![Ananth N Mavinakayanahalli](/assets/img/avatar_default.png)
This patch provides a debugfs knob to turn kprobes on/off o A new file /debug/kprobes/enabled indicates if kprobes is enabled or not (default enabled) o Echoing 0 to this file will disarm all installed probes o Any new probe registration when disabled will register the probe but not arm it. A message will be printed out in such a case. o When a value 1 is echoed to the file, all probes (including ones registered in the intervening period) will be enabled o Unregistration will happen irrespective of whether probes are globally enabled or not. o Update Documentation/kprobes.txt to reflect these changes. While there also update the doc to make it current. We are also looking at providing sysrq key support to tie to the disabling feature provided by this patch. [akpm@linux-foundation.org: Use bool like a bool!] [akpm@linux-foundation.org: add printk facility levels] [cornelia.huck@de.ibm.com: Add the missing arch_trampoline_kprobe() for s390] Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Srinivasa DS <srinivasa@in.ibm.com> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
755 lines
22 KiB
C
755 lines
22 KiB
C
/*
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* Kernel Probes (KProbes)
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* arch/i386/kernel/kprobes.c
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (C) IBM Corporation, 2002, 2004
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*
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* 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
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* Probes initial implementation ( includes contributions from
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* Rusty Russell).
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* 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
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* interface to access function arguments.
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* 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
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* <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
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* <prasanna@in.ibm.com> added function-return probes.
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*/
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#include <linux/kprobes.h>
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#include <linux/ptrace.h>
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#include <linux/preempt.h>
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#include <linux/kdebug.h>
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#include <asm/cacheflush.h>
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#include <asm/desc.h>
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#include <asm/uaccess.h>
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void jprobe_return_end(void);
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DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
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DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
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/* insert a jmp code */
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static __always_inline void set_jmp_op(void *from, void *to)
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{
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struct __arch_jmp_op {
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char op;
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long raddr;
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} __attribute__((packed)) *jop;
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jop = (struct __arch_jmp_op *)from;
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jop->raddr = (long)(to) - ((long)(from) + 5);
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jop->op = RELATIVEJUMP_INSTRUCTION;
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}
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/*
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* returns non-zero if opcodes can be boosted.
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*/
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static __always_inline int can_boost(kprobe_opcode_t *opcodes)
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{
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#define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \
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(((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
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(b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
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(b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
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(bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
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<< (row % 32))
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/*
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* Undefined/reserved opcodes, conditional jump, Opcode Extension
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* Groups, and some special opcodes can not be boost.
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*/
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static const unsigned long twobyte_is_boostable[256 / 32] = {
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/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
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/* ------------------------------- */
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W(0x00, 0,0,1,1,0,0,1,0,1,1,0,0,0,0,0,0)| /* 00 */
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W(0x10, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 10 */
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W(0x20, 1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0)| /* 20 */
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W(0x30, 0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 30 */
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W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 40 */
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W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 50 */
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W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,0,0,1,1)| /* 60 */
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W(0x70, 0,0,0,0,1,1,1,1,0,0,0,0,0,0,1,1), /* 70 */
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W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 80 */
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W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1), /* 90 */
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W(0xa0, 1,1,0,1,1,1,0,0,1,1,0,1,1,1,0,1)| /* a0 */
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W(0xb0, 1,1,1,1,1,1,1,1,0,0,0,1,1,1,1,1), /* b0 */
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W(0xc0, 1,1,0,0,0,0,0,0,1,1,1,1,1,1,1,1)| /* c0 */
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W(0xd0, 0,1,1,1,0,1,0,0,1,1,0,1,1,1,0,1), /* d0 */
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W(0xe0, 0,1,1,0,0,1,0,0,1,1,0,1,1,1,0,1)| /* e0 */
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W(0xf0, 0,1,1,1,0,1,0,0,1,1,1,0,1,1,1,0) /* f0 */
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/* ------------------------------- */
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/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
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};
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#undef W
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kprobe_opcode_t opcode;
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kprobe_opcode_t *orig_opcodes = opcodes;
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retry:
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if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
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return 0;
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opcode = *(opcodes++);
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/* 2nd-byte opcode */
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if (opcode == 0x0f) {
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if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
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return 0;
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return test_bit(*opcodes, twobyte_is_boostable);
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}
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switch (opcode & 0xf0) {
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case 0x60:
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if (0x63 < opcode && opcode < 0x67)
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goto retry; /* prefixes */
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/* can't boost Address-size override and bound */
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return (opcode != 0x62 && opcode != 0x67);
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case 0x70:
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return 0; /* can't boost conditional jump */
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case 0xc0:
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/* can't boost software-interruptions */
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return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf;
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case 0xd0:
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/* can boost AA* and XLAT */
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return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7);
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case 0xe0:
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/* can boost in/out and absolute jmps */
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return ((opcode & 0x04) || opcode == 0xea);
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case 0xf0:
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if ((opcode & 0x0c) == 0 && opcode != 0xf1)
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goto retry; /* lock/rep(ne) prefix */
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/* clear and set flags can be boost */
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return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
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default:
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if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)
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goto retry; /* prefixes */
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/* can't boost CS override and call */
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return (opcode != 0x2e && opcode != 0x9a);
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}
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}
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/*
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* returns non-zero if opcode modifies the interrupt flag.
