![Tony Lu](/assets/img/avatar_default.png)
This change includes support for Kprobes, Jprobes and Return Probes. Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Tony Lu <zlu@tilera.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
529 lines
13 KiB
C
529 lines
13 KiB
C
/*
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* arch/tile/kernel/kprobes.c
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* Kprobes on TILE-Gx
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*
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* Some portions copied from the MIPS version.
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*
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* Copyright (C) IBM Corporation, 2002, 2004
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* Copyright 2006 Sony Corp.
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* Copyright 2010 Cavium Networks
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*
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* Copyright 2012 Tilera Corporation. All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, version 2.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
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* NON INFRINGEMENT. See the GNU General Public License for
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* more details.
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*/
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#include <linux/kprobes.h>
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#include <linux/kdebug.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <asm/cacheflush.h>
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#include <arch/opcode.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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tile_bundle_bits breakpoint_insn = TILEGX_BPT_BUNDLE;
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tile_bundle_bits breakpoint2_insn = TILEGX_BPT_BUNDLE | DIE_SSTEPBP;
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/*
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* Check whether instruction is branch or jump, or if executing it
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* has different results depending on where it is executed (e.g. lnk).
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*/
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static int __kprobes insn_has_control(kprobe_opcode_t insn)
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{
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if (get_Mode(insn) != 0) { /* Y-format bundle */
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if (get_Opcode_Y1(insn) != RRR_1_OPCODE_Y1 ||
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get_RRROpcodeExtension_Y1(insn) != UNARY_RRR_1_OPCODE_Y1)
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return 0;
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switch (get_UnaryOpcodeExtension_Y1(insn)) {
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case JALRP_UNARY_OPCODE_Y1:
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case JALR_UNARY_OPCODE_Y1:
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case JRP_UNARY_OPCODE_Y1:
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case JR_UNARY_OPCODE_Y1:
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case LNK_UNARY_OPCODE_Y1:
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return 1;
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default:
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return 0;
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}
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}
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switch (get_Opcode_X1(insn)) {
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case BRANCH_OPCODE_X1: /* branch instructions */
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case JUMP_OPCODE_X1: /* jump instructions: j and jal */
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return 1;
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case RRR_0_OPCODE_X1: /* other jump instructions */
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if (get_RRROpcodeExtension_X1(insn) != UNARY_RRR_0_OPCODE_X1)
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return 0;
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switch (get_UnaryOpcodeExtension_X1(insn)) {
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case JALRP_UNARY_OPCODE_X1:
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case JALR_UNARY_OPCODE_X1:
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case JRP_UNARY_OPCODE_X1:
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case JR_UNARY_OPCODE_X1:
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case LNK_UNARY_OPCODE_X1:
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return 1;
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default:
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return 0;
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}
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default:
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return 0;
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}
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}
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int __kprobes arch_prepare_kprobe(struct kprobe *p)
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{
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unsigned long addr = (unsigned long)p->addr;
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if (addr & (sizeof(kprobe_opcode_t) - 1))
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return -EINVAL;
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if (insn_has_control(*p->addr)) {
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pr_notice("Kprobes for control instructions are not "
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"supported\n");
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return -EINVAL;
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}
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/* insn: must be on special executable page on tile. */
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p->ainsn.insn = get_insn_slot();
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if (!p->ainsn.insn)
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return -ENOMEM;
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/*
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* In the kprobe->ainsn.insn[] array we store the original
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* instruction at index zero and a break trap instruction at
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* index one.
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*/
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memcpy(&p->ainsn.insn[0], p->addr, sizeof(kprobe_opcode_t));
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p->ainsn.insn[1] = breakpoint2_insn;
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p->opcode = *p->addr;
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return 0;
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}
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void __kprobes arch_arm_kprobe(struct kprobe *p)
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{
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unsigned long addr_wr;
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/* Operate on writable kernel text mapping. */
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addr_wr = (unsigned long)p->addr - MEM_SV_START + PAGE_OFFSET;
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if (probe_kernel_write((void *)addr_wr, &breakpoint_insn,
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sizeof(breakpoint_insn)))
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pr_err("%s: failed to enable kprobe\n", __func__);
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smp_wmb();
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flush_insn_slot(p);
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}
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void __kprobes arch_disarm_kprobe(struct kprobe *kp)
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{
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unsigned long addr_wr;
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/* Operate on writable kernel text mapping. */
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addr_wr = (unsigned long)kp->addr - MEM_SV_START + PAGE_OFFSET;
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if (probe_kernel_write((void *)addr_wr, &kp->opcode,
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sizeof(kp->opcode)))
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pr_err("%s: failed to enable kprobe\n", __func__);
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smp_wmb();
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flush_insn_slot(kp);
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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 (p->ainsn.insn) {
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free_insn_slot(p->ainsn.insn, 0);
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p->ainsn.insn = NULL;
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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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kcb->prev_kprobe.saved_pc = kcb->kprobe_saved_pc;
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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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kcb->kprobe_saved_pc = kcb->prev_kprobe.saved_pc;
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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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kcb->kprobe_saved_pc = regs->pc;
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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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/* Single step inline if the instruction is a break. */
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if (p->opcode == breakpoint_insn ||
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p->opcode == breakpoint2_insn)
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regs->pc = (unsigned long)p->addr;
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else
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regs->pc = (unsigned long)&p->ainsn.insn[0];
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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;
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struct kprobe_ctlblk *kcb;
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addr = (kprobe_opcode_t *)regs->pc;
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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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/* 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[0] == breakpoint_insn) {
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goto no_kprobe;
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}
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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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if (*addr != breakpoint_insn) {
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/*
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* The breakpoint instruction was removed by
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* another cpu right after we hit, 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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goto no_kprobe;
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}
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p = __this_cpu_read(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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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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if (*addr != breakpoint_insn) {
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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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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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}
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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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* Called after single-stepping. p->addr is the address of the
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* instruction that has been replaced by the breakpoint. To avoid the
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* SMP problems that can occur when we temporarily put back the
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* original opcode to single-step, we single-stepped a copy of the
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* instruction. The address of this copy is p->ainsn.insn.
