757 lines
22 KiB
C
757 lines
22 KiB
C
/*
|
|
* Kernel Probes (KProbes)
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
|
|
*
|
|
* Copyright (C) IBM Corporation, 2002, 2004
|
|
*
|
|
* 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
|
|
* Probes initial implementation ( includes contributions from
|
|
* Rusty Russell).
|
|
* 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
|
|
* interface to access function arguments.
|
|
* 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
|
|
* <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
|
|
* <prasanna@in.ibm.com> added function-return probes.
|
|
*/
|
|
|
|
#include <linux/kprobes.h>
|
|
#include <linux/ptrace.h>
|
|
#include <linux/preempt.h>
|
|
#include <linux/kdebug.h>
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/desc.h>
|
|
#include <asm/uaccess.h>
|
|
#include <asm/alternative.h>
|
|
|
|
void jprobe_return_end(void);
|
|
|
|
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
|
|
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
|
|
|
|
struct kretprobe_blackpoint kretprobe_blacklist[] = {
|
|
{"__switch_to", }, /* This function switches only current task, but
|
|
doesn't switch kernel stack.*/
|
|
{NULL, NULL} /* Terminator */
|
|
};
|
|
const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist);
|
|
|
|
/* insert a jmp code */
|
|
static __always_inline void set_jmp_op(void *from, void *to)
|
|
{
|
|
struct __arch_jmp_op {
|
|
char op;
|
|
long raddr;
|
|
} __attribute__((packed)) *jop;
|
|
jop = (struct __arch_jmp_op *)from;
|
|
jop->raddr = (long)(to) - ((long)(from) + 5);
|
|
jop->op = RELATIVEJUMP_INSTRUCTION;
|
|
}
|
|
|
|
/*
|
|
* returns non-zero if opcodes can be boosted.
|
|
*/
|
|
static __always_inline int can_boost(kprobe_opcode_t *opcodes)
|
|
{
|
|
#define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \
|
|
(((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
|
|
(b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
|
|
(b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
|
|
(bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
|
|
<< (row % 32))
|
|
/*
|
|
* Undefined/reserved opcodes, conditional jump, Opcode Extension
|
|
* Groups, and some special opcodes can not be boost.
|
|
*/
|
|
static const unsigned long twobyte_is_boostable[256 / 32] = {
|
|
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
|
|
/* ------------------------------- */
|
|
W(0x00, 0,0,1,1,0,0,1,0,1,1,0,0,0,0,0,0)| /* 00 */
|
|
W(0x10, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 10 */
|
|
W(0x20, 1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0)| /* 20 */
|
|
W(0x30, 0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 30 */
|
|
W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 40 */
|
|
W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 50 */
|
|
W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,0,0,1,1)| /* 60 */
|
|
W(0x70, 0,0,0,0,1,1,1,1,0,0,0,0,0,0,1,1), /* 70 */
|
|
W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 80 */
|
|
W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1), /* 90 */
|
|
W(0xa0, 1,1,0,1,1,1,0,0,1,1,0,1,1,1,0,1)| /* a0 */
|
|
W(0xb0, 1,1,1,1,1,1,1,1,0,0,0,1,1,1,1,1), /* b0 */
|
|
W(0xc0, 1,1,0,0,0,0,0,0,1,1,1,1,1,1,1,1)| /* c0 */
|
|
W(0xd0, 0,1,1,1,0,1,0,0,1,1,0,1,1,1,0,1), /* d0 */
|
|
W(0xe0, 0,1,1,0,0,1,0,0,1,1,0,1,1,1,0,1)| /* e0 */
|
|
W(0xf0, 0,1,1,1,0,1,0,0,1,1,1,0,1,1,1,0) /* f0 */
|
|
/* ------------------------------- */
|
|
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
|
|
};
|
|
#undef W
|
|
kprobe_opcode_t opcode;
|
|
kprobe_opcode_t *orig_opcodes = opcodes;
|
|
retry:
|
|
if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
|
|
return 0;
|
|
opcode = *(opcodes++);
|
|
|
|
/* 2nd-byte opcode */
|
|
if (opcode == 0x0f) {
|
|
if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
|
|
return 0;
|
|
return test_bit(*opcodes, twobyte_is_boostable);
|
|
}
|
|
|
|
switch (opcode & 0xf0) {
|
|
case 0x60:
|
|
if (0x63 < opcode && opcode < 0x67)
|
|
goto retry; /* prefixes */
|
|
/* can't boost Address-size override and bound */
|
|
return (opcode != 0x62 && opcode != 0x67);
|
|
case 0x70:
|
|
return 0; /* can't boost conditional jump */
|
|
case 0xc0:
|
|
/* can't boost software-interruptions */
|
|
return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf;
|
|
case 0xd0:
|
|
/* can boost AA* and XLAT */
|
|
return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7);
|
|
case 0xe0:
|
|
/* can boost in/out and absolute jmps */
|
|
return ((opcode & 0x04) || opcode == 0xea);
|
|
case 0xf0:
|
|
if ((opcode & 0x0c) == 0 && opcode != 0xf1)
|
|
goto retry; /* lock/rep(ne) prefix */
|
|
/* clear and set flags can be boost */
|
|
return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
|
|
default:
|
|
if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)
|
|
goto retry; /* prefixes */
|
|
/* can't boost CS override and call */
|
|
return (opcode != 0x2e && opcode != 0x9a);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* returns non-zero if opcode modifies the interrupt flag.