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*/
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static int __kprobes is_IF_modifier(kprobe_opcode_t opcode)
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{
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switch (opcode) {
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case 0xfa: /* cli */
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case 0xfb: /* sti */
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case 0xcf: /* iret/iretd */
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case 0x9d: /* popf/popfd */
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return 1;
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}
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return 0;
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}
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int __kprobes arch_prepare_kprobe(struct kprobe *p)
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{
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/* insn: must be on special executable page on i386. */
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p->ainsn.insn = get_insn_slot();
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if (!p->ainsn.insn)
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return -ENOMEM;
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memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
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p->opcode = *p->addr;
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if (can_boost(p->addr)) {
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p->ainsn.boostable = 0;
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} else {
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p->ainsn.boostable = -1;
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}
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return 0;
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}
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void __kprobes arch_arm_kprobe(struct kprobe *p)
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{
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*p->addr = BREAKPOINT_INSTRUCTION;
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flush_icache_range((unsigned long) p->addr,
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(unsigned long) p->addr + sizeof(kprobe_opcode_t));
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}
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void __kprobes arch_disarm_kprobe(struct kprobe *p)
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{
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*p->addr = p->opcode;
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flush_icache_range((unsigned long) p->addr,
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(unsigned long) p->addr + sizeof(kprobe_opcode_t));
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}
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void __kprobes arch_remove_kprobe(struct kprobe *p)
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{
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mutex_lock(&kprobe_mutex);
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free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1));
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mutex_unlock(&kprobe_mutex);
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}
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static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
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{
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kcb->prev_kprobe.kp = kprobe_running();
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kcb->prev_kprobe.status = kcb->kprobe_status;
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kcb->prev_kprobe.old_eflags = kcb->kprobe_old_eflags;
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kcb->prev_kprobe.saved_eflags = kcb->kprobe_saved_eflags;
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}
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static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
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{
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__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
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kcb->kprobe_status = kcb->prev_kprobe.status;
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kcb->kprobe_old_eflags = kcb->prev_kprobe.old_eflags;
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kcb->kprobe_saved_eflags = kcb->prev_kprobe.saved_eflags;
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}
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static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
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struct kprobe_ctlblk *kcb)
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{
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__get_cpu_var(current_kprobe) = p;
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kcb->kprobe_saved_eflags = kcb->kprobe_old_eflags
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= (regs->eflags & (TF_MASK | IF_MASK));
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if (is_IF_modifier(p->opcode))
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kcb->kprobe_saved_eflags &= ~IF_MASK;
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}
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static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
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{
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regs->eflags |= TF_MASK;
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regs->eflags &= ~IF_MASK;
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/*single step inline if the instruction is an int3*/
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if (p->opcode == BREAKPOINT_INSTRUCTION)
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regs->eip = (unsigned long)p->addr;
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else
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regs->eip = (unsigned long)p->ainsn.insn;
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}
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/* Called with kretprobe_lock held */
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void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
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struct pt_regs *regs)
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{
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unsigned long *sara = (unsigned long *)®s->esp;
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ri->ret_addr = (kprobe_opcode_t *) *sara;
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/* Replace the return addr with trampoline addr */
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*sara = (unsigned long) &kretprobe_trampoline;
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}
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/*
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* Interrupts are disabled on entry as trap3 is an interrupt gate and they
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* remain disabled thorough out this function.
