From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757478Ab1DAOne (ORCPT ); Fri, 1 Apr 2011 10:43:34 -0400 Received: from e28smtp01.in.ibm.com ([122.248.162.1]:41269 "EHLO e28smtp01.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757324Ab1DAOna (ORCPT ); Fri, 1 Apr 2011 10:43:30 -0400 From: Srikar Dronamraju To: Peter Zijlstra , Ingo Molnar Cc: Steven Rostedt , Srikar Dronamraju , Linux-mm , Arnaldo Carvalho de Melo , Linus Torvalds , Andi Kleen , Christoph Hellwig , Jonathan Corbet , Thomas Gleixner , Masami Hiramatsu , Oleg Nesterov , LKML , SystemTap , Jim Keniston , Roland McGrath , Ananth N Mavinakayanahalli , Andrew Morton Date: Fri, 01 Apr 2011 20:03:48 +0530 Message-Id: <20110401143348.15455.68644.sendpatchset@localhost6.localdomain6> In-Reply-To: <20110401143223.15455.19844.sendpatchset@localhost6.localdomain6> References: <20110401143223.15455.19844.sendpatchset@localhost6.localdomain6> Subject: [PATCH v3 2.6.39-rc1-tip 7/26] 7: x86: analyze instruction and determine fixups. Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The instruction analysis is based on x86 instruction decoder and determines if an instruction can be probed and determines the necessary fixups after singlestep. Instruction analysis is done at probe insertion time so that we avoid having to repeat the same analysis every time a probe is hit. Signed-off-by: Jim Keniston Signed-off-by: Srikar Dronamraju --- arch/x86/include/asm/uprobes.h | 2 arch/x86/kernel/Makefile | 1 arch/x86/kernel/uprobes.c | 414 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 417 insertions(+), 0 deletions(-) create mode 100644 arch/x86/kernel/uprobes.c diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h index 5026359..0063207 100644 --- a/arch/x86/include/asm/uprobes.h +++ b/arch/x86/include/asm/uprobes.h @@ -37,4 +37,6 @@ struct uprobe_arch_info { #else struct uprobe_arch_info {}; #endif +struct uprobe; +extern int analyze_insn(struct task_struct *tsk, struct uprobe *uprobe); #endif /* _ASM_UPROBES_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 758b379..ef8ffff 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -111,6 +111,7 @@ obj-$(CONFIG_X86_CHECK_BIOS_CORRUPTION) += check.o obj-$(CONFIG_SWIOTLB) += pci-swiotlb.o obj-$(CONFIG_OF) += devicetree.o +obj-$(CONFIG_UPROBES) += uprobes.o ### # 64 bit specific files diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c new file mode 100644 index 0000000..f81e940 --- /dev/null +++ b/arch/x86/kernel/uprobes.c @@ -0,0 +1,414 @@ +/* + * Userspace Probes (UProbes) for x86 + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) IBM Corporation, 2008-2010 + * Authors: + * Srikar Dronamraju + * Jim Keniston + */ + +#include +#include +#include +#include + +#include +#include + +#ifdef CONFIG_X86_32 +#define is_32bit_app(tsk) 1 +#else +#define is_32bit_app(tsk) (test_tsk_thread_flag(tsk, TIF_IA32)) +#endif + +#define UPROBES_FIX_RIP_AX 0x8000 +#define UPROBES_FIX_RIP_CX 0x4000 + +/* Adaptations for mhiramat x86 decoder v14. */ +#define OPCODE1(insn) ((insn)->opcode.bytes[0]) +#define OPCODE2(insn) ((insn)->opcode.bytes[1]) +#define OPCODE3(insn) ((insn)->opcode.bytes[2]) +#define MODRM_REG(insn) X86_MODRM_REG(insn->modrm.value) + +#define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\ + (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ + (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ + (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ + (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ + << (row % 32)) + + +static const u32 good_insns_64[256 / 32] = { + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ + /* ---------------------------------------------- */ + W(0x00, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 00 */ + W(0x10, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 10 */ + W(0x20, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 20 */ + W(0x30, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 30 */ + W(0x40, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 40 */ + W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */ + W(0x60, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */ + W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */ + W(0x80, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */ + W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ + W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */ + W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */ + W(0xc0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */ + W(0xd0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ + W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */ + W(0xf0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1) /* f0 */ + /* ---------------------------------------------- */ + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ +}; + +/* Good-instruction tables for 32-bit apps */ + +static const u32 good_insns_32[256 / 32] = { + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ + /* ---------------------------------------------- */ + W(0x00, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) | /* 00 */ + W(0x10, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) , /* 10 */ + W(0x20, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1) | /* 20 */ + W(0x30, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1) , /* 30 */ + W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ + W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */ + W(0x60, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */ + W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */ + W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */ + W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ + W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */ + W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */ + W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */ + W(0xd0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ + W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */ + W(0xf0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1) /* f0 */ + /* ---------------------------------------------- */ + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ +}; + +/* Using this for both 64-bit and 32-bit apps */ +static const u32 good_2byte_insns[256 / 32] = { + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ + /* ---------------------------------------------- */ + W(0x00, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1) | /* 00 */ + W(0x10, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1) , /* 10 */ + W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* 20 */ + W(0x30, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */ + W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ + W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */ + W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 60 */ + W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */ + W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */ + W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ + W(0xa0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1) | /* a0 */ + W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1) , /* b0 */ + W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ + W(0xd0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ + W(0xe0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* e0 */ + W(0xf0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0) /* f0 */ + /* ---------------------------------------------- */ + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ +}; +#undef W + +/* + * opcodes we'll probably never support: + * 6c-6d, e4-e5, ec-ed - in + * 6e-6f, e6-e7, ee-ef - out + * cc, cd - int3, int + * cf - iret + * d6 - illegal instruction + * f1 - int1/icebp + * f4 - hlt + * fa, fb - cli, sti + * 0f - lar, lsl, syscall, clts, sysret, sysenter, sysexit, invd, wbinvd, ud2 + * + * invalid opcodes in 64-bit mode: + * 06, 0e, 16, 1e, 27, 2f, 37, 3f, 60-62, 82, c4-c5, d4-d5 + * + * 63 - we support this opcode in x86_64 but not in i386. + * + * opcodes we may need to refine support for: + * 0f - 2-byte instructions: For many of these instructions, the validity + * depends on the prefix and/or the reg field. On such instructions, we + * just consider the opcode combination valid if it corresponds to any + * valid instruction. + * 8f - Group 1 - only reg = 0 is OK + * c6-c7 - Group 11 - only reg = 0 is OK + * d9-df - fpu insns with some illegal encodings + * f2, f3 - repnz, repz prefixes. These are also the first byte for + * certain floating-point instructions, such as addsd. + * fe - Group 4 - only reg = 0 or 1 is OK + * ff - Group 5 - only reg = 0-6 is OK + * + * others -- Do we need to support these? + * 0f - (floating-point?) prefetch instructions + * 07, 17, 1f - pop es, pop ss, pop ds + * 26, 2e, 36, 3e - es:, cs:, ss:, ds: segment prefixes -- + * but 64 and 65 (fs: and gs:) seem to be used, so we support them + * 67 - addr16 prefix + * ce - into + * f0 - lock prefix + */ + +/* + * TODO: + * - Where necessary, examine the modrm byte and allow only valid instructions + * in the different Groups and fpu instructions. + */ + +static bool is_prefix_bad(struct insn *insn) +{ + int i; + + for (i = 0; i < insn->prefixes.nbytes; i++) { + switch (insn->prefixes.bytes[i]) { + case 0x26: /*INAT_PFX_ES */ + case 0x2E: /*INAT_PFX_CS */ + case 0x36: /*INAT_PFX_DS */ + case 0x3E: /*INAT_PFX_SS */ + case 0xF0: /*INAT_PFX_LOCK */ + return true; + } + } + return false; +} + +static void report_bad_prefix(void) +{ + printk(KERN_ERR "uprobes does not currently support probing " + "instructions with any of the following prefixes: " + "cs:, ds:, es:, ss:, lock:\n"); +} + +static void report_bad_1byte_opcode(int mode, uprobe_opcode_t op) +{ + printk(KERN_ERR "In %d-bit apps, " + "uprobes does not currently support probing " + "instructions whose first byte is 0x%2.2x\n", mode, op); +} + +static void report_bad_2byte_opcode(uprobe_opcode_t op) +{ + printk(KERN_ERR "uprobes does not currently support probing " + "instructions with the 2-byte opcode 0x0f 0x%2.2x\n", op); +} + +static int validate_insn_32bits(struct uprobe *uprobe, struct insn *insn) +{ + insn_init(insn, uprobe->insn, false); + + /* Skip good instruction prefixes; reject "bad" ones. */ + insn_get_opcode(insn); + if (is_prefix_bad(insn)) { + report_bad_prefix(); + return -ENOTSUPP; + } + if (test_bit(OPCODE1(insn), (unsigned long *) good_insns_32)) + return 0; + if (insn->opcode.nbytes == 2) { + if (test_bit(OPCODE2(insn), + (unsigned long *) good_2byte_insns)) + return 0; + report_bad_2byte_opcode(OPCODE2(insn)); + } else + report_bad_1byte_opcode(32, OPCODE1(insn)); + return -ENOTSUPP; +} + +static int validate_insn_64bits(struct uprobe *uprobe, struct insn *insn) +{ + insn_init(insn, uprobe->insn, true); + + /* Skip good instruction prefixes; reject "bad" ones. */ + insn_get_opcode(insn); + if (is_prefix_bad(insn)) { + report_bad_prefix(); + return -ENOTSUPP; + } + if (test_bit(OPCODE1(insn), (unsigned long *) good_insns_64)) + return 0; + if (insn->opcode.nbytes == 2) { + if (test_bit(OPCODE2(insn), + (unsigned long *) good_2byte_insns)) + return 0; + report_bad_2byte_opcode(OPCODE2(insn)); + } else + report_bad_1byte_opcode(64, OPCODE1(insn)); + return -ENOTSUPP; +} + +/* + * Figure out which fixups post_xol() will need to perform, and annotate + * uprobe->fixups accordingly. To start with, uprobe->fixups is + * either zero or it reflects rip-related fixups. + */ +static void prepare_fixups(struct uprobe *uprobe, struct insn *insn) +{ + bool fix_ip = true, fix_call = false; /* defaults */ + insn_get_opcode(insn); /* should be a nop */ + + switch (OPCODE1(insn)) { + case 0xc3: /* ret/lret */ + case 0xcb: + case 0xc2: + case 0xca: + /* ip is correct */ + fix_ip = false; + break; + case 0xe8: /* call relative - Fix return addr */ + fix_call = true; + break; + case 0x9a: /* call absolute - Fix return addr, not ip */ + fix_call = true; + fix_ip = false; + break; + case 0xff: + { + int reg; + insn_get_modrm(insn); + reg = MODRM_REG(insn); + if (reg == 2 || reg == 3) { + /* call or lcall, indirect */ + /* Fix