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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>
This commit is contained in:
Suresh Siddha 2008-05-07 12:09:52 -07:00 committed by Thomas Gleixner
parent 0646153921
commit fd3c3ed5d1
2 changed files with 19 additions and 3 deletions
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12
arch/x86/kernel/i387.c
View File

@ -450,7 +450,6 @@ static inline int restore_i387_fsave(struct _fpstate_ia32 __user *buf)
{
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 @@ static int restore_i387_fxsave(struct _fpstate_ia32 __user *buf)
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 restore_i387_ia32(struct _fpstate_ia32 __user *buf)
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

10
include/asm-x86/i387.h
View File

@ -175,7 +175,15 @@ static inline int save_i387(struct _fpstate __user *buf)
*/
static inline int restore_i387(struct _fpstate __user *buf)
{
set_used_math();
struct task_struct *tsk = current;
int err;
if (!used_math()) {
err = init_fpu(tsk);
if (err)
return err;
}
if (!(task_thread_info(current)->status & TS_USEDFPU)) {
clts();
task_thread_info(current)->status |= TS_USEDFPU;