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*/
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static int __kprobes kprobe_handler(struct pt_regs *regs)
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{
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struct kprobe *p;
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int ret = 0;
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kprobe_opcode_t *addr;
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struct kprobe_ctlblk *kcb;
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addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
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/*
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* We don't want to be preempted for the entire
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* duration of kprobe processing
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*/
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preempt_disable();
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kcb = get_kprobe_ctlblk();
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/* Check we're not actually recursing */
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if (kprobe_running()) {
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p = get_kprobe(addr);
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if (p) {
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if (kcb->kprobe_status == KPROBE_HIT_SS &&
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*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
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regs->eflags &= ~TF_MASK;
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regs->eflags |= kcb->kprobe_saved_eflags;
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goto no_kprobe;
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}
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/* We have reentered the kprobe_handler(), since
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* another probe was hit while within the handler.
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* We here save the original kprobes variables and
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* just single step on the instruction of the new probe
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* without calling any user handlers.
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*/
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save_previous_kprobe(kcb);
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set_current_kprobe(p, regs, kcb);
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kprobes_inc_nmissed_count(p);
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prepare_singlestep(p, regs);
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kcb->kprobe_status = KPROBE_REENTER;
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return 1;
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} else {
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if (*addr != BREAKPOINT_INSTRUCTION) {
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/* The breakpoint instruction was removed by
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* another cpu right after we hit, no further
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* handling of this interrupt is appropriate
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*/
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regs->eip -= sizeof(kprobe_opcode_t);
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ret = 1;
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goto no_kprobe;
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}
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p = __get_cpu_var(current_kprobe);
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if (p->break_handler && p->break_handler(p, regs)) {
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goto ss_probe;
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}
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}
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goto no_kprobe;
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}
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p = get_kprobe(addr);
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if (!p) {
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if (*addr != BREAKPOINT_INSTRUCTION) {
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/*
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* The breakpoint instruction was removed right
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* after we hit it. Another cpu has removed
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* either a probepoint or a debugger breakpoint
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* at this address. In either case, no further
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* handling of this interrupt is appropriate.
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* Back up over the (now missing) int3 and run
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* the original instruction.
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*/
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regs->eip -= sizeof(kprobe_opcode_t);
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ret = 1;
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}
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/* Not one of ours: let kernel handle it */
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goto no_kprobe;
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}
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set_current_kprobe(p, regs, kcb);
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kcb->kprobe_status = KPROBE_HIT_ACTIVE;
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if (p->pre_handler && p->pre_handler(p, regs))
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/* handler has already set things up, so skip ss setup */
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return 1;
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ss_probe:
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#if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM)
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if (p->ainsn.boostable == 1 && !p->post_handler){
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/* Boost up -- we can execute copied instructions directly */
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reset_current_kprobe();
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regs->eip = (unsigned long)p->ainsn.insn;
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preempt_enable_no_resched();
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return 1;
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}
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#endif
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prepare_singlestep(p, regs);
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kcb->kprobe_status = KPROBE_HIT_SS;
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return 1;
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no_kprobe:
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preempt_enable_no_resched();
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return ret;
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}
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/*
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* For function-return probes, init_kprobes() establishes a probepoint
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* here. When a retprobed function returns, this probe is hit and
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* trampoline_probe_handler() runs, calling the kretprobe's handler.
