You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
536 lines
15 KiB
536 lines
15 KiB
/*
|
|
* Kernel Probes (KProbes)
|
|
* arch/i386/kernel/kprobes.c
|
|
*
|
|
* 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/config.h>
|
|
#include <linux/kprobes.h>
|
|
#include <linux/ptrace.h>
|
|
#include <linux/spinlock.h>
|
|
#include <linux/preempt.h>
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/kdebug.h>
|
|
#include <asm/desc.h>
|
|
|
|
static struct kprobe *current_kprobe;
|
|
static unsigned long kprobe_status, kprobe_old_eflags, kprobe_saved_eflags;
|
|
static struct kprobe *kprobe_prev;
|
|
static unsigned long kprobe_status_prev, kprobe_old_eflags_prev, kprobe_saved_eflags_prev;
|
|
static struct pt_regs jprobe_saved_regs;
|
|
static long *jprobe_saved_esp;
|
|
/* copy of the kernel stack at the probe fire time */
|
|
static kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE];
|
|
void jprobe_return_end(void);
|
|
|
|
/*
|
|
* returns non-zero if opcode modifies the interrupt flag.
|
|
*/
|
|
static inline int 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 arch_prepare_kprobe(struct kprobe *p)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
void arch_copy_kprobe(struct kprobe *p)
|
|
{
|
|
memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
|
|
p->opcode = *p->addr;
|
|
}
|
|
|
|
void arch_arm_kprobe(struct kprobe *p)
|
|
{
|
|
*p->addr = BREAKPOINT_INSTRUCTION;
|
|
flush_icache_range((unsigned long) p->addr,
|
|
(unsigned long) p->addr + sizeof(kprobe_opcode_t));
|
|
}
|
|
|
|
void arch_disarm_kprobe(struct kprobe *p)
|
|
{
|
|
*p->addr = p->opcode;
|
|
flush_icache_range((unsigned long) p->addr,
|
|
(unsigned long) p->addr + sizeof(kprobe_opcode_t));
|
|
}
|
|
|
|
void arch_remove_kprobe(struct kprobe *p)
|
|
{
|
|
}
|
|
|
|
static inline void save_previous_kprobe(void)
|
|
{
|
|
kprobe_prev = current_kprobe;
|
|
kprobe_status_prev = kprobe_status;
|
|
kprobe_old_eflags_prev = kprobe_old_eflags;
|
|
kprobe_saved_eflags_prev = kprobe_saved_eflags;
|
|
}
|
|
|
|
static inline void restore_previous_kprobe(void)
|
|
{
|
|
current_kprobe = kprobe_prev;
|
|
kprobe_status = kprobe_status_prev;
|
|
kprobe_old_eflags = kprobe_old_eflags_prev;
|
|
kprobe_saved_eflags = kprobe_saved_eflags_prev;
|
|
}
|
|
|
|
static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
current_kprobe = p;
|
|
kprobe_saved_eflags = kprobe_old_eflags
|
|
= (regs->eflags & (TF_MASK | IF_MASK));
|
|
if (is_IF_modifier(p->opcode))
|
|
kprobe_saved_eflags &= ~IF_MASK;
|
|
}
|
|
|
|
static inline void 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;
|
|
}
|
|
|
|
struct task_struct *arch_get_kprobe_task(void *ptr)
|
|
{
|
|
return ((struct thread_info *) (((unsigned long) ptr) &
|
|
(~(THREAD_SIZE -1))))->task;
|
|
}
|
|
|
|
void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs)
|
|
{
|
|
unsigned long *sara = (unsigned long *)®s->esp;
|
|
struct kretprobe_instance *ri;
|
|
static void *orig_ret_addr;
|
|
|
|
/*
|
|
* Save the return address when the return probe hits
|
|
* the first time, and use it to populate the (krprobe
|
|
* instance)->ret_addr for subsequent return probes at
|
|
* the same addrress since stack address would have
|
|
* the kretprobe_trampoline by then.
