[PATCH 3/4] x86/asm/entry/64: use smaller insns

Denys Vlasenko
2015-03-25T17:19:01Z

The $AUDIT_ARCH_X86_64 parameter to syscall_trace_enter_phase1/2
is a 32-bit constant, loading it with 32-bit MOV produces 5-byte insn
instead of 10-byte 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 | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 11b7339..23aa43e 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -306,7 +306,7 @@ system_call_fastpath:
/* Do syscall entry tracing */
tracesys:
movq %rsp, %rdi
- movq $AUDIT_ARCH_X86_64, %rsi
+ movl $AUDIT_ARCH_X86_64, %esi
call syscall_trace_enter_phase1
test %rax, %rax
jnz tracesys_phase2 /* if needed, run the slow path */
@@ -317,7 +317,7 @@ tracesys:
tracesys_phase2:
SAVE_EXTRA_REGS
movq %rsp, %rdi
- movq $AUDIT_ARCH_X86_64, %rsi
+ movl $AUDIT_ARCH_X86_64, %esi
movq %rax,%rdx
call syscall_trace_enter_phase2

--
1.8.1.4