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*/
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void __kprobes kretprobe_trampoline_holder(void)
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{
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asm volatile ( ".global kretprobe_trampoline\n"
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"kretprobe_trampoline: \n"
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" pushf\n"
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/* skip cs, eip, orig_eax */
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" subl $12, %esp\n"
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" pushl %fs\n"
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" pushl %ds\n"
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" pushl %es\n"
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" pushl %eax\n"
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" pushl %ebp\n"
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" pushl %edi\n"
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" pushl %esi\n"
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" pushl %edx\n"
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" pushl %ecx\n"
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" pushl %ebx\n"
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" movl %esp, %eax\n"
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" call trampoline_handler\n"
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/* move eflags to cs */
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" movl 52(%esp), %edx\n"
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" movl %edx, 48(%esp)\n"
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/* save true return address on eflags */
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" movl %eax, 52(%esp)\n"
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" popl %ebx\n"
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" popl %ecx\n"
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" popl %edx\n"
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" popl %esi\n"
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" popl %edi\n"
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" popl %ebp\n"
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" popl %eax\n"
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/* skip eip, orig_eax, es, ds, fs */
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" addl $20, %esp\n"
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" popf\n"
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" ret\n");
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}
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/*
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* Called from kretprobe_trampoline
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*/
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fastcall void *__kprobes trampoline_handler(struct pt_regs *regs)
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{
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struct kretprobe_instance *ri = NULL;
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struct hlist_head *head, empty_rp;
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struct hlist_node *node, *tmp;
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unsigned long flags, orig_ret_address = 0;
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unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
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INIT_HLIST_HEAD(&empty_rp);
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spin_lock_irqsave(&kretprobe_lock, flags);
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head = kretprobe_inst_table_head(current);
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/* fixup registers */
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regs->xcs = __KERNEL_CS | get_kernel_rpl();
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regs->eip = trampoline_address;
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regs->orig_eax = 0xffffffff;
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/*
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* It is possible to have multiple instances associated with a given
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* task either because an multiple functions in the call path
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* have a return probe installed on them, and/or more then one return
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* return probe was registered for a target function.
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*
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* We can handle this because:
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* - instances are always inserted at the head of the list
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* - when multiple return probes are registered for the same
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* function, the first instance's ret_addr will point to the
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* real return address, and all the rest will point to
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* kretprobe_trampoline
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*/
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hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
|
|
if (ri->task != current)
|
|
/* another task is sharing our hash bucket */
|
|
continue;
|
|
|
|
if (ri->rp && ri->rp->handler){
|
|
__get_cpu_var(current_kprobe) = &ri->rp->kp;
|
|
get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
|
|
ri->rp->handler(ri, regs);
|
|
__get_cpu_var(current_kprobe) = NULL;
|
|
}
|
|
|
|
orig_ret_address = (unsigned long)ri->ret_addr;
|
|
recycle_rp_inst(ri, &empty_rp);
|
|
|
|
if (orig_ret_address != trampoline_address)
|
|
/*
|
|
* This is the real return address. Any other
|
|
* instances associated with this task are for
|
|
* other calls deeper on the call stack
|
|
*/
|
|
break;
|
|
}
|
|
|
|
kretprobe_assert(ri, orig_ret_address, trampoline_address);
|
|
spin_unlock_irqrestore(&kretprobe_lock, flags);
|
|
|
|
hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
|
|
hlist_del(&ri->hlist);
|
|
kfree(ri);
|
|
}
|
|
return (void*)orig_ret_address;
|
|
}
|
|
|
|
/*
|
|
* Called after single-stepping. p->addr is the address of the
|
|
* instruction whose first byte has been replaced by the "int 3"
|
|
* instruction. 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. The address of this
|
|
* copy is p->ainsn.insn.
|
|
*
|
|
* This function prepares to return from the post-single-step
|
|
* interrupt. We have to fix up the stack as follows:
|
|
*
|
|
* 0) Except in the case of absolute or indirect jump or call instructions,
|
|
* the new eip is relative to the copied instruction. We need to make
|
|
* it relative to the original instruction.
|
|
*
|
|
* 1) If the single-stepped instruction was pushfl, then the TF and IF
|
|
* flags are set in the just-pushed eflags, and may need to be cleared.
|
|
*
|
|
* 2) 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.
|
|
*
|
|
* This function also checks instruction size for preparing direct execution.
|
|
*/
|
|
static void __kprobes resume_execution(struct kprobe *p,
|
|
struct pt_regs *regs, struct kprobe_ctlblk *kcb)
|
|
{
|
|
unsigned long *tos = (unsigned long *)®s->esp;
|
|
unsigned long copy_eip = (unsigned long)p->ainsn.insn;
|
|
unsigned long orig_eip = (unsigned long)p->addr;
|
|
|
|
regs->eflags &= ~TF_MASK;
|
|
switch (p->ainsn.insn[0]) {
|
|
case 0x9c: /* pushfl */
|
|
*tos &= ~(TF_MASK | IF_MASK);
|
|
*tos |= kcb->kprobe_old_eflags;
|
|
break;
|
|
case 0xc2: /* iret/ret/lret */
|
|
case 0xc3:
|
|
case 0xca:
|
|
case 0xcb:
|
|
case 0xcf:
|
|
case 0xea: /* jmp absolute -- eip is correct */
|
|
/* eip is already adjusted, no more changes required */
|
|
p->ainsn.boostable = 1;
|
|
goto no_change;
|
|
case 0xe8: /* call relative - Fix return addr */
|
|
*tos = orig_eip + (*tos - copy_eip);
|
|
break;
|
|
case 0x9a: /* call absolute -- same as call absolute, indirect */
|
|
*tos = orig_eip + (*tos - copy_eip);
|
|
goto no_change;
|
|
case 0xff:
|
|
if ((p->ainsn.insn[1] & 0x30) == 0x10) {
|
|
/*
|
|
* call absolute, indirect
|
|
* Fix return addr; eip is correct.
