![Masami Hiramatsu](/assets/img/avatar_default.png)
Split out optprobe related code to arch/x86/kernel/kprobes-opt.c for maintenanceability. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Suggested-by: Ingo Molnar <mingo@elte.hu> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: yrl.pp-manager.tt@hitachi.com Cc: systemtap@sourceware.org Cc: anderson@redhat.com Link: http://lkml.kernel.org/r/20120305133222.5982.54794.stgit@localhost.localdomain [ Tidied up the code a tiny bit ] Signed-off-by: Ingo Molnar <mingo@elte.hu>
513 lines
14 KiB
C
513 lines
14 KiB
C
/*
|
|
* Kernel Probes Jump Optimization (Optprobes)
|
|
*
|
|
* 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
|
|
* Copyright (C) Hitachi Ltd., 2012
|
|
*/
|
|
#include <linux/kprobes.h>
|
|
#include <linux/ptrace.h>
|
|
#include <linux/string.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/hardirq.h>
|
|
#include <linux/preempt.h>
|
|
#include <linux/module.h>
|
|
#include <linux/kdebug.h>
|
|
#include <linux/kallsyms.h>
|
|
#include <linux/ftrace.h>
|
|
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/desc.h>
|
|
#include <asm/pgtable.h>
|
|
#include <asm/uaccess.h>
|
|
#include <asm/alternative.h>
|
|
#include <asm/insn.h>
|
|
#include <asm/debugreg.h>
|
|
|
|
#include "kprobes-common.h"
|
|
|
|
unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr)
|
|
{
|
|
struct optimized_kprobe *op;
|
|
struct kprobe *kp;
|
|
long offs;
|
|
int i;
|
|
|
|
for (i = 0; i < RELATIVEJUMP_SIZE; i++) {
|
|
kp = get_kprobe((void *)addr - i);
|
|
/* This function only handles jump-optimized kprobe */
|
|
if (kp && kprobe_optimized(kp)) {
|
|
op = container_of(kp, struct optimized_kprobe, kp);
|
|
/* If op->list is not empty, op is under optimizing */
|
|
if (list_empty(&op->list))
|
|
goto found;
|
|
}
|
|
}
|
|
|
|
return addr;
|
|
found:
|
|
/*
|
|
* If the kprobe can be optimized, original bytes which can be
|
|
* overwritten by jump destination address. In this case, original
|
|
* bytes must be recovered from op->optinsn.copied_insn buffer.
|
|
*/
|
|
memcpy(buf, (void *)addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
|
|
if (addr == (unsigned long)kp->addr) {
|
|
buf[0] = kp->opcode;
|
|
memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
|
|
} else {
|
|
offs = addr - (unsigned long)kp->addr - 1;
|
|
memcpy(buf, op->optinsn.copied_insn + offs, RELATIVE_ADDR_SIZE - offs);
|
|
}
|
|
|
|
return (unsigned long)buf;
|
|
}
|
|
|
|
/* Insert a move instruction which sets a pointer to eax/rdi (1st arg). */
|
|
static void __kprobes synthesize_set_arg1(kprobe_opcode_t *addr, unsigned long val)
|
|
{
|
|
#ifdef CONFIG_X86_64
|
|
*addr++ = 0x48;
|
|
*addr++ = 0xbf;
|
|
#else
|
|
*addr++ = 0xb8;
|
|
#endif
|
|
*(unsigned long *)addr = val;
|
|
}
|
|
|
|
static void __used __kprobes kprobes_optinsn_template_holder(void)
|
|
{
|
|
asm volatile (
|
|
".global optprobe_template_entry\n"
|
|
"optprobe_template_entry:\n"
|
|
#ifdef CONFIG_X86_64
|
|
/* We don't bother saving the ss register */
|
|
" pushq %rsp\n"
|
|
" pushfq\n"
|
|
SAVE_REGS_STRING
|
|
" movq %rsp, %rsi\n"
|
|
".global optprobe_template_val\n"
|
|
"optprobe_template_val:\n"
|
|
ASM_NOP5
|
|
ASM_NOP5
|
|
".global optprobe_template_call\n"
