x86: fix fpu restore from sig return
If the task never used fpu, initialize the fpu before restoring the FP
state from the signal handler context. This will allocate the fpu
state, if the task never needed it before.
Reported-and-bisected-by: Eric Sesterhenn <snakebyte@gmx.de>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Tested-by: Eric Sesterhenn <snakebyte@gmx.de>
Cc: Frederik Deweerdt <deweerdt@free.fr>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index db6839b..e03cc95 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -450,7 +450,6 @@
{
struct task_struct *tsk = current;
- clear_fpu(tsk);
return __copy_from_user(&tsk->thread.xstate->fsave, buf,
sizeof(struct i387_fsave_struct));
}
@@ -461,7 +460,6 @@
struct user_i387_ia32_struct env;
int err;
- clear_fpu(tsk);
err = __copy_from_user(&tsk->thread.xstate->fxsave, &buf->_fxsr_env[0],
sizeof(struct i387_fxsave_struct));
/* mxcsr reserved bits must be masked to zero for security reasons */
@@ -478,6 +476,16 @@
int err;
if (HAVE_HWFP) {
+ struct task_struct *tsk = current;
+
+ clear_fpu(tsk);
+
+ if (!used_math()) {
+ err = init_fpu(tsk);
+ if (err)
+ return err;
+ }
+
if (cpu_has_fxsr)
err = restore_i387_fxsave(buf);
else