, flags);
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}
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asmlinkage unsigned long sys_alloc_hugepages(int key, unsigned long addr, unsigned long len, int prot, int flag)
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{
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return -ENOMEM;
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}
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asmlinkage int sys_free_hugepages(unsigned long addr)
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{
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return -EINVAL;
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}
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long parisc_personality(unsigned long personality)
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{
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long err;
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if (personality(current->personality) == PER_LINUX32
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&& personality(personality) == PER_LINUX)
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personality = (personality & ~PER_MASK) | PER_LINUX32;
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err = sys_personality(personality);
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if (personality(err) == PER_LINUX32)
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err = (err & ~PER_MASK) | PER_LINUX;
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return err;
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}
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