453 lines
11 KiB
C
453 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Kernel probes (kprobes) for SuperH
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*
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* Copyright (C) 2007 Chris Smith <chris.smith@st.com>
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* Copyright (C) 2006 Lineo Solutions, Inc.
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*/
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#include <linux/kprobes.h>
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#include <linux/extable.h>
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#include <linux/ptrace.h>
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#include <linux/preempt.h>
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#include <linux/kdebug.h>
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#include <linux/slab.h>
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#include <asm/cacheflush.h>
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#include <linux/uaccess.h>
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DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
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DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
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static DEFINE_PER_CPU(struct kprobe, saved_current_opcode);
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static DEFINE_PER_CPU(struct kprobe, saved_next_opcode);
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static DEFINE_PER_CPU(struct kprobe, saved_next_opcode2);
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#define OPCODE_JMP(x) (((x) & 0xF0FF) == 0x402b)
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#define OPCODE_JSR(x) (((x) & 0xF0FF) == 0x400b)
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#define OPCODE_BRA(x) (((x) & 0xF000) == 0xa000)
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#define OPCODE_BRAF(x) (((x) & 0xF0FF) == 0x0023)
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#define OPCODE_BSR(x) (((x) & 0xF000) == 0xb000)
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#define OPCODE_BSRF(x) (((x) & 0xF0FF) == 0x0003)
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#define OPCODE_BF_S(x) (((x) & 0xFF00) == 0x8f00)
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#define OPCODE_BT_S(x) (((x) & 0xFF00) == 0x8d00)
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#define OPCODE_BF(x) (((x) & 0xFF00) == 0x8b00)
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#define OPCODE_BT(x) (((x) & 0xFF00) == 0x8900)
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#define OPCODE_RTS(x) (((x) & 0x000F) == 0x000b)
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#define OPCODE_RTE(x) (((x) & 0xFFFF) == 0x002b)
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int __kprobes arch_prepare_kprobe(struct kprobe *p)
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{
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kprobe_opcode_t opcode = *(kprobe_opcode_t *) (p->addr);
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if (OPCODE_RTE(opcode))
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return -EFAULT; /* Bad breakpoint */
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p->opcode = opcode;
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return 0;
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}
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void __kprobes arch_copy_kprobe(struct kprobe *p)
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{
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memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
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p->opcode = *p->addr;
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}
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void __kprobes arch_arm_kprobe(struct kprobe *p)
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{
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*p->addr = BREAKPOINT_INSTRUCTION;
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flush_icache_range((unsigned long)p->addr,
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(unsigned long)p->addr + sizeof(kprobe_opcode_t));
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}
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void __kprobes arch_disarm_kprobe(struct kprobe *p)
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{
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*p->addr = p->opcode;
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flush_icache_range((unsigned long)p->addr,
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(unsigned long)p->addr + sizeof(kprobe_opcode_t));
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}
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int __kprobes arch_trampoline_kprobe(struct kprobe *p)
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{
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if (*p->addr == BREAKPOINT_INSTRUCTION)
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return 1;
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return 0;
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}
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/**
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* If an illegal slot instruction exception occurs for an address
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* containing a kprobe, remove the probe.
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*
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* Returns 0 if the exception was handled successfully, 1 otherwise.
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*/
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int __kprobes kprobe_handle_illslot(unsigned long pc)
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{
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struct kprobe *p = get_kprobe((kprobe_opcode_t *) pc + 1);
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if (p != NULL) {
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printk("Warning: removing kprobe from delay slot: 0x%.8x\n",
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(unsigned int)pc + 2);
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unregister_kprobe(p);
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return 0;
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}
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return 1;
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}
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void __kprobes arch_remove_kprobe(struct kprobe *p)
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{
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struct kprobe *saved = this_cpu_ptr(&saved_next_opcode);
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if (saved->addr) {
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arch_disarm_kprobe(p);
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arch_disarm_kprobe(saved);
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saved->addr = NULL;
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saved->opcode = 0;
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saved = this_cpu_ptr(&saved_next_opcode2);
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if (saved->addr) {
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arch_disarm_kprobe(saved);
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saved->addr = NULL;
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saved->opcode = 0;
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}
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}
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}
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static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
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{
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kcb->prev_kprobe.kp = kprobe_running();
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kcb->prev_kprobe.status = kcb->kprobe_status;
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}
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static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
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{
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__this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
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kcb->kprobe_status = kcb->prev_kprobe.status;
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}
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static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
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struct kprobe_ctlblk *kcb)
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{
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__this_cpu_write(current_kprobe, p);
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}
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/*
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* Singlestep is implemented by disabling the current kprobe and setting one
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* on the next instruction, following branches. Two probes are set if the
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* branch is conditional.