|
|
"optprobe_template_call:\n"
|
|
ASM_NOP5
|
|
/* Move flags to rsp */
|
|
" movq 144(%rsp), %rdx\n"
|
|
" movq %rdx, 152(%rsp)\n"
|
|
RESTORE_REGS_STRING
|
|
/* Skip flags entry */
|
|
" addq $8, %rsp\n"
|
|
" popfq\n"
|
|
#else /* CONFIG_X86_32 */
|
|
" pushf\n"
|
|
SAVE_REGS_STRING
|
|
" movl %esp, %edx\n"
|
|
".global optprobe_template_val\n"
|
|
"optprobe_template_val:\n"
|
|
ASM_NOP5
|
|
".global optprobe_template_call\n"
|
|
"optprobe_template_call:\n"
|
|
ASM_NOP5
|
|
RESTORE_REGS_STRING
|
|
" addl $4, %esp\n" /* skip cs */
|
|
" popf\n"
|
|
#endif
|
|
".global optprobe_template_end\n"
|
|
"optprobe_template_end:\n");
|
|
}
|
|
|
|
#define TMPL_MOVE_IDX \
|
|
((long)&optprobe_template_val - (long)&optprobe_template_entry)
|
|
#define TMPL_CALL_IDX \
|
|
((long)&optprobe_template_call - (long)&optprobe_template_entry)
|
|
#define TMPL_END_IDX \
|
|
((long)&optprobe_template_end - (long)&optprobe_template_entry)
|
|
|
|
#define INT3_SIZE sizeof(kprobe_opcode_t)
|
|
|
|
/* Optimized kprobe call back function: called from optinsn */
|
|
static void __kprobes optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
|
|
{
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
unsigned long flags;
|
|
|
|
/* This is possible if op is under delayed unoptimizing */
|
|
if (kprobe_disabled(&op->kp))
|
|
return;
|
|
|
|
local_irq_save(flags);
|
|
if (kprobe_running()) {
|
|
kprobes_inc_nmissed_count(&op->kp);
|
|
} else {
|
|
/* Save skipped registers */
|
|
#ifdef CONFIG_X86_64
|
|
regs->cs = __KERNEL_CS;
|
|
#else
|
|
regs->cs = __KERNEL_CS | get_kernel_rpl();
|
|
regs->gs = 0;
|
|
#endif
|
|
regs->ip = (unsigned long)op->kp.addr + INT3_SIZE;
|
|
regs->orig_ax = ~0UL;
|
|
|
|
__this_cpu_write(current_kprobe, &op->kp);
|
|
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
|
|
opt_pre_handler(&op->kp, regs);
|
|
__this_cpu_write(current_kprobe, NULL);
|
|
}
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
static int __kprobes copy_optimized_instructions(u8 *dest, u8 *src)
|
|
{
|
|
int len = 0, ret;
|
|
|
|
while (len < RELATIVEJUMP_SIZE) {
|
|
ret = __copy_instruction(dest + len, src + len);
|
|
if (!ret || !can_boost(dest + len))
|
|
return -EINVAL;
|
|
len += ret;
|
|
}
|
|
/* Check whether the address range is reserved */
|
|
if (ftrace_text_reserved(src, src + len - 1) ||
|
|
alternatives_text_reserved(src, src + len - 1) ||
|
|
jump_label_text_reserved(src, src + len - 1))
|
|
return -EBUSY;
|
|
|
|
return len;
|
|
}
|
|
|
|
/* Check whether insn is indirect jump */
|
|
static int __kprobes insn_is_indirect_jump(struct insn *insn)
|
|
{
|
|
return ((insn->opcode.bytes[0] == 0xff &&
|
|
(X86_MODRM_REG(insn->modrm.value) & 6) == 4) || /* Jump */
|
|
insn->opcode.bytes[0] == 0xea); /* Segment based jump */
|
|
}
|
|
|
|
/* Check whether insn jumps into specified address range */
|
|
static int insn_jump_into_range(struct insn *insn, unsigned long start, int len)
|
|
{
|
|
unsigned long target = 0;
|
|
|
|
switch (insn->opcode.bytes[0]) {
|
|
case 0xe0: /* loopne */
|
|
case 0xe1: /* loope */
|
|
case 0xe2: /* loop */
|
|
case 0xe3: /* jcxz */
|
|
case 0xe9: /* near relative jump */
|
|
case 0xeb: /* short relative jump */
|
|
break;
|
