/*
* Kernel probes (kprobes) for SuperH
*
* Copyright (C) 2007 Chris Smith <chris.smith@st.com>
* Copyright (C) 2006 Lineo Solutions, Inc.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/kprobes.h>
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/preempt.h>
#include <linux/kdebug.h>
#include <linux/slab.h>
#include <asm/cacheflush.h>
#include <asm/uaccess.h>
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
static struct kprobe saved_current_opcode;
static struct kprobe saved_next_opcode;
static struct kprobe saved_next_opcode2;
#define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b)
#define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b)
#define OPCODE_BRA(x) (((x) & 0xF000) == 0xa000)
#define OPCODE_BRAF(x) (((x) & 0xF0FF) == 0x0023)
#define OPCODE_BSR(x) (((x) & 0xF000) == 0xb000)
#define OPCODE_BSRF(x) (((x) & 0xF0FF) == 0x0003)
#define OPCODE_BF_S(x) (((x) & 0xFF00) == 0x8f00)
#define OPCODE_BT_S(x) (((x) & 0xFF00) == 0x8d00)
#define OPCODE_BF(x) (((x) & 0xFF00) == 0x8b00)
#define OPCODE_BT(x) (((x) & 0xFF00) == 0x8900)
#define OPCODE_RTS(x) (((x) & 0x000F) == 0x000b)
#define OPCODE_RTE(x) (((x) & 0xFFFF) == 0x002b)
int __kprobes arch_prepare_kprobe(struct kprobe *p)
{
kprobe_opcode_t opcode = *(kprobe_opcode_t *) (p->addr);
if (OPCODE_RTE(opcode))
return -EFAULT; /* Bad breakpoint */
p->opcode = opcode;
return 0;
}
void __kprobes arch_copy_kprobe(struct kprobe *p)
{
memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
p->opcode = *p->addr;
}
void __kprobes 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 __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));
}
int __kprobes arch_trampoline_kprobe(struct kprobe *p)
{
if (*p->addr == BREAKPOINT_INSTRUCTION)
return 1;
return 0;
}
/**
* If an illegal slot instruction exception occurs for an address
* containing a kprobe, remove the probe.
*
* Returns 0 if the exception was handled successfully, 1 otherwise.
*/
int __kprobes kprobe_handle_illslot(unsigned long pc)
{
struct kprobe *p = get_kprobe((kprobe_opcode_t *) pc + 1);
if (p != NULL) {
printk("Warning: removing kprobe from delay slot: 0x%.8x\n",
(unsigned int)pc + 2);
unregister_kprobe(p);
return 0;
}
return 1;
}
void __kprobes arch_remove_kprobe(struct kprobe *p)
{
if (saved_next_opcode.addr != 0x0) {
arch_disarm_kprobe(p);
arch_disarm_kprobe(&saved_next_opcode);
saved_next_opcode.addr = 0x0;
saved_next_opcode.opcode = 0x0;
if (saved_next_opcode2.addr != 0x0) {
arch_disarm_kprobe(&saved_next_opcode2);
saved_next_opcode2.addr = 0x0;
saved_next_opcode2.opcode = 0x0;
}
}
}
static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
{
kcb->prev_kprobe.kp = kprobe_running();
kcb->prev_kprobe.status = kcb->kprobe_status;
}
static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
{
__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
kcb->kprobe_status = kcb->prev_kprobe.status;
}
static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
struct kprobe_ctlblk *kcb)
{
__get_cpu_var(current_kprobe) = p;
}
/*
* Singlestep is implemented by disabling the current kprobe and setting one
* on the next instruction, following branches. Two probes are set if the
* branch is conditional.
