/*
* Adjust the displacement if the instruction uses the %rip-relative
* addressing mode.
* If it does, Return the address of the 32-bit displacement word.
* If not, return null.
* Only applicable to 64-bit x86.
*/
static void __kprobes fix_riprel(struct kprobe *p)
{
#ifdef CONFIG_X86_64
struct insn insn;
kernel_insn_init(&insn, p->ainsn.insn);
if (insn_rip_relative(&insn)) {
s64 newdisp;
u8 *disp;
insn_get_displacement(&insn);
/*
* The copied instruction uses the %rip-relative addressing
* mode. Adjust the displacement for the difference between
* the original location of this instruction and the location
* of the copy that will actually be run. The tricky bit here
* is making sure that the sign extension happens correctly in
* this calculation, since we need a signed 32-bit result to
* be sign-extended to 64 bits when it's added to the %rip
* value and yield the same 64-bit result that the sign-
* extension of the original signed 32-bit displacement would
* have given.
*/
newdisp = (u8 *) p->addr + (s64) insn.displacement.value -
(u8 *) p->ainsn.insn;
BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */
disp = (u8 *) p->ainsn.insn + insn_offset_displacement(&insn);
*(s32 *) disp = (s32) newdisp;
}
#endif
}
/*
* Copy an instruction and adjust the displacement if the instruction
* uses the %rip-relative addressing mode.
* If it does, Return the address of the 32-bit displacement word.
* If not, return null.
* Only applicable to 64-bit x86.
*/
int __copy_instruction(u8 *dest, u8 *src)
{
struct insn insn;
kprobe_opcode_t buf[MAX_INSN_SIZE];
int length;
unsigned long recovered_insn =
recover_probed_instruction(buf, (unsigned long)src);
if (!recovered_insn)
return 0;
kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);
insn_get_length(&insn);
length = insn.length;
/* Another subsystem puts a breakpoint, failed to recover */
if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
return 0;
pax_open_kernel();
memcpy(dest, insn.kaddr, length);
pax_close_kernel();
#ifdef CONFIG_X86_64
if (insn_rip_relative(&insn)) {
s64 newdisp;
u8 *disp;
kernel_insn_init(&insn, dest, length);
insn_get_displacement(&insn);
/*
* The copied instruction uses the %rip-relative addressing
* mode. Adjust the displacement for the difference between
* the original location of this instruction and the location
* of the copy that will actually be run. The tricky bit here
* is making sure that the sign extension happens correctly in
* this calculation, since we need a signed 32-bit result to
* be sign-extended to 64 bits when it's added to the %rip
* value and yield the same 64-bit result that the sign-
* extension of the original signed 32-bit displacement would
* have given.
*/
newdisp = (u8 *) src + (s64) insn.displacement.value - (u8 *) dest;
if ((s64) (s32) newdisp != newdisp) {
pr_err("Kprobes error: new displacement does not fit into s32 (%llx)\n", newdisp);
pr_err("\tSrc: %p, Dest: %p, old disp: %x\n", src, dest, insn.displacement.value);
return 0;
}
disp = (u8 *) dest + insn_offset_displacement(&insn);
pax_open_kernel();
*(s32 *) disp = (s32) newdisp;
pax_close_kernel();
}
#endif
return length;
}
/*
* Copy an instruction and adjust the displacement if the instruction
* uses the %rip-relative addressing mode.
* If it does, Return the address of the 32-bit displacement word.
* If not, return null.
* Only applicable to 64-bit x86.
*/
static int __kprobes __copy_instruction(u8 *dest, u8 *src, int recover)
{
struct insn insn;
int ret;
kprobe_opcode_t buf[MAX_INSN_SIZE];
kernel_insn_init(&insn, src);
if (recover) {
insn_get_opcode(&insn);
if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) {
ret = recover_probed_instruction(buf,
(unsigned long)src);
if (ret)
return 0;
kernel_insn_init(&insn, buf);
}
}
insn_get_length(&insn);
memcpy(dest, insn.kaddr, insn.length);
#ifdef CONFIG_X86_64
if (insn_rip_relative(&insn)) {
s64 newdisp;
u8 *disp;
kernel_insn_init(&insn, dest);
insn_get_displacement(&insn);
/*
* The copied instruction uses the %rip-relative addressing
* mode. Adjust the displacement for the difference between
* the original location of this instruction and the location
* of the copy that will actually be run. The tricky bit here
* is making sure that the sign extension happens correctly in
* this calculation, since we need a signed 32-bit result to
* be sign-extended to 64 bits when it's added to the %rip
* value and yield the same 64-bit result that the sign-
* extension of the original signed 32-bit displacement would
* have given.
*/
newdisp = (u8 *) src + (s64) insn.displacement.value -
(u8 *) dest;
BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */
disp = (u8 *) dest + insn_offset_displacement(&insn);
*(s32 *) disp = (s32) newdisp;
}
#endif
return insn.length;
}
