![Jan Beulich](/assets/img/avatar_default.png)
What was called show_registers() so far already showed a stack trace for kernel faults, and kernel_stack_pointer() isn't even valid to be used for faults from user mode, hence it was pointless for show_regs() to call show_trace() after show_registers(). Simply rename show_registers() to show_regs() and eliminate the old definition. Signed-off-by: Jan Beulich <jbeulich@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Link: http://lkml.kernel.org/r/4FAA3D3902000078000826E1@nat28.tlf.novell.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
1064 lines
31 KiB
C
1064 lines
31 KiB
C
/*
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* Kernel Probes (KProbes)
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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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* 2004-Oct Jim Keniston <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
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* <prasanna@in.ibm.com> adapted for x86_64 from i386.
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* 2005-Mar Roland McGrath <roland@redhat.com>
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* Fixed to handle %rip-relative addressing mode correctly.
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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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* 2005-May Rusty Lynch <rusty.lynch@intel.com>
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* Added function return probes functionality
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* 2006-Feb Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> added
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* kprobe-booster and kretprobe-booster for i386.
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* 2007-Dec Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster
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* and kretprobe-booster for x86-64
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* 2007-Dec Masami Hiramatsu <mhiramat@redhat.com>, Arjan van de Ven
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* <arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com>
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* unified x86 kprobes code.
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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/string.h>
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#include <linux/slab.h>
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#include <linux/hardirq.h>
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#include <linux/preempt.h>
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#include <linux/module.h>
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#include <linux/kdebug.h>
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#include <linux/kallsyms.h>
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#include <linux/ftrace.h>
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#include <asm/cacheflush.h>
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#include <asm/desc.h>
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#include <asm/pgtable.h>
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#include <asm/uaccess.h>
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#include <asm/alternative.h>
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#include <asm/insn.h>
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#include <asm/debugreg.h>
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#include "kprobes-common.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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#define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs))
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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 boost.
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* This is non-const and volatile to keep gcc from statically
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* optimizing it out, as variable_test_bit makes gcc think only
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* *(unsigned long*) is used.
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*/
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static volatile u32 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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struct kretprobe_blackpoint kretprobe_blacklist[] = {
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{"__switch_to", }, /* This function switches only current task, but
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doesn't switch kernel stack.*/
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{NULL, NULL} /* Terminator */
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};
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const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist);
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static void __kprobes __synthesize_relative_insn(void *from, void *to, u8 op)
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{
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struct __arch_relative_insn {
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u8 op;
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s32 raddr;
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} __attribute__((packed)) *insn;
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insn = (struct __arch_relative_insn *)from;
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insn->raddr = (s32)((long)(to) - ((long)(from) + 5));
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insn->op = op;
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}
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/* Insert a jump instruction at address 'from', which jumps to address 'to'.*/
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void __kprobes synthesize_reljump(void *from, void *to)
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{
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__synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE);
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}
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/* Insert a call instruction at address 'from', which calls address 'to'.*/
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void __kprobes synthesize_relcall(void *from, void *to)
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{
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__synthesize_relative_insn(from, to, RELATIVECALL_OPCODE);
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}
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/*
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* Skip the prefixes of the instruction.
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*/
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static kprobe_opcode_t *__kprobes skip_prefixes(kprobe_opcode_t *insn)
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{
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insn_attr_t attr;
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attr = inat_get_opcode_attribute((insn_byte_t)*insn);
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while (inat_is_legacy_prefix(attr)) {
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insn++;
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attr = inat_get_opcode_attribute((insn_byte_t)*insn);
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}
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#ifdef CONFIG_X86_64
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if (inat_is_rex_prefix(attr))
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insn++;
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#endif
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return insn;
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}
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/*
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* Returns non-zero if opcode is boostable.