|
|
*/
|
|
static int __kprobes is_IF_modifier(kprobe_opcode_t opcode)
|
|
{
|
|
switch (opcode) {
|
|
case 0xfa: /* cli */
|
|
case 0xfb: /* sti */
|
|
case 0xcf: /* iret/iretd */
|
|
case 0x9d: /* popf/popfd */
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int __kprobes arch_prepare_kprobe(struct kprobe *p)
|
|
{
|
|
/* insn: must be on special executable page on i386. */
|
|
p->ainsn.insn = get_insn_slot();
|
|
if (!p->ainsn.insn)
|
|
return -ENOMEM;
|
|
|
|
memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
|
|
p->opcode = *p->addr;
|
|
if (can_boost(p->addr)) {
|
|
p->ainsn.boostable = 0;
|
|
} else {
|
|
p->ainsn.boostable = -1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
void __kprobes arch_arm_kprobe(struct kprobe *p)
|
|
{
|
|
text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
|
|
}
|
|
|
|
void __kprobes arch_disarm_kprobe(struct kprobe *p)
|
|
{
|
|
text_poke(p->addr, &p->opcode, 1);
|
|
}
|
|
|
|
void __kprobes arch_remove_kprobe(struct kprobe *p)
|
|
{
|
|
mutex_lock(&kprobe_mutex);
|
|
free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1));
|
|
mutex_unlock(&kprobe_mutex);
|
|
}
|
|
|
|
static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
|
|
{
|
|
kcb->prev_kprobe.kp = kprobe_running();
|
|
kcb->prev_kprobe.status = kcb->kprobe_status;
|
|
kcb->prev_kprobe.old_eflags = kcb->kprobe_old_eflags;
|
|
kcb->prev_kprobe.saved_eflags = kcb->kprobe_saved_eflags;
|
|
}
|
|
|
|
static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
|
|
{
|
|
__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
|
|
kcb->kprobe_status = kcb->prev_kprobe.status;
|
|
kcb->kprobe_old_eflags = kcb->prev_kprobe.old_eflags;
|
|
kcb->kprobe_saved_eflags = kcb->prev_kprobe.saved_eflags;
|
|
}
|
|
|
|
static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
|
|
struct kprobe_ctlblk *kcb)
|
|
{
|
|
__get_cpu_var(current_kprobe) = p;
|
|
kcb->kprobe_saved_eflags = kcb->kprobe_old_eflags
|
|
= (regs->eflags & (TF_MASK | IF_MASK));
|
|
if (is_IF_modifier(p->opcode))
|
|
kcb->kprobe_saved_eflags &= ~IF_MASK;
|
|
}
|
|
|
|
static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
regs->eflags |= TF_MASK;
|
|
regs->eflags &= ~IF_MASK;
|
|
/*single step inline if the instruction is an int3*/
|
|
if (p->opcode == BREAKPOINT_INSTRUCTION)
|
|
regs->eip = (unsigned long)p->addr;
|
|
else
|
|
regs->eip = (unsigned long)p->ainsn.insn;
|
|
}
|
|
|
|
/* Called with kretprobe_lock held */
|
|
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
|
|
struct pt_regs *regs)
|
|
{
|
|
unsigned long *sara = (unsigned long *)®s->esp;
|
|
|
|
ri->ret_addr = (kprobe_opcode_t *) *sara;
|
|
|
|
/* Replace the return addr with trampoline addr */
|
|
*sara = (unsigned long) &kretprobe_trampoline;
|
|
}
|
|
|
|
/*
|
|
* Interrupts are disabled on entry as trap3 is an interrupt gate and they
|
|
* remain disabled thorough out this function.
|
|
*/
|
|
static int __kprobes kprobe_handler(struct pt_regs *regs)
|
|
{
|
|
struct kprobe *p;
|
|
int ret = 0;
|
|
kprobe_opcode_t *addr;
|
|
struct kprobe_ctlblk *kcb;
|
|
|
|
addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
|
|
|
|
/*
|
|
* We don't want to be preempted for the entire
|
|
* duration of kprobe processing
|
|
*/
|
|
preempt_disable();
|
|
kcb = get_kprobe_ctlblk();
|
|
|
|
/* Check we're not actually recursing */
|
|
if (kprobe_running()) {
|
|
p = get_kprobe(addr);
|
|
if (p) {
|
|
if (kcb->kprobe_status == KPROBE_HIT_SS &&
|
|
*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
|
|
regs->eflags &= ~TF_MASK;
|
|
regs->eflags |= kcb->kprobe_saved_eflags;
|
|
goto no_kprobe;
|
|
}
|
|
/* We have reentered the kprobe_handler(), since
|
|
* another probe was hit while within the handler.
|
|
* We here save the original kprobes variables and
|
|
* just single step on the instruction of the new probe
|
|
* without calling any user handlers.