|
case 0x0f:
|
|
if ((insn->opcode.bytes[1] & 0xf0) == 0x80) /* jcc near */
|
|
break;
|
|
return 0;
|
|
default:
|
|
if ((insn->opcode.bytes[0] & 0xf0) == 0x70) /* jcc short */
|
|
break;
|
|
return 0;
|
|
}
|
|
target = (unsigned long)insn->next_byte + insn->immediate.value;
|
|
|
|
return (start <= target && target <= start + len);
|
|
}
|
|
|
|
/* Decode whole function to ensure any instructions don't jump into target */
|
|
static int __kprobes can_optimize(unsigned long paddr)
|
|
{
|
|
unsigned long addr, size = 0, offset = 0;
|
|
struct insn insn;
|
|
kprobe_opcode_t buf[MAX_INSN_SIZE];
|
|
|
|
/* Lookup symbol including addr */
|
|
if (!kallsyms_lookup_size_offset(paddr, &size, &offset))
|
|
return 0;
|
|
|
|
/*
|
|
* Do not optimize in the entry code due to the unstable
|
|
* stack handling.
|
|
*/
|
|
if ((paddr >= (unsigned long)__entry_text_start) &&
|
|
(paddr < (unsigned long)__entry_text_end))
|
|
return 0;
|
|
|
|
/* Check there is enough space for a relative jump. */
|
|
if (size - offset < RELATIVEJUMP_SIZE)
|
|
return 0;
|
|
|
|
/* Decode instructions */
|
|
addr = paddr - offset;
|
|
while (addr < paddr - offset + size) { /* Decode until function end */
|
|
if (search_exception_tables(addr))
|
|
/*
|
|
* Since some fixup code will jumps into this function,
|
|
* we can't optimize kprobe in this function.
|
|
*/
|
|
return 0;
|
|
kernel_insn_init(&insn, (void *)recover_probed_instruction(buf, addr));
|
|
insn_get_length(&insn);
|
|
/* Another subsystem puts a breakpoint */
|
|
if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
|
|
return 0;
|
|
/* Recover address */
|
|
insn.kaddr = (void *)addr;
|
|
insn.next_byte = (void *)(addr + insn.length);
|
|
/* Check any instructions don't jump into target */
|
|
if (insn_is_indirect_jump(&insn) ||
|
|
insn_jump_into_range(&insn, paddr + INT3_SIZE,
|
|
RELATIVE_ADDR_SIZE))
|
|
return 0;
|
|
addr += insn.length;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/* Check optimized_kprobe can actually be optimized. */
|
|
int __kprobes arch_check_optimized_kprobe(struct optimized_kprobe *op)
|
|
{
|
|
int i;
|
|
struct kprobe *p;
|
|
|
|
for (i = 1; i < op->optinsn.size; i++) {
|
|
p = get_kprobe(op->kp.addr + i);
|
|
if (p && !kprobe_disabled(p))
|
|
return -EEXIST;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Check the addr is within the optimized instructions. */
|
|
int __kprobes
|
|
arch_within_optimized_kprobe(struct optimized_kprobe *op, unsigned long addr)
|
|
{
|
|
return ((unsigned long)op->kp.addr <= addr &&
|
|
(unsigned long)op->kp.addr + op->optinsn.size > addr);
|
|
}
|
|
|
|
/* Free optimized instruction slot */
|
|
static __kprobes
|
|
void __arch_remove_optimized_kprobe(struct optimized_kprobe *op, int dirty)
|
|
{
|
|
if (op->optinsn.insn) {
|
|
free_optinsn_slot(op->optinsn.insn, dirty);
|
|
op->optinsn.insn = NULL;
|
|
op->optinsn.size = 0;
|
|
}
|
|
}
|
|
|
|
void __kprobes arch_remove_optimized_kprobe(struct optimized_kprobe *op)
|
|
{
|
|
__arch_remove_optimized_kprobe(op, 1);
|
|
}
|
|
|
|
/*
|
|
* Copy replacing target instructions
|
|
* Target instructions MUST be relocatable (checked inside)
|
|
* This is called when new aggr(opt)probe is allocated or reused.
