Messages in this thread Patch in this message | | | Date | Fri, 7 Jun 2019 16:29:16 +0200 | From | Sebastian Andrzej Siewior <> | Subject | [PATCH] x86/fpu: Update kernel's FPU state before using for the fsave header |
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In commit
39388e80f9b0c ("x86/fpu: Don't save fxregs for ia32 frames in copy_fpstate_to_sigframe()")
I removed the statement | if (ia32_fxstate) | copy_fxregs_to_kernel(fpu);
and argued that is was wrongly merged because the content was already saved in kernel's state and the content. This was wrong: It is required to write it back because it is only saved on the user-stack and save_fsave_header() reads it from task's FPU-state. I missed that part…
Save x87 FPU state unless thread's FPU registers are already up to date.
Fixes: 39388e80f9b0c ("x86/fpu: Don't save fxregs for ia32 frames in copy_fpstate_to_sigframe()") Reported-by: Eric Biggers <ebiggers@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- arch/x86/kernel/fpu/signal.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 060d6188b4533..0071b794ed193 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -62,6 +62,11 @@ static inline int save_fsave_header(struct task_struct *tsk, void __user *buf) struct user_i387_ia32_struct env; struct _fpstate_32 __user *fp = buf; + fpregs_lock(); + if (!test_thread_flag(TIF_NEED_FPU_LOAD)) + copy_fxregs_to_kernel(&tsk->thread.fpu); + fpregs_unlock(); + convert_from_fxsr(&env, tsk); if (__copy_to_user(buf, &env, sizeof(env)) || -- 2.20.1
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