*/
static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
kprobe_opcode_t *addr = NULL;
saved_current_opcode.addr = (kprobe_opcode_t *) (regs->pc);
addr = saved_current_opcode.addr;
if (p != NULL) {
arch_disarm_kprobe(p);
if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) {
unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
saved_next_opcode.addr =
(kprobe_opcode_t *) regs->regs[reg_nr];
} else if (OPCODE_BRA(p->opcode) || OPCODE_BSR(p->opcode)) {
unsigned long disp = (p->opcode & 0x0FFF);
saved_next_opcode.addr =
(kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
} else if (OPCODE_BRAF(p->opcode) || OPCODE_BSRF(p->opcode)) {
unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
saved_next_opcode.addr =
(kprobe_opcode_t *) (regs->pc + 4 +
regs->regs[reg_nr]);
} else if (OPCODE_RTS(p->opcode)) {
saved_next_opcode.addr = (kprobe_opcode_t *) regs->pr;
} else if (OPCODE_BF(p->opcode) || OPCODE_BT(p->opcode)) {
unsigned long disp = (p->opcode & 0x00FF);
/* case 1 */
saved_next_opcode.addr = p->addr + 1;
/* case 2 */
saved_next_opcode2.addr =
(kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
arch_arm_kprobe(&saved_next_opcode2);
} else if (OPCODE_BF_S(p->opcode) || OPCODE_BT_S(p->opcode)) {
unsigned long disp = (p->opcode & 0x00FF);
/* case 1 */
saved_next_opcode.addr = p->addr + 2;
/* case 2 */
saved_next_opcode2.addr =
(kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
arch_arm_kprobe(&saved_next_opcode2);
} else {
saved_next_opcode.addr = p->addr + 1;
}
saved_next_opcode.opcode = *(saved_next_opcode.addr);
arch_arm_kprobe(&saved_next_opcode);
}
}
/* Called with kretprobe_lock held */
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
ri->ret_addr = (kprobe_opcode_t *) regs->pr;
/* Replace the return addr with trampoline addr */
regs->pr = (unsigned long)kretprobe_trampoline;
}
static int __kprobes kprobe_handler(struct pt_regs *regs)
{
struct kprobe *p;
int ret = 0;
kprobe_opcode_t *addr = NULL;
struct kprobe_ctlblk *kcb;
/*
* We don't want to be preempted for the entire
* duration of kprobe processing
*/
preempt_disable();
kcb = get_kprobe_ctlblk();
addr = (kprobe_opcode_t *) (regs->pc);
/* Check we're not actually recursing */
if (kprobe_running()) {
p = get_kprobe(addr);
if (p) {
if (kcb->kprobe_status == KPROBE_HIT_SS &&
*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
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(kcb);
set_current_kprobe(p, regs, kcb);
kprobes_inc_nmissed_count(p);
prepare_singlestep(p, regs);
kcb->kprobe_status = KPROBE_REENTER;
return 1;
} else {
p = __get_cpu_var(current_kprobe);
if (p->break_handler && p->break_handler(p, regs)) {
goto ss_probe;
}
}
goto no_kprobe;
}
p = get_kprobe(addr);
if (!p) {
/* Not one of ours: let kernel handle it */
if (*(kprobe_opcode_t *)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;
}
goto no_kprobe;
}
set_current_kprobe(p, regs, kcb);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
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);
kcb->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.
*/
static void __used kretprobe_trampoline_holder(void)
{
asm volatile (".globl kretprobe_trampoline\n"
"kretprobe_trampoline:\n\t"
"nop\n");
}
/*
* Called when we hit the probe point at kretprobe_trampoline
*/
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 *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 then 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, node, tmp, head, hlist) {
if (ri->task != current)
/* another task is sharing our hash bucket */
continue;
if (ri->rp && ri->rp->handler) {
__get_cpu_var(current_kprobe) = &ri->rp->kp;
ri->rp->handler(ri, regs);
__get_cpu_var(current_kprobe) = NULL;
}
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->pc = orig_ret_address;
kretprobe_hash_unlock(current, &flags);
preempt_enable_no_resched();
hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
hlist_del(&ri->hlist);
kfree(ri);
}
return orig_ret_address;
}
static int __kprobes post_kprobe_handler(struct pt_regs *regs)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
kprobe_opcode_t *addr = NULL;
struct kprobe *p = NULL;
if (!cur)
return 0;
if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
kcb->kprobe_status = KPROBE_HIT_SSDONE;
cur->post_handler(cur, regs, 0);
}
if (saved_next_opcode.addr != 0x0) {
arch_disarm_kprobe(&saved_next_opcode);
saved_next_opcode.addr = 0x0;
saved_next_opcode.opcode = 0x0;
addr = saved_current_opcode.addr;
saved_current_opcode.addr = 0x0;
p = get_kprobe(addr);
arch_arm_kprobe(p);
if (saved_next_opcode2.addr != 0x0) {
arch_disarm_kprobe(&saved_next_opcode2);
saved_next_opcode2.addr = 0x0;
saved_next_opcode2.opcode = 0x0;
}
}
/* Restore back the original saved kprobes variables and continue. */
if (kcb->kprobe_status == KPROBE_REENTER) {
restore_previous_kprobe(kcb);
goto out;
}
reset_current_kprobe();
out:
preempt_enable_no_resched();
return 1;
}
int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
const struct exception_table_entry *entry;
switch (kcb->kprobe_status) {
case KPROBE_HIT_SS:
case KPROBE_REENTER:
/*
* We are here because the instruction being single
* stepped caused a page fault. We reset the current
* kprobe, point the pc back to the probe address
* and allow the page fault handler to continue as a
* normal page fault.