|
|
* But this is not boostable
|
|
*/
|
|
*tos = orig_eip + (*tos - copy_eip);
|
|
goto no_change;
|
|
} else if (((p->ainsn.insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */
|
|
((p->ainsn.insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */
|
|
/* eip is correct. And this is boostable */
|
|
p->ainsn.boostable = 1;
|
|
goto no_change;
|
|
}
|
|
default:
|
|
break;
|
|
}
|
|
|
|
if (p->ainsn.boostable == 0) {
|
|
if ((regs->eip > copy_eip) &&
|
|
(regs->eip - copy_eip) + 5 < MAX_INSN_SIZE) {
|
|
/*
|
|
* These instructions can be executed directly if it
|
|
* jumps back to correct address.
|
|
*/
|
|
set_jmp_op((void *)regs->eip,
|
|
(void *)orig_eip + (regs->eip - copy_eip));
|
|
p->ainsn.boostable = 1;
|
|
} else {
|
|
p->ainsn.boostable = -1;
|
|
}
|
|
}
|
|
|
|
regs->eip = orig_eip + (regs->eip - copy_eip);
|
|
|
|
no_change:
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Interrupts are disabled on entry as trap1 is an interrupt gate and they
|
|
* remain disabled thoroughout this function.
|
|
*/
|
|
static int __kprobes post_kprobe_handler(struct pt_regs *regs)
|
|
{
|
|
struct kprobe *cur = kprobe_running();
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
|
|
if (!cur)
|
|
return 0;
|
|
|
|
if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
|
|
kcb->kprobe_status = KPROBE_HIT_SSDONE;
|
|
cur->post_handler(cur, regs, 0);
|
|
}
|
|
|
|
resume_execution(cur, regs, kcb);
|
|
regs->eflags |= kcb->kprobe_saved_eflags;
|
|
|
|
/*Restore back the original saved kprobes variables and continue. */
|
|
if (kcb->kprobe_status == KPROBE_REENTER) {
|
|
restore_previous_kprobe(kcb);
|
|
goto out;
|
|
}
|
|
reset_current_kprobe();
|
|
out:
|
|
preempt_enable_no_resched();
|
|
|
|
/*
|
|
* if somebody else is singlestepping across a probe point, eflags
|
|
* will have TF set, in which case, continue the remaining processing
|
|
* of do_debug, as if this is not a probe hit.
|
|
*/
|
|
if (regs->eflags & TF_MASK)
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
|
|
{
|
|
struct kprobe *cur = kprobe_running();
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
|
|
switch(kcb->kprobe_status) {
|
|
case KPROBE_HIT_SS:
|
|
case KPROBE_REENTER:
|
|
/*
|
|
* We are here because the instruction being single
|
|
* stepped caused a page fault. We reset the current
|
|
* kprobe and the eip points back to the probe address
|
|
* and allow the page fault handler to continue as a
|
|
* normal page fault.
|
|
*/
|
|
regs->eip = (unsigned long)cur->addr;
|
|
regs->eflags |= kcb->kprobe_old_eflags;
|
|
if (kcb->kprobe_status == KPROBE_REENTER)
|
|
restore_previous_kprobe(kcb);
|
|
else
|
|
reset_current_kprobe();
|
|
preempt_enable_no_resched();
|
|
break;
|
|
case KPROBE_HIT_ACTIVE:
|
|
case KPROBE_HIT_SSDONE:
|
|
/*
|
|
* We increment the nmissed count for accounting,
|
|
* we can also use npre/npostfault count for accouting
|
|
* these specific fault cases.
