TononixOS/ubports_kernel_google_msm
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

x86/kprobes: Split out optprobe related code to kprobes-opt.c

Browse Source 
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>
This commit is contained in:
Masami Hiramatsu
2012-03-05 22:32:22 +09:00
committed by Ingo Molnar
parent 464846888d
commit 3f33ab1c0c
4 changed files with 646 additions and 594 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/kernel/Makefile
View File

@@ -69,6 +69,7 @@ obj-$(CONFIG_KEXEC) += machine_kexec_$(BITS).o
obj-$(CONFIG_KEXEC) += relocate_kernel_$(BITS).o crash.o obj-$(CONFIG_KEXEC) += relocate_kernel_$(BITS).o crash.o
obj-$(CONFIG_CRASH_DUMP) += crash_dump_$(BITS).o obj-$(CONFIG_CRASH_DUMP) += crash_dump_$(BITS).o
obj-$(CONFIG_KPROBES) += kprobes.o obj-$(CONFIG_KPROBES) += kprobes.o
obj-$(CONFIG_OPTPROBES) += kprobes-opt.o
obj-$(CONFIG_MODULES) += module.o obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_DOUBLEFAULT) += doublefault_32.o obj-$(CONFIG_DOUBLEFAULT) += doublefault_32.o
obj-$(CONFIG_KGDB) += kgdb.o obj-$(CONFIG_KGDB) += kgdb.o

102
arch/x86/kernel/kprobes-common.h Normal file
View File

@@ -0,0 +1,102 @@
#ifndef __X86_KERNEL_KPROBES_COMMON_H
#define __X86_KERNEL_KPROBES_COMMON_H
/* Kprobes and Optprobes common header */
#ifdef CONFIG_X86_64
#define SAVE_REGS_STRING \
/* Skip cs, ip, orig_ax. */ \
" subq $24, %rsp\n" \
" pushq %rdi\n" \
" pushq %rsi\n" \
" pushq %rdx\n" \
" pushq %rcx\n" \
" pushq %rax\n" \
" pushq %r8\n" \
" pushq %r9\n" \
" pushq %r10\n" \
" pushq %r11\n" \
" pushq %rbx\n" \
" pushq %rbp\n" \
" pushq %r12\n" \
" pushq %r13\n" \
" pushq %r14\n" \
" pushq %r15\n"
#define RESTORE_REGS_STRING \
" popq %r15\n" \
" popq %r14\n" \
" popq %r13\n" \
" popq %r12\n" \
" popq %rbp\n" \
" popq %rbx\n" \
" popq %r11\n" \
" popq %r10\n" \
" popq %r9\n" \
" popq %r8\n" \
" popq %rax\n" \
" popq %rcx\n" \
" popq %rdx\n" \
" popq %rsi\n" \
" popq %rdi\n" \
/* Skip orig_ax, ip, cs */ \
" addq $24, %rsp\n"
#else
#define SAVE_REGS_STRING \
/* Skip cs, ip, orig_ax and gs. */ \
" subl $16, %esp\n" \
" pushl %fs\n" \
" pushl %es\n" \
" pushl %ds\n" \
" pushl %eax\n" \
" pushl %ebp\n" \
" pushl %edi\n" \
" pushl %esi\n" \
" pushl %edx\n" \
" pushl %ecx\n" \
" pushl %ebx\n"
#define RESTORE_REGS_STRING \
" popl %ebx\n" \
" popl %ecx\n" \
" popl %edx\n" \
" popl %esi\n" \
" popl %edi\n" \
" popl %ebp\n" \
" popl %eax\n" \
/* Skip ds, es, fs, gs, orig_ax, and ip. Note: don't pop cs here*/\
" addl $24, %esp\n"
#endif
/* Ensure if the instruction can be boostable */
extern int can_boost(kprobe_opcode_t *instruction);
/* Recover instruction if given address is probed */
extern unsigned long recover_probed_instruction(kprobe_opcode_t *buf,
unsigned long addr);
/*
* Copy an instruction and adjust the displacement if the instruction
* uses the %rip-relative addressing mode.
*/
extern int __copy_instruction(u8 *dest, u8 *src);
/* Generate a relative-jump/call instruction */
extern void synthesize_reljump(void *from, void *to);
extern void synthesize_relcall(void *from, void *to);
#ifdef CONFIG_OPTPROBES
extern int arch_init_optprobes(void);
extern int setup_detour_execution(struct kprobe *p, struct pt_regs *regs, int reenter);
extern unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr);
#else /* !CONFIG_OPTPROBES */
static inline int arch_init_optprobes(void)
{
return 0;
}
static inline int setup_detour_execution(struct kprobe *p, struct pt_regs *regs, int reenter)
{
return 0;
}
static inline unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr)
{
return addr;
}
#endif
#endif

