- 根目录:
- arch
- tile
- kernel
- kprobes.c
/*
* arch/tile/kernel/kprobes.c
* Kprobes on TILE-Gx
*
* Some portions copied from the MIPS version.
*
* Copyright (C) IBM Corporation, 2002, 2004
* Copyright 2006 Sony Corp.
* Copyright 2010 Cavium Networks
*
* Copyright 2012 Tilera Corporation. All Rights Reserved.
*
* 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, version 2.
*
* 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, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*/
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <arch/opcode.h>
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
tile_bundle_bits breakpoint_insn = TILEGX_BPT_BUNDLE;
tile_bundle_bits breakpoint2_insn = TILEGX_BPT_BUNDLE | DIE_SSTEPBP;
/*
* Check whether instruction is branch or jump, or if executing it
* has different results depending on where it is executed (e.g. lnk).
*/
static int __kprobes insn_has_control(kprobe_opcode_t insn)
{
if (get_Mode(insn) != 0) { /* Y-format bundle */
if (get_Opcode_Y1(insn) != RRR_1_OPCODE_Y1 ||
get_RRROpcodeExtension_Y1(insn) != UNARY_RRR_1_OPCODE_Y1)
return 0;
switch (get_UnaryOpcodeExtension_Y1(insn)) {
case JALRP_UNARY_OPCODE_Y1:
case JALR_UNARY_OPCODE_Y1:
case JRP_UNARY_OPCODE_Y1:
case JR_UNARY_OPCODE_Y1:
case LNK_UNARY_OPCODE_Y1:
return 1;
default:
return 0;
}
}
switch (get_Opcode_X1(insn)) {
case BRANCH_OPCODE_X1: /* branch instructions */
case JUMP_OPCODE_X1: /* jump instructions: j and jal */
return 1;
case RRR_0_OPCODE_X1: /* other jump instructions */
if (get_RRROpcodeExtension_X1(insn) != UNARY_RRR_0_OPCODE_X1)
return 0;
switch (get_UnaryOpcodeExtension_X1(insn)) {
case JALRP_UNARY_OPCODE_X1:
case JALR_UNARY_OPCODE_X1:
case JRP_UNARY_OPCODE_X1:
case JR_UNARY_OPCODE_X1:
case LNK_UNARY_OPCODE_X1:
return 1;
default:
return 0;
}
default:
return 0;
}
}
int __kprobes arch_prepare_kprobe(struct kprobe *p)
{
unsigned long addr = (unsigned long)p->addr;
if (addr & (sizeof(kprobe_opcode_t) - 1))
return -EINVAL;
if (insn_has_control(*p->addr)) {
pr_notice("Kprobes for control instructions are not supported\n");
return -EINVAL;
}
/* insn: must be on special executable page on tile. */
p->ainsn.insn = get_insn_slot();
if (!p->ainsn.insn)
return -ENOMEM;
/*
* In the kprobe->ainsn.insn[] array we store the original
* instruction at index zero and a break trap instruction at
* index one.
*/
memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t));
p->ainsn.insn[1] = breakpoint2_insn;
p->opcode = *p->addr;
return 0;
}
void __kprobes arch_arm_kprobe(struct kprobe *p)
{
unsigned long addr_wr;
/* Operate on writable kernel text mapping. */
addr_wr = (unsigned long)p->addr - MEM_SV_START + PAGE_OFFSET;
if (probe_kernel_write((void *)addr_wr, &breakpoint_insn,
sizeof(breakpoint_insn)))
pr_err("%s: failed to enable kprobe\n", __func__);
smp_wmb();
flush_insn_slot(p);
}
void __kprobes arch_disarm_kprobe(struct kprobe *kp)
{
unsigned long addr_wr;
/* Operate on writable kernel text mapping. */
addr_wr = (unsigned long)kp->addr - MEM_SV_START + PAGE_OFFSET;
if (probe_kernel_write((void *)addr_wr, &kp->opcode,
sizeof(kp->opcode)))
pr_err("%s: failed to enable kprobe\n", __func__);
smp_wmb();
flush_insn_slot(kp);
}
void __kprobes arch_remove_kprobe(struct kprobe *p)
{
if (p->ainsn.insn) {
free_insn_slot(p->ainsn.insn, 0);
p->ainsn.insn = NULL;
}
}
static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
{
kcb->prev_kprobe.kp = kprobe_running();
kcb->prev_kprobe.status = kcb->kprobe_status;
kcb->prev_kprobe.saved_pc = kcb->kprobe_saved_pc;
}
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;
kcb->kprobe_saved_pc = kcb->prev_kprobe.saved_pc;
}
static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
struct kprobe_ctlblk *kcb)
{
__this_cpu_write(current_kprobe, p);
kcb->kprobe_saved_pc = regs->pc;
}
static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
{
/* Single step inline if the instruction is a break. */
if (p->opcode == breakpoint_insn ||
p->opcode == breakpoint2_insn)
regs->pc = (unsigned long)p->addr;
else
regs->pc = (unsigned long)&p->ainsn.insn[0];
}
static int __kprobes kprobe_handler(struct pt_regs *regs)
{
struct kprobe *p;
int ret = 0;
kprobe_opcode_t *addr;
struct kprobe_ctlblk *kcb;
addr = (kprobe_opcode_t *)regs->pc;
/*
* We don't want to be preempted for the entire
* duration of kprobe processing.