|
|
*/
|
|
save_previous_kprobe(kcb);
|
|
set_current_kprobe(p, regs, kcb);
|
|
kprobes_inc_nmissed_count(p);
|
|
prepare_singlestep(p, regs);
|
|
kcb->kprobe_status = KPROBE_REENTER;
|
|
return 1;
|
|
} else {
|
|
if (*addr != BREAKPOINT_INSTRUCTION) {
|
|
/* The breakpoint instruction was removed by
|
|
* another cpu right after we hit, no further
|
|
* handling of this interrupt is appropriate
|
|
*/
|
|
regs->eip -= sizeof(kprobe_opcode_t);
|
|
ret = 1;
|
|
goto no_kprobe;
|
|
}
|
|
p = __get_cpu_var(current_kprobe);
|
|
if (p->break_handler && p->break_handler(p, regs)) {
|
|
goto ss_probe;
|
|
}
|
|
}
|
|
goto no_kprobe;
|
|
}
|
|
|
|
p = get_kprobe(addr);
|
|
if (!p) {
|
|
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->eip -= sizeof(kprobe_opcode_t);
|
|
ret = 1;
|
|
}
|
|
/* Not one of ours: let kernel handle it */
|
|
goto no_kprobe;
|
|
}
|
|
|
|
set_current_kprobe(p, regs, kcb);
|
|
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
|
|
|
|
if (p->pre_handler && p->pre_handler(p, regs))
|
|
/* handler has already set things up, so skip ss setup */
|
|
return 1;
|
|
|
|
ss_probe:
|
|
#if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM)
|
|
if (p->ainsn.boostable == 1 && !p->post_handler){
|
|
/* Boost up -- we can execute copied instructions directly */
|
|
reset_current_kprobe();
|
|
regs->eip = (unsigned long)p->ainsn.insn;
|
|
preempt_enable_no_resched();
|
|
return 1;
|
|
}
|
|
#endif
|
|
prepare_singlestep(p, regs);
|
|
kcb->kprobe_status = KPROBE_HIT_SS;
|
|
return 1;
|
|
|
|
no_kprobe:
|
|
preempt_enable_no_resched();
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* For function-return probes, init_kprobes() establishes a probepoint
|
|
* here. When a retprobed function returns, this probe is hit and
|
|
* trampoline_probe_handler() runs, calling the kretprobe's handler.
|
|
*/
|
|
void __kprobes kretprobe_trampoline_holder(void)
|
|
{
|
|
asm volatile ( ".global kretprobe_trampoline\n"
|
|
"kretprobe_trampoline: \n"
|
|
" pushf\n"
|
|
/* skip cs, eip, orig_eax */
|
|
" subl $12, %esp\n"
|
|
" pushl %fs\n"
|
|
" pushl %ds\n"
|
|
" pushl %es\n"
|
|
" pushl %eax\n"
|
|
" pushl %ebp\n"
|
|
" pushl %edi\n"
|
|
" pushl %esi\n"
|
|
" pushl %edx\n"
|
|
" pushl %ecx\n"
|
|
" pushl %ebx\n"
|
|
" movl %esp, %eax\n"
|
|
" call trampoline_handler\n"
|
|
/* move eflags to cs */
|
|
" movl 52(%esp), %edx\n"
|
|
" movl %edx, 48(%esp)\n"
|
|
/* save true return address on eflags */
|
|
" movl %eax, 52(%esp)\n"
|
|
" popl %ebx\n"
|
|
" popl %ecx\n"
|
|
" popl %edx\n"
|
|
" popl %esi\n"
|
|
" popl %edi\n"
|
|
" popl %ebp\n"
|
|
" popl %eax\n"
|
|
/* skip eip, orig_eax, es, ds, fs */
|
|
" addl $20, %esp\n"
|
|
" popf\n"
|
|
" ret\n");
|
|
}
|
|
|
|
/*
|
|
* Called from kretprobe_trampoline
|
|
*/
|
|
fastcall void *__kprobes 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;
|
|
|
|
INIT_HLIST_HEAD(&empty_rp);
|
|
spin_lock_irqsave(&kretprobe_lock, flags);
|
|
head = kretprobe_inst_table_head(current);
|
|
/* fixup registers */
|
|
regs->xcs = __KERNEL_CS | get_kernel_rpl();
|
|
regs->eip = trampoline_address;
|
|
regs->orig_eax = 0xffffffff;
|
|
|
|
/*
|
|
* It is possible to have multiple instances associated with a given
|
|
* task either because an multiple functions in the call path
|
|
* have a return probe installed on them, and/or more then one return
|
|
* return probe was registered for a target function.
|
|
*
|
|
* We can handle this because:
|
|
* - instances are always inserted at the head of the list
|
|
* - when multiple return probes are registered for the same
|
|
* function, the first instance's ret_addr will point to 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;
|
|
|
|
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;
|
|
trace_hardirqs_fixup_flags(regs->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;
|
|
}
|
|
|
|
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:
|
|
/* 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;
|
|
trace_hardirqs_off();
|
|
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 = &kcb->jprobe_saved_regs;
|
|
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;
|
|
}
|