*/
regs->pc = (unsigned long)cur->addr;
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 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 ((entry = search_exception_tables(regs->pc)) != NULL) {
regs->pc = entry->fixup;
return 1;
}
/*
* fixup_exception() could not handle it,
* Let do_page_fault() fix it.
*/
break;
default:
break;
}
return 0;
}
/*
* Wrapper routine to for handling exceptions.
*/
int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data)
{
struct kprobe *p = NULL;
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
kprobe_opcode_t *addr = NULL;
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
addr = (kprobe_opcode_t *) (args->regs->pc);
if (val == DIE_TRAP) {
if (!kprobe_running()) {
if (kprobe_handler(args->regs)) {
ret = NOTIFY_STOP;
} else {
/* Not a kprobe trap */
ret = NOTIFY_DONE;
}
} else {
p = get_kprobe(addr);
if ((kcb->kprobe_status == KPROBE_HIT_SS) ||
(kcb->kprobe_status == KPROBE_REENTER)) {
if (post_kprobe_handler(args->regs))
ret = NOTIFY_STOP;
} else {
if (kprobe_handler(args->regs)) {
ret = NOTIFY_STOP;
} else {
p = __get_cpu_var(current_kprobe);
if (p->break_handler &&
p->break_handler(p, args->regs))
ret = NOTIFY_STOP;
}
}
}
}
return ret;
}
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct jprobe *jp = container_of(p, struct jprobe, kp);
unsigned long addr;
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
kcb->jprobe_saved_regs = *regs;
kcb->jprobe_saved_r15 = regs->regs[15];
addr = kcb->jprobe_saved_r15;
/*
* 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(kcb->jprobes_stack, (kprobe_opcode_t *) addr,
MIN_STACK_SIZE(addr));
regs->pc = (unsigned long)(jp->entry);
return 1;
}
void __kprobes jprobe_return(void)
{
asm volatile ("trapa #0x3a\n\t" "jprobe_return_end:\n\t" "nop\n\t");
}
int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
unsigned long stack_addr = kcb->jprobe_saved_r15;
u8 *addr = (u8 *)regs->pc;
if ((addr >= (u8 *)jprobe_return) &&
(addr <= (u8 *)jprobe_return_end)) {
*regs = kcb->jprobe_saved_regs;
memcpy((kprobe_opcode_t *)stack_addr, kcb->jprobes_stack,
MIN_STACK_SIZE(stack_addr));
kcb->kprobe_status = KPROBE_HIT_SS;
preempt_enable_no_resched();
return 1;
}
return 0;
}
static struct kprobe trampoline_p = {
.addr = (kprobe_opcode_t *)&kretprobe_trampoline,
.pre_handler = trampoline_probe_handler
};
int __init arch_init_kprobes(void)
{
saved_next_opcode.addr = 0x0;
saved_next_opcode.opcode = 0x0;
saved_current_opcode.addr = 0x0;
saved_current_opcode.opcode = 0x0;
saved_next_opcode2.addr = 0x0;
saved_next_opcode2.opcode = 0x0;
return register_kprobe(&trampoline_p);
}
