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![Linus Torvalds](/assets/img/avatar_default.png)
Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument of the user address range verification function since we got rid of the old racy i386-only code to walk page tables by hand. It existed because the original 80386 would not honor the write protect bit when in kernel mode, so you had to do COW by hand before doing any user access. But we haven't supported that in a long time, and these days the 'type' argument is a purely historical artifact. A discussion about extending 'user_access_begin()' to do the range checking resulted this patch, because there is no way we're going to move the old VERIFY_xyz interface to that model. And it's best done at the end of the merge window when I've done most of my merges, so let's just get this done once and for all. This patch was mostly done with a sed-script, with manual fix-ups for the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form. There were a couple of notable cases: - csky still had the old "verify_area()" name as an alias. - the iter_iov code had magical hardcoded knowledge of the actual values of VERIFY_{READ,WRITE} (not that they mattered, since nothing really used it) - microblaze used the type argument for a debug printout but other than those oddities this should be a total no-op patch. I tried to fix up all architectures, did fairly extensive grepping for access_ok() uses, and the changes are trivial, but I may have missed something. Any missed conversion should be trivially fixable, though. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
248 lines
5.6 KiB
C
248 lines
5.6 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 1995, 1996, 1997, 2000, 2001, 05 by Ralf Baechle
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* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
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* Copyright (C) 2001 MIPS Technologies, Inc.
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*/
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#include <linux/capability.h>
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#include <linux/errno.h>
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#include <linux/linkage.h>
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#include <linux/fs.h>
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#include <linux/smp.h>
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#include <linux/ptrace.h>
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#include <linux/string.h>
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#include <linux/syscalls.h>
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#include <linux/file.h>
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#include <linux/utsname.h>
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#include <linux/unistd.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/compiler.h>
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#include <linux/ipc.h>
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#include <linux/uaccess.h>
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#include <linux/slab.h>
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#include <linux/elf.h>
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#include <linux/sched/task_stack.h>
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#include <asm/asm.h>
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#include <asm/asm-eva.h>
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#include <asm/branch.h>
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#include <asm/cachectl.h>
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#include <asm/cacheflush.h>
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#include <asm/asm-offsets.h>
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#include <asm/signal.h>
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#include <asm/sim.h>
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#include <asm/shmparam.h>
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#include <asm/sysmips.h>
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#include <asm/switch_to.h>
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/*
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* For historic reasons the pipe(2) syscall on MIPS has an unusual calling
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* convention. It returns results in registers $v0 / $v1 which means there
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* is no need for it to do verify the validity of a userspace pointer
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* argument. Historically that used to be expensive in Linux. These days
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* the performance advantage is negligible.
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*/
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asmlinkage int sysm_pipe(void)
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{
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int fd[2];
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int error = do_pipe_flags(fd, 0);
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if (error)
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return error;
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current_pt_regs()->regs[3] = fd[1];
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return fd[0];
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}
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SYSCALL_DEFINE6(mips_mmap, unsigned long, addr, unsigned long, len,
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unsigned long, prot, unsigned long, flags, unsigned long,
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fd, off_t, offset)
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{
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if (offset & ~PAGE_MASK)
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return -EINVAL;
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return ksys_mmap_pgoff(addr, len, prot, flags, fd,
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offset >> PAGE_SHIFT);
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}
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SYSCALL_DEFINE6(mips_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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if (pgoff & (~PAGE_MASK >> 12))
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return -EINVAL;
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return ksys_mmap_pgoff(addr, len, prot, flags, fd,
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pgoff >> (PAGE_SHIFT - 12));
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}
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save_static_function(sys_fork);
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save_static_function(sys_clone);
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SYSCALL_DEFINE1(set_thread_area, unsigned long, addr)
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{
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struct thread_info *ti = task_thread_info(current);
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ti->tp_value = addr;
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if (cpu_has_userlocal)
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write_c0_userlocal(addr);
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return 0;
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}
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static inline int mips_atomic_set(unsigned long addr, unsigned long new)
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{
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unsigned long old, tmp;
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struct pt_regs *regs;
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unsigned int err;
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if (unlikely(addr & 3))
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return -EINVAL;
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if (unlikely(!access_ok((const void __user *)addr, 4)))
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return -EINVAL;
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if (cpu_has_llsc && R10000_LLSC_WAR) {
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__asm__ __volatile__ (
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" .set push \n"
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" .set arch=r4000 \n"
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" li %[err], 0 \n"
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"1: ll %[old], (%[addr]) \n"
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" move %[tmp], %[new] \n"