|
|
*/
|
|
if (((void*) *sara) != kretprobe_trampoline)
|
|
orig_ret_addr = (void*) *sara;
|
|
|
|
if ((ri = get_free_rp_inst(rp)) != NULL) {
|
|
ri->rp = rp;
|
|
ri->stack_addr = sara;
|
|
ri->ret_addr = orig_ret_addr;
|
|
add_rp_inst(ri);
|
|
/* Replace the return addr with trampoline addr */
|
|
*sara = (unsigned long) &kretprobe_trampoline;
|
|
} else {
|
|
rp->nmissed++;
|
|
}
|
|
}
|
|
|
|
void arch_kprobe_flush_task(struct task_struct *tk)
|
|
{
|
|
struct kretprobe_instance *ri;
|
|
while ((ri = get_rp_inst_tsk(tk)) != NULL) {
|
|
*((unsigned long *)(ri->stack_addr)) =
|
|
(unsigned long) ri->ret_addr;
|
|
recycle_rp_inst(ri);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Interrupts are disabled on entry as trap3 is an interrupt gate and they
|
|
* remain disabled thorough out this function.
|
|
*/
|
|
static int kprobe_handler(struct pt_regs *regs)
|
|
{
|
|
struct kprobe *p;
|
|
int ret = 0;
|
|
kprobe_opcode_t *addr = NULL;
|
|
unsigned long *lp;
|
|
|
|
/* We're in an interrupt, but this is clear and BUG()-safe. */
|
|
preempt_disable();
|
|
/* Check if the application is using LDT entry for its code segment and
|
|
* calculate the address by reading the base address from the LDT entry.
|
|
*/
|
|
if ((regs->xcs & 4) && (current->mm)) {
|
|
lp = (unsigned long *) ((unsigned long)((regs->xcs >> 3) * 8)
|
|
+ (char *) current->mm->context.ldt);
|
|
addr = (kprobe_opcode_t *) (get_desc_base(lp) + regs->eip -
|
|
sizeof(kprobe_opcode_t));
|
|
} else {
|
|
addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
|
|
}
|
|
/* Check we're not actually recursing */
|
|
if (kprobe_running()) {
|
|
/* We *are* holding lock here, so this is safe.
|
|
Disarm the probe we just hit, and ignore it. */
|
|
p = get_kprobe(addr);
|
|
if (p) {
|
|
if (kprobe_status == KPROBE_HIT_SS) {
|
|
regs->eflags &= ~TF_MASK;
|
|
regs->eflags |= kprobe_saved_eflags;
|
|
unlock_kprobes();
|
|
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();
|
|
set_current_kprobe(p, regs);
|
|
p->nmissed++;
|
|
prepare_singlestep(p, regs);
|
|
kprobe_status = KPROBE_REENTER;
|
|
return 1;
|
|
} else {
|
|
p = current_kprobe;
|
|
if (p->break_handler && p->break_handler(p, regs)) {
|
|
goto ss_probe;
|
|
}
|
|
}
|
|
/* If it's not ours, can't be delete race, (we hold lock). */
|
|
goto no_kprobe;
|
|
}
|
|
|
|
lock_kprobes();
|
|
p = get_kprobe(addr);
|
|
if (!p) {
|
|
unlock_kprobes();
|
|
if (regs->eflags & VM_MASK) {
|
|
/* We are in virtual-8086 mode. Return 0 */
|
|
goto no_kprobe;
|
|
}
|
|
|
|
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.
