Release 4.14 arch/arc/kernel/kprobes.c
/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/types.h>
#include <linux/kprobes.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/kdebug.h>
#include <linux/sched.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/current.h>
#include <asm/disasm.h>
#define MIN_STACK_SIZE(addr) min((unsigned long)MAX_STACK_SIZE, \
(unsigned long)current_thread_info() + THREAD_SIZE - (addr))
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
int __kprobes arch_prepare_kprobe(struct kprobe *p)
{
/* Attempt to probe at unaligned address */
if ((unsigned long)p->addr & 0x01)
return -EINVAL;
/* Address should not be in exception handling code */
p->ainsn.is_short = is_short_instr((unsigned long)p->addr);
p->opcode = *p->addr;
return 0;
}
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void __kprobes arch_arm_kprobe(struct kprobe *p)
{
*p->addr = UNIMP_S_INSTRUCTION;
flush_icache_range((unsigned long)p->addr,
(unsigned long)p->addr + sizeof(kprobe_opcode_t));
}
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void __kprobes 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));
}
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void __kprobes arch_remove_kprobe(struct kprobe *p)
{
arch_disarm_kprobe(p);
/* Can we remove the kprobe in the middle of kprobe handling? */
if (p->ainsn.t1_addr) {
*(p->ainsn.t1_addr) = p->ainsn.t1_opcode;
flush_icache_range((unsigned long)p->ainsn.t1_addr,
(unsigned long)p->ainsn.t1_addr +
sizeof(kprobe_opcode_t));
p->ainsn.t1_addr = NULL;
}
if (p->ainsn.t2_addr) {
*(p->ainsn.t2_addr) = p->ainsn.t2_opcode;
flush_icache_range((unsigned long)p->ainsn.t2_addr,
(unsigned long)p->ainsn.t2_addr +
sizeof(kprobe_opcode_t));
p->ainsn.t2_addr = NULL;
}
}
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static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
{
kcb->prev_kprobe.kp = kprobe_running();
kcb->prev_kprobe.status = kcb->kprobe_status;
}
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static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
{
__this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
kcb->kprobe_status = kcb->prev_kprobe.status;
}
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static inline void __kprobes set_current_kprobe(struct kprobe *p)
{
__this_cpu_write(current_kprobe, p);
}
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static void __kprobes resume_execution(struct kprobe *p, unsigned long addr,
struct pt_regs *regs)
{
/* Remove the trap instructions inserted for single step and
* restore the original instructions
*/
if (p->ainsn.t1_addr) {
*(p->ainsn.t1_addr) = p->ainsn.t1_opcode;
flush_icache_range((unsigned long)p->ainsn.t1_addr,
(unsigned long)p->ainsn.t1_addr +
sizeof(kprobe_opcode_t));
p->ainsn.t1_addr = NULL;
}
if (p->ainsn.t2_addr) {
*(p->ainsn.t2_addr) = p->ainsn.t2_opcode;
flush_icache_range((unsigned long)p->ainsn.t2_addr,
(unsigned long)p->ainsn.t2_addr +
sizeof(kprobe_opcode_t));
p->ainsn.t2_addr = NULL;
}
return;
}
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static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs)
{
unsigned long next_pc;
unsigned long tgt_if_br = 0;
int is_branch;
unsigned long bta;
/* Copy the opcode back to the kprobe location and execute the
* instruction. Because of this we will not be able to get into the
* same kprobe until this kprobe is done
*/
*(p->addr) = p->opcode;
flush_icache_range((unsigned long)p->addr,
(unsigned long)p->addr + sizeof(kprobe_opcode_t));
/* Now we insert the trap at the next location after this instruction to
* single step. If it is a branch we insert the trap at possible branch
* targets
*/
bta = regs->bta;
if (regs->status32 & 0x40) {
/* We are in a delay slot with the branch taken */
next_pc = bta & ~0x01;
if (!p->ainsn.is_short) {
if (bta & 0x01)
regs->blink += 2;
else {
/* Branch not taken */
next_pc += 2;
/* next pc is taken from bta after executing the
* delay slot instruction
*/
regs->bta += 2;
}
}
is_branch = 0;
} else
is_branch =
disasm_next_pc((unsigned long)p->addr, regs,