|
|
*/
|
|
kprobes_inc_nmissed_count(cur);
|
|
|
|
/*
|
|
* We come here because instructions in the pre/post
|
|
* handler caused the page_fault, this could happen
|
|
* if handler tries to access user space by
|
|
* copy_from_user(), get_user() etc. Let the
|
|
* user-specified handler try to fix it first.
|
|
*/
|
|
if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
|
|
return 1;
|
|
|
|
/*
|
|
* In case the user-specified fault handler returned
|
|
* zero, try to fix up.
|
|
*/
|
|
if (fixup_exception(regs))
|
|
return 1;
|
|
|
|
/*
|
|
* fixup_exception() could not handle it,
|
|
* Let do_page_fault() fix it.
|
|
*/
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Wrapper routine to for handling exceptions.
|
|
*/
|
|
int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
|
|
unsigned long val, void *data)
|
|
{
|
|
struct die_args *args = (struct die_args *)data;
|
|
int ret = NOTIFY_DONE;
|
|
|
|
if (args->regs && user_mode_vm(args->regs))
|
|
return ret;
|
|
|
|
switch (val) {
|
|
case DIE_INT3:
|
|
if (kprobe_handler(args->regs))
|
|
ret = NOTIFY_STOP;
|
|
break;
|
|
case DIE_DEBUG:
|
|
if (post_kprobe_handler(args->regs))
|
|
ret = NOTIFY_STOP;
|
|
break;
|
|
case DIE_GPF:
|
|
case DIE_PAGE_FAULT:
|
|
/* kprobe_running() needs smp_processor_id() */
|
|
preempt_disable();
|
|
if (kprobe_running() &&
|
|
kprobe_fault_handler(args->regs, args->trapnr))
|
|
ret = NOTIFY_STOP;
|
|
preempt_enable();
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
struct jprobe *jp = container_of(p, struct jprobe, kp);
|
|
unsigned long addr;
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
|
|
kcb->jprobe_saved_regs = *regs;
|
|
kcb->jprobe_saved_esp = ®s->esp;
|
|
addr = (unsigned long)(kcb->jprobe_saved_esp);
|
|
|
|
/*
|
|
* TBD: As Linus pointed out, gcc assumes that the callee
|
|
* owns the argument space and could overwrite it, e.g.
|
|
* tailcall optimization. So, to be absolutely safe
|
|
* we also save and restore enough stack bytes to cover
|
|
* the argument area.
|
|
*/
|
|
memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
|
|
MIN_STACK_SIZE(addr));
|
|
regs->eflags &= ~IF_MASK;
|
|
regs->eip = (unsigned long)(jp->entry);
|
|
return 1;
|
|
}
|
|
|
|
void __kprobes jprobe_return(void)
|
|
{
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
|
|
asm volatile (" xchgl %%ebx,%%esp \n"
|
|
" int3 \n"
|
|
" .globl jprobe_return_end \n"
|
|
" jprobe_return_end: \n"
|
|
" nop \n"::"b"
|
|
(kcb->jprobe_saved_esp):"memory");
|
|
}
|
|
|
|
int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
u8 *addr = (u8 *) (regs->eip - 1);
|
|
unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_esp);
|
|
struct jprobe *jp = container_of(p, struct jprobe, kp);
|
|
|
|
if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) {
|
|
if (®s->esp != kcb->jprobe_saved_esp) {
|
|
struct pt_regs *saved_regs =
|
|
container_of(kcb->jprobe_saved_esp,
|
|
struct pt_regs, esp);
|
|
printk("current esp %p does not match saved esp %p\n",
|
|
®s->esp, kcb->jprobe_saved_esp);
|
|
printk("Saved registers for jprobe %p\n", jp);
|
|
show_registers(saved_regs);
|
|
printk("Current registers\n");
|
|
show_registers(regs);
|
|
BUG();
|
|
}
|
|
*regs = kcb->jprobe_saved_regs;
|
|
memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
|
|
MIN_STACK_SIZE(stack_addr));
|
|
preempt_enable_no_resched();
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int __kprobes arch_trampoline_kprobe(struct kprobe *p)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
int __init arch_init_kprobes(void)
|
|
{
|
|
return 0;
|
|
}
|