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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
*/
#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;
}
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));
}
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));
}
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;
}
}
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)
{
__this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
kcb->kprobe_status = kcb->prev_kprobe.status;
}
static inline void __kprobes set_current_kprobe(struct kprobe *p)
{
__this_cpu_write(current_kprobe, p);
}
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;
}
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));
}
}
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 means user handler setup registers to exit
* to another instruction, we must skip the single stepping.
*/
if (!p->pre_handler || !p->pre_handler(p, regs)) {
setup_singlestep(p, regs);
kcb->kprobe_status = KPROBE_HIT_SS;
} else {
reset_current_kprobe();
preempt_enable_no_resched();
}
return 1;
}
/* no_kprobe: */
preempt_enable_no_resched();
return 0;
}
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;
}
/*
* 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 ke
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