[tip:x86/pti] x86/entry/64: Move PUSH_AND_CLEAR_REGS from interrupt macro to helper function

[tip-bot for Dominik Brodowski]

Commit-ID:  6014809adf04188c4bce4a5d231f13a602203c95
Gitweb:     https://git.kernel.org/tip/6014809adf04188c4bce4a5d231f13a602203c95
Author:     Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
AuthorDate: Tue, 20 Feb 2018 22:01:08 +0100
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 21 Feb 2018 10:04:46 +0100

x86/entry/64: Move PUSH_AND_CLEAR_REGS from interrupt macro to helper function

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>
Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: dan.j.williams@xxxxxxxxx
Link: http://lkml.kernel.org/r/20180220210113.6725-2-linux@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 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 7a53879..b0ae0c3 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