512
arch/x86/kernel/kprobes-opt.c Normal file
View File

@@ -0,0 +1,512 @@
/*
* 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;
}

615
arch/x86/kernel/kprobes.c
View File

@@ -39,7 +39,6 @@
* <arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com> * <arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com>
* unified x86 kprobes code. * unified x86 kprobes code.
*/ */
#include <linux/kprobes.h> #include <linux/kprobes.h>
#include <linux/ptrace.h> #include <linux/ptrace.h>
#include <linux/string.h> #include <linux/string.h>
@@ -59,6 +58,8 @@
#include <asm/insn.h> #include <asm/insn.h>
#include <asm/debugreg.h> #include <asm/debugreg.h>
#include "kprobes-common.h"
void jprobe_return_end(void); void jprobe_return_end(void);
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
@@ -108,6 +109,7 @@ struct kretprobe_blackpoint kretprobe_blacklist[] = {
doesn't switch kernel stack.*/ doesn't switch kernel stack.*/
{NULL, NULL} /* Terminator */ {NULL, NULL} /* Terminator */
}; };
const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist);
static void __kprobes __synthesize_relative_insn(void *from, void *to, u8 op) static void __kprobes __synthesize_relative_insn(void *from, void *to, u8 op)
@@ -123,11 +125,17 @@ static void __kprobes __synthesize_relative_insn(void *from, void *to, u8 op)
} }
/* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/
static void __kprobes synthesize_reljump(void *from, void *to) void __kprobes synthesize_reljump(void *from, void *to)
{ {
__synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE); __synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE);
} }
/* Insert a call instruction at address 'from', which calls address 'to'.*/
void __kprobes synthesize_relcall(void *from, void *to)
{
__synthesize_relative_insn(from, to, RELATIVECALL_OPCODE);
}
/* /*
* Skip the prefixes of the instruction. * Skip the prefixes of the instruction.
*/ */
@@ -151,7 +159,7 @@ static kprobe_opcode_t *__kprobes skip_prefixes(kprobe_opcode_t *insn)
* Returns non-zero if opcode is boostable. * Returns non-zero if opcode is boostable.
* RIP relative instructions are adjusted at copying time in 64 bits mode * RIP relative instructions are adjusted at copying time in 64 bits mode
*/ */
static int __kprobes can_boost(kprobe_opcode_t *opcodes) int __kprobes can_boost(kprobe_opcode_t *opcodes)
{ {
kprobe_opcode_t opcode; kprobe_opcode_t opcode;
kprobe_opcode_t *orig_opcodes = opcodes; kprobe_opcode_t *orig_opcodes = opcodes;
@@ -207,8 +215,8 @@ retry:
} }
} }
static unsigned long __recover_probed_insn(kprobe_opcode_t *buf, static unsigned long
unsigned long addr) __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr)
{ {
struct kprobe *kp; struct kprobe *kp;
@@ -235,59 +243,12 @@ static unsigned long __recover_probed_insn(kprobe_opcode_t *buf,
return (unsigned long)buf; return (unsigned long)buf;
} }
#ifdef CONFIG_OPTPROBES
static 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;
}
#else
static inline unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf,
unsigned long addr)
{
return addr;
}
#endif
/* /*
* Recover the probed instruction at addr for further analysis. * Recover the probed instruction at addr for further analysis.
* Caller must lock kprobes by kprobe_mutex, or disable preemption * Caller must lock kprobes by kprobe_mutex, or disable preemption
* for preventing to release referencing kprobes. * for preventing to release referencing kprobes.
*/ */
static unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr)
unsigned long addr)
{ {
unsigned long __addr; unsigned long __addr;
@@ -361,7 +322,7 @@ static int __kprobes is_IF_modifier(kprobe_opcode_t *insn)
* If not, return null. * If not, return null.
* Only applicable to 64-bit x86. * Only applicable to 64-bit x86.
*/ */
static int __kprobes __copy_instruction(u8 *dest, u8 *src) int __kprobes __copy_instruction(u8 *dest, u8 *src)
{ {
struct insn insn; struct insn insn;
kprobe_opcode_t buf[MAX_INSN_SIZE]; kprobe_opcode_t buf[MAX_INSN_SIZE];
@@ -497,8 +458,8 @@ static void __kprobes restore_btf(void)
} }
} }
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, void __kprobes
struct pt_regs *regs) arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
{ {
unsigned long *sara = stack_addr(regs); unsigned long *sara = stack_addr(regs);
@@ -508,16 +469,8 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
*sara = (unsigned long) &kretprobe_trampoline; *sara = (unsigned long) &kretprobe_trampoline;
} }