|
|
*/
|
|
int __kprobes arch_prepare_optimized_kprobe(struct optimized_kprobe *op)
|
|
{
|
|
u8 *buf;
|
|
int ret;
|
|
long rel;
|
|
|
|
if (!can_optimize((unsigned long)op->kp.addr))
|
|
return -EILSEQ;
|
|
|
|
op->optinsn.insn = get_optinsn_slot();
|
|
if (!op->optinsn.insn)
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* Verify if the address gap is in 2GB range, because this uses
|
|
* a relative jump.
|
|
*/
|
|
rel = (long)op->optinsn.insn - (long)op->kp.addr + RELATIVEJUMP_SIZE;
|
|
if (abs(rel) > 0x7fffffff)
|
|
return -ERANGE;
|
|
|
|
buf = (u8 *)op->optinsn.insn;
|
|
|
|
/* Copy instructions into the out-of-line buffer */
|
|
ret = copy_optimized_instructions(buf + TMPL_END_IDX, op->kp.addr);
|
|
if (ret < 0) {
|
|
__arch_remove_optimized_kprobe(op, 0);
|
|
return ret;
|
|
}
|
|
op->optinsn.size = ret;
|
|
|
|
/* Copy arch-dep-instance from template */
|
|
memcpy(buf, &optprobe_template_entry, TMPL_END_IDX);
|
|
|
|
/* Set probe information */
|
|
synthesize_set_arg1(buf + TMPL_MOVE_IDX, (unsigned long)op);
|
|
|
|
/* Set probe function call */
|
|
synthesize_relcall(buf + TMPL_CALL_IDX, optimized_callback);
|
|
|
|
/* Set returning jmp instruction at the tail of out-of-line buffer */
|
|
synthesize_reljump(buf + TMPL_END_IDX + op->optinsn.size,
|
|
(u8 *)op->kp.addr + op->optinsn.size);
|
|
|
|
flush_icache_range((unsigned long) buf,
|
|
(unsigned long) buf + TMPL_END_IDX +
|
|
op->optinsn.size + RELATIVEJUMP_SIZE);
|
|
return 0;
|
|
}
|
|
|
|
#define MAX_OPTIMIZE_PROBES 256
|
|
static struct text_poke_param *jump_poke_params;
|
|
static struct jump_poke_buffer {
|
|
u8 buf[RELATIVEJUMP_SIZE];
|
|
} *jump_poke_bufs;
|
|
|
|
static void __kprobes setup_optimize_kprobe(struct text_poke_param *tprm,
|
|
u8 *insn_buf,
|
|
struct optimized_kprobe *op)
|
|
{
|
|
s32 rel = (s32)((long)op->optinsn.insn -
|
|
((long)op->kp.addr + RELATIVEJUMP_SIZE));
|
|
|
|
/* Backup instructions which will be replaced by jump address */
|
|
memcpy(op->optinsn.copied_insn, op->kp.addr + INT3_SIZE,
|
|
RELATIVE_ADDR_SIZE);
|
|
|
|
insn_buf[0] = RELATIVEJUMP_OPCODE;
|
|
*(s32 *)(&insn_buf[1]) = rel;
|
|
|
|
tprm->addr = op->kp.addr;
|
|
tprm->opcode = insn_buf;
|
|
tprm->len = RELATIVEJUMP_SIZE;
|
|
}
|
|
|
|
/*
|
|
* Replace breakpoints (int3) with relative jumps.
|
|
* Caller must call with locking kprobe_mutex and text_mutex.
|
|
*/
|
|
void __kprobes arch_optimize_kprobes(struct list_head *oplist)
|
|
{
|
|
struct optimized_kprobe *op, *tmp;
|
|
int c = 0;
|
|
|
|
list_for_each_entry_safe(op, tmp, oplist, list) {
|
|
WARN_ON(kprobe_disabled(&op->kp));
|
|
/* Setup param */
|
|
setup_optimize_kprobe(&jump_poke_params[c],
|
|
jump_poke_bufs[c].buf, op);
|
|
list_del_init(&op->list);
|
|
if (++c >= MAX_OPTIMIZE_PROBES)
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* text_poke_smp doesn't support NMI/MCE code modifying.
