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 80F30C61DA4 for ; Wed, 15 Feb 2023 00:11:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232371AbjBOAK7 (ORCPT ); Tue, 14 Feb 2023 19:10:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52990 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229765AbjBOAK4 (ORCPT ); Tue, 14 Feb 2023 19:10:56 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F713311D4 for ; Tue, 14 Feb 2023 16:10:30 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 24D30B81F62 for ; Wed, 15 Feb 2023 00:10:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F240C433D2; Wed, 15 Feb 2023 00:10:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1676419827; bh=3J6SK8xX///7h1Dumxc1Ibt18+tu5um71PTnl4nqrdk=; h=From:To:Cc:Subject:Date:From; b=o0v3agpCzjFLGmJpdUgnhyIzfE6pp51RRQykQEKv6MkKepWZ801Lqz0aYWlG45weu 38BLOunOHDEZEMJVJdLZVKwndv+gZNvEpC9MPFfIYmpxqlNZG2X9e2TOsnfQS632E1 Q/VXjydkCuwrieXtfrIMZf2SZA1qj4mDWX9Eu2l7+q4dkFTm7dcg6iSBcsD9K2tB8x MeEDKYRZK7+tBofeQofVlCVSD5aWvcaKg6CsqcKCMZjVB+WKfG5VuycMnkd1jAmZCa IJygfX1teQNAq7S0WtKhbdgHB3BzIWzkB5v60hImrl0eCC655i5RYcU2C48z5AxJtx pX3QQjflyBYBA== From: "Masami Hiramatsu (Google)" To: x86@kernel.org Cc: Nadav Amit , Borislav Petkov , Peter Zijlstra , Steven Rostedt , Masami Hiramatsu , linux-kernel@vger.kernel.org Subject: [PATCH -tip v2] x86/kprobes: Remove unneeded casting from immediate value Date: Wed, 15 Feb 2023 09:10:24 +0900 Message-Id: <167641982421.1677831.18379341946856978545.stgit@mhiramat.roam.corp.google.com> X-Mailer: git-send-email 2.39.1.581.gbfd45094c4-goog User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu (Google) Remove unneeded casting from immediate value assignments for relative jump offset. Since the immediate values in the 'insn' data structure are assigned from immediate bytes as a signed value to insn.immediate.value by insn_field_set(). Thus, if we need to access that value as a signed value (in this kprobe's case), we don't need to cast it. This is a kind of clean up (should not change behavior) follows Nadav's bugfix. Link: https://lore.kernel.org/all/20230208071708.4048-1-namit@vmware.com/ Signed-off-by: Masami Hiramatsu (Google) --- Changes in v2: - Remove meaningless immediate size branches too. --- arch/x86/kernel/kprobes/core.c | 19 ++++--------------- 1 file changed, 4 insertions(+), 15 deletions(-) diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 695873c0f50b..41ffdf04d9c4 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -606,20 +606,12 @@ static int prepare_emulation(struct kprobe *p, struct insn *insn) break; case 0xe8: /* near call relative */ p->ainsn.emulate_op = kprobe_emulate_call; - if (insn->immediate.nbytes == 2) - p->ainsn.rel32 = *(s16 *)&insn->immediate.value; - else - p->ainsn.rel32 = *(s32 *)&insn->immediate.value; + p->ainsn.rel32 = insn->immediate.value; break; case 0xeb: /* short jump relative */ case 0xe9: /* near jump relative */ p->ainsn.emulate_op = kprobe_emulate_jmp; - if (insn->immediate.nbytes == 1) - p->ainsn.rel32 = *(s8 *)&insn->immediate.value; - else if (insn->immediate.nbytes == 2) - p->ainsn.rel32 = *(s16 *)&insn->immediate.value; - else - p->ainsn.rel32 = *(s32 *)&insn->immediate.value; + p->ainsn.rel32 = insn->immediate.value; break; case 0x70 ... 0x7f: /* 1 byte conditional jump */ @@ -633,10 +625,7 @@ static int prepare_emulation(struct kprobe *p, struct insn *insn) /* 2 bytes Conditional Jump */ p->ainsn.emulate_op = kprobe_emulate_jcc; p->ainsn.jcc.type = opcode & 0xf; - if (insn->immediate.nbytes == 2) - p->ainsn.rel32 = *(s16 *)&insn->immediate.value; - else - p->ainsn.rel32 = *(s32 *)&insn->immediate.value; + p->ainsn.rel32 = insn->immediate.value; } else if (opcode == 0x01 && X86_MODRM_REG(insn->modrm.bytes[0]) == 0 && X86_MODRM_MOD(insn->modrm.bytes[0]) == 3) { @@ -651,7 +640,7 @@ static int prepare_emulation(struct kprobe *p, struct insn *insn) p->ainsn.emulate_op = kprobe_emulate_loop; p->ainsn.loop.type = opcode & 0x3; p->ainsn.loop.asize = insn->addr_bytes * 8; - p->ainsn.rel32 = *(s8 *)&insn->immediate.value; + p->ainsn.rel32 = insn->immediate.value; break; case 0xff: /*