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89 lines
2.3 KiB
89 lines
2.3 KiB
/* |
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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/sched/mm.h> |
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#include <linux/syscalls.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 option, |
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unsigned long __user *arg2) |
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{ |
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unsigned long *ptr = arg2, 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 (option) { |
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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, option, ptr); |
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if (ret) |
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return ret; |
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switch (option) { |
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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, arg2); |
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break; |
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case ARCH_GET_GS: |
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ret = put_user(tmp, arg2); |
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break; |
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} |
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return ret; |
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} |
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SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2) |
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{ |
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return arch_prctl(current, option, (unsigned long __user *) arg2); |
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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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