87 lines
2.2 KiB
C
87 lines
2.2 KiB
C
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/*
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* Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Copyright 2003 PathScale, Inc.
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*
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* Licensed under the GPL
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*/
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#include <linux/sched.h>
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#include <linux/uaccess.h>
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#include <asm/prctl.h> /* XXX This should get the constants from libc */
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#include <os.h>
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long arch_prctl(struct task_struct *task, int code, unsigned long __user *addr)
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{
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unsigned long *ptr = addr, tmp;
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long ret;
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int pid = task->mm->context.id.u.pid;
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/*
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* With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to
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* be safe), we need to call arch_prctl on the host because
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* setting %fs may result in something else happening (like a
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* GDT or thread.fs being set instead). So, we let the host
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* fiddle the registers and thread struct and restore the
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* registers afterwards.
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*
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* So, the saved registers are stored to the process (this
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* needed because a stub may have been the last thing to run),
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* arch_prctl is run on the host, then the registers are read
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* back.
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*/
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switch (code) {
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case ARCH_SET_FS:
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case ARCH_SET_GS:
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ret = restore_registers(pid, ¤t->thread.regs.regs);
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if (ret)
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return ret;
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break;
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case ARCH_GET_FS:
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case ARCH_GET_GS:
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/*
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* With these two, we read to a local pointer and
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* put_user it to the userspace pointer that we were
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* given. If addr isn't valid (because it hasn't been
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* faulted in or is just bogus), we want put_user to
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* fault it in (or return -EFAULT) instead of having
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* the host return -EFAULT.
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*/
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ptr = &tmp;
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}
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ret = os_arch_prctl(pid, code, ptr);
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if (ret)
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return ret;
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switch (code) {
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case ARCH_SET_FS:
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current->thread.arch.fs = (unsigned long) ptr;
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ret = save_registers(pid, ¤t->thread.regs.regs);
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break;
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case ARCH_SET_GS:
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ret = save_registers(pid, ¤t->thread.regs.regs);
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break;
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case ARCH_GET_FS:
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ret = put_user(tmp, addr);
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break;
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case ARCH_GET_GS:
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ret = put_user(tmp, addr);
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break;
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}
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return ret;
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}
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long sys_arch_prctl(int code, unsigned long addr)
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{
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return arch_prctl(current, code, (unsigned long __user *) addr);
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}
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void arch_switch_to(struct task_struct *to)
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{
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if ((to->thread.arch.fs == 0) || (to->mm == NULL))
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return;
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arch_prctl(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs);
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}
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