From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752143AbdC0Hxv (ORCPT ); Mon, 27 Mar 2017 03:53:51 -0400 Received: from mail.kernel.org ([198.145.29.136]:48030 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751977AbdC0Hxe (ORCPT ); Mon, 27 Mar 2017 03:53:34 -0400 From: Masami Hiramatsu To: linux-kernel@vger.kernel.org, Ingo Molnar Cc: Peter Zijlstra , Thomas Gleixner , "H . Peter Anvin" , Ananth N Mavinakayanahalli , Anil S Keshavamurthy , "David S . Miller" , Andrey Ryabinin , Ye Xiaolong , mhiramat@kernel.org Subject: [RFC PATCH tip/master V2 3/8] kprobes/x86: Use instruction decoder for booster Date: Mon, 27 Mar 2017 16:52:17 +0900 Message-Id: <149060112763.12303.4615300671782298564.stgit@devbox> X-Mailer: git-send-email 2.9.3 In-Reply-To: <149060091581.12303.13449343279538504544.stgit@devbox> References: <149060091581.12303.13449343279538504544.stgit@devbox> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Use x86 instruction decoder for checking whether the probed instruction is able to boost or not, instead of hand-written code. Signed-off-by: Masami Hiramatsu --- arch/x86/kernel/kprobes/core.c | 39 ++++++++++++++++----------------------- 1 file changed, 16 insertions(+), 23 deletions(-) diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 81d4dc7..6327f95 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -169,35 +169,33 @@ NOKPROBE_SYMBOL(skip_prefixes); */ int can_boost(kprobe_opcode_t *opcodes, void *addr) { + struct insn insn; kprobe_opcode_t opcode; - kprobe_opcode_t *orig_opcodes = opcodes; if (search_exception_tables((unsigned long)addr)) return 0; /* Page fault may occur on this address. */ -retry: - if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) - return 0; - opcode = *(opcodes++); + kernel_insn_init(&insn, (void *)opcodes, MAX_INSN_SIZE); + insn_get_opcode(&insn); /* 2nd-byte opcode */ - if (opcode == 0x0f) { - if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) - return 0; - return test_bit(*opcodes, + if (insn.opcode.nbytes == 2) + return test_bit(insn.opcode.bytes[1], (unsigned long *)twobyte_is_boostable); - } + + if (insn.opcode.nbytes != 1) + return 0; + + /* Can't boost Address-size override prefix */ + if (unlikely(inat_is_address_size_prefix(insn.attr))) + return 0; + + opcode = insn.opcode.bytes[0]; switch (opcode & 0xf0) { -#ifdef CONFIG_X86_64 - case 0x40: - goto retry; /* REX prefix is boostable */ -#endif case 0x60: - if (0x63 < opcode && opcode < 0x67) - goto retry; /* prefixes */ - /* can't boost Address-size override and bound */ - return (opcode != 0x62 && opcode != 0x67); + /* can't boost "bound" */ + return (opcode != 0x62); case 0x70: return 0; /* can't boost conditional jump */ case 0x90: @@ -212,14 +210,9 @@ int can_boost(kprobe_opcode_t *opcodes, void *addr) /* can boost in/out and absolute jmps */ return ((opcode & 0x04) || opcode == 0xea); case 0xf0: - if ((opcode & 0x0c) == 0 && opcode != 0xf1) - goto retry; /* lock/rep(ne) prefix */ /* clear and set flags are boostable */ return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); default: - /* segment override prefixes are boostable */ - if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) - goto retry; /* prefixes */ /* CS override prefix and call are not boostable */ return (opcode != 0x2e && opcode != 0x9a); }