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