/*
* This restores directly out of user space. Exceptions are handled.
*/
int restore_i387_xstate(void __user *buf)
{
struct task_struct *tsk = current;
int err = 0;
if (!buf) {
if (used_math())
goto clear;
return 0;
} else if (!access_ok(VERIFY_READ, buf, sig_xstate_size))
return -EACCES;
if (!used_math()) {
err = init_fpu(tsk);
if (err)
return err;
}
user_fpu_begin();
if (use_xsave())
err = restore_user_xstate(buf);
else
err = fxrstor_checking((__force struct i387_fxsave_struct *)
buf);
if (unlikely(err)) {
/*
* Encountered an error while doing the restore from the
* user buffer, clear the fpu state.
*/
clear:
clear_fpu(tsk);
clear_used_math();
}
return err;
}
/*
* Restore the extended state if present. Otherwise, restore the FP/SSE
* state.
*/
static int restore_user_xstate(void __user *buf)
{
struct _fpx_sw_bytes fx_sw_user;
u64 mask;
int err;
if (((unsigned long)buf % 64) ||
check_for_xstate(buf, buf, &fx_sw_user))
goto fx_only;
mask = fx_sw_user.xstate_bv;
/*
* restore the state passed by the user.
*/
err = xrestore_user(buf, mask);
if (err)
return err;
/*
* init the state skipped by the user.
*/
mask = pcntxt_mask & ~mask;
if (unlikely(mask))
xrstor_state(init_xstate_buf, mask);
return 0;
fx_only:
/*
* couldn't find the extended state information in the
* memory layout. Restore just the FP/SSE and init all
* the other extended state.
*/
xrstor_state(init_xstate_buf, pcntxt_mask & ~XSTATE_FPSSE);
return fxrstor_checking((struct i387_fxsave_struct __force_kernel *)buf);
}
static int restore_user_xstate(void __user *buf)
{
struct _fpx_sw_bytes fx_sw_user;
u64 mask;
int err;
if (((unsigned long)buf % 64) ||
check_for_xstate(buf, buf, &fx_sw_user))
goto fx_only;
mask = fx_sw_user.xstate_bv;
/*
*/
err = xrestore_user(buf, mask);
if (err)
return err;
/*
*/
mask = pcntxt_mask & ~mask;
if (unlikely(mask))
xrstor_state(init_xstate_buf, mask);
return 0;
fx_only:
/*
*/
xrstor_state(init_xstate_buf, pcntxt_mask & ~XSTATE_FPSSE);
return fxrstor_checking((__force struct i387_fxsave_struct *)buf);
}