(struct callee_regs *) current->thread.callee_reg,
&next_pc, &tgt_if_br);
p->ainsn.t1_addr = (kprobe_opcode_t *) next_pc;
p->ainsn.t1_opcode = *(p->ainsn.t1_addr);
*(p->ainsn.t1_addr) = TRAP_S_2_INSTRUCTION;
flush_icache_range((unsigned long)p->ainsn.t1_addr,
(unsigned long)p->ainsn.t1_addr +
sizeof(kprobe_opcode_t));
if (is_branch) {
p->ainsn.t2_addr = (kprobe_opcode_t *) tgt_if_br;
p->ainsn.t2_opcode = *(p->ainsn.t2_addr);
*(p->ainsn.t2_addr) = TRAP_S_2_INSTRUCTION;
flush_icache_range((unsigned long)p->ainsn.t2_addr,
(unsigned long)p->ainsn.t2_addr +
sizeof(kprobe_opcode_t));
}
}
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int __kprobes arc_kprobe_handler(unsigned long addr, struct pt_regs *regs)
{
struct kprobe *p;
struct kprobe_ctlblk *kcb;
preempt_disable();
kcb = get_kprobe_ctlblk();
p = get_kprobe((unsigned long *)addr);
if (p) {
/*
* We have reentered the kprobe_handler, since another kprobe
* was hit while within the handler, we save the original
* kprobes and single step on the instruction of the new probe
* without calling any user handlers to avoid recursive
* kprobes.
*/
if (kprobe_running()) {
save_previous_kprobe(kcb);
set_current_kprobe(p);
kprobes_inc_nmissed_count(p);
setup_singlestep(p, regs);
kcb->kprobe_status = KPROBE_REENTER;
return 1;
}
set_current_kprobe(p);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
/* If we have no pre-handler or it returned 0, we continue with
* normal processing. If we have a pre-handler and it returned
* non-zero - which is expected from setjmp_pre_handler for
* jprobe, we return without single stepping and leave that to
* the break-handler which is invoked by a kprobe from
* jprobe_return
*/
if (!p->pre_handler || !p->pre_handler(p, regs)) {
setup_singlestep(p, regs);
kcb->kprobe_status = KPROBE_HIT_SS;
}
return 1;
} else if (kprobe_running()) {
p = __this_cpu_read(current_kprobe);
if (p->break_handler && p->break_handler(p, regs)) {
setup_singlestep(p, regs);
kcb->kprobe_status = KPROBE_HIT_SS;
return 1;
}
}
/* no_kprobe: */
preempt_enable_no_resched();
return 0;
}
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static int __kprobes arc_post_kprobe_handler(unsigned long addr,
struct pt_regs *regs)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
if (!cur)
return 0;
resume_execution(cur, addr, regs);
/* Rearm the kprobe */
arch_arm_kprobe(cur);
/*
* When we return from trap instruction we go to the next instruction
* We restored the actual instruction in resume_exectuiont and we to
* return to the same address and execute it
*/
regs->ret = addr;
if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
kcb->kprobe_status = KPROBE_HIT_SSDONE;
cur->post_handler(cur, regs, 0);
}
if (kcb->kprobe_status == KPROBE_REENTER) {
restore_previous_kprobe(kcb);
goto out;
}
reset_current_kprobe();
out:
preempt_enable_no_resched();
return 1;
}
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/*
* Fault can be for the instruction being single stepped or for the
* pre/post handlers in the module.
* This is applicable for applications like user probes, where we have the
* probe in user space and the handlers in the kernel
*/
int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned long trapnr)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
switch (kcb->kprobe_status) {
case KPROBE_HIT_SS:
case KPROBE_REENTER:
/*
* We are here because the instruction being single stepped
* caused the fault. We reset the current kprobe and allow the
* exception handler as if it is regular exception. In our
* case it doesn't matter because the system will be halted
*/
resume_execution(cur, (unsigned long)cur->addr, regs);
if (kcb->kprobe_status == KPROBE_REENTER)
restore_previous_kprobe(kcb);
else
reset_current_kprobe();
preempt_enable_no_resched();
break;
case KPROBE_HIT_ACTIVE:
case KPROBE_HIT_SSDONE:
/*
* We are here because the instructions in the pre/post handler
* caused the fault.
*/
/* We increment the nmissed count for accounting,
* we can also use npre/npostfault count for accounting
* these specific fault cases.