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* RIP relative instructions are adjusted at copying time in 64 bits mode
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*/
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int __kprobes can_boost(kprobe_opcode_t *opcodes)
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{
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kprobe_opcode_t opcode;
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kprobe_opcode_t *orig_opcodes = opcodes;
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if (search_exception_tables((unsigned long)opcodes))
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return 0; /* Page fault may occur on this address. */
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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,
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(unsigned long *)twobyte_is_boostable);
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}
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switch (opcode & 0xf0) {
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#ifdef CONFIG_X86_64
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case 0x40:
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goto retry; /* REX prefix is boostable */
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#endif
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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 are boostable */
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return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
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default:
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/* segment override prefixes are boostable */
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if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)
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goto retry; /* prefixes */
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/* CS override prefix and call are not boostable */
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return (opcode != 0x2e && opcode != 0x9a);
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}
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}
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static unsigned long
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__recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr)
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{
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struct kprobe *kp;
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kp = get_kprobe((void *)addr);
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/* There is no probe, return original address */
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if (!kp)
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return addr;
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/*
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* Basically, kp->ainsn.insn has an original instruction.
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* However, RIP-relative instruction can not do single-stepping
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* at different place, __copy_instruction() tweaks the displacement of
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* that instruction. In that case, we can't recover the instruction
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* from the kp->ainsn.insn.
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*
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* On the other hand, kp->opcode has a copy of the first byte of
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* the probed instruction, which is overwritten by int3. And
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* the instruction at kp->addr is not modified by kprobes except
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* for the first byte, we can recover the original instruction
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* from it and kp->opcode.
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*/
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memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
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buf[0] = kp->opcode;
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return (unsigned long)buf;
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}
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/*
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* Recover the probed instruction at addr for further analysis.
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* Caller must lock kprobes by kprobe_mutex, or disable preemption
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* for preventing to release referencing kprobes.
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*/
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unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr)
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{
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unsigned long __addr;
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__addr = __recover_optprobed_insn(buf, addr);
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if (__addr != addr)
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return __addr;
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return __recover_probed_insn(buf, addr);
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}
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/* Check if paddr is at an instruction boundary */
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static int __kprobes can_probe(unsigned long paddr)
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{
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unsigned long addr, __addr, offset = 0;
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struct insn insn;
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kprobe_opcode_t buf[MAX_INSN_SIZE];
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if (!kallsyms_lookup_size_offset(paddr, NULL, &offset))
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return 0;
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/* Decode instructions */
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addr = paddr - offset;
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while (addr < paddr) {
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/*
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* Check if the instruction has been modified by another
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* kprobe, in which case we replace the breakpoint by the
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* original instruction in our buffer.
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* Also, jump optimization will change the breakpoint to
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* relative-jump. Since the relative-jump itself is
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* normally used, we just go through if there is no kprobe.
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*/
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__addr = recover_probed_instruction(buf, addr);
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kernel_insn_init(&insn, (void *)__addr);
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insn_get_length(&insn);
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/*
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* Another debugging subsystem might insert this breakpoint.
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* In that case, we can't recover it.
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*/
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if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
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return 0;
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addr += insn.length;
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}
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return (addr == paddr);
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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 *insn)
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{
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/* Skip prefixes */
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insn = skip_prefixes(insn);
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switch (*insn) {
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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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/*
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* Copy an instruction and adjust the displacement if the instruction
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* uses the %rip-relative addressing mode.
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* If it does, Return the address of the 32-bit displacement word.
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* If not, return null.
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* Only applicable to 64-bit x86.
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*/
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int __kprobes __copy_instruction(u8 *dest, u8 *src)
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{
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struct insn insn;
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kprobe_opcode_t buf[MAX_INSN_SIZE];
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kernel_insn_init(&insn, (void *)recover_probed_instruction(buf, (unsigned long)src));
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insn_get_length(&insn);
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/* Another subsystem puts a breakpoint, failed to recover */
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if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
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return 0;
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memcpy(dest, insn.kaddr, insn.length);
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#ifdef CONFIG_X86_64
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if (insn_rip_relative(&insn)) {
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s64 newdisp;
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u8 *disp;
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kernel_insn_init(&insn, dest);
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insn_get_displacement(&insn);
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/*
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* The copied instruction uses the %rip-relative addressing
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* mode. Adjust the displacement for the difference between
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* the original location of this instruction and the location
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* of the copy that will actually be run. The tricky bit here
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* is making sure that the sign extension happens correctly in
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* this calculation, since we need a signed 32-bit result to
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* be sign-extended to 64 bits when it's added to the %rip
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* value and yield the same 64-bit result that the sign-
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* extension of the original signed 32-bit displacement would
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* have given.
