/*
* 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;
}
int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
{
int ia32_fxstate = (buf != buf_fx);
struct task_struct *tsk = current;
int state_size = xstate_size;
u64 xstate_bv = 0;
int fx_only = 0;
ia32_fxstate &= (config_enabled(CONFIG_X86_32) ||
config_enabled(CONFIG_IA32_EMULATION));
if (!buf) {
drop_init_fpu(tsk);
return 0;
}
if (!access_ok(VERIFY_READ, buf, size))
return -EACCES;
if (!used_math() && init_fpu(tsk))
return -1;
if (!static_cpu_has(X86_FEATURE_FPU))
return fpregs_soft_set(current, NULL,
0, sizeof(struct user_i387_ia32_struct),
NULL, buf) != 0;
if (use_xsave()) {
struct _fpx_sw_bytes fx_sw_user;
if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) {
/*
* Couldn't find the extended state information in the
* memory layout. Restore just the FP/SSE and init all
* the other extended state.
*/
state_size = sizeof(struct i387_fxsave_struct);
fx_only = 1;
} else {
state_size = fx_sw_user.xstate_size;
xstate_bv = fx_sw_user.xstate_bv;
}
}
if (ia32_fxstate) {
/*
* For 32-bit frames with fxstate, copy the user state to the
* thread's fpu state, reconstruct fxstate from the fsave
* header. Sanitize the copied state etc.
*/
struct xsave_struct *xsave = &tsk->thread.fpu.state->xsave;
struct user_i387_ia32_struct env;
int err = 0;
/*
* Drop the current fpu which clears used_math(). This ensures
* that any context-switch during the copy of the new state,
* avoids the intermediate state from getting restored/saved.
* Thus avoiding the new restored state from getting corrupted.
* We will be ready to restore/save the state only after
* set_used_math() is again set.
*/
drop_fpu(tsk);
if (__copy_from_user(xsave, buf_fx, state_size) ||
__copy_from_user(&env, buf, sizeof(env))) {
err = -1;
} else {
sanitize_restored_xstate(tsk, &env, xstate_bv, fx_only);
set_used_math();
}
if (use_eager_fpu())
math_state_restore();
return err;
} else {
/*
* For 64-bit frames and 32-bit fsave frames, restore the user
* state to the registers directly (with exceptions handled).
*/
user_fpu_begin();
if (restore_user_xstate(buf_fx, xstate_bv, fx_only)) {
drop_init_fpu(tsk);
return -1;
}
}
return 0;
}