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*
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* This function prepares to return from the post-single-step
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* breakpoint trap.
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*/
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static void __kprobes resume_execution(struct kprobe *p,
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struct pt_regs *regs,
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struct kprobe_ctlblk *kcb)
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{
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unsigned long orig_pc = kcb->kprobe_saved_pc;
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regs->pc = orig_pc + 8;
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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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struct kprobe *cur = kprobe_running();
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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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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resume_execution(cur, regs, kcb);
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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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static inline int 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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if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
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return 1;
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if (kcb->kprobe_status & KPROBE_HIT_SS) {
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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 and the ip points 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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resume_execution(cur, regs, kcb);
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reset_current_kprobe();
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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 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 die_args *args = (struct die_args *)data;
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int ret = NOTIFY_DONE;
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switch (val) {
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case DIE_BREAK:
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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_SSTEPBP:
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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_PAGE_FAULT:
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/* kprobe_running() needs smp_processor_id(). */
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preempt_disable();
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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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preempt_enable();
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break;
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default:
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break;
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}
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return ret;
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}
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int __kprobes 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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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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kcb->jprobe_saved_regs = *regs;
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kcb->jprobe_saved_sp = regs->sp;
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memcpy(kcb->jprobes_stack, (void *)kcb->jprobe_saved_sp,
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MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
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regs->pc = (unsigned long)(jp->entry);
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return 1;
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}
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/* Defined in the inline asm below. */
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void jprobe_return_end(void);
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void __kprobes jprobe_return(void)
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{
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asm volatile(
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"bpt\n\t"
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".globl jprobe_return_end\n"
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"jprobe_return_end:\n");
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}
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int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
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{
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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if (regs->pc >= (unsigned long)jprobe_return &&
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regs->pc <= (unsigned long)jprobe_return_end) {
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*regs = kcb->jprobe_saved_regs;
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memcpy((void *)kcb->jprobe_saved_sp, kcb->jprobes_stack,
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MIN_JPROBES_STACK_SIZE(kcb->jprobe_saved_sp));
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preempt_enable_no_resched();
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return 1;
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}
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return 0;
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}
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/*
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* Function return probe trampoline:
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* - init_kprobes() establishes a probepoint here
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* - When the probed function returns, this probe causes the
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* handlers to fire
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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(
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"nop\n\t"
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".global kretprobe_trampoline\n"
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"kretprobe_trampoline:\n\t"
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"nop\n\t"
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: : : "memory");
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}
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void kretprobe_trampoline(void);
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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->lr;
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/* Replace the return addr with trampoline addr */
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regs->lr = (unsigned long)kretprobe_trampoline;
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}
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/*
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* Called when the probe at kretprobe trampoline is hit.
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*/
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static int __kprobes trampoline_probe_handler(struct kprobe *p,
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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 *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 multiple functions in the call path have
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* a return probe installed on them, and/or more than 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, 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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ri->rp->handler(ri, regs);
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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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}
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kretprobe_assert(ri, orig_ret_address, trampoline_address);
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instruction_pointer(regs) = orig_ret_address;
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reset_current_kprobe();
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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, tmp, &empty_rp, hlist) {
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hlist_del(&ri->hlist);
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kfree(ri);
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}
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/*
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* By returning a non-zero value, we are telling
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* kprobe_handler() that we don't want the post_handler
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* to run (and have re-enabled preemption)
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*/
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return 1;
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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 == (kprobe_opcode_t *)kretprobe_trampoline)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static struct kprobe trampoline_p = {
|
|
.addr = (kprobe_opcode_t *)kretprobe_trampoline,
|
|
.pre_handler = trampoline_probe_handler
|
|
};
|
|
|
|
int __init arch_init_kprobes(void)
|
|
{
|
|
register_kprobe(&trampoline_p);
|
|
return 0;
|
|
}
|