|
|
* However, since kprobes itself also doesn't support NMI/MCE
|
|
* code probing, it's not a problem.
|
|
*/
|
|
text_poke_smp_batch(jump_poke_params, c);
|
|
}
|
|
|
|
static void __kprobes setup_unoptimize_kprobe(struct text_poke_param *tprm,
|
|
u8 *insn_buf,
|
|
struct optimized_kprobe *op)
|
|
{
|
|
/* Set int3 to first byte for kprobes */
|
|
insn_buf[0] = BREAKPOINT_INSTRUCTION;
|
|
memcpy(insn_buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
|
|
|
|
tprm->addr = op->kp.addr;
|
|
tprm->opcode = insn_buf;
|
|
tprm->len = RELATIVEJUMP_SIZE;
|
|
}
|
|
|
|
/*
|
|
* Recover original instructions and breakpoints from relative jumps.
|
|
* Caller must call with locking kprobe_mutex.
|
|
*/
|
|
extern void arch_unoptimize_kprobes(struct list_head *oplist,
|
|
struct list_head *done_list)
|
|
{
|
|
struct optimized_kprobe *op, *tmp;
|
|
int c = 0;
|
|
|
|
list_for_each_entry_safe(op, tmp, oplist, list) {
|
|
/* Setup param */
|
|
setup_unoptimize_kprobe(&jump_poke_params[c],
|
|
jump_poke_bufs[c].buf, op);
|
|
list_move(&op->list, done_list);
|
|
if (++c >= MAX_OPTIMIZE_PROBES)
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* text_poke_smp doesn't support NMI/MCE code modifying.
|
|
* However, since kprobes itself also doesn't support NMI/MCE
|
|
* code probing, it's not a problem.
|
|
*/
|
|
text_poke_smp_batch(jump_poke_params, c);
|
|
}
|
|
|
|
/* Replace a relative jump with a breakpoint (int3). */
|
|
void __kprobes arch_unoptimize_kprobe(struct optimized_kprobe *op)
|
|
{
|
|
u8 buf[RELATIVEJUMP_SIZE];
|
|
|
|
/* Set int3 to first byte for kprobes */
|
|
buf[0] = BREAKPOINT_INSTRUCTION;
|
|
memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
|
|
text_poke_smp(op->kp.addr, buf, RELATIVEJUMP_SIZE);
|
|
}
|
|
|
|
int __kprobes
|
|
setup_detour_execution(struct kprobe *p, struct pt_regs *regs, int reenter)
|
|
{
|
|
struct optimized_kprobe *op;
|
|
|
|
if (p->flags & KPROBE_FLAG_OPTIMIZED) {
|
|
/* This kprobe is really able to run optimized path. */
|
|
op = container_of(p, struct optimized_kprobe, kp);
|
|
/* Detour through copied instructions */
|
|
regs->ip = (unsigned long)op->optinsn.insn + TMPL_END_IDX;
|
|
if (!reenter)
|
|
reset_current_kprobe();
|
|
preempt_enable_no_resched();
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
int __kprobes arch_init_optprobes(void)
|
|
{
|
|
/* Allocate code buffer and parameter array */
|
|
jump_poke_bufs = kmalloc(sizeof(struct jump_poke_buffer) *
|
|
MAX_OPTIMIZE_PROBES, GFP_KERNEL);
|
|
if (!jump_poke_bufs)
|
|
return -ENOMEM;
|
|
|
|
jump_poke_params = kmalloc(sizeof(struct text_poke_param) *
|
|
MAX_OPTIMIZE_PROBES, GFP_KERNEL);
|
|
if (!jump_poke_params) {
|
|
kfree(jump_poke_bufs);
|
|
jump_poke_bufs = NULL;
|
|
return -ENOMEM;
|
|
}
|
|
|
|
return 0;
|
|
}
|