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From: Denys Vlasenko <dvlasenk@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Denys Vlasenko <dvlasenk@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Andy Lutomirski <luto@amacapital.net>,
	Frederic Weisbecker <fweisbec@gmail.com>, X86 ML <x86@kernel.org>,
	Alexei Starovoitov <ast@plumgrid.com>,
	Will Drewry <wad@chromium.org>, Kees Cook <keescook@chromium.org>
Subject: [PATCH 16/17] x86: entry_64.S: trivial optimization for ENOSYS
Date: Fri,  8 Aug 2014 19:44:39 +0200	[thread overview]
Message-ID: <1407519880-6719-17-git-send-email-dvlasenk@redhat.com> (raw)
In-Reply-To: <1407519880-6719-1-git-send-email-dvlasenk@redhat.com>

This code uses a slightly shorter insn.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
CC: Linus Torvalds <torvalds@linux-foundation.org>
CC: Oleg Nesterov <oleg@redhat.com>
CC: "H. Peter Anvin" <hpa@zytor.com>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: X86 ML <x86@kernel.org>
CC: Alexei Starovoitov <ast@plumgrid.com>
CC: Will Drewry <wad@chromium.org>
CC: Kees Cook <keescook@chromium.org>
CC: linux-kernel@vger.kernel.org
---
 arch/x86/kernel/entry_64.S | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 7bc8c24..5d639a6 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -272,6 +272,7 @@ system_call_fastpath:
 	ja badsys
 	movq %r10,%rcx
 	call *sys_call_table(,%rax,8)  # XXX:	 rip relative
+from_badsys:
 	movq %rax,RAX(%rsp)
 /*
  * Syscall return path ending with SYSRET (fast path)
@@ -334,8 +335,8 @@ sysret_signal:
 	jmp int_check_syscall_exit_work
 
 badsys:
-	movq $-ENOSYS,RAX(%rsp)
-	jmp ret_from_sys_call
+	movq	$-ENOSYS,%rax
+	jmp	from_badsys
 
 #ifdef CONFIG_AUDITSYSCALL
 	/*
-- 
1.8.1.4


  parent reply	other threads:[~2014-08-08 17:46 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-08-08 17:44 [PATCH v4 0/17] x86: entry.S optimizations Denys Vlasenko
2014-08-08 17:44 ` [PATCH 01/17] x86: entry_64.S: delete unused code Denys Vlasenko
2014-08-08 17:44 ` [PATCH 02/17] x86: ia32entry.S: fix wrong symbolic constant usage: R11->ARGOFFSET Denys Vlasenko
2014-08-08 17:44 ` [PATCH 03/17] x86: open-code register save/restore in trace_hardirqs thunks Denys Vlasenko
2014-08-08 17:44 ` [PATCH 04/17] x86: entry_64.S: fold SAVE_ARGS_IRQ macro into its sole user Denys Vlasenko
2014-08-08 17:44 ` [PATCH 05/17] x86: entry_64.S: always allocate complete "struct pt_regs" Denys Vlasenko
2014-08-08 17:44 ` [PATCH 06/17] x86: mass removal of ARGOFFSET Denys Vlasenko
2014-08-08 17:44 ` [PATCH 07/17] x86: rename some macros and labels, no code changes Denys Vlasenko
2014-08-08 17:44 ` [PATCH 08/17] x86: add comments about various syscall instructions, " Denys Vlasenko
2014-08-08 17:44 ` [PATCH 09/17] x86: entry_64.S: move save_paranoid and ret_from_fork closer to their users Denys Vlasenko
2014-08-08 17:44 ` [PATCH 10/17] x86: entry_64.S: rename save_paranoid to paranoid_entry, no code changes Denys Vlasenko
2014-08-08 17:44 ` [PATCH 11/17] x86: entry_64.S: fold test_in_nmi macro into its only user Denys Vlasenko
2014-08-08 17:44 ` [PATCH 12/17] x86: get rid of KERNEL_STACK_OFFSET Denys Vlasenko
2014-08-08 17:44 ` [PATCH 13/17] x86: ia32entry.S: fold IA32_ARG_FIXUP macro into its callers Denys Vlasenko
2014-08-08 17:44 ` [PATCH 14/17] x86: ia32entry.S: use mov instead of push/pop where possible Denys Vlasenko
2014-08-08 17:44 ` [PATCH 15/17] x86: code shrink in paranoid_exit Denys Vlasenko
2014-08-08 17:44 ` Denys Vlasenko [this message]
2014-08-08 22:48   ` [PATCH 16/17] x86: entry_64.S: trivial optimization for ENOSYS Andy Lutomirski
2014-08-08 17:44 ` [PATCH 17/17] x86: simplify iret stack handling on SYSCALL64 fastpath Denys Vlasenko
2014-08-08 22:59   ` Andy Lutomirski
2014-08-10 15:00     ` Denys Vlasenko
2014-08-10 22:42       ` Andy Lutomirski
2014-08-11 12:24         ` Denys Vlasenko
2014-08-11 20:06           ` Andy Lutomirski
2014-08-12  9:21             ` Denys Vlasenko
2014-08-13  1:02               ` Andy Lutomirski
2014-08-10 18:47   ` [PATCH 17/17 v2] " Denys Vlasenko
2014-08-09  0:27 ` [PATCH v4 0/17] x86: entry.S optimizations H. Peter Anvin

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