*/
preempt_disable();
kcb = get_kprobe_ctlblk();
/* 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[0] == breakpoint_insn) {
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 {
if (*addr != breakpoint_insn) {
/*
* The breakpoint instruction was removed by
* another cpu right after we hit, no further
* handling of this interrupt is appropriate.
*/
ret = 1;
goto no_kprobe;
}
p = __this_cpu_read(current_kprobe);
if (p->break_handler && p->break_handler(p, regs))
goto ss_probe;
}
goto no_kprobe;
}
p = get_kprobe(addr);
if (!p) {
if (*addr != breakpoint_insn) {
/*
* 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;
}
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;
}
/*
* Called after single-stepping. p->addr is the address of the
* instruction that has been replaced by the breakpoint. 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
* breakpoint trap.
*/
static void __kprobes resume_execution(struct kprobe *p,
struct pt_regs *regs,
struct kprobe_ctlblk *kcb)
{
unsigned long orig_pc = kcb->kprobe_saved_pc;
regs->pc = orig_pc + 8;
}
static inline int post_kprobe_handler(struct pt_regs *regs)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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);
}
resume_execution(cur, regs, kcb);
/* 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;
}
static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
{
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
return 1;
if (kcb->kprobe_status & KPROBE_HIT_SS) {
/*
* We are here because the instruction being single
* stepped caused a page fault. We reset the current
* kprobe and the ip points back to the probe address
* and allow the page fault handler to continue as a
* normal page fault.
*/
resume_execution(cur, regs, kcb);
reset_current_kprobe();
preempt_enable_no_resched();
}
return 0;
}
/*
* Wrapper routine for handling exceptions.
*/
int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data)
{
struct die_args *args = (struct die_args *)data;
int ret = NOTIFY_DONE;
switch (val) {
case DIE_BREAK:
if (kprobe_handler(args->regs))
ret = NOTIFY_STOP;
break;
case DIE_SSTEPBP:
if (post_kprobe_handler(args->regs))
ret = NOTIFY_STOP;
break;
case DIE_PAGE_FAULT:
/* kprobe_running() needs smp_processor_id(). */
preempt_disable();
if (kprobe_running()
&& kprobe_fault_handler(args->regs, args->trapnr))
ret = NOTIFY_STOP;
preempt_enable();
break;
default:
break;
}
return ret;
}
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();
kcb->jprobe_saved_regs = *regs;
kcb->jprobe_saved_sp = regs->sp;
memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp,
MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
regs->pc = (unsigned long)(jp->entry);
return 1;
}
/* Defined in the inline asm below. */
void jprobe_return_end(void);
void __kprobes jprobe_return(void)
{
asm volatile(
"bpt\n\t"
".globl jprobe_return_end\n"
"jprobe_return_end:\n");
}
int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
if (regs->pc >= (unsigned long)jprobe_return &&
regs->pc <= (unsigned long)jprobe_return_end) {
*regs = kcb->jprobe_saved_regs;
memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack,
MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
preempt_enable_no_resched();
return 1;
}
return 0;
}
/*
* Function return probe trampoline:
* - init_kprobes() establishes a probepoint here
* - When the probed function returns, this probe causes the
* handlers to fire
*/
static void __used kretprobe_trampoline_holder(void)
{
asm volatile(
"nop\n\t"
".global kretprobe_trampoline\n"
"kretprobe_trampoline:\n\t"
"nop\n\t"
: : : "memory");
}
void kretprobe_trampoline(void);
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
struct pt_regs *regs)
{
ri->ret_addr = (kprobe_opcode_t *) regs->lr;
/* Replace the return addr with trampoline addr */
regs->lr = (unsigned long)kretprobe_trampoline;
}
/*
* Called when the probe at kretprobe trampoline is hit.
*/
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 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);
instruction_pointer(regs) = 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
* kprobe_handler() that we don't want the post_handler
* to run (and have re-enabled preemption)
*/
return 1;
}
int __kprobes arch_trampoline_kprobe(struct kprobe *p)
{
if (p->addr == (kprobe_opcode_t *)kretprobe_trampoline)
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)
{
register_kprobe(&trampoline_p);
return 0;
}