cf535ea52e
This patch updates and fixes sys_tas() routine for m32r. In the previous implementation, a lockup rarely caused at sys_tas() routine in SMP environment. > > The problem is that touching *addr will generate an oops if that page isn't > > paged in. If we convert it to use get_user() then that's an improvement, > > but we must not run get_user() under spinlock or local_irq_disable(). I rewrote sys_tas() routine by using "lock -> unlock" instructions, and utilizing the m32r's interrupt handling characteristics; the m32r processor can accept interrupts only at the 32-bit instruction boundary. So, the "unlock" instruction can be executed continuously after the "lock" instruction execution without any interruptions. In addition, to solve such a page_fault problem, I use a fixup code like get_user(). And, as for the kernel lockup problem, we found that a calling do_page_fault() routine with disabling interrupts might cause a lockup at flush_tlb_others(), because we checked a completion of IPI handler's operations in a spin-locked critical section. Therefore, by using "lock -> unlock" code, we can implement the sys_tas() rouitine without disabling interrupts explicitly, then no lockups would happen at flush_tlb_others(), I hope. Compile check and some working test in SMP environment have done. Signed-off-by: Hirokazu Takata <takata@linux-m32r.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
226 lines
5 KiB
C
226 lines
5 KiB
C
/*
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* linux/arch/m32r/kernel/sys_m32r.c
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*
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* This file contains various random system calls that
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* have a non-standard calling sequence on the Linux/M32R platform.
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*
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* Taken from i386 version.
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*/
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#include <linux/config.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/smp_lock.h>
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#include <linux/sem.h>
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#include <linux/msg.h>
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#include <linux/shm.h>
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#include <linux/stat.h>
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#include <linux/syscalls.h>
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#include <linux/mman.h>
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#include <linux/file.h>
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#include <linux/utsname.h>
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#include <asm/uaccess.h>
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#include <asm/cachectl.h>
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#include <asm/cacheflush.h>
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#include <asm/ipc.h>
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/*
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* sys_tas() - test-and-set
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*/
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asmlinkage int sys_tas(int *addr)
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{
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int oldval;
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if (!access_ok(VERIFY_WRITE, addr, sizeof (int)))
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return -EFAULT;
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/* atomic operation:
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* oldval = *addr; *addr = 1;
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*/
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__asm__ __volatile__ (
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DCACHE_CLEAR("%0", "r4", "%1")
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" .fillinsn\n"
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"1:\n"
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" lock %0, @%1 -> unlock %2, @%1\n"
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"2:\n"
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/* NOTE:
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* The m32r processor can accept interrupts only
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* at the 32-bit instruction boundary.
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* So, in the above code, the "unlock" instruction
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* can be executed continuously after the "lock"
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* instruction execution without any interruptions.
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*/
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".section .fixup,\"ax\"\n"
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" .balign 4\n"
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"3: ldi %0, #%3\n"
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" seth r14, #high(2b)\n"
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" or3 r14, r14, #low(2b)\n"
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" jmp r14\n"
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".previous\n"
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".section __ex_table,\"a\"\n"
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" .balign 4\n"
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" .long 1b,3b\n"
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".previous\n"
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: "=&r" (oldval)
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: "r" (addr), "r" (1), "i"(-EFAULT)
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: "r14", "memory"
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#ifdef CONFIG_CHIP_M32700_TS1
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, "r4"
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#endif /* CONFIG_CHIP_M32700_TS1 */
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);
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return oldval;
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}
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/*
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* sys_pipe() is the normal C calling standard for creating
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* a pipe. It's not the way Unix traditionally does this, though.
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*/
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asmlinkage int
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sys_pipe(unsigned long r0, unsigned long r1, unsigned long r2,
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unsigned long r3, unsigned long r4, unsigned long r5,
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unsigned long r6, struct pt_regs regs)
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{
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int fd[2];
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int error;
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error = do_pipe(fd);
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if (!error) {
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if (copy_to_user((void *)r0, (void *)fd, 2*sizeof(int)))
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error = -EFAULT;
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}
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return error;
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}
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asmlinkage long sys_mmap2(unsigned long addr, unsigned long len,
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unsigned long prot, unsigned long flags,
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unsigned long fd, unsigned long pgoff)
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{
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int error = -EBADF;
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struct file *file = NULL;
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flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
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if (!(flags & MAP_ANONYMOUS)) {
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file = fget(fd);
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if (!file)
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goto out;
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}
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down_write(¤t->mm->mmap_sem);
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error = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
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up_write(¤t->mm->mmap_sem);
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if (file)
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fput(file);
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out:
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return error;
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}
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/*
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* sys_ipc() is the de-multiplexer for the SysV IPC calls..
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*
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* This is really horribly ugly.
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*/
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asmlinkage int sys_ipc(uint call, int first, int second,
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int third, void __user *ptr, long fifth)
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{
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int version, ret;
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version = call >> 16; /* hack for backward compatibility */
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call &= 0xffff;
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switch (call) {
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case SEMOP:
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return sys_semtimedop(first, (struct sembuf __user *)ptr,
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second, NULL);
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case SEMTIMEDOP:
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return sys_semtimedop(first, (struct sembuf __user *)ptr,
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second, (const struct timespec __user *)fifth);
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case SEMGET:
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return sys_semget (first, second, third);
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case SEMCTL: {
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union semun fourth;
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if (!ptr)
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return -EINVAL;
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if (get_user(fourth.__pad, (void __user * __user *) ptr))
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return -EFAULT;
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return sys_semctl (first, second, third, fourth);
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}
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case MSGSND:
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return sys_msgsnd (first, (struct msgbuf __user *) ptr,
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second, third);
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case MSGRCV:
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switch (version) {
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case 0: {
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struct ipc_kludge tmp;
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if (!ptr)
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return -EINVAL;
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if (copy_from_user(&tmp,
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(struct ipc_kludge __user *) ptr,
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sizeof (tmp)))
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return -EFAULT;
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return sys_msgrcv (first, tmp.msgp, second,
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tmp.msgtyp, third);
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}
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default:
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return sys_msgrcv (first,
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(struct msgbuf __user *) ptr,
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second, fifth, third);
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}
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case MSGGET:
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return sys_msgget ((key_t) first, second);
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case MSGCTL:
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return sys_msgctl (first, second,
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(struct msqid_ds __user *) ptr);
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case SHMAT: {
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ulong raddr;
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if (!access_ok(VERIFY_WRITE, (ulong __user *) third,
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sizeof(ulong)))
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return -EFAULT;
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ret = do_shmat (first, (char __user *) ptr, second, &raddr);
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if (ret)
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return ret;
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return put_user (raddr, (ulong __user *) third);
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}
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case SHMDT:
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return sys_shmdt ((char __user *)ptr);
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case SHMGET:
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return sys_shmget (first, second, third);
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case SHMCTL:
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return sys_shmctl (first, second,
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(struct shmid_ds __user *) ptr);
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default:
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return -ENOSYS;
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}
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}
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asmlinkage int sys_uname(struct old_utsname * name)
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{
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int err;
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if (!name)
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return -EFAULT;
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down_read(&uts_sem);
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err=copy_to_user(name, &system_utsname, sizeof (*name));
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up_read(&uts_sem);
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return err?-EFAULT:0;
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}
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asmlinkage int sys_cacheflush(void *addr, int bytes, int cache)
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{
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/* This should flush more selectivly ... */
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_flush_cache_all();
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return 0;
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}
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asmlinkage int sys_cachectl(char *addr, int nbytes, int op)
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{
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/* Not implemented yet. */
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return -ENOSYS;
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}
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