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*/
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newdisp = (u8 *) src + (s64) insn.displacement.value - (u8 *) dest;
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BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */
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disp = (u8 *) dest + insn_offset_displacement(&insn);
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*(s32 *) disp = (s32) newdisp;
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}
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#endif
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return insn.length;
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}
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static void __kprobes arch_copy_kprobe(struct kprobe *p)
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{
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/* Copy an instruction with recovering if other optprobe modifies it.*/
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__copy_instruction(p->ainsn.insn, p->addr);
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/*
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* __copy_instruction can modify the displacement of the instruction,
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* but it doesn't affect boostable check.
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*/
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if (can_boost(p->ainsn.insn))
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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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/* Also, displacement change doesn't affect the first byte */
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p->opcode = p->ainsn.insn[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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if (alternatives_text_reserved(p->addr, p->addr))
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return -EINVAL;
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if (!can_probe((unsigned long)p->addr))
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return -EILSEQ;
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/* insn: must be on special executable page on x86. */
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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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arch_copy_kprobe(p);
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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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text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
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}
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void __kprobes arch_disarm_kprobe(struct kprobe *p)
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{
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text_poke(p->addr, &p->opcode, 1);
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}
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void __kprobes arch_remove_kprobe(struct kprobe *p)
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{
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if (p->ainsn.insn) {
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free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1));
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p->ainsn.insn = NULL;
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}
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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_flags = kcb->kprobe_old_flags;
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kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags;
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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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__this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
|
|
kcb->kprobe_status = kcb->prev_kprobe.status;
|
|
kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags;
|
|
kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags;
|
|
}
|
|
|
|
static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
|
|
struct kprobe_ctlblk *kcb)
|
|
{
|
|
__this_cpu_write(current_kprobe, p);
|
|
kcb->kprobe_saved_flags = kcb->kprobe_old_flags
|
|
= (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF));
|
|
if (is_IF_modifier(p->ainsn.insn))
|
|
kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF;
|
|
}
|
|
|
|
static void __kprobes clear_btf(void)
|
|
{
|
|
if (test_thread_flag(TIF_BLOCKSTEP)) {
|
|
unsigned long debugctl = get_debugctlmsr();
|
|
|
|
debugctl &= ~DEBUGCTLMSR_BTF;
|
|
update_debugctlmsr(debugctl);
|
|
}
|
|
}
|
|
|
|
static void __kprobes restore_btf(void)
|
|
{
|
|
if (test_thread_flag(TIF_BLOCKSTEP)) {
|
|
unsigned long debugctl = get_debugctlmsr();
|
|
|
|
debugctl |= DEBUGCTLMSR_BTF;
|
|
update_debugctlmsr(debugctl);
|
|
}
|
|
}
|
|
|
|
void __kprobes
|
|
arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
|
|
{
|
|
unsigned long *sara = stack_addr(regs);
|
|
|
|
ri->ret_addr = (kprobe_opcode_t *) *sara;
|
|
|
|
/* Replace the return addr with trampoline addr */
|
|
*sara = (unsigned long) &kretprobe_trampoline;
|
|
}
|
|
|
|
static void __kprobes
|
|
setup_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb, int reenter)
|
|
{
|
|
if (setup_detour_execution(p, regs, reenter))
|
|
return;
|
|
|
|
#if !defined(CONFIG_PREEMPT)
|
|
if (p->ainsn.boostable == 1 && !p->post_handler) {
|
|
/* Boost up -- we can execute copied instructions directly */
|
|
if (!reenter)
|
|
reset_current_kprobe();
|
|
/*
|
|
* Reentering boosted probe doesn't reset current_kprobe,
|
|
* nor set current_kprobe, because it doesn't use single
|
|
* stepping.
