From patchwork Fri Nov 17 18:21:59 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 10063213 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 6D4866023A for ; Fri, 17 Nov 2017 18:27:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5D7D02AD30 for ; Fri, 17 Nov 2017 18:27:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5250E2AD1B; Fri, 17 Nov 2017 18:27:01 +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,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_MED autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 812B72ACC2 for ; Fri, 17 Nov 2017 18:26:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=tjXPCbumbICxeUBoa/UHK4fMJ5LguMURsYX3Em8qGE0=; b=DtClwtmIPbIXMt1AwlfbezRyJB Kf1NXSJ5ZWw2lT47iKPHOVjrpubHZQ1BE2B9bp0rvI+4D9w4C9ArXbmm/Tu+U+WAnvTWvZLQJZpYj cwa+uVddAYrr4XZ9+AH/tUWEiaWcUWOou/zqb4meOl6EPhg7egPZMgZ1QMPV3jc5MD1/A3R3yIeOR PCZ77zGuLjN/CIN8be4PfS7uMAxTcW9QLpufSAJn8gmPXKi9e6GwbdCVhgfnT8d1dMTWuvqbUUjzC 5HnyE9MEbc0SlbMv6CsNOvmJu8/Vy9fiMC6i8lFX2FvcDWpQyA41TL8FG2mBSevkHGYq4gRKhXKXb 8I7tDOOA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1eFlLm-0002eM-Cf; Fri, 17 Nov 2017 18:26:50 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1eFlHj-0005r9-Bo for linux-arm-kernel@lists.infradead.org; Fri, 17 Nov 2017 18:22:49 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D903E1A9A; Fri, 17 Nov 2017 10:21:55 -0800 (PST) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id AA5E23F246; Fri, 17 Nov 2017 10:21:55 -0800 (PST) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id DB1601AE10B5; Fri, 17 Nov 2017 18:22:03 +0000 (GMT) From: Will Deacon To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 16/18] arm64: entry: Add fake CPU feature for mapping the kernel at EL0 Date: Fri, 17 Nov 2017 18:21:59 +0000 Message-Id: <1510942921-12564-17-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1510942921-12564-1-git-send-email-will.deacon@arm.com> References: <1510942921-12564-1-git-send-email-will.deacon@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20171117_102239_580711_8EDA649F X-CRM114-Status: GOOD ( 12.30 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, keescook@chromium.org, ard.biesheuvel@linaro.org, catalin.marinas@arm.com, dave.hansen@linux.intel.com, sboyd@codeaurora.org, linux-kernel@vger.kernel.org, Will Deacon MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Allow explicit disabling of the entry trampoline on the kernel command line by adding a fake CPU feature (ARM64_MAP_KERNEL_AT_EL0) that can be used to apply alternative sequences to our entry code and avoid use of the trampoline altogether. Signed-off-by: Will Deacon --- arch/arm64/include/asm/cpucaps.h | 3 ++- arch/arm64/kernel/cpufeature.c | 11 +++++++++++ arch/arm64/kernel/entry.S | 6 +++++- arch/arm64/mm/mmu.c | 7 +++++++ 4 files changed, 25 insertions(+), 2 deletions(-) diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h index 8da621627d7c..f61d85f76683 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -40,7 +40,8 @@ #define ARM64_WORKAROUND_858921 19 #define ARM64_WORKAROUND_CAVIUM_30115 20 #define ARM64_HAS_DCPOP 21 +#define ARM64_MAP_KERNEL_AT_EL0 22 -#define ARM64_NCAPS 22 +#define ARM64_NCAPS 23 #endif /* __ASM_CPUCAPS_H */ diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 21e2c95d24e7..aa6b90de6591 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -796,6 +796,12 @@ static bool has_no_fpsimd(const struct arm64_cpu_capabilities *entry, int __unus ID_AA64PFR0_FP_SHIFT) < 0; } +static bool map_kernel_at_el0(const struct arm64_cpu_capabilities *entry, + int __unused) +{ + return arm64_kernel_mapped_at_el0(); +} + static const struct arm64_cpu_capabilities arm64_features[] = { { .desc = "GIC system register CPU interface", @@ -883,6 +889,11 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .matches = hyp_offset_low, }, { + .capability = ARM64_MAP_KERNEL_AT_EL0, + .def_scope = SCOPE_SYSTEM, + .matches = map_kernel_at_el0, + }, + { /* FP/SIMD is not implemented */ .capability = ARM64_HAS_NO_FPSIMD, .def_scope = SCOPE_SYSTEM, diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index a600879939ce..a74253defc5b 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -73,6 +73,7 @@ .macro kernel_ventry, el, label, regsize = 64 .align 7 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 +alternative_if_not ARM64_MAP_KERNEL_AT_EL0 .if \el == 0 .if \regsize == 64 mrs x30, tpidrro_el0 @@ -80,6 +81,7 @@ mov x30, xzr .endif .endif +alternative_else_nop_endif #endif sub sp, sp, #S_FRAME_SIZE @@ -300,6 +302,7 @@ alternative_if ARM64_WORKAROUND_845719 alternative_else_nop_endif #endif #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 +alternative_if_not ARM64_MAP_KERNEL_AT_EL0 tramp_alias x30, tramp_exit_compat b 4f 3: @@ -308,6 +311,7 @@ alternative_else_nop_endif tramp_alias x30, tramp_exit_native 4: prfm plil1strm, [x30] +alternative_else_nop_endif #else 3: #endif @@ -332,7 +336,7 @@ alternative_else_nop_endif #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 .if \el == 0 - br x30 + alternative_insn "br x30", nop, ARM64_MAP_KERNEL_AT_EL0 .endif #endif eret diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 5ce5cb1249da..dab987f2912c 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -571,6 +571,13 @@ static int __init map_entry_trampoline(void) return 0; } core_initcall(map_entry_trampoline); + +static int __init parse_nokaiser(char *__unused) +{ + static_branch_disable(&__unmap_kernel_at_el0); + return 0; +} +__setup("nokaiser", parse_nokaiser); #else static void __init add_tramp_vma(void) {} #endif