2008-09-05 08:15:39 +00:00
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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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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/kprobes.h>
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#include <linux/module.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 <asm/cacheflush.h>
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#include <asm/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 struct kprobe saved_current_opcode;
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static struct kprobe saved_next_opcode;
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static 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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if (saved_next_opcode.addr != 0x0) {
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arch_disarm_kprobe(p);
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arch_disarm_kprobe(&saved_next_opcode);
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saved_next_opcode.addr = 0x0;
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saved_next_opcode.opcode = 0x0;
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if (saved_next_opcode2.addr != 0x0) {
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arch_disarm_kprobe(&saved_next_opcode2);
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saved_next_opcode2.addr = 0x0;
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saved_next_opcode2.opcode = 0x0;
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}
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}
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}
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static inline void 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 inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb)
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{
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__get_cpu_var(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 inline void 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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__get_cpu_var(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 inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
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{
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kprobe_opcode_t *addr = NULL;
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saved_current_opcode.addr = (kprobe_opcode_t *) (regs->pc);
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addr = saved_current_opcode.addr;
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if (p != NULL) {
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arch_disarm_kprobe(p);
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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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saved_next_opcode.addr =
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(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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saved_next_opcode.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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saved_next_opcode.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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saved_next_opcode.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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saved_next_opcode.addr = p->addr + 1;
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/* case 2 */
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saved_next_opcode2.addr =
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(kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
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saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
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arch_arm_kprobe(&saved_next_opcode2);
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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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saved_next_opcode.addr = p->addr + 2;
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/* case 2 */
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saved_next_opcode2.addr =
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(kprobe_opcode_t *) (regs->pc + 4 + disp * 2);
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saved_next_opcode2.opcode = *(saved_next_opcode2.addr);
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arch_arm_kprobe(&saved_next_opcode2);
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} else {
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saved_next_opcode.addr = p->addr + 1;
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}
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saved_next_opcode.opcode = *(saved_next_opcode.addr);
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arch_arm_kprobe(&saved_next_opcode);
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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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/* 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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} else {
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p = __get_cpu_var(current_kprobe);
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if (p->break_handler && p->break_handler(p, regs)) {
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goto ss_probe;
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}
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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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2008-09-08 09:15:55 +00:00
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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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2008-09-05 08:15:39 +00:00
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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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return 1;
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ss_probe:
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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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2008-09-08 03:02:17 +00:00
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static void __used kretprobe_trampoline_holder(void)
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2008-09-05 08:15:39 +00:00
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{
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asm volatile ("kretprobe_trampoline: \n" "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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struct kretprobe_instance *ri = NULL;
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struct hlist_head *head, empty_rp;
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struct hlist_node *node, *tmp;
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unsigned long flags, orig_ret_address = 0;
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unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
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INIT_HLIST_HEAD(&empty_rp);
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kretprobe_hash_lock(current, &head, &flags);
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/*
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* It is possible to have multiple instances associated with a given
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* task either because an multiple functions in the call path
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* have a return probe installed on them, and/or more then one return
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* return probe was registered for a target function.
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*
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* We can handle this because:
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* - instances are always inserted at the head of the list
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* - when multiple return probes are registered for the same
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* function, the first instance's ret_addr will point to the
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* real return address, and all the rest will point to
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* kretprobe_trampoline
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*/
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hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
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if (ri->task != current)
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/* another task is sharing our hash bucket */
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continue;
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if (ri->rp && ri->rp->handler) {
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__get_cpu_var(current_kprobe) = &ri->rp->kp;
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ri->rp->handler(ri, regs);
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__get_cpu_var(current_kprobe) = NULL;
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}
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orig_ret_address = (unsigned long)ri->ret_addr;
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recycle_rp_inst(ri, &empty_rp);
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if (orig_ret_address != trampoline_address)
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/*
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* This is the real return address. Any other
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* instances associated with this task are for
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* other calls deeper on the call stack
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*/
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break;
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}
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kretprobe_assert(ri, orig_ret_address, trampoline_address);
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regs->pc = orig_ret_address;
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kretprobe_hash_unlock(current, &flags);
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preempt_enable_no_resched();
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hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
|
|
|
|
hlist_del(&ri->hlist);
|
|
|
|
kfree(ri);
|
|
|
|
}
|
|
|
|
|
|
|
|
return orig_ret_address;
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline int 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;
|
|
|
|
}
|
|
|
|
|
2008-09-08 03:22:47 +00:00
|
|
|
int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
|
2008-09-05 08:15:39 +00:00
|
|
|
{
|
|
|
|
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 */
|
2008-09-08 09:12:33 +00:00
|
|
|
ret = NOTIFY_DONE;
|
2008-09-05 08:15:39 +00:00
|
|
|
}
|
|
|
|
} 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)
|
|
|
|
{
|
2008-09-08 09:10:10 +00:00
|
|
|
asm volatile ("trapa #0x3a\n\t" "jprobe_return_end:\n\t" "nop\n\t");
|
2008-09-05 08:15:39 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
|
|
|
|
{
|
|
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
|
|
u8 *addr = (u8 *) regs->pc;
|
|
|
|
unsigned long stack_addr = kcb->jprobe_saved_r15;
|
|
|
|
|
|
|
|
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;
|
2008-09-08 09:14:50 +00:00
|
|
|
preempt_enable_no_resched();
|
2008-09-05 08:15:39 +00:00
|
|
|
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);
|
|
|
|
}
|