From patchwork Fri Sep 5 22:13:56 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andy Lutomirski X-Patchwork-Id: 4855141 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 90BCA9F32F for ; Fri, 5 Sep 2014 22:17:12 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id AC6B12021A for ; Fri, 5 Sep 2014 22:17:11 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 21EF7201FB for ; Fri, 5 Sep 2014 22:17:10 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1XQ1ma-00016S-IT; Fri, 05 Sep 2014 22:15:04 +0000 Received: from mail-yk0-f176.google.com ([209.85.160.176]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1XQ1mO-0000ZF-2F for linux-arm-kernel@lists.infradead.org; Fri, 05 Sep 2014 22:14:52 +0000 Received: by mail-yk0-f176.google.com with SMTP id 19so7350379ykq.35 for ; Fri, 05 Sep 2014 15:14:34 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:in-reply-to:references; bh=Ly2ged3LV5UtVnaiJ5dRlmi0SXluoTfKNyARUuR+YCg=; b=Ks6K7lfxtd26gEZ3EuOwrbWtDTNLPnaXxP2tyQ5nloRBsaKmbVsxG9DH6Kaiqe163P eKG9krDAKZEukOhgOZ+9O/dmpnVPoXLRwQiK6WBrrvYwaFDvHXgc8FdYGMcSY8PuBGyF 1x5Mq3Lsp+4NvUUFKfaaqHFOJmTte5+01UiH554XGm8ERi4m1ATfmjtc2re0WGY+B/lS AGDfy/OBzSkLKUnmCsN8VrDncKrWUO2mjNh2ULjyX3MRISf1sLnMgMWGt0BjqqGEOZzL rX06rHef/di5ppFuCtgsw9A6+K64YWml2SDxq5Achd6JxaG6I8kjz65doMTtWIjt+RCo FJ8w== X-Gm-Message-State: ALoCoQnswZmZbZN1SZK3ALxG99fW+JhWdq31yDnLrceparwBAKtEvy0BwDbbftlZ2jTJeXcB/9vQ X-Received: by 10.236.103.170 with SMTP id f30mr18442880yhg.76.1409955274172; Fri, 05 Sep 2014 15:14:34 -0700 (PDT) Received: from localhost ([2602:301:77d8:1800:bd9e:fe09:e642:968]) by mx.google.com with ESMTPSA id n36sm1276309yhp.49.2014.09.05.15.14.32 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 05 Sep 2014 15:14:33 -0700 (PDT) From: Andy Lutomirski To: linux-kernel@vger.kernel.org, Kees Cook , Will Drewry , Oleg Nesterov Subject: [PATCH v5 5/5] x86_64, entry: Use split-phase syscall_trace_enter for 64-bit syscalls Date: Fri, 5 Sep 2014 15:13:56 -0700 Message-Id: X-Mailer: git-send-email 1.9.3 In-Reply-To: References: In-Reply-To: References: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140905_151452_208850_1F2E450D X-CRM114-Status: GOOD ( 10.53 ) X-Spam-Score: -0.9 (/) Cc: linux-arch@vger.kernel.org, linux-mips@linux-mips.org, Frederic Weisbecker , x86@kernel.org, Andy Lutomirski , linux-security-module@vger.kernel.org, hpa@zytor.com, linux-arm-kernel@lists.infradead.org, Alexei Starovoitov X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-3.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On KVM on my box, this reduces the overhead from an always-accept seccomp filter from ~130ns to ~17ns. Most of that comes from avoiding IRET on every syscall when seccomp is enabled. In extremely approximate hacked-up benchmarking, just bypassing IRET saves about 80ns, so there's another 43ns of savings here from simplifying the seccomp path. The diffstat is also rather nice :) Signed-off-by: Andy Lutomirski --- arch/x86/kernel/entry_64.S | 38 +++++++++++++++----------------------- 1 file changed, 15 insertions(+), 23 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 0bd6d3c28064..df088bb03fb3 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -478,22 +478,6 @@ sysret_signal: #ifdef CONFIG_AUDITSYSCALL /* - * Fast path for syscall audit without full syscall trace. - * We just call __audit_syscall_entry() directly, and then - * jump back to the normal fast path. - */ -auditsys: - movq %r10,%r9 /* 6th arg: 4th syscall arg */ - movq %rdx,%r8 /* 5th arg: 3rd syscall arg */ - movq %rsi,%rcx /* 4th arg: 2nd syscall arg */ - movq %rdi,%rdx /* 3rd arg: 1st syscall arg */ - movq %rax,%rsi /* 2nd arg: syscall number */ - movl $AUDIT_ARCH_X86_64,%edi /* 1st arg: audit arch */ - call __audit_syscall_entry - LOAD_ARGS 0 /* reload call-clobbered registers */ - jmp system_call_fastpath - - /* * Return fast path for syscall audit. Call __audit_syscall_exit() * directly and then jump back to the fast path with TIF_SYSCALL_AUDIT * masked off. @@ -510,17 +494,25 @@ sysret_audit: /* Do syscall tracing */ tracesys: -#ifdef CONFIG_AUDITSYSCALL - testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET) - jz auditsys -#endif + leaq -REST_SKIP(%rsp), %rdi + movq $AUDIT_ARCH_X86_64, %rsi + call syscall_trace_enter_phase1 + test %rax, %rax + jnz tracesys_phase2 /* if needed, run the slow path */ + LOAD_ARGS 0 /* else restore clobbered regs */ + jmp system_call_fastpath /* and return to the fast path */ + +tracesys_phase2: SAVE_REST FIXUP_TOP_OF_STACK %rdi - movq %rsp,%rdi - call syscall_trace_enter + movq %rsp, %rdi + movq $AUDIT_ARCH_X86_64, %rsi + movq %rax,%rdx + call syscall_trace_enter_phase2 + /* * Reload arg registers from stack in case ptrace changed them. - * We don't reload %rax because syscall_trace_enter() returned + * We don't reload %rax because syscall_trace_entry_phase2() returned * the value it wants us to use in the table lookup. */ LOAD_ARGS ARGOFFSET, 1