diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/Kconfig | 17 | ||||
| -rw-r--r-- | arch/x86/Kconfig | 5 | ||||
| -rw-r--r-- | arch/x86/include/asm/thread_info.h | 2 | ||||
| -rw-r--r-- | arch/x86/include/asm/uprobes.h | 57 | ||||
| -rw-r--r-- | arch/x86/kernel/Makefile | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/signal.c | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/uprobes.c | 674 |
7 files changed, 761 insertions, 1 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index 1f9461b9cc89..e9a910876cda 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -76,6 +76,23 @@ config OPTPROBES depends on KPROBES && HAVE_OPTPROBES depends on !PREEMPT +config UPROBES + bool "Transparent user-space probes (EXPERIMENTAL)" + depends on UPROBE_EVENT && PERF_EVENTS + default n + help + Uprobes is the user-space counterpart to kprobes: they + enable instrumentation applications (such as 'perf probe') + to establish unintrusive probes in user-space binaries and + libraries, by executing handler functions when the probes + are hit by user-space applications. + + ( These probes come in the form of single-byte breakpoints, + managed by the kernel and kept transparent to the probed + application. ) + + If in doubt, say "N". + config HAVE_EFFICIENT_UNALIGNED_ACCESS bool help diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index d6168994e115..0b2d5f24c946 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -87,7 +87,7 @@ config X86 select BUILDTIME_EXTABLE_SORT config INSTRUCTION_DECODER - def_bool (KPROBES || PERF_EVENTS) + def_bool (KPROBES || PERF_EVENTS || UPROBES) config OUTPUT_FORMAT string @@ -243,6 +243,9 @@ config ARCH_CPU_PROBE_RELEASE def_bool y depends on HOTPLUG_CPU +config ARCH_SUPPORTS_UPROBES + def_bool y + source "init/Kconfig" source "kernel/Kconfig.freezer" diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index 3c9aebc00d39..5c25de07cba8 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -85,6 +85,7 @@ struct thread_info { #define TIF_SECCOMP 8 /* secure computing */ #define TIF_MCE_NOTIFY 10 /* notify userspace of an MCE */ #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ +#define TIF_UPROBE 12 /* breakpointed or singlestepping */ #define TIF_NOTSC 16 /* TSC is not accessible in userland */ #define TIF_IA32 17 /* IA32 compatibility process */ #define TIF_FORK 18 /* ret_from_fork */ @@ -109,6 +110,7 @@ struct thread_info { #define _TIF_SECCOMP (1 << TIF_SECCOMP) #define _TIF_MCE_NOTIFY (1 << TIF_MCE_NOTIFY) #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) +#define _TIF_UPROBE (1 << TIF_UPROBE) #define _TIF_NOTSC (1 << TIF_NOTSC) #define _TIF_IA32 (1 << TIF_IA32) #define _TIF_FORK (1 << TIF_FORK) diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h new file mode 100644 index 000000000000..1e9bed14f7ae --- /dev/null +++ b/arch/x86/include/asm/uprobes.h @@ -0,0 +1,57 @@ +#ifndef _ASM_UPROBES_H +#define _ASM_UPROBES_H +/* + * User-space 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, 2008-2011 + * Authors: + * Srikar Dronamraju + * Jim Keniston + */ + +#include <linux/notifier.h> + +typedef u8 uprobe_opcode_t; + +#define MAX_UINSN_BYTES 16 +#define UPROBE_XOL_SLOT_BYTES 128 /* to keep it cache aligned */ + +#define UPROBE_SWBP_INSN 0xcc +#define UPROBE_SWBP_INSN_SIZE 1 + +struct arch_uprobe { + u16 fixups; + u8 insn[MAX_UINSN_BYTES]; +#ifdef CONFIG_X86_64 + unsigned long rip_rela_target_address; +#endif +}; + +struct arch_uprobe_task { + unsigned long saved_trap_nr; +#ifdef CONFIG_X86_64 + unsigned long saved_scratch_register; +#endif +}; + +extern int arch_uprobe_analyze_insn(struct arch_uprobe *aup, struct mm_struct *mm); +extern int arch_uprobe_pre_xol(struct arch_uprobe *aup, struct pt_regs *regs); +extern int arch_uprobe_post_xol(struct arch_uprobe *aup, struct pt_regs *regs); +extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk); +extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data); +extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs); +#endif /* _ASM_UPROBES_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index bb8529275aab..9bba5b79902b 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -100,6 +100,7 @@ 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/signal.c