return addr; ip is correct. */ + fix_call = true; + fix_ip = false; + } else if (reg == 4 || reg == 5) { + /* jmp or ljmp, indirect */ + /* ip is correct. */ + fix_ip = false; + } + break; + } + case 0xea: /* jmp absolute -- ip is correct */ + fix_ip = false; + break; + default: + break; + } + if (fix_ip) + uprobe->fixups |= UPROBES_FIX_IP; + if (fix_call) + uprobe->fixups |= + (UPROBES_FIX_CALL | UPROBES_FIX_SLEEPY); +} + +#ifdef CONFIG_X86_64 +/* + * If uprobe->insn doesn't use rip-relative addressing, return + * immediately. Otherwise, rewrite the instruction so that it accesses + * its memory operand indirectly through a scratch register. Set + * uprobe->fixups and uprobe->arch_info.rip_rela_target_address + * accordingly. (The contents of the scratch register will be saved + * before we single-step the modified instruction, and restored + * afterward.) + * + * We do this because a rip-relative instruction can access only a + * relatively small area (+/- 2 GB from the instruction), and the XOL + * area typically lies beyond that area. At least for instructions + * that store to memory, we can't execute the original instruction + * and "fix things up" later, because the misdirected store could be + * disastrous. + * + * Some useful facts about rip-relative instructions: + * - There's always a modrm byte. + * - There's never a SIB byte. + * - The displacement is always 4 bytes. + */ +static void handle_riprel_insn(struct uprobe *uprobe, struct insn *insn) +{ + u8 *cursor; + u8 reg; + + uprobe->arch_info.rip_rela_target_address = 0x0; + if (!insn_rip_relative(insn)) + return; + + /* + * Point cursor at the modrm byte. The next 4 bytes are the + * displacement. Beyond the displacement, for some instructions, + * is the immediate operand. + */ + cursor = uprobe->insn + insn->prefixes.nbytes + + insn->rex_prefix.nbytes + insn->opcode.nbytes; + insn_get_length(insn); + + /* + * Convert from rip-relative addressing to indirect addressing + * via a scratch register. Change the r/m field from 0x5 (%rip) + * to 0x0 (%rax) or 0x1 (%rcx), and squeeze out the offset field. + */ + reg = MODRM_REG(insn); + if (reg == 0) { + /* + * The register operand (if any) is either the A register + * (%rax, %eax, etc.) or (if the 0x4 bit is set in the + * REX prefix) %r8. In any case, we know the C register + * is NOT the register operand, so we use %rcx (register + * #1) for the scratch register. + */ + uprobe->fixups = UPROBES_FIX_RIP_CX; + /* Change modrm from 00 000 101 to 00 000 001. */ + *cursor = 0x1; + } else { + /* Use %rax (register #0) for the scratch register. */ + uprobe->fixups = UPROBES_FIX_RIP_AX; + /* Change modrm from 00 xxx 101 to 00 xxx 000 */ + *cursor = (reg << 3); + } + + /* Target address = address of next instruction + (signed) offset */ + uprobe->arch_info.rip_rela_target_address = (long) insn->length + + insn->displacement.value; + /* Displacement field is gone; slide immediate field (if any) over. */ + if (insn->immediate.nbytes) { + cursor++; + memmove(cursor, cursor + insn->displacement.nbytes, + insn->immediate.nbytes); + } + return; +} +#else +static void handle_riprel_insn(struct uprobe *uprobe, struct insn *insn) +{ + return; +} +#endif /* CONFIG_X86_64 */ + +/** + * analyze_insn - instruction analysis including validity and fixups. + * @tsk: the probed task. + * @uprobe: the probepoint information. + * Return 0 on success or a -ve number on error. + */ +int analyze_insn(struct task_struct *tsk, struct uprobe *uprobe) +{ + int ret; + struct insn insn; + + uprobe->fixups = 0; + if (is_32bit_app(tsk)) + ret = validate_insn_32bits(uprobe, &insn); + else + ret = validate_insn_64bits(uprobe, &insn); + if (ret != 0) + return ret; + if (!is_32bit_app(tsk)) + handle_riprel_insn(uprobe, &insn); + prepare_fixups(uprobe, &insn); + return 0; +} From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 4C90A8D0040 for ; Fri, 1 Apr 2011 10:43:33 -0400 (EDT) Received: from d28relay05.in.ibm.com (d28relay05.in.ibm.com [9.184.220.62]) by e28smtp04.in.ibm.com (8.14.4/8.13.1) with ESMTP id p31EhPPD002282 for ; Fri, 1 Apr 2011 20:13:25 +0530 Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay05.