|
|
*/
|
|
ret = 1;
|
|
}
|
|
/* Not one of ours: let kernel handle it */
|
|
goto no_kprobe;
|
|
}
|
|
|
|
kprobe_status = KPROBE_HIT_ACTIVE;
|
|
set_current_kprobe(p, regs);
|
|
|
|
if (p->pre_handler && p->pre_handler(p, regs))
|
|
/* handler has already set things up, so skip ss setup */
|
|
return 1;
|
|
|
|
ss_probe:
|
|
prepare_singlestep(p, regs);
|
|
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 kretprobe_trampoline_holder(void)
|
|
{
|
|
asm volatile ( ".global kretprobe_trampoline\n"
|
|
"kretprobe_trampoline: \n"
|
|
"nop\n");
|
|
}
|
|
|
|
/*
|
|
* Called when we hit the probe point at kretprobe_trampoline
|
|
*/
|
|
int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
struct task_struct *tsk;
|
|
struct kretprobe_instance *ri;
|
|
struct hlist_head *head;
|
|
struct hlist_node *node;
|
|
unsigned long *sara = ((unsigned long *) ®s->esp) - 1;
|
|
|
|
tsk = arch_get_kprobe_task(sara);
|
|
head = kretprobe_inst_table_head(tsk);
|
|
|
|
hlist_for_each_entry(ri, node, head, hlist) {
|
|
if (ri->stack_addr == sara && ri->rp) {
|
|
if (ri->rp->handler)
|
|
ri->rp->handler(ri, regs);
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
void trampoline_post_handler(struct kprobe *p, struct pt_regs *regs,
|
|
unsigned long flags)
|
|
{
|
|
struct kretprobe_instance *ri;
|
|
/* RA already popped */
|
|
unsigned long *sara = ((unsigned long *)®s->esp) - 1;
|
|
|
|
while ((ri = get_rp_inst(sara))) {
|
|
regs->eip = (unsigned long)ri->ret_addr;
|
|
recycle_rp_inst(ri);
|
|
}
|
|
regs->eflags &= ~TF_MASK;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
static void resume_execution(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
unsigned long *tos = (unsigned long *)®s->esp;
|
|
unsigned long next_eip = 0;
|
|
unsigned long copy_eip = (unsigned long)&p->ainsn.insn;
|
|
unsigned long orig_eip = (unsigned long)p->addr;
|
|
|
|
switch (p->ainsn.insn[0]) {
|
|
case 0x9c: /* pushfl */
|
|
*tos &= ~(TF_MASK | IF_MASK);
|
|
*tos |= kprobe_old_eflags;
|
|
break;
|
|
case 0xc3: /* ret/lret */
|
|
case 0xcb:
|
|
case 0xc2:
|
|
case 0xca:
|
|
regs->eflags &= ~TF_MASK;
|
|
/* eip is already adjusted, no more changes required*/
|
|
return;
|
|
case 0xe8: /* call relative - Fix return addr */
|
|
*tos = orig_eip + (*tos - copy_eip);
|
|
break;
|
|
case 0xff:
|
|
if ((p->ainsn.insn[1] & 0x30) == 0x10) {
|
|
/* call absolute, indirect */
|
|
/* Fix return addr; eip is correct. */
|
|
next_eip = regs->eip;
|
|
*tos = orig_eip + (*tos - copy_eip);
|
|
} 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. */
|
|
next_eip = regs->eip;
|
|
}
|
|
break;
|
|
case 0xea: /* jmp absolute -- eip is correct */
|
|
next_eip = regs->eip;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
regs->eflags &= ~TF_MASK;
|
|
if (next_eip) {
|
|
regs->eip = next_eip;
|
|
} else {
|
|
regs->eip = orig_eip + (regs->eip - copy_eip);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Interrupts are disabled on entry as trap1 is an interrupt gate and they
|
|
* remain disabled thoroughout this function. And we hold kprobe lock.
