--- /dev/null
+/*
+ * Kernel Probes (KProbes)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2002, 2006
+ *
+ * s390 port, used ppc64 as template. Mike Grundy <grundym@us.ibm.com>
+ */
+
+#include <linux/config.h>
+#include <linux/kprobes.h>
+#include <linux/ptrace.h>
+#include <linux/preempt.h>
+#include <linux/stop_machine.h>
+#include <asm/cacheflush.h>
+#include <asm/kdebug.h>
+#include <asm/sections.h>
+#include <asm/uaccess.h>
+#include <linux/module.h>
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+ /* Make sure the probe isn't going on a difficult instruction */
+ if (is_prohibited_opcode((kprobe_opcode_t *) p->addr))
+ return -EINVAL;
+
+ if ((unsigned long)p->addr & 0x01) {
+ printk("Attempt to register kprobe at an unaligned address\n");
+ return -EINVAL;
+ }
+
+ /* Use the get_insn_slot() facility for correctness */
+ if (!(p->ainsn.insn = get_insn_slot()))
+ return -ENOMEM;
+
+ memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
+
+ get_instruction_type(&p->ainsn);
+ p->opcode = *p->addr;
+ return 0;
+}
+
+int __kprobes is_prohibited_opcode(kprobe_opcode_t *instruction)
+{
+ switch (*(__u8 *) instruction) {
+ case 0x0c: /* bassm */
+ case 0x0b: /* bsm */
+ case 0x83: /* diag */
+ case 0x44: /* ex */
+ return -EINVAL;
+ }
+ switch (*(__u16 *) instruction) {
+ case 0x0101: /* pr */
+ case 0xb25a: /* bsa */
+ case 0xb240: /* bakr */
+ case 0xb258: /* bsg */
+ case 0xb218: /* pc */
+ case 0xb228: /* pt */
+ return -EINVAL;
+ }
+ return 0;
+}
+
+void __kprobes get_instruction_type(struct arch_specific_insn *ainsn)
+{
+ /* default fixup method */
+ ainsn->fixup = FIXUP_PSW_NORMAL;
+
+ /* save r1 operand */
+ ainsn->reg = (*ainsn->insn & 0xf0) >> 4;
+
+ /* save the instruction length (pop 5-5) in bytes */
+ switch (*(__u8 *) (ainsn->insn) >> 4) {
+ case 0:
+ ainsn->ilen = 2;
+ break;
+ case 1:
+ case 2:
+ ainsn->ilen = 4;
+ break;
+ case 3:
+ ainsn->ilen = 6;
+ break;
+ }
+
+ switch (*(__u8 *) ainsn->insn) {
+ case 0x05: /* balr */
+ case 0x0d: /* basr */
+ ainsn->fixup = FIXUP_RETURN_REGISTER;
+ /* if r2 = 0, no branch will be taken */
+ if ((*ainsn->insn & 0x0f) == 0)
+ ainsn->fixup |= FIXUP_BRANCH_NOT_TAKEN;
+ break;
+ case 0x06: /* bctr */
+ case 0x07: /* bcr */
+ ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
+ break;
+ case 0x45: /* bal */
+ case 0x4d: /* bas */
+ ainsn->fixup = FIXUP_RETURN_REGISTER;
+ break;
+ case 0x47: /* bc */
+ case 0x46: /* bct */
+ case 0x86: /* bxh */
+ case 0x87: /* bxle */
+ ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
+ break;
+ case 0x82: /* lpsw */
+ ainsn->fixup = FIXUP_NOT_REQUIRED;
+ break;
+ case 0xb2: /* lpswe */
+ if (*(((__u8 *) ainsn->insn) + 1) == 0xb2) {
+ ainsn->fixup = FIXUP_NOT_REQUIRED;
+ }
+ break;
+ case 0xa7: /* bras */
+ if ((*ainsn->insn & 0x0f) == 0x05) {
+ ainsn->fixup |= FIXUP_RETURN_REGISTER;
+ }
+ break;
+ case 0xc0:
+ if ((*ainsn->insn & 0x0f) == 0x00 /* larl */
+ || (*ainsn->insn & 0x0f) == 0x05) /* brasl */
+ ainsn->fixup |= FIXUP_RETURN_REGISTER;
+ break;
+ case 0xeb:
+ if (*(((__u8 *) ainsn->insn) + 5 ) == 0x44 || /* bxhg */
+ *(((__u8 *) ainsn->insn) + 5) == 0x45) {/* bxleg */
+ ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
+ }
+ break;
+ case 0xe3: /* bctg */
+ if (*(((__u8 *) ainsn->insn) + 5) == 0x46) {
+ ainsn->fixup = FIXUP_BRANCH_NOT_TAKEN;
+ }
+ break;
+ }
+}
+
+static int __kprobes swap_instruction(void *aref)
+{
+ struct ins_replace_args *args = aref;
+ int err = -EFAULT;
+
+ asm volatile(
+ "0: mvc 0(2,%2),0(%3)\n"
+ "1: la %0,0\n"
+ "2:\n"
+ EX_TABLE(0b,2b)
+ : "+d" (err), "=m" (*args->ptr)
+ : "a" (args->ptr), "a" (&args->new), "m" (args->new));
+ return err;
+}
+
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ unsigned long status = kcb->kprobe_status;
