x86: Move kernel_fpu_using to irq_fpu_usable in asm/i387.h

This function measures whether the FPU/SSE state can be touched in
interrupt context. If the interrupted code is in user space or has no
valid FPU/SSE context (CR0.TS == 1), FPU/SSE state can be used in IRQ
or soft_irq context too.

This is used by AES-NI accelerated AES implementation and PCLMULQDQ
accelerated GHASH implementation.

v3:
 - Renamed to irq_fpu_usable to reflect the purpose of the function.

v2:
 - Renamed to irq_is_fpu_using to reflect the real situation.

Signed-off-by: Huang Ying <ying.huang@intel.com>
CC: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 175adf58dd4f..fb7f0d64e14f 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -301,6 +301,14 @@ static inline void kernel_fpu_end(void)
 	preempt_enable();
 }
 
+static inline bool irq_fpu_usable(void)
+{
+	struct pt_regs *regs;
+
+	return !in_interrupt() || !(regs = get_irq_regs()) || \
+		user_mode(regs) || (read_cr0() & X86_CR0_TS);
+}
+
 /*
  * Some instructions like VIA's padlock instructions generate a spurious
  * DNA fault but don't modify SSE registers. And these instructions