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Diffstat (limited to 'arch/x86/um/syscalls_64.c')
-rw-r--r--arch/x86/um/syscalls_64.c62
1 files changed, 13 insertions, 49 deletions
diff --git a/arch/x86/um/syscalls_64.c b/arch/x86/um/syscalls_64.c
index 27b29ae6c4..6a00a28c9c 100644
--- a/arch/x86/um/syscalls_64.c
+++ b/arch/x86/um/syscalls_64.c
@@ -16,60 +16,24 @@
long arch_prctl(struct task_struct *task, int option,
unsigned long __user *arg2)
{
- unsigned long *ptr = arg2, 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 (option) {
- case ARCH_SET_FS:
- case ARCH_SET_GS:
- ret = restore_pid_registers(pid, &current->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, option, ptr);
- if (ret)
- return ret;
+ long ret = -EINVAL;
switch (option) {
case ARCH_SET_FS:
- current->thread.arch.fs = (unsigned long) ptr;
- ret = save_registers(pid, &current->thread.regs.regs);
+ current->thread.regs.regs.gp[FS_BASE / sizeof(unsigned long)] =
+ (unsigned long) arg2;
+ ret = 0;
break;
case ARCH_SET_GS:
- ret = save_registers(pid, &current->thread.regs.regs);
+ current->thread.regs.regs.gp[GS_BASE / sizeof(unsigned long)] =
+ (unsigned long) arg2;
+ ret = 0;
break;
case ARCH_GET_FS:
- ret = put_user(tmp, arg2);
+ ret = put_user(current->thread.regs.regs.gp[FS_BASE / sizeof(unsigned long)], arg2);
break;
case ARCH_GET_GS:
- ret = put_user(tmp, arg2);
+ ret = put_user(current->thread.regs.regs.gp[GS_BASE / sizeof(unsigned long)], arg2);
break;
}
@@ -83,10 +47,10 @@ SYSCALL_DEFINE2(arch_prctl, int, option, unsigned long, arg2)
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);
+ /*
+ * Nothing needs to be done on x86_64.
+ * The FS_BASE/GS_BASE registers are saved in the ptrace register set.
+ */
}
SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,