static int arch_copy_kprobe(struct kprobe *p)
{
struct insn insn;
kprobe_opcode_t buf[MAX_INSN_SIZE];
int len;
/* Copy an instruction with recovering if other optprobe modifies it.*/
len = __copy_instruction(buf, p->addr, p->ainsn.insn, &insn);
if (!len)
return -EINVAL;
/*
* __copy_instruction can modify the displacement of the instruction,
* but it doesn't affect boostable check.
*/
len = prepare_boost(buf, p, &insn);
/* Check whether the instruction modifies Interrupt Flag or not */
p->ainsn.if_modifier = is_IF_modifier(buf);
/* Also, displacement change doesn't affect the first byte */
p->opcode = buf[0];
/* OK, write back the instruction(s) into ROX insn buffer */
text_poke(p->ainsn.insn, buf, len);
return 0;
}
static int arch_copy_kprobe(struct kprobe *p)
{
int ret;
/* Copy an instruction with recovering if other optprobe modifies it.*/
ret = __copy_instruction(p->ainsn.insn, p->addr);
if (!ret)
return -EINVAL;
/*
* __copy_instruction can modify the displacement of the instruction,
* but it doesn't affect boostable check.
*/
if (can_boost(p->ainsn.insn))
p->ainsn.boostable = 0;
else
p->ainsn.boostable = -1;
/* Check whether the instruction modifies Interrupt Flag or not */
p->ainsn.if_modifier = is_IF_modifier(p->ainsn.insn);
/* Also, displacement change doesn't affect the first byte */
p->opcode = p->ainsn.insn[0];
return 0;
}
static inline void 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;
}
/*
* Returns non-zero if opcode modifies the interrupt flag.
*/
static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
{
switch (*insn) {
case 0xfa: /* cli */
case 0xfb: /* sti */
case 0xcf: /* iret/iretd */
case 0x9d: /* popf/popfd */
return 1;
}
/*
* on X86_64, 0x40-0x4f are REX prefixes so we need to look
* at the next byte instead.. but of course not recurse infinitely
*/
if (is_REX_prefix(insn))
return is_IF_modifier(++insn);
return 0;
}
