2005-04-16 16:20:36 -06:00
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/*
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* Kernel Probes (KProbes)
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* arch/ppc64/kernel/kprobes.c
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* Copyright (C) IBM Corporation, 2002, 2004
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*
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* 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
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* Probes initial implementation ( includes contributions from
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* Rusty Russell).
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* 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
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* interface to access function arguments.
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* 2004-Nov Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port
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* for PPC64
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*/
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#include <linux/config.h>
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#include <linux/kprobes.h>
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#include <linux/ptrace.h>
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#include <linux/spinlock.h>
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#include <linux/preempt.h>
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2005-06-23 01:09:25 -06:00
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#include <asm/cacheflush.h>
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2005-04-16 16:20:36 -06:00
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#include <asm/kdebug.h>
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#include <asm/sstep.h>
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/* kprobe_status settings */
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#define KPROBE_HIT_ACTIVE 0x00000001
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#define KPROBE_HIT_SS 0x00000002
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static struct kprobe *current_kprobe;
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static unsigned long kprobe_status, kprobe_saved_msr;
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static struct pt_regs jprobe_saved_regs;
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int arch_prepare_kprobe(struct kprobe *p)
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{
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2005-06-08 16:49:41 -06:00
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int ret = 0;
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2005-04-16 16:20:36 -06:00
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kprobe_opcode_t insn = *p->addr;
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2005-06-08 16:49:41 -06:00
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if ((unsigned long)p->addr & 0x03) {
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printk("Attempt to register kprobe at an unaligned address\n");
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ret = -EINVAL;
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} else if (IS_MTMSRD(insn) || IS_RFID(insn)) {
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printk("Cannot register a kprobe on rfid or mtmsrd\n");
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ret = -EINVAL;
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}
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return ret;
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2005-04-16 16:20:36 -06:00
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}
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void 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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2005-06-23 01:09:25 -06:00
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p->opcode = *p->addr;
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2005-04-16 16:20:36 -06:00
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}
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2005-06-23 01:09:25 -06:00
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void arch_arm_kprobe(struct kprobe *p)
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2005-04-16 16:20:36 -06:00
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{
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2005-06-23 01:09:25 -06:00
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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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2005-04-16 16:20:36 -06:00
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}
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2005-06-23 01:09:25 -06:00
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void arch_disarm_kprobe(struct kprobe *p)
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2005-04-16 16:20:36 -06:00
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{
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*p->addr = p->opcode;
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2005-06-23 01:09:25 -06:00
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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 arch_remove_kprobe(struct kprobe *p)
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{
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2005-04-16 16:20:36 -06:00
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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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regs->msr |= MSR_SE;
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/*single step inline if it a breakpoint instruction*/
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if (p->opcode == BREAKPOINT_INSTRUCTION)
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regs->nip = (unsigned long)p->addr;
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else
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regs->nip = (unsigned long)&p->ainsn.insn;
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}
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static inline int 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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unsigned int *addr = (unsigned int *)regs->nip;
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/* Check we're not actually recursing */
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if (kprobe_running()) {
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/* We *are* holding lock here, so this is safe.
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Disarm the probe we just hit, and ignore it. */
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p = get_kprobe(addr);
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if (p) {
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if (kprobe_status == KPROBE_HIT_SS) {
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regs->msr &= ~MSR_SE;
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regs->msr |= kprobe_saved_msr;
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unlock_kprobes();
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goto no_kprobe;
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}
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2005-06-23 01:09:25 -06:00
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arch_disarm_kprobe(p);
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regs->nip = (unsigned long)p->addr;
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2005-04-16 16:20:36 -06:00
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ret = 1;
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} else {
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p = 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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/* If it's not ours, can't be delete race, (we hold lock). */
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goto no_kprobe;
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}
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lock_kprobes();
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p = get_kprobe(addr);
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if (!p) {
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unlock_kprobes();
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if (*addr != BREAKPOINT_INSTRUCTION) {
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/*
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* PowerPC has multiple variants of the "trap"
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* instruction. If the current instruction is a
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* trap variant, it could belong to someone else
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*/
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kprobe_opcode_t cur_insn = *addr;
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if (IS_TW(cur_insn) || IS_TD(cur_insn) ||
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IS_TWI(cur_insn) || IS_TDI(cur_insn))
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goto no_kprobe;
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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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/* Not one of ours: let kernel handle it */
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goto no_kprobe;
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}
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kprobe_status = KPROBE_HIT_ACTIVE;
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current_kprobe = p;
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kprobe_saved_msr = regs->msr;
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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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kprobe_status = KPROBE_HIT_SS;
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/*
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* This preempt_disable() matches the preempt_enable_no_resched()
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* in post_kprobe_handler().