*/
kprobes_inc_nmissed_count(cur);
/*
* We come here because instructions in the pre/post
* handler caused the page_fault, this could happen
* if handler tries to access user space by
* copy_from_user(), get_user() etc. Let the
* user-specified handler try to fix it first.
*/
if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
return 1;
/*
* In case the user-specified fault handler returned zero,
* try to fix up.
*/
if (fixup_exception(regs))
return 1;
/*
* fixup_exception() could not handle it,
* Let do_page_fault() fix it.
*/
break;
default:
break;
}
return 0;
}
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int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data)
{
struct die_args *args = data;
unsigned long addr = args->err;
int ret = NOTIFY_DONE;
switch (val) {
case DIE_IERR:
if (arc_kprobe_handler(addr, args->regs))
return NOTIFY_STOP;
break;
case DIE_TRAP:
if (arc_post_kprobe_handler(addr, args->regs))
return NOTIFY_STOP;
break;
default:
break;
}
return ret;
}
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int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct jprobe *jp = container_of(p, struct jprobe, kp);
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
unsigned long sp_addr = regs->sp;
kcb->jprobe_saved_regs = *regs;
memcpy(kcb->jprobes_stack, (void *)sp_addr, MIN_STACK_SIZE(sp_addr));
regs->ret = (unsigned long)(jp->entry);
return 1;
}
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void __kprobes jprobe_return(void)
{
__asm__ __volatile__("unimp_s");
return;
}
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int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
unsigned long sp_addr;
*regs = kcb->jprobe_saved_regs;
sp_addr = regs->sp;
memcpy((void *)sp_addr, kcb->jprobes_stack, MIN_STACK_SIZE(sp_addr));
preempt_enable_no_resched();
return 1;
}
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static void __used kretprobe_trampoline_holder(void)
{
__asm__ __volatile__(".global kretprobe_trampoline\n"
"kretprobe_trampoline:\n" "nop\n");
}
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void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
ri->ret_addr = (kprobe_opcode_t *) regs->blink;
/* Replace the return addr with trampoline addr */
regs->blink = (unsigned long)&kretprobe_trampoline;
}
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static int __kprobes trampoline_probe_handler(struct kprobe *p,
struct pt_regs *regs)
{
struct kretprobe_instance *ri = NULL;
struct hlist_head *head, empty_rp;
struct hlist_node *tmp;
unsigned long flags, orig_ret_address = 0;
unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
INIT_HLIST_HEAD(&empty_rp);
kretprobe_hash_lock(current, &head, &flags);
/*
* It is possible to have multiple instances associated with a given
* task either because an multiple functions in the call path
* have a return probe installed on them, and/or more than one return
* return probe was registered for a target function.
*
* We can handle this because:
* - instances are always inserted at the head of the list
* - when multiple return probes are registered for the same
* function, the first instance's ret_addr will point to the
* real return address, and all the rest will point to
* kretprobe_trampoline
*/
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
if (ri->task != current)
/* another task is sharing our hash bucket */
continue;
if (ri->rp && ri->rp->handler)
ri->rp->handler(ri, regs);
orig_ret_address = (unsigned long)ri->ret_addr;
recycle_rp_inst(ri, &empty_rp);
if (orig_ret_address != trampoline_address) {
/*
* This is the real return address. Any other
* instances associated with this task are for
* other calls deeper on the call stack
*/
break;
}
}
kretprobe_assert(ri, orig_ret_address, trampoline_address);
regs->ret = orig_ret_address;
reset_current_kprobe();
kretprobe_hash_unlock(current, &flags);
preempt_enable_no_resched();
hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
hlist_del(&ri->hlist);
kfree(ri);
}
/* By returning a non zero value, we are telling the kprobe handler
* that we don't want the post_handler to run
*/
return 1;
}
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static struct kprobe trampoline_p = {
.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
.pre_handler = trampoline_probe_handler
};
int __init arch_init_kprobes(void)
{
/* Registering the trampoline code for the kret probe */
return register_kprobe(&trampoline_p);
}
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int __kprobes arch_trampoline_kprobe(struct kprobe *p)
{
if (p->addr == (kprobe_opcode_t *) &kretprobe_trampoline)
return 1;
return 0;
}
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void trap_is_kprobe(unsigned long address, struct pt_regs *regs)
{
notify_die(DIE_TRAP, "kprobe_trap", regs, address, 0, SIGTRAP);
}
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