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p31EhPNZ1314878 for ; Fri, 1 Apr 2011 20:13:25 +0530 Received: from d28av05.in.ibm.com (loopback [127.0.0.1]) by d28av05.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p31EhOBM002310 for ; Sat, 2 Apr 2011 01:43:25 +1100 From: Srikar Dronamraju Date: Fri, 01 Apr 2011 20:03:48 +0530 Message-Id: <20110401143348.15455.68644.sendpatchset@localhost6.localdomain6> In-Reply-To: <20110401143223.15455.19844.sendpatchset@localhost6.localdomain6> References: <20110401143223.15455.19844.sendpatchset@localhost6.localdomain6> Subject: [PATCH v3 2.6.39-rc1-tip 7/26] 7: x86: analyze instruction and determine fixups. Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra , Ingo Molnar Cc: Steven Rostedt , Srikar Dronamraju , Linux-mm , Arnaldo Carvalho de Melo , Linus Torvalds , Andi Kleen , Christoph Hellwig , Jonathan Corbet , Thomas Gleixner , Masami Hiramatsu , Oleg Nesterov , LKML , SystemTap , Jim Keniston , Roland McGrath , Ananth N Mavinakayanahalli , Andrew Morton The instruction analysis is based on x86 instruction decoder and determines if an instruction can be probed and determines the necessary fixups after singlestep. Instruction analysis is done at probe insertion time so that we avoid having to repeat the same analysis every time a probe is hit. Signed-off-by: Jim Keniston Signed-off-by: Srikar Dronamraju --- arch/x86/include/asm/uprobes.h | 2 arch/x86/kernel/Makefile | 1 arch/x86/kernel/uprobes.c | 414 ++++++++++++++++++++++++++++++++++++++++ 3 files changed, 417 insertions(+), 0 deletions(-) create mode 100644 arch/x86/kernel/uprobes.c diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h index 5026359..0063207 100644 --- a/arch/x86/include/asm/uprobes.h +++ b/arch/x86/include/asm/uprobes.h @@ -37,4 +37,6 @@ struct uprobe_arch_info { #else struct uprobe_arch_info {}; #endif +struct uprobe; +extern int analyze_insn(struct task_struct *tsk, struct uprobe *uprobe); #endif /* _ASM_UPROBES_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 758b379..ef8ffff 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -111,6 +111,7 @@ obj-$(CONFIG_X86_CHECK_BIOS_CORRUPTION) += check.o obj-$(CONFIG_SWIOTLB) += pci-swiotlb.o obj-$(CONFIG_OF) += devicetree.o +obj-$(CONFIG_UPROBES) += uprobes.o ### # 64 bit specific files diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c new file mode 100644 index 0000000..f81e940 --- /dev/null +++ b/arch/x86/kernel/uprobes.c @@ -0,0 +1,414 @@ +/* + * Userspace Probes (UProbes) for x86 + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. + * + * Copyright (C) IBM Corporation, 2008-2010 + * Authors: + * Srikar Dronamraju + * Jim Keniston + */ + +#include +#include +#include +#include + +#include +#include + +#ifdef CONFIG_X86_32 +#define is_32bit_app(tsk) 1 +#else +#define is_32bit_app(tsk) (test_tsk_thread_flag(tsk, TIF_IA32)) +#endif + +#define UPROBES_FIX_RIP_AX 0x8000 +#define UPROBES_FIX_RIP_CX 0x4000 + +/* Adaptations for mhiramat x86 decoder v14. */ +#define OPCODE1(insn) ((insn)->opcode.bytes[0]) +#define OPCODE2(insn) ((insn)->opcode.bytes[1]) +#define OPCODE3(insn) ((insn)->opcode.bytes[2]) +#define MODRM_REG(insn) X86_MODRM_REG(insn->modrm.value) + +#define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\ + (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ + (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ + (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ + (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ + << (row % 32)) + + +static const u32 good_insns_64[256 / 32] = { + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ + /* ---------------------------------------------- */ + W(0x00, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 00 */ + W(0x10, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 10 */ + W(0x20, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 20 */ + W(0x30, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 