|
|
*/
|
|
regs->ip = (unsigned long)p->ainsn.insn;
|
|
preempt_enable_no_resched();
|
|
return;
|
|
}
|
|
#endif
|
|
if (reenter) {
|
|
save_previous_kprobe(kcb);
|
|
set_current_kprobe(p, regs, kcb);
|
|
kcb->kprobe_status = KPROBE_REENTER;
|
|
} else
|
|
kcb->kprobe_status = KPROBE_HIT_SS;
|
|
/* Prepare real single stepping */
|
|
clear_btf();
|
|
regs->flags |= X86_EFLAGS_TF;
|
|
regs->flags &= ~X86_EFLAGS_IF;
|
|
/* single step inline if the instruction is an int3 */
|
|
if (p->opcode == BREAKPOINT_INSTRUCTION)
|
|
regs->ip = (unsigned long)p->addr;
|
|
else
|
|
regs->ip = (unsigned long)p->ainsn.insn;
|
|
}
|
|
|
|
/*
|
|
* We have reentered the kprobe_handler(), since another probe was hit while
|
|
* within the handler. We save the original kprobes variables and just single
|
|
* step on the instruction of the new probe without calling any user handlers.
|
|
*/
|
|
static int __kprobes
|
|
reenter_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
|
|
{
|
|
switch (kcb->kprobe_status) {
|
|
case KPROBE_HIT_SSDONE:
|
|
case KPROBE_HIT_ACTIVE:
|
|
kprobes_inc_nmissed_count(p);
|
|
setup_singlestep(p, regs, kcb, 1);
|
|
break;
|
|
case KPROBE_HIT_SS:
|
|
/* A probe has been hit in the codepath leading up to, or just
|
|
* after, single-stepping of a probed instruction. This entire
|
|
* codepath should strictly reside in .kprobes.text section.
|
|
* Raise a BUG or we'll continue in an endless reentering loop
|
|
* and eventually a stack overflow.
|
|
*/
|
|
printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n",
|
|
p->addr);
|
|
dump_kprobe(p);
|
|
BUG();
|
|
default:
|
|
/* impossible cases */
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* Interrupts are disabled on entry as trap3 is an interrupt gate and they
|
|
* remain disabled throughout this function.
|
|
*/
|
|
static int __kprobes kprobe_handler(struct pt_regs *regs)
|
|
{
|
|
kprobe_opcode_t *addr;
|
|
struct kprobe *p;
|
|
struct kprobe_ctlblk *kcb;
|
|
|
|
addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t));
|
|
/*
|
|
* We don't want to be preempted for the entire
|
|
* duration of kprobe processing. We conditionally
|
|
* re-enable preemption at the end of this function,
|
|
* and also in reenter_kprobe() and setup_singlestep().
|
|
*/
|
|
preempt_disable();
|
|
|
|
kcb = get_kprobe_ctlblk();
|
|
p = get_kprobe(addr);
|
|
|
|
if (p) {
|
|
if (kprobe_running()) {
|
|
if (reenter_kprobe(p, regs, kcb))
|
|
return 1;
|
|
} else {
|
|
set_current_kprobe(p, regs, kcb);
|
|
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
|
|
|
|
/*
|
|
* If we have no pre-handler or it returned 0, we
|
|
* continue with normal processing. If we have a
|
|
* pre-handler and it returned non-zero, it prepped
|
|
* for calling the break_handler below on re-entry
|
|
* for jprobe processing, so get out doing nothing
|
|
* more here.
|
|
*/
|
|
if (!p->pre_handler || !p->pre_handler(p, regs))
|
|
setup_singlestep(p, regs, kcb, 0);
|
|
return 1;
|
|
}
|
|
} else if (*addr != BREAKPOINT_INSTRUCTION) {
|
|
/*
|
|
* The breakpoint instruction was removed right
|
|
* after we hit it. Another cpu has removed
|
|
* either a probepoint or a debugger breakpoint
|
|
* at this address. In either case, no further
|
|
* handling of this interrupt is appropriate.