#ifdef CONFIG_OPTPROBES static void __kprobes
static int __kprobes setup_detour_execution(struct kprobe *p, setup_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb, int reenter)
struct pt_regs *regs,
int reenter);
#else
#define setup_detour_execution(p, regs, reenter) (0)
#endif
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)) if (setup_detour_execution(p, regs, reenter))
return; return;
@@ -559,8 +512,8 @@ static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs,
* within the handler. We save the original kprobes variables and just single * 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. * 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, static int __kprobes
struct kprobe_ctlblk *kcb) reenter_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
{ {
switch (kcb->kprobe_status) { switch (kcb->kprobe_status) {
case KPROBE_HIT_SSDONE: case KPROBE_HIT_SSDONE:
@@ -655,69 +608,6 @@ static int __kprobes kprobe_handler(struct pt_regs *regs)
return 0; return 0;
} }
#ifdef CONFIG_X86_64
#define SAVE_REGS_STRING \
/* Skip cs, ip, orig_ax. */ \
" subq $24, %rsp\n" \
" pushq %rdi\n" \
" pushq %rsi\n" \
" pushq %rdx\n" \
" pushq %rcx\n" \
" pushq %rax\n" \
" pushq %r8\n" \
" pushq %r9\n" \
" pushq %r10\n" \
" pushq %r11\n" \
" pushq %rbx\n" \
" pushq %rbp\n" \
" pushq %r12\n" \
" pushq %r13\n" \
" pushq %r14\n" \
" pushq %r15\n"
#define RESTORE_REGS_STRING \
" popq %r15\n" \
" popq %r14\n" \
" popq %r13\n" \
" popq %r12\n" \
" popq %rbp\n" \
" popq %rbx\n" \
" popq %r11\n" \
" popq %r10\n" \
" popq %r9\n" \
" popq %r8\n" \
" popq %rax\n" \
" popq %rcx\n" \
" popq %rdx\n" \
" popq %rsi\n" \
" popq %rdi\n" \
/* Skip orig_ax, ip, cs */ \
" addq $24, %rsp\n"
#else
#define SAVE_REGS_STRING \
/* Skip cs, ip, orig_ax and gs. */ \
" subl $16, %esp\n" \
" pushl %fs\n" \
" pushl %es\n" \
" pushl %ds\n" \
" pushl %eax\n" \
" pushl %ebp\n" \
" pushl %edi\n" \
" pushl %esi\n" \
" pushl %edx\n" \
" pushl %ecx\n" \
" pushl %ebx\n"
#define RESTORE_REGS_STRING \
" popl %ebx\n" \
" popl %ecx\n" \
" popl %edx\n" \
" popl %esi\n" \
" popl %edi\n" \
" popl %ebp\n" \
" popl %eax\n" \
/* Skip ds, es, fs, gs, orig_ax, and ip. Note: don't pop cs here*/\
" addl $24, %esp\n"
#endif
/* /*
* When a retprobed function returns, this code saves registers and * When a retprobed function returns, this code saves registers and
* calls trampoline_handler() runs, which calls the kretprobe's handler. * calls trampoline_handler() runs, which calls the kretprobe's handler.
@@ -871,8 +761,8 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
* jump instruction after the copied instruction, that jumps to the next * jump instruction after the copied instruction, that jumps to the next
* instruction after the probepoint. * instruction after the probepoint.
*/ */
static void __kprobes resume_execution(struct kprobe *p, static void __kprobes
struct pt_regs *regs, struct kprobe_ctlblk *kcb) resume_execution(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb)
{ {
unsigned long *tos = stack_addr(regs); unsigned long *tos = stack_addr(regs);
unsigned long copy_ip = (unsigned long)p->ainsn.insn; unsigned long copy_ip = (unsigned long)p->ainsn.insn;
@@ -1051,8 +941,8 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
/* /*
* Wrapper routine for handling exceptions. * Wrapper routine for handling exceptions.
*/ */
int __kprobes kprobe_exceptions_notify(struct notifier_block *self, int __kprobes
unsigned long val, void *data) kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data)
{ {
struct die_args *args = data; struct die_args *args = data;
int ret = NOTIFY_DONE; int ret = NOTIFY_DONE;
@@ -1162,462 +1052,9 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
return 0; return 0;
} }
#ifdef CONFIG_OPTPROBES
/* Insert a call instruction at address 'from', which calls address 'to'.*/
static void __kprobes synthesize_relcall(void *from, void *to)
{
__synthesize_relative_insn(from, to, RELATIVECALL_OPCODE);
}
/* 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);
}
static 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;
}
static int __kprobes init_poke_params(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;
}
#else /* !CONFIG_OPTPROBES */
static int __kprobes init_poke_params(void)
{
return 0;
}
#endif
int __init arch_init_kprobes(void) int __init arch_init_kprobes(void)
{ {
return init_poke_params(); return arch_init_optprobes();
} }
int __kprobes arch_trampoline_kprobe(struct kprobe *p) int __kprobes arch_trampoline_kprobe(struct kprobe *p)