+ struct ins_replace_args args;
+
+ args.ptr = p->addr;
+ args.old = p->opcode;
+ args.new = BREAKPOINT_INSTRUCTION;
+
+ kcb->kprobe_status = KPROBE_SWAP_INST;
+ stop_machine_run(swap_instruction, &args, NR_CPUS);
+ kcb->kprobe_status = status;
+}
+
+void __kprobes arch_disarm_kprobe(struct kprobe *p)
+{
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ unsigned long status = kcb->kprobe_status;
+ struct ins_replace_args args;
+
+ args.ptr = p->addr;
+ args.old = BREAKPOINT_INSTRUCTION;
+ args.new = p->opcode;
+
+ kcb->kprobe_status = KPROBE_SWAP_INST;
+ stop_machine_run(swap_instruction, &args, NR_CPUS);
+ kcb->kprobe_status = status;
+}
+
+void __kprobes arch_remove_kprobe(struct kprobe *p)
+{
+ mutex_lock(&kprobe_mutex);
+ free_insn_slot(p->ainsn.insn);
+ mutex_unlock(&kprobe_mutex);
+}
+
+static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
+{
+ per_cr_bits kprobe_per_regs[1];
+
+ memset(kprobe_per_regs, 0, sizeof(per_cr_bits));
+ regs->psw.addr = (unsigned long)p->ainsn.insn | PSW_ADDR_AMODE;
+
+ /* Set up the per control reg info, will pass to lctl */
+ kprobe_per_regs[0].em_instruction_fetch = 1;
+ kprobe_per_regs[0].starting_addr = (unsigned long)p->ainsn.insn;
+ kprobe_per_regs[0].ending_addr = (unsigned long)p->ainsn.insn + 1;
+
+ /* Set the PER control regs, turns on single step for this address */
+ __ctl_load(kprobe_per_regs, 9, 11);
+ regs->psw.mask |= PSW_MASK_PER;
+ regs->psw.mask &= ~(PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
+}
+
+static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ kcb->prev_kprobe.kp = kprobe_running();
+ kcb->prev_kprobe.status = kcb->kprobe_status;
+ kcb->prev_kprobe.kprobe_saved_imask = kcb->kprobe_saved_imask;
+ memcpy(kcb->prev_kprobe.kprobe_saved_ctl, kcb->kprobe_saved_ctl,
+ sizeof(kcb->kprobe_saved_ctl));
+}
+
+static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
+ kcb->kprobe_status = kcb->prev_kprobe.status;
+ kcb->kprobe_saved_imask = kcb->prev_kprobe.kprobe_saved_imask;
+ memcpy(kcb->kprobe_saved_ctl, kcb->prev_kprobe.kprobe_saved_ctl,
+ sizeof(kcb->kprobe_saved_ctl));
+}
+
+static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ __get_cpu_var(current_kprobe) = p;
+ /* Save the interrupt and per flags */
+ kcb->kprobe_saved_imask = regs->psw.mask &
+ (PSW_MASK_PER | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK);
+ /* Save the control regs that govern PER */
+ __ctl_store(kcb->kprobe_saved_ctl, 9, 11);
+}
+
+/* Called with kretprobe_lock held */
+void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
+ struct pt_regs *regs)
+{
+ struct kretprobe_instance *ri;
+
+ if ((ri = get_free_rp_inst(rp)) != NULL) {
+ ri->rp = rp;
+ ri->task = current;
+ ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
+
+ /* Replace the return addr with trampoline addr */
+ regs->gprs[14] = (unsigned long)&kretprobe_trampoline;
+
+ add_rp_inst(ri);
+ } else {
+ rp->nmissed++;
+ }
+}
+
+static int __kprobes kprobe_handler(struct pt_regs *regs)
+{
+ struct kprobe *p;
+ int ret = 0;
+ unsigned long *addr = (unsigned long *)
+ ((regs->psw.addr & PSW_ADDR_INSN) - 2);
+ struct kprobe_ctlblk *kcb;
+
+ /*
+ * We don't want to be preempted for the entire
+ * duration of kprobe processing
+ */
+ preempt_disable();
+ kcb = get_kprobe_ctlblk();
+
+ /* Check we're not actually recursing */
+ if (kprobe_running()) {
+ p = get_kprobe(addr);
+ if (p) {
+ if (kcb->kprobe_status == KPROBE_HIT_SS &&
+ *p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
+ regs->psw.mask &= ~PSW_MASK_PER;
+ regs->psw.mask |= kcb->kprobe_saved_imask;
+ goto no_kprobe;
+ }
+ /* We have reentered the kprobe_handler(), since
+ * another probe was hit while within the handler.