|
|
* Back up over the (now missing) int3 and run
|
|
* the original instruction.
|
|
*/
|
|
regs->ip = (unsigned long)addr;
|
|
preempt_enable_no_resched();
|
|
return 1;
|
|
} else if (kprobe_running()) {
|
|
p = __this_cpu_read(current_kprobe);
|
|
if (p->break_handler && p->break_handler(p, regs)) {
|
|
setup_singlestep(p, regs, kcb, 0);
|
|
return 1;
|
|
}
|
|
} /* else: not a kprobe fault; let the kernel handle it */
|
|
|
|
preempt_enable_no_resched();
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* When a retprobed function returns, this code saves registers and
|
|
* calls trampoline_handler() runs, which calls the kretprobe's handler.
|
|
*/
|
|
static void __used __kprobes kretprobe_trampoline_holder(void)
|
|
{
|
|
asm volatile (
|
|
".global kretprobe_trampoline\n"
|
|
"kretprobe_trampoline: \n"
|
|
#ifdef CONFIG_X86_64
|
|
/* We don't bother saving the ss register */
|
|
" pushq %rsp\n"
|
|
" pushfq\n"
|
|
SAVE_REGS_STRING
|
|
" movq %rsp, %rdi\n"
|
|
" call trampoline_handler\n"
|
|
/* Replace saved sp with true return address. */
|
|
" movq %rax, 152(%rsp)\n"
|
|
RESTORE_REGS_STRING
|
|
" popfq\n"
|
|
#else
|
|
" pushf\n"
|
|
SAVE_REGS_STRING
|
|
" movl %esp, %eax\n"
|
|
" call trampoline_handler\n"
|
|
/* Move flags to cs */
|
|
" movl 56(%esp), %edx\n"
|
|
" movl %edx, 52(%esp)\n"
|
|
/* Replace saved flags with true return address. */
|
|
" movl %eax, 56(%esp)\n"
|
|
RESTORE_REGS_STRING
|
|
" popf\n"
|
|
#endif
|
|
" ret\n");
|
|
}
|
|
|
|
/*
|
|
* Called from kretprobe_trampoline
|
|
*/
|
|
static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
|
|
{
|
|
struct kretprobe_instance *ri = NULL;
|
|
struct hlist_head *head, empty_rp;
|
|
struct hlist_node *node, *tmp;
|
|
unsigned long flags, orig_ret_address = 0;
|
|
unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
|
|
kprobe_opcode_t *correct_ret_addr = NULL;
|
|
|
|
INIT_HLIST_HEAD(&empty_rp);
|
|
kretprobe_hash_lock(current, &head, &flags);
|
|
/* fixup registers */
|
|
#ifdef CONFIG_X86_64
|
|
regs->cs = __KERNEL_CS;
|
|
#else
|
|
regs->cs = __KERNEL_CS | get_kernel_rpl();
|
|
regs->gs = 0;
|
|
#endif
|
|
regs->ip = trampoline_address;
|
|
regs->orig_ax = ~0UL;
|
|
|
|
/*
|
|
* It is possible to have multiple instances associated with a given
|
|
* task either because multiple functions in the call path have
|
|
* return probes installed on them, and/or more than one
|
|
* return probe was registered for a target function.
|
|
*
|
|
* We can handle this because:
|
|
* - instances are always pushed into the head of the list
|
|
* - when multiple return probes are registered for the same
|
|
* function, the (chronologically) first instance's ret_addr
|
|
* will be the real return address, and all the rest will
|
|
* point to kretprobe_trampoline.