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*/
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preempt_disable();
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return 1;
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no_kprobe:
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return ret;
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}
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/*
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* Called after single-stepping. p->addr is the address of the
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* instruction whose first byte has been replaced by the "breakpoint"
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* instruction. To avoid the SMP problems that can occur when we
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* temporarily put back the original opcode to single-step, we
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* single-stepped a copy of the instruction. The address of this
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* copy is p->ainsn.insn.
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*/
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static void resume_execution(struct kprobe *p, struct pt_regs *regs)
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{
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int ret;
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regs->nip = (unsigned long)p->addr;
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ret = emulate_step(regs, p->ainsn.insn[0]);
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if (ret == 0)
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regs->nip = (unsigned long)p->addr + 4;
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}
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static inline int post_kprobe_handler(struct pt_regs *regs)
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{
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if (!kprobe_running())
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return 0;
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if (current_kprobe->post_handler)
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current_kprobe->post_handler(current_kprobe, regs, 0);
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resume_execution(current_kprobe, regs);
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regs->msr |= kprobe_saved_msr;
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unlock_kprobes();
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preempt_enable_no_resched();
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/*
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* if somebody else is singlestepping across a probe point, msr
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* will have SE set, in which case, continue the remaining processing
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* of do_debug, as if this is not a probe hit.
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*/
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if (regs->msr & MSR_SE)
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return 0;
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return 1;
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}
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/* Interrupts disabled, kprobe_lock held. */
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static inline int kprobe_fault_handler(struct pt_regs *regs, int trapnr)
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{
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if (current_kprobe->fault_handler
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&& current_kprobe->fault_handler(current_kprobe, regs, trapnr))
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return 1;
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if (kprobe_status & KPROBE_HIT_SS) {
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resume_execution(current_kprobe, regs);
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2005-06-08 16:50:00 -06:00
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regs->msr &= ~MSR_SE;
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regs->msr |= kprobe_saved_msr;
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unlock_kprobes();
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preempt_enable_no_resched();
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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 kprobe_exceptions_notify(struct notifier_block *self, unsigned long val,
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void *data)
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{
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struct die_args *args = (struct die_args *)data;
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int ret = NOTIFY_DONE;
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/*
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* Interrupts are not disabled here. We need to disable
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* preemption, because kprobe_running() uses smp_processor_id().
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*/
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preempt_disable();
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switch (val) {
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case DIE_BPT:
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if (kprobe_handler(args->regs))
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ret = NOTIFY_STOP;
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break;
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case DIE_SSTEP:
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if (post_kprobe_handler(args->regs))
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ret = NOTIFY_STOP;
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break;
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case DIE_GPF:
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case DIE_PAGE_FAULT:
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if (kprobe_running() &&
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kprobe_fault_handler(args->regs, args->trapnr))
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ret = NOTIFY_STOP;
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break;
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default:
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break;
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}
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preempt_enable();
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return ret;
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}
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int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
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{
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struct jprobe *jp = container_of(p, struct jprobe, kp);
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memcpy(&jprobe_saved_regs, regs, sizeof(struct pt_regs));
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/* setup return addr to the jprobe handler routine */
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regs->nip = (unsigned long)(((func_descr_t *)jp->entry)->entry);
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regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc);
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return 1;
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}
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void jprobe_return(void)
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{
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asm volatile("trap" ::: "memory");
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}
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void jprobe_return_end(void)
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{
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};
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int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
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{
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/*
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* FIXME - we should ideally be validating that we got here 'cos
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* of the "trap" in jprobe_return() above, before restoring the
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* saved regs...
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*/
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memcpy(regs, &jprobe_saved_regs, sizeof(struct pt_regs));
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return 1;
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}
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