From patchwork Thu Sep 15 13:49:06 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 9333691 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id AAFF86077A for ; Thu, 15 Sep 2016 13:50:36 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 95F5029085 for ; Thu, 15 Sep 2016 13:50:36 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8A6FC297BB; Thu, 15 Sep 2016 13:50:36 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 0D5B429085 for ; Thu, 15 Sep 2016 13:50:32 +0000 (UTC) Received: (qmail 12280 invoked by uid 550); 15 Sep 2016 13:50:19 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: kernel-hardening@lists.openwall.com Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 12073 invoked from network); 15 Sep 2016 13:50:16 -0000 From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Cc: akpm@linux-foundation.org, ard.biesheuvel@linaro.org, catalin.marinas@arm.com, james.morse@arm.com, keescook@chromium.org, linux-kernel@vger.kernel.org, lorenzo.pieralisi@arm.com, luto@kernel.org, mark.rutland@arm.com, suzuki.poulose@arm.com, takahiro.akashi@linaro.org, will.deacon@arm.com, kernel-hardening@lists.openwall.com Date: Thu, 15 Sep 2016 14:49:06 +0100 Message-Id: <1473947349-14521-6-git-send-email-mark.rutland@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1473947349-14521-1-git-send-email-mark.rutland@arm.com> References: <1473947349-14521-1-git-send-email-mark.rutland@arm.com> Subject: [kernel-hardening] [RFC PATCH 5/8] arm64: assembler: introduce ldr_this_cpu X-Virus-Scanned: ClamAV using ClamSMTP Shortly we will want to load a percpu variable in the return from userspace path. We can save an instruction by folding the addition of the percpu offset into the load instruction, and this patch adds a new helper to do so. At the same time, we clean up this_cpu_ptr for consistency. As with {adr,ldr,str}_l, we change the template to take the destination register first, and name this dst. Secondly, we rename the macro to adr_this_cpu, following the scheme of adr_l, and matching the newly added ldr_this_cpu. Signed-off-by: Mark Rutland Cc: Ard Biesheuvel Cc: Catalin Marinas Cc: James Morse Cc: Will Deacon --- arch/arm64/include/asm/assembler.h | 19 +++++++++++++++---- arch/arm64/kernel/entry.S | 2 +- 2 files changed, 16 insertions(+), 5 deletions(-) diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index d5025c6..265fd81 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -193,14 +193,25 @@ lr .req x30 // link register .endm /* + * @dst: Result of per_cpu(sym, smp_processor_id()) * @sym: The name of the per-cpu variable - * @reg: Result of per_cpu(sym, smp_processor_id()) * @tmp: scratch register */ - .macro this_cpu_ptr, sym, reg, tmp - adr_l \reg, \sym + .macro adr_this_cpu, dst, sym, tmp + adr_l \dst, \sym mrs \tmp, tpidr_el1 - add \reg, \reg, \tmp + add \dst, \dst, \tmp + .endm + + /* + * @dst: Result of READ_ONCE(per_cpu(sym, smp_processor_id())) + * @sym: The name of the per-cpu variable + * @tmp: scratch register + */ + .macro ldr_this_cpu dst, sym, tmp + adr_l \dst, \sym + mrs \tmp, tpidr_el1 + ldr \dst, [\dst, \tmp] .endm /* diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 441420c..52b4241 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -206,7 +206,7 @@ alternative_endif cmp x25, tsk b.ne 9998f - this_cpu_ptr irq_stack, x25, x26 + adr_this_cpu x25, irq_stack, x26 mov x26, #IRQ_STACK_START_SP add x26, x25, x26