30 */ + W(0x40, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 40 */ + W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */ + W(0x60, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */ + W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */ + W(0x80, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */ + W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ + W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */ + W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */ + W(0xc0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */ + W(0xd0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ + W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */ + W(0xf0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1) /* f0 */ + /* ---------------------------------------------- */ + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ +}; + +/* Good-instruction tables for 32-bit apps */ + +static const u32 good_insns_32[256 / 32] = { + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ + /* ---------------------------------------------- */ + W(0x00, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) | /* 00 */ + W(0x10, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) , /* 10 */ + W(0x20, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1) | /* 20 */ + W(0x30, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1) , /* 30 */ + W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ + W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */ + W(0x60, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */ + W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */ + W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */ + W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ + W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */ + W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */ + W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */ + W(0xd0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ + W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */ + W(0xf0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1) /* f0 */ + /* ---------------------------------------------- */ + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ +}; + +/* Using this for both 64-bit and 32-bit apps */ +static const u32 good_2byte_insns[256 / 32] = { + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ + /* ---------------------------------------------- */ + W(0x00, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1) | /* 00 */ + W(0x10, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1) , /* 10 */ + W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* 20 */ + W(0x30, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */ + W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ + W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */ + W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 60 */ + W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */ + W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */ + W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ + W(0xa0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1) | /* a0 */ + W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1) , /* b0 */ + W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ + W(0xd0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ + W(0xe0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* e0 */ + W(0xf0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0) /* f0 */ + /* ---------------------------------------------- */ + /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ +}; +#undef W + +/* + * opcodes we'll probably never support: + * 6c-6d, e4-e5, ec-ed - in + * 6e-6f, e6-e7, ee-ef - out + * cc, cd - int3, int + * cf - iret + * d6 - illegal instruction + * f1 - int1/icebp + * f4 - hlt + * fa, fb - cli, sti + * 0f - lar, lsl, syscall, clts, sysret, sysenter, sysexit, invd, wbinvd, ud2 + * + * invalid opcodes in 64-bit mode: + * 06, 0e, 16, 1e, 27, 2f, 37, 3f, 60-62, 82, c4-c5, d4-d5 + * + * 63 - we support this opcode in x86_64 but not in i386. + * + * opcodes we may need to refine support for: + * 0f - 2-byte instructions: For many of these instructions, the validity + * depends on the prefix and/or the reg field. On such instructions, we + * just consider the opcode combination valid if it corresponds to any + * valid instruction. + * 8f - Group 1 - only reg = 0 is OK + * c6-c7 - Group 11 - only reg = 0 is OK + * d9-df - fpu insns with some illegal encodings + * f2, f3 - repnz, repz prefixes. These are also the first byte for + * certain floating-point instructions, such as addsd. + * fe - Group 4 - only reg = 0 or 1 is OK + * ff - Group 5 - only reg = 0-6 is OK + * + * others -- Do we need to support these? + * 0f - (floating-point?) prefetch instructions + * 07, 17, 1f - pop es, pop ss, pop ds + * 26, 2e, 36, 3e - es:, cs:, ss:, ds: segment prefixes -- + * but 64 and 65 (fs: and gs:) seem to be used, so we support them + * 67 - addr16 prefix + * ce - into + * f0 - lock prefix + */ + +/* + * TODO: + * - Where necessary, examine the modrm byte and allow only valid instructions + * in the different Groups and fpu instructions. + */ + +static bool is_prefix_bad(struct insn *insn) +{ + int i; + + for (i = 0; i < insn->prefixes.nbytes; i++) { + switch (insn->prefixes.bytes[i]) { + case 0x26: /*INAT_PFX_ES */ + case 0x2E: /*INAT_PFX_CS */ + case 0x36: /*INAT_PFX_DS */ + case 0x3E: /*INAT_PFX_SS */ + case 0xF0: /*INAT_PFX_LOCK */ + return true; + } + } + return false; +} + +static void report_bad_prefix(void) +{ + printk(KERN_ERR "uprobes does not currently support probing " + "instructions with any of the following prefixes: " + "cs:, ds:, es:, ss:, lock:\n"); +} + +static void report_bad_1byte_opcode(int mode, uprobe_opcode_t op) +{ + printk(KERN_ERR "In %d-bit apps, " + "uprobes does not currently support probing " + "instructions whose first byte is 0x%2.2x\n", mode, op); +} + +static void report_bad_2byte_opcode(uprobe_opcode_t op) +{ + printk(KERN_ERR "uprobes does not currently support probing " + "instructions with the 2-byte opcode 0x0f 0x%2.2x\n", op); +} + +static int validate_insn_32bits(struct uprobe *uprobe, struct insn *insn) +{ + insn_init(insn, uprobe->insn, false); + + /* Skip good instruction prefixes; reject "bad" ones. */ + insn_get_opcode(insn); + if (is_prefix_bad(insn)) { + report_bad_prefix(); + return -ENOTSUPP; + } + if (test_bit(OPCODE1(insn), (unsigned long *) good_insns_32)) + return 0; + if (insn->opcode.nbytes == 2) { + if (test_bit(OPCODE2(insn), + (unsigned long *) good_2byte_insns)) + return 0; + report_bad_2byte_opcode(OPCODE2(insn)); + } else + report_bad_1byte_opcode(32, OPCODE1(insn)); + return -ENOTSUPP; +} + +static int validate_insn_64bits(struct uprobe *uprobe, struct insn *insn) +{ + insn_init(insn, uprobe->insn, true); + + /* Skip good instruction prefixes; reject "bad" ones. */ + insn_get_opcode(insn); + if (is_prefix_bad(insn)) { + report_bad_prefix(); + return -ENOTSUPP; + } + if (test_bit(OPCODE1(insn), (unsigned long *) good_insns_64)) + return 0; + if (insn->opcode.nbytes == 2) { + if (test_bit(OPCODE2(insn), + (unsigned long *) good_2byte_insns)) + return 0; + report_bad_2byte_opcode(OPCODE2(insn)); + } else + report_bad_1byte_opcode(64, OPCODE1(insn)); + return -ENOTSUPP; +} + +/* + * Figure out which fixups post_xol() will need to perform, and annotate + * uprobe->fixups accordingly. To start with, uprobe->fixups is + * either zero or it reflects rip-related fixups. + */ +static void prepare_fixups(struct uprobe *uprobe, struct insn *insn) +{ + bool fix_ip = true, fix_call = false; /* defaults */ + insn_get_opcode(insn); /* should be a nop */ + + switch (OPCODE1(insn)) { + case 0xc3: /* ret/lret */ + case 0xcb: + case 0xc2: + case 0xca: + /* ip is correct */ + fix_ip = false; + break; + case 0xe8: /* call relative - Fix return addr */ + fix_call = true; + break; + case 0x9a: /* call absolute - Fix return addr, not ip */ + fix_call = true; + fix_ip = false; + break; + case 0xff: + { + int