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"2: sc %[tmp], (%[addr]) \n"
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" beqzl %[tmp], 1b \n"
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"3: \n"
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" .insn \n"
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" .section .fixup,\"ax\" \n"
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"4: li %[err], %[efault] \n"
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" j 3b \n"
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" .previous \n"
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" .section __ex_table,\"a\" \n"
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" "STR(PTR)" 1b, 4b \n"
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" "STR(PTR)" 2b, 4b \n"
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" .previous \n"
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" .set pop \n"
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: [old] "=&r" (old),
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[err] "=&r" (err),
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[tmp] "=&r" (tmp)
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: [addr] "r" (addr),
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[new] "r" (new),
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[efault] "i" (-EFAULT)
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: "memory");
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} else if (cpu_has_llsc) {
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__asm__ __volatile__ (
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" .set push \n"
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" .set "MIPS_ISA_ARCH_LEVEL" \n"
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" li %[err], 0 \n"
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"1: \n"
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user_ll("%[old]", "(%[addr])")
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" move %[tmp], %[new] \n"
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"2: \n"
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user_sc("%[tmp]", "(%[addr])")
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" beqz %[tmp], 1b \n"
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"3: \n"
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" .insn \n"
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" .section .fixup,\"ax\" \n"
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"5: li %[err], %[efault] \n"
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" j 3b \n"
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" .previous \n"
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" .section __ex_table,\"a\" \n"
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" "STR(PTR)" 1b, 5b \n"
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" "STR(PTR)" 2b, 5b \n"
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" .previous \n"
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" .set pop \n"
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: [old] "=&r" (old),
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[err] "=&r" (err),
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[tmp] "=&r" (tmp)
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: [addr] "r" (addr),
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[new] "r" (new),
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[efault] "i" (-EFAULT)
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: "memory");
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} else {
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do {
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preempt_disable();
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ll_bit = 1;
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ll_task = current;
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preempt_enable();
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err = __get_user(old, (unsigned int *) addr);
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err |= __put_user(new, (unsigned int *) addr);
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if (err)
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break;
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rmb();
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} while (!ll_bit);
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}
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if (unlikely(err))
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return err;
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regs = current_pt_regs();
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regs->regs[2] = old;
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regs->regs[7] = 0; /* No error */
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/*
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* Don't let your children do this ...
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*/
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__asm__ __volatile__(
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" move $29, %0 \n"
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" j syscall_exit \n"
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: /* no outputs */
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: "r" (regs));
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/* unreached. Honestly. */
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unreachable();
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}
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/*
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* mips_atomic_set() normally returns directly via syscall_exit potentially
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* clobbering static registers, so be sure to preserve them.
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*/
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save_static_function(sys_sysmips);
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SYSCALL_DEFINE3(sysmips, long, cmd, long, arg1, long, arg2)
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{
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switch (cmd) {
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case MIPS_ATOMIC_SET:
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return mips_atomic_set(arg1, arg2);
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case MIPS_FIXADE:
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if (arg1 & ~3)
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return -EINVAL;
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if (arg1 & 1)
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set_thread_flag(TIF_FIXADE);
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else
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clear_thread_flag(TIF_FIXADE);
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if (arg1 & 2)
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set_thread_flag(TIF_LOGADE);
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else
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clear_thread_flag(TIF_LOGADE);
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return 0;
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case FLUSH_CACHE:
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__flush_cache_all();
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return 0;
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}
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return -EINVAL;
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}
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/*
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* No implemented yet ...
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*/
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SYSCALL_DEFINE3(cachectl, char *, addr, int, nbytes, int, op)
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{
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return -ENOSYS;
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}
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/*
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* If we ever come here the user sp is bad. Zap the process right away.
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* Due to the bad stack signaling wouldn't work.
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*/
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asmlinkage void bad_stack(void)
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{
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do_exit(SIGSEGV);
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}
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