[RFC PATCH v3 1/6] x86/entry/64: move PUSH_AND_CLEAR_REGS from interrupt macro to helper function

[Dominik Brodowski]

The PUSH_AND_CLEAR_REGS macro is able to insert the GP registers
"above" the original return address. This allows us to move a sizeable
part of the interrupt entry macro to an interrupt entry helper function:

   text	   data	    bss	    dec	    hex	filename
  21088	      0	      0	  21088	   5260	entry_64.o-orig
  18006	      0	      0	  18006	   4656	entry_64.o

Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
---
 arch/x86/entry/entry_64.S | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 7a53879ec689..b0ae0c3e3815 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -525,6 +525,14 @@ END(irq_entries_start)
  *
  * Entry runs with interrupts off.
  */
+ENTRY(interrupt_entry)
+	UNWIND_HINT_FUNC
+
+	PUSH_AND_CLEAR_REGS save_ret=1
+	ENCODE_FRAME_POINTER 8
+
+	ret
+END(interrupt_entry)
 
 /* 0(%rsp): ~(interrupt number) */
 	.macro interrupt func
@@ -536,8 +544,7 @@ END(irq_entries_start)
 	call	switch_to_thread_stack
 1:
 
-	PUSH_AND_CLEAR_REGS
-	ENCODE_FRAME_POINTER
+	call	interrupt_entry
 
 	testb	$3, CS(%rsp)
 	jz	1f
-- 
2.16.2