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Subject[RFC PATCH v2 1/5] x86/entry/64: move PUSH_AND_CLEAR_REGS from interrupt macro to helper function
Date
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@linux-foundation.org>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
---
arch/x86/entry/entry_64.S | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 77edc2390868..5690391cb7c7 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -526,6 +526,15 @@ END(irq_entries_start)
*
* Entry runs with interrupts off.
*/
+ENTRY(interrupt_helper)
+ UNWIND_HINT_FUNC
+ cld
+
+ PUSH_AND_CLEAR_REGS save_ret=1
+ ENCODE_FRAME_POINTER 8
+
+ ret
+END(interrupt_helper)

/* 0(%rsp): ~(interrupt number) */
.macro interrupt func
@@ -537,8 +546,7 @@ END(irq_entries_start)
call switch_to_thread_stack
1:

- PUSH_AND_CLEAR_REGS
- ENCODE_FRAME_POINTER
+ call interrupt_helper

testb $3, CS(%rsp)
jz 1f
--
2.16.1
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