From mboxrd@z Thu Jan 1 00:00:00 1970 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 C7B5BC3DA66 for ; Fri, 25 Aug 2023 08:00:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236781AbjHYIAL (ORCPT ); Fri, 25 Aug 2023 04:00:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59224 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243371AbjHYH77 (ORCPT ); Fri, 25 Aug 2023 03:59:59 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 81B3ACF1; Fri, 25 Aug 2023 00:59:56 -0700 (PDT) Received: from kwepemi500020.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4RXC4Y4q45z1L9Xm; Fri, 25 Aug 2023 15:58:21 +0800 (CST) Received: from [10.67.109.184] (10.67.109.184) by kwepemi500020.china.huawei.com (7.221.188.8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Fri, 25 Aug 2023 15:59:52 +0800 Message-ID: Date: Fri, 25 Aug 2023 15:59:52 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.3.0 Subject: Re: [PATCH bpf-next v2 2/3] riscv: implement a memset like function for text Content-Language: en-US To: Puranjay Mohan References: <20230824133135.1176709-1-puranjay12@gmail.com> <20230824133135.1176709-3-puranjay12@gmail.com> CC: , , , , , , , , , , , , , , From: Pu Lehui In-Reply-To: <20230824133135.1176709-3-puranjay12@gmail.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.109.184] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemi500020.china.huawei.com (7.221.188.8) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/8/24 21:31, Puranjay Mohan wrote: > The BPF JIT needs to write invalid instructions to RX regions of memory > to invalidate removed BPF programs. This needs a function like memset() > that can work with RX memory. > > Implement patch_text_set_nosync() which is similar to text_poke_set() of > x86. > > Signed-off-by: Puranjay Mohan > --- > arch/riscv/include/asm/patch.h | 1 + > arch/riscv/kernel/patch.c | 74 ++++++++++++++++++++++++++++++++++ > 2 files changed, 75 insertions(+) > > diff --git a/arch/riscv/include/asm/patch.h b/arch/riscv/include/asm/patch.h > index 63c98833d510..aa5c1830ea43 100644 > --- a/arch/riscv/include/asm/patch.h > +++ b/arch/riscv/include/asm/patch.h > @@ -7,6 +7,7 @@ > #define _ASM_RISCV_PATCH_H > > int patch_text_nosync(void *addr, const void *insns, size_t len); > +int patch_text_set_nosync(void *addr, const int c, size_t len); > int patch_text(void *addr, u32 *insns, int ninsns); > > extern int riscv_patch_in_stop_machine; > diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c > index 465b2eebbc37..24d49999ac1a 100644 > --- a/arch/riscv/kernel/patch.c > +++ b/arch/riscv/kernel/patch.c > @@ -13,6 +13,7 @@ > #include > #include > #include > +#include > > struct patch_insn { > void *addr; > @@ -53,6 +54,34 @@ static void patch_unmap(int fixmap) > } > NOKPROBE_SYMBOL(patch_unmap); > > +static int __patch_insn_set(void *addr, const int c, size_t len) > +{ > + void *waddr = addr; > + bool across_pages = (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE; > + int ret; > + > + /* > + * Only two pages can be mapped at a time for writing. > + */ > + if (len > 2 * PAGE_SIZE) > + return -EINVAL; > + As a generic part, it better to add text_mutex lock assert. > + if (across_pages) > + patch_map(addr + PAGE_SIZE, FIX_TEXT_POKE1); > + > + waddr = patch_map(addr, FIX_TEXT_POKE0); > + > + memset(waddr, c, len); > + > + patch_unmap(FIX_TEXT_POKE0); > + > + if (across_pages) > + patch_unmap(FIX_TEXT_POKE1); > + > + return 0; > +} > +NOKPROBE_SYMBOL(__patch_insn_set); > + > static int __patch_insn_write(void *addr, const void *insn, size_t len) > { > void *waddr = addr; > @@ -95,6 +124,14 @@ static int __patch_insn_write(void *addr, const void *insn, size_t len) > } > NOKPROBE_SYMBOL(__patch_insn_write); > #else > +static int __patch_insn_set (void *addr, const int c, size_t len) > +{ > + memset(addr, c, len); > + > + return 0; > +} > +NOKPROBE_SYMBOL(__patch_insn_set); > + > static int __patch_insn_write(void *addr, const void *insn, size_t len) > { > return copy_to_kernel_nofault(addr, insn, len); > @@ -102,6 +139,43 @@ static int __patch_insn_write(void *addr, const void *insn, size_t len) > NOKPROBE_SYMBOL(__patch_insn_write); > #endif /* CONFIG_MMU */ > > +static int patch_insn_set(void *addr, const int c, size_t len) > +{ > + size_t patched = 0; > + size_t size; > + int ret = 0; > + > + /* > + * __patch_insn_set() can only work on 2 pages at a time so call it in a > + * loop with len <= 2 * PAGE_SIZE. > + */ > + while (patched < len && !ret) { > + size = min_t(size_t, > + PAGE_SIZE * 2 - offset_in_page(addr + patched), > + len - patched); > + ret = __patch_insn_set(addr + patched, c, size); > + > + patched += size; > + } > + > + return ret; > +} > +NOKPROBE_SYMBOL(patch_insn_set); > + > +int patch_text_set_nosync(void *addr, const int c, size_t len) > +{ > + u32 *tp = addr; > + int ret; > + > + ret = patch_insn_set(tp, c, len); > + > + if (!ret) > + flush_icache_range((uintptr_t) tp, (uintptr_t) tp + len); > + > + return ret; > +} > +NOKPROBE_SYMBOL(patch_text_set_nosync); > + > static int patch_insn_write(void *addr, const void *insn, size_t len) > { > size_t patched = 0;