[PATCH 1/5] x86/asm/entry/64: move retint_kernel code block closer to its user

Denys Vlasenko
2015-03-30T18:10:28Z

"retint_kernel" code block is misplaced. Since its logical continuation
is "retint_restore_args", it is more natural to place it above that label.
This also makes two jumps "short".

This change only moves code block around, without changing logic.

This enables the next simplification: making "retint_restore_args"
label a local numeric one.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Ingo Molnar <mingo@kernel.org>
CC: Borislav Petkov <bp@alien8.de>
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Alexei Starovoitov <ast@plumgrid.com>
CC: Will Drewry <wad@chromium.org>
CC: Kees Cook <keescook@chromium.org>
CC: x86@kernel.org
CC: linux-kernel@vger.kernel.org
---
arch/x86/kernel/entry_64.S | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index dbfc8875..34d60c3 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -740,7 +740,19 @@ opportunistic_sysret_failed:
SWAPGS
jmp restore_args

-retint_restore_args: /* return to kernel space */
+/* Returning to kernel space */
+#ifdef CONFIG_PREEMPT
+ /* Interrupts are off */
+ /* Check if we need preemption */
+ENTRY(retint_kernel)
+ cmpl $0,PER_CPU_VAR(__preempt_count)
+ jnz retint_restore_args
+ bt $9,EFLAGS(%rsp) /* interrupts were off? */
+ jnc retint_restore_args
+ call preempt_schedule_irq
+ jmp exit_intr
+#endif
+retint_restore_args:
DISABLE_INTERRUPTS(CLBR_ANY)
/*
* The iretq could re-enable interrupts:
@@ -830,17 +842,6 @@ retint_signal:
GET_THREAD_INFO(%rcx)
jmp retint_with_reschedule

-#ifdef CONFIG_PREEMPT
- /* Returning to kernel space. Check if we need preemption */
- /* rcx: threadinfo. interrupts off. */
-ENTRY(retint_kernel)
- cmpl $0,PER_CPU_VAR(__preempt_count)
- jnz retint_restore_args
- bt $9,EFLAGS(%rsp) /* interrupts off? */
- jnc retint_restore_args
- call preempt_schedule_irq
- jmp exit_intr
-#endif
CFI_ENDPROC
END(common_interrupt)

--
1.8.1.4