|
|
*/
|
|
static inline int post_kprobe_handler(struct pt_regs *regs)
|
|
{
|
|
if (!kprobe_running())
|
|
return 0;
|
|
|
|
if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) {
|
|
kprobe_status = KPROBE_HIT_SSDONE;
|
|
current_kprobe->post_handler(current_kprobe, regs, 0);
|
|
}
|
|
|
|
if (current_kprobe->post_handler != trampoline_post_handler)
|
|
resume_execution(current_kprobe, regs);
|
|
regs->eflags |= kprobe_saved_eflags;
|
|
|
|
/*Restore back the original saved kprobes variables and continue. */
|
|
if (kprobe_status == KPROBE_REENTER) {
|
|
restore_previous_kprobe();
|
|
goto out;
|
|
}
|
|
unlock_kprobes();
|
|
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;
|
|
}
|
|
|
|
/* Interrupts disabled, kprobe_lock held. */
|
|
static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
|
|
{
|
|
if (current_kprobe->fault_handler
|
|
&& current_kprobe->fault_handler(current_kprobe, regs, trapnr))
|
|
return 1;
|
|
|
|
if (kprobe_status & KPROBE_HIT_SS) {
|
|
resume_execution(current_kprobe, regs);
|
|
regs->eflags |= kprobe_old_eflags;
|
|
|
|
unlock_kprobes();
|
|
preempt_enable_no_resched();
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Wrapper routine to for handling exceptions.
|
|
*/
|
|
int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
|
|
void *data)
|
|
{
|
|
struct die_args *args = (struct die_args *)data;
|
|
switch (val) {
|
|
case DIE_INT3:
|
|
if (kprobe_handler(args->regs))
|
|
return NOTIFY_STOP;
|
|
break;
|
|
case DIE_DEBUG:
|
|
if (post_kprobe_handler(args->regs))
|
|
return NOTIFY_STOP;
|
|
break;
|
|
case DIE_GPF:
|
|
if (kprobe_running() &&
|
|
kprobe_fault_handler(args->regs, args->trapnr))
|
|
return NOTIFY_STOP;
|
|
break;
|
|
case DIE_PAGE_FAULT:
|
|
if (kprobe_running() &&
|
|
kprobe_fault_handler(args->regs, args->trapnr))
|
|
return NOTIFY_STOP;
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
return NOTIFY_DONE;
|
|
}
|
|
|
|
int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
struct jprobe *jp = container_of(p, struct jprobe, kp);
|
|
unsigned long addr;
|
|
|
|
jprobe_saved_regs = *regs;
|
|
jprobe_saved_esp = ®s->esp;
|
|
addr = (unsigned long)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(jprobes_stack, (kprobe_opcode_t *) addr, MIN_STACK_SIZE(addr));
|
|
regs->eflags &= ~IF_MASK;
|
|
regs->eip = (unsigned long)(jp->entry);
|
|
return 1;
|
|
}
|
|
|
|
void jprobe_return(void)
|
|
{
|
|
preempt_enable_no_resched();
|
|
asm volatile (" xchgl %%ebx,%%esp \n"
|
|
" int3 \n"
|
|
" .globl jprobe_return_end \n"
|
|
" jprobe_return_end: \n"
|
|
" nop \n"::"b"
|
|
(jprobe_saved_esp):"memory");
|
|
}
|
|
|
|
int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
u8 *addr = (u8 *) (regs->eip - 1);
|
|
unsigned long stack_addr = (unsigned long)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 != jprobe_saved_esp) {
|
|
struct pt_regs *saved_regs =
|
|
container_of(jprobe_saved_esp, struct pt_regs, esp);
|
|
printk("current esp %p does not match saved esp %p\n",
|
|
®s->esp, jprobe_saved_esp);
|
|
printk("Saved registers for jprobe %p\n", jp);
|
|
show_registers(saved_regs);
|
|
printk("Current registers\n");
|
|
show_registers(regs);
|
|
BUG();
|
|
}
|
|
*regs = jprobe_saved_regs;
|
|
memcpy((kprobe_opcode_t *) stack_addr, jprobes_stack,
|
|
MIN_STACK_SIZE(stack_addr));
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|