x86/entry/64: Simplify reg restore code in the standard IRET paths
The old code restored all the registers with movq instead of pop.
In theory, this was done because some CPUs have higher movq
throughput, but any gain there would be tiny and is almost certainly
outweighed by the higher text size.
This saves 96 bytes of text.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/ad82520a207ccd851b04ba613f4f752b33ac05f7.1509609304.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index d6ffdc9..925d562 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -618,9 +618,9 @@
1:
#endif
SWAPGS
- RESTORE_EXTRA_REGS
- RESTORE_C_REGS
- REMOVE_PT_GPREGS_FROM_STACK 8
+ POP_EXTRA_REGS
+ POP_C_REGS
+ addq $8, %rsp /* skip regs->orig_ax */
INTERRUPT_RETURN
@@ -650,9 +650,9 @@
ud2
1:
#endif
- RESTORE_EXTRA_REGS
- RESTORE_C_REGS
- REMOVE_PT_GPREGS_FROM_STACK 8
+ POP_EXTRA_REGS
+ POP_C_REGS
+ addq $8, %rsp /* skip regs->orig_ax */
INTERRUPT_RETURN
ENTRY(native_iret)