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*/
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static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
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{
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__this_cpu_write(saved_current_opcode.addr, (kprobe_opcode_t *)regs->pc);
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if (p != NULL) {
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struct kprobe *op1, *op2;
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arch_disarm_kprobe(p);
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op1 = this_cpu_ptr(&saved_next_opcode);
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op2 = this_cpu_ptr(&saved_next_opcode2);
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if (OPCODE_JSR(p->opcode) || OPCODE_JMP(p->opcode)) {
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unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
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op1->addr = (kprobe_opcode_t *) regs->regs[reg_nr];
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} else if (OPCODE_BRA(p->opcode) || OPCODE_BSR(p->opcode)) {
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unsigned long disp = (p->opcode & 0x0FFF);
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op1->addr =
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(kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
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} else if (OPCODE_BRAF(p->opcode) || OPCODE_BSRF(p->opcode)) {
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unsigned int reg_nr = ((p->opcode >> 8) & 0x000F);
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op1->addr =
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(kprobe_opcode_t *) (regs->pc + 4 +
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regs->regs[reg_nr]);
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} else if (OPCODE_RTS(p->opcode)) {
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op1->addr = (kprobe_opcode_t *) regs->pr;
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} else if (OPCODE_BF(p->opcode) || OPCODE_BT(p->opcode)) {
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unsigned long disp = (p->opcode & 0x00FF);
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/* case 1 */
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op1->addr = p->addr + 1;
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/* case 2 */
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op2->addr =
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(kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
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op2->opcode = *(op2->addr);
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arch_arm_kprobe(op2);
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} else if (OPCODE_BF_S(p->opcode) || OPCODE_BT_S(p->opcode)) {
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unsigned long disp = (p->opcode & 0x00FF);
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/* case 1 */
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op1->addr = p->addr + 2;
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/* case 2 */
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op2->addr =
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(kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
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op2->opcode = *(op2->addr);
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arch_arm_kprobe(op2);
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} else {
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op1->addr = p->addr + 1;
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}
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op1->opcode = *(op1->addr);
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arch_arm_kprobe(op1);
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}
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}
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/* Called with kretprobe_lock held */
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void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
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struct pt_regs *regs)
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{
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ri->ret_addr = (kprobe_opcode_t *) regs->pr;
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ri->fp = NULL;
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/* Replace the return addr with trampoline addr */
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regs->pr = (unsigned long)__kretprobe_trampoline;
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}
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static int __kprobes kprobe_handler(struct pt_regs *regs)
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{
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struct kprobe *p;
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int ret = 0;
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kprobe_opcode_t *addr = NULL;
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struct kprobe_ctlblk *kcb;
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/*
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* We don't want to be preempted for the entire
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* duration of kprobe processing
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*/
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preempt_disable();
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kcb = get_kprobe_ctlblk();
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addr = (kprobe_opcode_t *) (regs->pc);
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/* Check we're not actually recursing */
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if (kprobe_running()) {
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p = get_kprobe(addr);
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if (p) {
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if (kcb->kprobe_status == KPROBE_HIT_SS &&
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*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
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goto no_kprobe;
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}
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/* We have reentered the kprobe_handler(), since
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* another probe was hit while within the handler.
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* We here save the original kprobes variables and
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* just single step on the instruction of the new probe
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* without calling any user handlers.
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*/
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save_previous_kprobe(kcb);
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set_current_kprobe(p, regs, kcb);
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kprobes_inc_nmissed_count(p);
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prepare_singlestep(p, regs);
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kcb->kprobe_status = KPROBE_REENTER;
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return 1;
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}
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goto no_kprobe;
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}
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p = get_kprobe(addr);
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if (!p) {
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/* Not one of ours: let kernel handle it */
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if (*(kprobe_opcode_t *)addr != BREAKPOINT_INSTRUCTION) {
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/*
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* The breakpoint instruction was removed right
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* after we hit it. Another cpu has removed
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* either a probepoint or a debugger breakpoint
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* at this address. In either case, no further
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* handling of this interrupt is appropriate.
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*/
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ret = 1;
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}
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goto no_kprobe;
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}
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set_current_kprobe(p, regs, kcb);
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kcb->kprobe_status = KPROBE_HIT_ACTIVE;
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if (p->pre_handler && p->pre_handler(p, regs)) {
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/* handler has already set things up, so skip ss setup */
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reset_current_kprobe();
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preempt_enable_no_resched();
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return 1;
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}
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prepare_singlestep(p, regs);
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kcb->kprobe_status = KPROBE_HIT_SS;
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return 1;
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no_kprobe:
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preempt_enable_no_resched();
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return ret;
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}
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/*
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* For function-return probes, init_kprobes() establishes a probepoint
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* here. When a retprobed function returns, this probe is hit and
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* trampoline_probe_handler() runs, calling the kretprobe's handler.
