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SubjectRe: Oops with strace_test
On Wed, 7 May 2008, Suresh Siddha wrote:
> On Wed, May 07, 2008 at 07:26:20PM +0200, Thomas Gleixner wrote:
> >
> > Ok, we decoded the problem in meantime. Suresh will send a patch soon.
>
> Appended patch should fix it. Eric, can you please check if it fixes the issue?
> I have to fix the math-emu aswell. But I will send a different patch for it.

Suresh,

looks good. Applied to x86.git. Waiting for Erics confirmation.

Thanks,
tglx

> thanks,
> suresh
> ---
>
> [patch] fix fpu restore during 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.
>
> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
> ---
>
> diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
> index db6839b..45e19ee 100644
> --- a/arch/x86/kernel/i387.c
> +++ b/arch/x86/kernel/i387.c
> @@ -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
> diff --git a/include/asm-x86/i387.h b/include/asm-x86/i387.h
> index da2adb4..6b722d3 100644
> --- a/include/asm-x86/i387.h
> +++ b/include/asm-x86/i387.h
> @@ -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;
>


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