reg; + insn_get_modrm(insn); + reg = MODRM_REG(insn); + if (reg == 2 || reg == 3) { + /* call or lcall, indirect */ + /* Fix return addr; ip is correct. */ + fix_call = true; + fix_ip = false; + } else if (reg == 4 || reg == 5) { + /* jmp or ljmp, indirect */ + /* ip is correct. */ + fix_ip = false; + } + break; + } + case 0xea: /* jmp absolute -- ip is correct */ + fix_ip = false; + break; + default: + break; + } + if (fix_ip) + uprobe->fixups |= UPROBES_FIX_IP; + if (fix_call) + uprobe->fixups |= + (UPROBES_FIX_CALL | UPROBES_FIX_SLEEPY); +} + +#ifdef CONFIG_X86_64 +/* + * If uprobe->insn doesn't use rip-relative addressing, return + * immediately. Otherwise, rewrite the instruction so that it accesses + * its memory operand indirectly through a scratch register. Set + * uprobe->fixups and uprobe->arch_info.rip_rela_target_address + * accordingly. (The contents of the scratch register will be saved + * before we single-step the modified instruction, and restored + * afterward.) + * + * We do this because a rip-relative instruction can access only a + * relatively small area (+/- 2 GB from the instruction), and the XOL + * area typically lies beyond that area. At least for instructions + * that store to memory, we can't execute the original instruction + * and "fix things up" later, because the misdirected store could be + * disastrous. + * + * Some useful facts about rip-relative instructions: + * - There's always a modrm byte. + * - There's never a SIB byte. + * - The displacement is always 4 bytes. + */ +static void handle_riprel_insn(struct uprobe *uprobe, struct insn *insn) +{ + u8 *cursor; + u8 reg; + + uprobe->arch_info.rip_rela_target_address = 0x0; + if (!insn_rip_relative(insn)) + return; + + /* + * Point cursor at the modrm byte. The next 4 bytes are the + * displacement. Beyond the displacement, for some instructions, + * is the immediate operand. + */ + cursor = uprobe->insn + insn->prefixes.nbytes + + insn->rex_prefix.nbytes + insn->opcode.nbytes; + insn_get_length(insn); + + /* + * Convert from rip-relative addressing to indirect addressing + * via a scratch register. Change the r/m field from 0x5 (%rip) + * to 0x0 (%rax) or 0x1 (%rcx), and squeeze out the offset field. + */ + reg = MODRM_REG(insn); + if (reg == 0) { + /* + * The register operand (if any) is either the A register + * (%rax, %eax, etc.) or (if the 0x4 bit is set in the + * REX prefix) %r8. In any case, we know the C register + * is NOT the register operand, so we use %rcx (register + * #1) for the scratch register. + */ + uprobe->fixups = UPROBES_FIX_RIP_CX; + /* Change modrm from 00 000 101 to 00 000 001. */ + *cursor = 0x1; + } else { + /* Use %rax (register #0) for the scratch register. */ + uprobe->fixups = UPROBES_FIX_RIP_AX; + /* Change modrm from 00 xxx 101 to 00 xxx 000 */ + *cursor = (reg << 3); + } + + /* Target address = address of next instruction + (signed) offset */ + uprobe->arch_info.rip_rela_target_address = (long) insn->length + + insn->displacement.value; + /* Displacement field is gone; slide immediate field (if any) over. */ + if (insn->immediate.nbytes) { + cursor++; + memmove(cursor, cursor + insn->displacement.nbytes, + insn->immediate.nbytes); + } + return; +} +#else +static void handle_riprel_insn(struct uprobe *uprobe, struct insn *insn) +{ + return; +} +#endif /* CONFIG_X86_64 */ + +/** + * analyze_insn - instruction analysis including validity and fixups. + * @tsk: the probed task. + * @uprobe: the probepoint information. + * Return 0 on success or a -ve number on error. + */ +int analyze_insn(struct task_struct *tsk, struct uprobe *uprobe) +{ + int ret; + struct insn insn; + + uprobe->fixups = 0; + if (is_32bit_app(tsk)) + ret = validate_insn_32bits(uprobe, &insn); + else + ret = validate_insn_64bits(uprobe, &insn); + if (ret != 0) + return ret; + if (!is_32bit_app(tsk)) + handle_riprel_insn(uprobe, &insn); + prepare_fixups(uprobe, &insn); + return 0; +} -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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