From patchwork Fri Mar 18 17:48:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Morse X-Patchwork-Id: 553003 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A21EC43217 for ; Fri, 18 Mar 2022 17:49:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239884AbiCRRvO (ORCPT ); Fri, 18 Mar 2022 13:51:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37398 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239838AbiCRRvH (ORCPT ); Fri, 18 Mar 2022 13:51:07 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id BA96317DC85; Fri, 18 Mar 2022 10:49:40 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 875D91515; Fri, 18 Mar 2022 10:49:40 -0700 (PDT) Received: from eglon.cambridge.arm.com (eglon.cambridge.arm.com [10.1.196.218]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DBC163F7B4; Fri, 18 Mar 2022 10:49:39 -0700 (PDT) From: James Morse To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, james.morse@arm.com, catalin.marinas@arm.com Subject: [stable:PATCH v4.19.235 08/22] arm64: entry: Allow tramp_alias to access symbols after the 4K boundary Date: Fri, 18 Mar 2022 17:48:28 +0000 Message-Id: <20220318174842.2321061-9-james.morse@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220318174842.2321061-1-james.morse@arm.com> References: <20220318174842.2321061-1-james.morse@arm.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org commit 6c5bf79b69f911560fbf82214c0971af6e58e682 upstream. Systems using kpti enter and exit the kernel through a trampoline mapping that is always mapped, even when the kernel is not. tramp_valias is a macro to find the address of a symbol in the trampoline mapping. Adding extra sets of vectors will expand the size of the entry.tramp.text section to beyond 4K. tramp_valias will be unable to generate addresses for symbols beyond 4K as it uses the 12 bit immediate of the add instruction. As there are now two registers available when tramp_alias is called, use the extra register to avoid the 4K limit of the 12 bit immediate. Reviewed-by: Russell King (Oracle) Reviewed-by: Catalin Marinas Signed-off-by: James Morse --- arch/arm64/kernel/entry.S | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 1df718f53a1f..5d174c119563 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -135,9 +135,12 @@ .org .Lventry_start\@ + 128 // Did we overflow the ventry slot? .endm - .macro tramp_alias, dst, sym + .macro tramp_alias, dst, sym, tmp mov_q \dst, TRAMP_VALIAS - add \dst, \dst, #(\sym - .entry.tramp.text) + adr_l \tmp, \sym + add \dst, \dst, \tmp + adr_l \tmp, .entry.tramp.text + sub \dst, \dst, \tmp .endm // This macro corrupts x0-x3. It is the caller's duty @@ -362,10 +365,10 @@ alternative_else_nop_endif #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 bne 4f msr far_el1, x29 - tramp_alias x30, tramp_exit_native + tramp_alias x30, tramp_exit_native, x29 br x30 4: - tramp_alias x30, tramp_exit_compat + tramp_alias x30, tramp_exit_compat, x29 br x30 #endif .else @@ -1265,7 +1268,7 @@ alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0 alternative_else_nop_endif #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 - tramp_alias dst=x5, sym=__sdei_asm_exit_trampoline + tramp_alias dst=x5, sym=__sdei_asm_exit_trampoline, tmp=x3 br x5 #endif ENDPROC(__sdei_asm_handler)