|
|
*/
|
|
hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
|
|
if (ri->task != current)
|
|
/* another task is sharing our hash bucket */
|
|
continue;
|
|
|
|
orig_ret_address = (unsigned long)ri->ret_addr;
|
|
|
|
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);
|
|
|
|
correct_ret_addr = ri->ret_addr;
|
|
hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
|
|
if (ri->task != current)
|
|
/* another task is sharing our hash bucket */
|
|
continue;
|
|
|
|
orig_ret_address = (unsigned long)ri->ret_addr;
|
|
if (ri->rp && ri->rp->handler) {
|
|
__this_cpu_write(current_kprobe, &ri->rp->kp);
|
|
get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
|
|
ri->ret_addr = correct_ret_addr;
|
|
ri->rp->handler(ri, regs);
|
|
__this_cpu_write(current_kprobe, NULL);
|
|
}
|
|
|
|
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_hash_unlock(current, &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 ip 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 flags, 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.
|
|
*
|
|
* If this is the first time we've single-stepped the instruction at
|
|
* this probepoint, and the instruction is boostable, boost it: add a
|
|
* jump instruction after the copied instruction, that jumps to the next
|
|
* instruction after the probepoint.
|
|
*/
|
|
static void __kprobes
|
|
resume_execution(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
|
|
{
|
|
unsigned long *tos = stack_addr(regs);
|
|
unsigned long copy_ip = (unsigned long)p->ainsn.insn;
|
|
unsigned long orig_ip = (unsigned long)p->addr;
|
|
kprobe_opcode_t *insn = p->ainsn.insn;
|
|
|
|
/* Skip prefixes */
|
|
insn = skip_prefixes(insn);
|
|
|
|
regs->flags &= ~X86_EFLAGS_TF;
|
|
switch (*insn) {
|
|
case 0x9c: /* pushfl */
|
|
*tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF);
|
|
*tos |= kcb->kprobe_old_flags;
|
|
break;
|
|
case 0xc2: /* iret/ret/lret */
|
|
case 0xc3:
|
|
case 0xca:
|
|
case 0xcb:
|
|
case 0xcf:
|
|
case 0xea: /* jmp absolute -- ip is correct */
|
|
/* ip is already adjusted, no more changes required */
|
|
p->ainsn.boostable = 1;
|
|
goto no_change;
|
|
case 0xe8: /* call relative - Fix return addr */
|
|
*tos = orig_ip + (*tos - copy_ip);
|
|
break;
|
|
#ifdef CONFIG_X86_32
|
|
case 0x9a: /* call absolute -- same as call absolute, indirect */
|
|
*tos = orig_ip + (*tos - copy_ip);
|
|
goto no_change;
|
|
#endif
|
|
case 0xff:
|
|
if ((insn[1] & 0x30) == 0x10) {
|
|
/*
|
|
* call absolute, indirect
|
|
* Fix return addr; ip is correct.
|
|
* But this is not boostable
|
|
*/
|
|
*tos = orig_ip + (*tos - copy_ip);
|
|
goto no_change;
|
|
} else if (((insn[1] & 0x31) == 0x20) ||
|
|
((insn[1] & 0x31) == 0x21)) {
|
|
/*
|
|
* jmp near and far, absolute indirect
|
|
* ip is correct. And this is boostable
|
|
*/
|
|
p->ainsn.boostable = 1;
|
|
goto no_change;
|
|
}
|
|
default:
|
|
break;
|
|
}
|
|
|
|
if (p->ainsn.boostable == 0) {
|
|
if ((regs->ip > copy_ip) &&
|
|
(regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) {
|
|
/*
|
|
* These instructions can be executed directly if it
|
|
* jumps back to correct address.
|
|
*/
|
|
synthesize_reljump((void *)regs->ip,
|
|
(void *)orig_ip + (regs->ip - copy_ip));
|
|
p->ainsn.boostable = 1;
|
|
} else {
|
|
p->ainsn.boostable = -1;
|
|
}
|
|
}
|
|
|
|
regs->ip += orig_ip - copy_ip;
|
|
|
|
no_change:
|
|
restore_btf();
|
|
}
|
|
|
|
/*
|
|
* Interrupts are disabled on entry as trap1 is an interrupt gate and they
|
|
* remain disabled throughout 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;
|
|
|
|
resume_execution(cur, regs, kcb);
|
|
regs->flags |= kcb->kprobe_saved_flags;
|
|
|
|
if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
|
|
kcb->kprobe_status = KPROBE_HIT_SSDONE;
|
|
cur->post_handler(cur, regs, 0);
|
|
}
|
|
|
|
/* 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, flags
|
|
* will have TF set, in which case, continue the remaining processing
|
|
* of do_debug, as if this is not a probe hit.