b/arch/x86/kernel/signal.c index b68ccadd2ff4..965dfda0fd5e 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -18,6 +18,7 @@ #include <linux/personality.h> #include <linux/uaccess.h> #include <linux/user-return-notifier.h> +#include <linux/uprobes.h> #include <asm/processor.h> #include <asm/ucontext.h> @@ -814,6 +815,11 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) mce_notify_process(); #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */ + if (thread_info_flags & _TIF_UPROBE) { + clear_thread_flag(TIF_UPROBE); + uprobe_notify_resume(regs); + } + /* deal with pending signal delivery */ if (thread_info_flags & _TIF_SIGPENDING) do_signal(regs); diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c new file mode 100644 index 000000000000..dc4e910a7d96 --- /dev/null +++ b/arch/x86/kernel/uprobes.c @@ -0,0 +1,674 @@ +/* + * User-space 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, 2008-2011 + * Authors: + * Srikar Dronamraju + * Jim Keniston + */ +#include <linux/kernel.h> +#include <linux/sched.h> +#include <linux/ptrace.h> +#include <linux/uprobes.h> +#include <linux/uaccess.h> + +#include <linux/kdebug.h> +#include <asm/processor.h> +#include <asm/insn.h> + +/* Post-execution fixups. */ + +/* No fixup needed */ +#define UPROBE_FIX_NONE 0x0 + +/* Adjust IP back to vicinity of actual insn */ +#define UPROBE_FIX_IP 0x1 + +/* Adjust the return address of a call insn */ +#define UPROBE_FIX_CALL 0x2 + +#define UPROBE_FIX_RIP_AX 0x8000 +#define UPROBE_FIX_RIP_CX 0x4000 + +#define UPROBE_TRAP_NR UINT_MAX + +/* 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)) + +/* + * Good-instruction tables for 32-bit apps. This is non-const and volatile + * to keep gcc from statically optimizing it out, as variable_test_bit makes + * some versions of gcc to think only *(unsigned long*) is used. + */ +static volatile 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 volatile 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 */ +}; + +#ifdef CONFIG_X86_64 +/* Good-instruction tables for 64-bit apps */ +static volatile 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 */ +}; +#endif +#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 int validate_insn_32bits(struct arch_uprobe *auprobe, struct insn *insn) +{ + insn_init(insn, auprobe->insn, false); + + /* Skip good instruction prefixes; reject "bad" ones. */ + insn_get_opcode(insn); + if (is_prefix_bad(insn)) + 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; + } + + return -ENOTSUPP; +} + +/* + * Figure out which fixups arch_uprobe_post_xol() will need to perform, and + * annotate arch_uprobe->fixups accordingly. To start with, + * arch_uprobe->fixups is either zero or it reflects rip-related fixups. + */ +static void prepare_fixups(struct arch_uprobe *auprobe, struct insn *insn) +{ + bool fix_ip = true, fix_call = false; /* defaults */ + int reg; + + 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: + 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) + auprobe->fixups |= UPROBE_FIX_IP; + if (fix_call) + auprobe->fixups |= UPROBE_FIX_CALL; +} + +#ifdef CONFIG_X86_64 +/* + * If arch_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 + * arch_uprobe->fixups and arch_uprobe->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 arch_uprobe *auprobe, struct mm_struct *mm, struct insn *insn) +{ + u8 *cursor; + u8 reg; + + if (mm->context.ia32_compat) + return; + + auprobe->rip_rela_target_address = 0x0; + if (!insn_rip_relative(insn)) + return; + + /* + * insn_rip_relative() would have decoded rex_prefix, modrm. + * Clear REX.b bit (extension of MODRM.rm field): + * we want to encode rax/rcx, not r8/r9. + */ + if (insn->rex_prefix.nbytes) { + cursor = auprobe->insn + insn_offset_rex_prefix(insn); + *cursor &= 0xfe; /* Clearing REX.B bit */ + } + + /* + * Point cursor at the modrm byte. The next 4 bytes are the + * displacement. Beyond the displacement, for some instructions, + * is the immediate operand. + */ + cursor = auprobe->insn + insn_offset_modrm(insn); + 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. + */ + auprobe->fixups = UPROBE_FIX_RIP_CX; + /* Change modrm from 00 000 101 to 00 000 001. */ + *cursor = 0x1; + } else { + /* Use %rax (register #0) for the scratch register. */ + auprobe->fixups = UPROBE_FIX_RIP_AX; + /* Change modrm from 00 xxx 101 to 00 xxx 000 */ + *cursor = (reg << 3); + } + + /* Target address = address of next instruction + (signed) offset */ + auprobe->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; +} + +static int validate_insn_64bits(struct arch_uprobe *auprobe, struct insn *insn) +{ + insn_init(insn, auprobe->insn, true); + + /* Skip good instruction prefixes; reject "bad" ones. */ + insn_get_opcode(insn); + if (is_prefix_bad(insn)) + 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; + } + return -ENOTSUPP; +} + +static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm, struct insn *insn) +{ + if (mm->context.ia32_compat) + return validate_insn_32bits(auprobe, insn); + return validate_insn_64bits(auprobe, insn); +} +#else /* 32-bit: */ +static void handle_riprel_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, struct insn *insn) +{ + /* No RIP-relative addressing on 32-bit */ +} + +static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm, struct insn *insn) +{ + return validate_insn_32bits(auprobe, insn); +} +#endif /* CONFIG_X86_64 */ + +/** + * arch_uprobe_analyze_insn - instruction analysis including validity and fixups. + * @mm: the probed address space. + * @arch_uprobe: the probepoint information. + * Return 0 on success or a -ve number on error. + */ +int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm) +{ + int ret; + struct insn insn; + + auprobe->fixups = 0; + ret = validate_insn_bits(auprobe, mm, &insn); + if (ret != 0) + return ret; + + handle_riprel_insn(auprobe, mm, &insn); + prepare_fixups(auprobe, &insn); + + return 0; +} + +#ifdef CONFIG_X86_64 +/* + * If we're emulating a rip-relative instruction, save the contents + * of the scratch register and store the target address in that register. + */ +static void +pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs, + struct arch_uprobe_task *autask) +{ + if (auprobe->fixups & UPROBE_FIX_RIP_AX) { + autask->saved_scratch_register = regs->ax; + regs->ax = current->utask->vaddr; + regs->ax += auprobe->rip_rela_target_address; + } else if (auprobe->fixups & UPROBE_FIX_RIP_CX) { + autask->saved_scratch_register = regs->cx; + regs->cx = current->utask->vaddr; + regs->cx += auprobe->rip_rela_target_address; + } +} +#else +static void +pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs, + struct arch_uprobe_task *autask) +{ + /* No RIP-relative addressing on 32-bit */ +} +#endif + +/* + * arch_uprobe_pre_xol - prepare to execute out of line. + * @auprobe: the probepoint information. + * @regs: reflects the saved user state of current task. + */ +int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + struct arch_uprobe_task *autask; + + autask = ¤t->utask->autask; + autask->saved_trap_nr = current->thread.trap_nr; + current->thread.trap_nr = UPROBE_TRAP_NR; + regs->ip = current->utask->xol_vaddr; + pre_xol_rip_insn(auprobe, regs, autask); + + return 0; +} + +/* + * This function is called by arch_uprobe_post_xol() to adjust the return + * address pushed by a call instruction executed out of line. + */ +static int adjust_ret_addr(unsigned long sp, long correction) +{ + int rasize, ncopied; + long ra = 0; + + if (is_ia32_task()) + rasize = 4; + else + rasize = 8; + + ncopied = copy_from_user(&ra, (void __user *)sp, rasize); + if (unlikely(ncopied)) + return -EFAULT; + + ra += correction; + ncopied = copy_to_user((void __user *)sp, &ra, rasize); + if (unlikely(ncopied)) + return -EFAULT; + + return 0; +} + +#ifdef CONFIG_X86_64 +static bool is_riprel_insn(struct arch_uprobe *auprobe) +{ + return ((auprobe->fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) != 0); +} + +static void +handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction) +{ + if (is_riprel_insn(auprobe)) { + struct arch_uprobe_task *autask; + + autask = ¤t->utask->autask; + if (auprobe->fixups & UPROBE_FIX_RIP_AX) + regs->ax = autask->saved_scratch_register; + else + regs->cx = autask->saved_scratch_register; + + /* + * The original instruction includes a displacement, and so + * is 4 bytes longer than what we've just single-stepped. + * Fall through to handle stuff like "jmpq *...(%rip)" and + * "callq *...