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*/
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static void __used kretprobe_trampoline_holder(void)
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{
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asm volatile (".globl __kretprobe_trampoline\n"
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"__kretprobe_trampoline:\n\t"
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"nop\n");
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}
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/*
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* Called when we hit the probe point at __kretprobe_trampoline
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*/
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int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
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{
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regs->pc = __kretprobe_trampoline_handler(regs, NULL);
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return 1;
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}
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static int __kprobes post_kprobe_handler(struct pt_regs *regs)
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{
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struct kprobe *cur = kprobe_running();
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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kprobe_opcode_t *addr = NULL;
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struct kprobe *p = NULL;
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if (!cur)
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return 0;
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if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
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kcb->kprobe_status = KPROBE_HIT_SSDONE;
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cur->post_handler(cur, regs, 0);
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}
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p = this_cpu_ptr(&saved_next_opcode);
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if (p->addr) {
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arch_disarm_kprobe(p);
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p->addr = NULL;
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p->opcode = 0;
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addr = __this_cpu_read(saved_current_opcode.addr);
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__this_cpu_write(saved_current_opcode.addr, NULL);
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p = get_kprobe(addr);
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arch_arm_kprobe(p);
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p = this_cpu_ptr(&saved_next_opcode2);
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if (p->addr) {
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arch_disarm_kprobe(p);
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p->addr = NULL;
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p->opcode = 0;
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}
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}
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/* Restore back the original saved kprobes variables and continue. */
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if (kcb->kprobe_status == KPROBE_REENTER) {
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restore_previous_kprobe(kcb);
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goto out;
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}
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reset_current_kprobe();
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out:
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preempt_enable_no_resched();
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return 1;
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}
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int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
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{
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struct kprobe *cur = kprobe_running();
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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const struct exception_table_entry *entry;
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switch (kcb->kprobe_status) {
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case KPROBE_HIT_SS:
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case KPROBE_REENTER:
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/*
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* We are here because the instruction being single
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* stepped caused a page fault. We reset the current
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* kprobe, point the pc back to the probe address
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* and allow the page fault handler to continue as a
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* normal page fault.
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*/
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regs->pc = (unsigned long)cur->addr;
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if (kcb->kprobe_status == KPROBE_REENTER)
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restore_previous_kprobe(kcb);
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else
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reset_current_kprobe();
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preempt_enable_no_resched();
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break;
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case KPROBE_HIT_ACTIVE:
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case KPROBE_HIT_SSDONE:
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/*
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* In case the user-specified fault handler returned
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* zero, try to fix up.
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*/
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if ((entry = search_exception_tables(regs->pc)) != NULL) {
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regs->pc = entry->fixup;
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return 1;
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}
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/*
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* fixup_exception() could not handle it,
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* Let do_page_fault() fix it.
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*/
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break;
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default:
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break;
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}
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return 0;
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}
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/*
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* Wrapper routine to for handling exceptions.
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*/
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int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
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unsigned long val, void *data)
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{
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struct kprobe *p = NULL;
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struct die_args *args = (struct die_args *)data;
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int ret = NOTIFY_DONE;
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kprobe_opcode_t *addr = NULL;
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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addr = (kprobe_opcode_t *) (args->regs->pc);
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if (val == DIE_TRAP &&
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args->trapnr == (BREAKPOINT_INSTRUCTION & 0xff)) {
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if (!kprobe_running()) {
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if (kprobe_handler(args->regs)) {
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ret = NOTIFY_STOP;
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} else {
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/* Not a kprobe trap */
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ret = NOTIFY_DONE;
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}
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} else {
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p = get_kprobe(addr);
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if ((kcb->kprobe_status == KPROBE_HIT_SS) ||
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(kcb->kprobe_status == KPROBE_REENTER)) {
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if (post_kprobe_handler(args->regs))
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ret = NOTIFY_STOP;
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} else {
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if (kprobe_handler(args->regs))
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ret = NOTIFY_STOP;
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}
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}
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}
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return ret;
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}
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static struct kprobe trampoline_p = {
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.addr = (kprobe_opcode_t *)&__kretprobe_trampoline,
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.pre_handler = trampoline_probe_handler
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};
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int __init arch_init_kprobes(void)
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{
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return register_kprobe(&trampoline_p);
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}
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