|
|
*/
|
|
if (regs->flags & X86_EFLAGS_TF)
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
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 ip points back to the probe address
|
|
* and allow the page fault handler to continue as a
|
|
* normal page fault.
|
|
*/
|
|
regs->ip = (unsigned long)cur->addr;
|
|
regs->flags |= kcb->kprobe_old_flags;
|
|
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 accounting
|
|
* 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 routine could not handle it,
|
|
* Let do_page_fault() fix it.
|
|
*/
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Wrapper routine for handling exceptions.
|
|
*/
|
|
int __kprobes
|
|
kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data)
|
|
{
|
|
struct die_args *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)) {
|
|
/*
|
|
* Reset the BS bit in dr6 (pointed by args->err) to
|
|
* denote completion of processing
|
|
*/
|
|
(*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
|
|
ret = NOTIFY_STOP;
|
|
}
|
|
break;
|
|
case DIE_GPF:
|
|
/*
|
|
* To be potentially processing a kprobe fault and to
|
|
* trust the result from kprobe_running(), we have
|
|
* be non-preemptible.
|
|
*/
|
|
if (!preemptible() && kprobe_running() &&
|
|
kprobe_fault_handler(args->regs, args->trapnr))
|
|
ret = NOTIFY_STOP;
|
|
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_sp = stack_addr(regs);
|
|
addr = (unsigned long)(kcb->jprobe_saved_sp);
|
|
|
|
/*
|
|
* 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->flags &= ~X86_EFLAGS_IF;
|
|
trace_hardirqs_off();
|
|
regs->ip = (unsigned long)(jp->entry);
|
|
return 1;
|
|
}
|
|
|
|
void __kprobes jprobe_return(void)
|
|
{
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
|
|
asm volatile (
|
|
#ifdef CONFIG_X86_64
|
|
" xchg %%rbx,%%rsp \n"
|
|
#else
|
|
" xchgl %%ebx,%%esp \n"
|
|
#endif
|
|
" int3 \n"
|
|
" .globl jprobe_return_end\n"
|
|
" jprobe_return_end: \n"
|
|
" nop \n"::"b"
|
|
(kcb->jprobe_saved_sp):"memory");
|
|
}
|
|
|
|
int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
u8 *addr = (u8 *) (regs->ip - 1);
|
|
struct jprobe *jp = container_of(p, struct jprobe, kp);
|
|
|
|
if ((addr > (u8 *) jprobe_return) &&
|
|
(addr < (u8 *) jprobe_return_end)) {
|
|
if (stack_addr(regs) != kcb->jprobe_saved_sp) {
|
|
struct pt_regs *saved_regs = &kcb->jprobe_saved_regs;
|
|
printk(KERN_ERR
|
|
"current sp %p does not match saved sp %p\n",
|
|
stack_addr(regs), kcb->jprobe_saved_sp);
|
|
printk(KERN_ERR "Saved registers for jprobe %p\n", jp);
|
|
show_regs(saved_regs);
|
|
printk(KERN_ERR "Current registers\n");
|
|
show_regs(regs);
|
|
BUG();
|
|
}
|
|
*regs = kcb->jprobe_saved_regs;
|
|
memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp),
|
|
kcb->jprobes_stack,
|
|
MIN_STACK_SIZE(kcb->jprobe_saved_sp));
|
|
preempt_enable_no_resched();
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int __init arch_init_kprobes(void)
|
|
{
|
|
return arch_init_optprobes();
|
|
}
|
|
|
|
int __kprobes arch_trampoline_kprobe(struct kprobe *p)
|
|
{
|
|
return 0;
|
|
}
|