(%rip)". + */ + if (correction) + *correction += 4; + } +} +#else +static void +handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction) +{ + /* No RIP-relative addressing on 32-bit */ +} +#endif + +/* + * If xol insn itself traps and generates a signal(Say, + * SIGILL/SIGSEGV/etc), then detect the case where a singlestepped + * instruction jumps back to its own address. It is assumed that anything + * like do_page_fault/do_trap/etc sets thread.trap_nr != -1. + * + * arch_uprobe_pre_xol/arch_uprobe_post_xol save/restore thread.trap_nr, + * arch_uprobe_xol_was_trapped() simply checks that ->trap_nr is not equal to + * UPROBE_TRAP_NR == -1 set by arch_uprobe_pre_xol(). + */ +bool arch_uprobe_xol_was_trapped(struct task_struct *t) +{ + if (t->thread.trap_nr != UPROBE_TRAP_NR) + return true; + + return false; +} + +/* + * Called after single-stepping. To avoid the SMP problems that can + * occur when we temporarily put back the original opcode to + * single-step, we single-stepped a copy of the instruction. + * + * This function prepares to resume execution after the single-step. + * We have to fix things up as follows: + * + * Typically, the new ip is relative to the copied instruction. We need + * to make it relative to the original instruction (FIX_IP). Exceptions + * are return instructions and absolute or indirect jump or call instructions. + * + * If the single-stepped instruction was a call, the return address that + * is atop the stack is the address following the copied instruction. We + * need to make it the address following the original instruction (FIX_CALL). + * + * If the original instruction was a rip-relative instruction such as + * "movl %edx,0xnnnn(%rip)", we have instead executed an equivalent + * instruction using a scratch register -- e.g., "movl %edx,(%rax)". + * We need to restore the contents of the scratch register and adjust + * the ip, keeping in mind that the instruction we executed is 4 bytes + * shorter than the original instruction (since we squeezed out the offset + * field). (FIX_RIP_AX or FIX_RIP_CX) + */ +int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + struct uprobe_task *utask; + long correction; + int result = 0; + + WARN_ON_ONCE(current->thread.trap_nr != UPROBE_TRAP_NR); + + utask = current->utask; + current->thread.trap_nr = utask->autask.saved_trap_nr; + correction = (long)(utask->vaddr - utask->xol_vaddr); + handle_riprel_post_xol(auprobe, regs, &correction); + if (auprobe->fixups & UPROBE_FIX_IP) + regs->ip += correction; + + if (auprobe->fixups & UPROBE_FIX_CALL) + result = adjust_ret_addr(regs->sp, correction); + + return result; +} + +/* callback routine for handling exceptions. */ +int arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data) +{ + struct die_args *args = data; + struct pt_regs *regs = args->regs; + int ret = NOTIFY_DONE; + + /* We are only interested in userspace traps */ + if (regs && !user_mode_vm(regs)) + return NOTIFY_DONE; + + switch (val) { + case DIE_INT3: + if (uprobe_pre_sstep_notifier(regs)) + ret = NOTIFY_STOP; + + break; + + case DIE_DEBUG: + if (uprobe_post_sstep_notifier(regs)) + ret = NOTIFY_STOP; + + default: + break; + } + + return ret; +} + +/* + * This function gets called when XOL instruction either gets trapped or + * the thread has a fatal signal, so reset the instruction pointer to its + * probed address. + */ +void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + struct uprobe_task *utask = current->utask; + + current->thread.trap_nr = utask->autask.saved_trap_nr; + handle_riprel_post_xol(auprobe, regs, NULL); + instruction_pointer_set(regs, utask->vaddr); +} + +/* + * Skip these instructions as per the currently known x86 ISA. + * 0x66* { 0x90 | 0x0f 0x1f | 0x0f 0x19 | 0x87 0xc0 } + */ +bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) +{ + int i; + + for (i = 0; i < MAX_UINSN_BYTES; i++) { + if ((auprobe->insn[i] == 0x66)) + continue; + + if (auprobe->insn[i] == 0x90) + return true; + + if (i == (MAX_UINSN_BYTES - 1)) + break; + + if ((auprobe->insn[i] == 0x0f) && (auprobe->insn[i+1] == 0x1f)) + return true; + + if ((auprobe->insn[i] == 0x0f) && (auprobe->insn[i+1] == 0x19)) + return true; + + if ((auprobe->insn[i] == 0x87) && (auprobe->insn[i+1] == 0xc0)) + return true; + + break; + } + return false; +} |
