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-rw-r--r--arch/x86/include/asm/i387.h4
-rw-r--r--arch/x86/kernel/i387.c11
-rw-r--r--arch/x86/kernel/traps.c12
3 files changed, 20 insertions, 7 deletions
diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 5e275d3..6eb6fcb 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -51,6 +51,10 @@ static inline void kernel_fpu_end(void)
preempt_enable();
}
+/* Must be called with preempt disabled */
+extern void kernel_fpu_disable(void);
+extern void kernel_fpu_enable(void);
+
/*
* Some instructions like VIA's padlock instructions generate a spurious
* DNA fault but don't modify SSE registers. And these instructions
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 12088a3..81049ff 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -21,6 +21,17 @@
static DEFINE_PER_CPU(bool, in_kernel_fpu);
+void kernel_fpu_disable(void)
+{
+ WARN_ON(this_cpu_read(in_kernel_fpu));
+ this_cpu_write(in_kernel_fpu, true);
+}
+
+void kernel_fpu_enable(void)
+{
+ this_cpu_write(in_kernel_fpu, false);
+}
+
/*
* Were we in an interrupt that interrupted kernel mode?
*
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 88900e2..fb4cb6a 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -788,18 +788,16 @@ void math_state_restore(void)
local_irq_disable();
}
+ /* Avoid __kernel_fpu_begin() right after __thread_fpu_begin() */
+ kernel_fpu_disable();
__thread_fpu_begin(tsk);
-
- /*
- * Paranoid restore. send a SIGSEGV if we fail to restore the state.
- */
if (unlikely(restore_fpu_checking(tsk))) {
drop_init_fpu(tsk);
force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
- return;
+ } else {
+ tsk->thread.fpu_counter++;
}
-
- tsk->thread.fpu_counter++;
+ kernel_fpu_enable();
}
EXPORT_SYMBOL_GPL(math_state_restore);