From nobody Sun Apr 19 17:04:00 2026 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 7E7FEECAAA1 for ; Tue, 13 Sep 2022 02:27:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229937AbiIMC1K (ORCPT ); Mon, 12 Sep 2022 22:27:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37500 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229650AbiIMC1I (ORCPT ); Mon, 12 Sep 2022 22:27:08 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7450152DD7 for ; Mon, 12 Sep 2022 19:27:07 -0700 (PDT) Received: from kwepemi500012.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4MRS0l04YxzNm9d; Tue, 13 Sep 2022 10:22:30 +0800 (CST) Received: from huawei.com (10.67.174.53) by kwepemi500012.china.huawei.com (7.221.188.12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 13 Sep 2022 10:27:05 +0800 From: Liao Chang To: , , , , , CC: , , , Subject: [PATCH V2] riscv/kprobes: allocate detour buffer from module area Date: Tue, 13 Sep 2022 10:23:34 +0800 Message-ID: <20220913022334.83997-1-liaochang1@huawei.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.67.174.53] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemi500012.china.huawei.com (7.221.188.12) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" To address the limitation of PC-relative branch instruction on riscv architecture, detour buffer slot used for optprobes is allocated from a region, the distance of which from kernel should be less than 4GB. For the time being, Modules region always live before the kernel. But Vmalloc region reside far from kernel, the distance is half of the kernel address space (See Documentation/riscv/vm-layout.rst), hence it needs to override the alloc_optinsn_page() to make sure allocate detour buffer from jump-safe region. Signed-off-by: Liao Chang --- v2: 1. Avoid to depend on CONFIG_MODUELS. 2. Override alloc_optinsn_page to allocate slot from jump-safe region. --- arch/riscv/kernel/probes/kprobes.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/= kprobes.c index e6e950b7cf32..fd62b0b086d2 100644 --- a/arch/riscv/kernel/probes/kprobes.c +++ b/arch/riscv/kernel/probes/kprobes.c @@ -12,6 +12,7 @@ #include #include #include +#include =20 #include "decode-insn.h" =20 @@ -84,6 +85,30 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) } =20 #ifdef CONFIG_MMU +#ifdef CONFIG_OPTPROBES +void *alloc_optinsn_page(void) +{ + void *page; + + page =3D __vmalloc_node_range(PAGE_SIZE, 1, MODULES_VADDR, + MODULES_END, GFP_KERNEL, + PAGE_KERNEL, 0, NUMA_NO_NODE, + __builtin_return_address(0)); + if (!page) + return NULL; + + set_vm_flush_reset_perms(page); + /* + * First make the page read-only, and only then make it executable to + * prevent it from being W+X in between. + */ + set_memory_ro((unsigned long)page, 1); + set_memory_x((unsigned long)page, 1); + + return page; +} +#endif + void *alloc_insn_page(void) { return __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, VMALLOC_END, --=20 2.17.1