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 X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B173C48BDF for ; Tue, 15 Jun 2021 03:41:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 38D7E613DA for ; Tue, 15 Jun 2021 03:41:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230208AbhFODnk (ORCPT ); Mon, 14 Jun 2021 23:43:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33204 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229869AbhFODnh (ORCPT ); Mon, 14 Jun 2021 23:43:37 -0400 Received: from mail-yb1-xb34.google.com (mail-yb1-xb34.google.com [IPv6:2607:f8b0:4864:20::b34]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 408FEC061574 for ; Mon, 14 Jun 2021 20:41:34 -0700 (PDT) Received: by mail-yb1-xb34.google.com with SMTP id h15so18406900ybm.13 for ; Mon, 14 Jun 2021 20:41:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=t/YamNGP+ckwga9loSudtTcbfG6KNZMYD9dgrRElUEY=; b=enOTOgUPsHecPapW0EVbJYb4dNAsLVbTc7It8jRha4hyxFAsCO7rCIN/4hGnR3aOy6 cDdSp2lR3seoHr8Nm530jsODbJyul5qZA3eXWJULxB0tDVLDU0rRcMN/NU5fTzyXTKKi CbDVz2unkihaqMs6J0/IJsj6KxfY3/69d8NACWUTqppeVkJgiIQPKxgi/y2ef7DwZLH5 2bFxRdEwpnVsgpGE8vQ8NFoACN0C8Sy988+fMrjtSTOBqtiiEqILIPrihaVgJ078w4hq vJViARxaY98Ti0OEHm6kRSd0qxzHao4VklA+Vhw2rUCr/0F8wokrccwoyguF+sXBdPm2 0ZYA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=t/YamNGP+ckwga9loSudtTcbfG6KNZMYD9dgrRElUEY=; b=gWM2St+8g73v6yY4xFvGzVGbX1DdOBVVNHy52xkx8EMC35pT37o6V6kkpz4IiOSvZj 4LeYGuTl3ZQ/5JsAdfu+Z5cZTprBrve7T+L3/Qn7JKU5U2zUddOWGqFJ0ywjfCkZf81w 1iGQQg2xG/aXJeDjEslt7rB21tX0on2Re7ZZfVTWMZThrSxEeYhGEdjiMpOQkxD9i1ys ADHQkev4ihz6Cvapj782YLT94JRGzgNzQwTj6ksTniw/dfejxAXvIx2MGDuoIh2INylJ FOXImb5sb2fCBgbaIvbcgqSrhP/r2ORjDBdY3Ctsjizput+UuRO8tHruuUx3YUAoWicR fzvw== X-Gm-Message-State: AOAM531iVynSQOmbZnVK8n5Ni6dMAxBJFxmYSPWN9uaVxUuR6GiehVLU yk8mQAf9VYcTkTSnmPYGVajwMgrAXSlK+G4Hkvo= X-Google-Smtp-Source: ABdhPJw/GJouabv8wuGtyUdszFLf/gI1rZKiJqk5oAbZvePMYRuZPppJfnLCUIPqqVHUy0xvodHT7ZT/7ifMp2uN3II= X-Received: by 2002:a25:b8c:: with SMTP id 134mr29650853ybl.332.1623728493419; Mon, 14 Jun 2021 20:41:33 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Jordan Niethe Date: Tue, 15 Jun 2021 13:41:22 +1000 Message-ID: Subject: Re: [PATCH v2 05/12] powerpc: Do not dereference code as 'struct ppc_inst' (uprobe, code-patching, feature-fixups) To: Christophe Leroy Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , "Naveen N. Rao" , linux-kernel@vger.kernel.org, linuxppc-dev Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 20, 2021 at 11:50 PM Christophe Leroy wrote: > > 'struct ppc_inst' is an internal structure to represent an instruction, > it is not directly the representation of that instruction in text code. > It is not meant to map and dereference code. > > Dereferencing code directly through 'struct ppc_inst' has two main issues: > - On powerpc, structs are expected to be 8 bytes aligned while code is > spread every 4 byte. > - Should a non prefixed instruction lie at the end of the page and the > following page not be mapped, it would generate a page fault. > > In-memory code must be accessed with ppc_inst_read(). > > Signed-off-by: Christophe Leroy > --- > arch/powerpc/kernel/uprobes.c | 2 +- > arch/powerpc/lib/code-patching.c | 8 ++++---- > arch/powerpc/lib/feature-fixups.c | 2 +- > 3 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/arch/powerpc/kernel/uprobes.c b/arch/powerpc/kernel/uprobes.c > index 186f69b11e94..46971bb41d05 100644 > --- a/arch/powerpc/kernel/uprobes.c > +++ b/arch/powerpc/kernel/uprobes.c > @@ -42,7 +42,7 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, > return -EINVAL; > > if (cpu_has_feature(CPU_FTR_ARCH_31) && > - ppc_inst_prefixed(auprobe->insn) && > + ppc_inst_prefixed(ppc_inst_read(&auprobe->insn)) && > (addr & 0x3f) == 60) { > pr_info_ratelimited("Cannot register a uprobe on 64 byte unaligned prefixed instruction\n"); > return -EINVAL; > diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c > index 870b30d9be2f..0308429b0d1a 100644 > --- a/arch/powerpc/lib/code-patching.c > +++ b/arch/powerpc/lib/code-patching.c > @@ -329,13 +329,13 @@ static unsigned long branch_iform_target(const struct ppc_inst *instr) > { > signed long imm; > > - imm = ppc_inst_val(*instr) & 0x3FFFFFC; > + imm = ppc_inst_val(ppc_inst_read(instr)) & 0x3FFFFFC; > > /* If the top bit of the immediate value is set this is negative */ > if (imm & 0x2000000) > imm -= 0x4000000; > > - if ((ppc_inst_val(*instr) & BRANCH_ABSOLUTE) == 0) > + if ((ppc_inst_val(ppc_inst_read(instr)) & BRANCH_ABSOLUTE) == 0) > imm += (unsigned long)instr; > > return (unsigned long)imm; > @@ -345,13 +345,13 @@ static unsigned long branch_bform_target(const struct ppc_inst *instr) > { > signed long imm; > > - imm = ppc_inst_val(*instr) & 0xFFFC; > + imm = ppc_inst_val(ppc_inst_read(instr)) & 0xFFFC; > > /* If the top bit of the immediate value is set this is negative */ > if (imm & 0x8000) > imm -= 0x10000; > > - if ((ppc_inst_val(*instr) & BRANCH_ABSOLUTE) == 0) > + if ((ppc_inst_val(ppc_inst_read(instr)) & BRANCH_ABSOLUTE) == 0) > imm += (unsigned long)instr; > > return (unsigned long)imm; > diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c > index fe26f2fa0f3f..8905b53109bc 100644 > --- a/arch/powerpc/lib/feature-fixups.c > +++ b/arch/powerpc/lib/feature-fixups.c > @@ -51,7 +51,7 @@ static int patch_alt_instruction(struct ppc_inst *src, struct ppc_inst *dest, > > instr = ppc_inst_read(src); > > - if (instr_is_relative_branch(*src)) { > + if (instr_is_relative_branch(ppc_inst_read(src))) { The above variable instr could be used here, but that is not an issue with this patch. > struct ppc_inst *target = (struct ppc_inst *)branch_target(src); > > /* Branch within the section doesn't need translating */ > -- > 2.25.0 > Reviewed by: Jordan Niethe