+ * We here save the original kprobes variables and
+ * just single step on the instruction of the new probe
+ * without calling any user handlers.
+ */
+ save_previous_kprobe(kcb);
+ set_current_kprobe(p, regs, kcb);
+ kprobes_inc_nmissed_count(p);
+ prepare_singlestep(p, regs);
+ kcb->kprobe_status = KPROBE_REENTER;
+ return 1;
+ } else {
+ p = __get_cpu_var(current_kprobe);
+ if (p->break_handler && p->break_handler(p, regs)) {
+ goto ss_probe;
+ }
+ }
+ goto no_kprobe;
+ }
+
+ p = get_kprobe(addr);
+ if (!p) {
+ if (*addr != BREAKPOINT_INSTRUCTION) {
+ /*
+ * The breakpoint instruction was removed right
+ * after we hit it. Another cpu has removed
+ * either a probepoint or a debugger breakpoint
+ * at this address. In either case, no further
+ * handling of this interrupt is appropriate.
+ *
+ */
+ ret = 1;
+ }
+ /* Not one of ours: let kernel handle it */
+ goto no_kprobe;
+ }
+
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+ set_current_kprobe(p, regs, kcb);
+ if (p->pre_handler && p->pre_handler(p, regs))
+ /* handler has already set things up, so skip ss setup */
+ return 1;
+
+ss_probe:
+ prepare_singlestep(p, regs);
+ kcb->kprobe_status = KPROBE_HIT_SS;
+ return 1;
+
+no_kprobe:
+ preempt_enable_no_resched();
+ return ret;
+}
+
+/*
+ * Function return probe trampoline:
+ * - init_kprobes() establishes a probepoint here
+ * - When the probed function returns, this probe
+ * causes the handlers to fire
+ */
+void __kprobes kretprobe_trampoline_holder(void)
+{
+ asm volatile(".global kretprobe_trampoline\n"
+ "kretprobe_trampoline: bcr 0,0\n");
+}
+
+/*
+ * Called when the probe at kretprobe trampoline is hit
+ */
+int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct kretprobe_instance *ri = NULL;
+ struct hlist_head *head;
+ struct hlist_node *node, *tmp;
+ unsigned long flags, orig_ret_address = 0;
+ unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
+
+ spin_lock_irqsave(&kretprobe_lock, flags);
+ head = kretprobe_inst_table_head(current);
+
+ /*
+ * It is possible to have multiple instances associated with a given
+ * task either because an multiple functions in the call path
+ * have a return probe installed on them, and/or more then one return
+ * return probe was registered for a target function.
+ *
+ * We can handle this because:
+ * - instances are always inserted at the head of the list
+ * - when multiple return probes are registered for the same
+ * function, the first instance's ret_addr will point to the
+ * real return address, and all the rest will point to
+ * kretprobe_trampoline
+ */
+ hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
+ if (ri->task != current)
+ /* another task is sharing our hash bucket */
+ continue;
+
+ if (ri->rp && ri->rp->handler)
+ ri->rp->handler(ri, regs);
+
+ orig_ret_address = (unsigned long)ri->ret_addr;
+ recycle_rp_inst(ri);
+
+ if (orig_ret_address != trampoline_address) {
+ /*
+ * This is the real return address. Any other
+ * instances associated with this task are for
+ * other calls deeper on the call stack
+ */
+ break;
+ }
+ }
+ BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
+ regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
+
+ reset_current_kprobe();
+ spin_unlock_irqrestore(&kretprobe_lock, flags);
+ preempt_enable_no_resched();
+
+ /*
+ * By returning a non-zero value, we are telling
+ * kprobe_handler() that we don't want the post_handler
+ * to run (and have re-enabled preemption)
+ */
+ return 1;
+}
+
+/*
+ * Called after single-stepping. p->addr is the address of the
+ * instruction whose first byte has been replaced by the "breakpoint"
+ * instruction. To avoid the SMP problems that can occur when we
+ * temporarily put back the original opcode to single-step, we
+ * single-stepped a copy of the instruction. The address of this
+ * copy is p->ainsn.insn.
+ */
+static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
+{
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ regs->psw.addr &= PSW_ADDR_INSN;
+
+ if (p->ainsn.fixup & FIXUP_PSW_NORMAL)
+ regs->psw.addr = (unsigned long)p->addr +
+ ((unsigned long)regs->psw.addr -
+ (unsigned long)p->ainsn.insn);
+
+ if (p->ainsn.fixup & FIXUP_BRANCH_NOT_TAKEN)
+ if ((unsigned long)regs->psw.addr -
+ (unsigned long)p->ainsn.insn == p->ainsn.ilen)
+ regs->psw.addr = (unsigned long)p->addr + p->ainsn.ilen;
+
+ if (p->ainsn.fixup & FIXUP_RETURN_REGISTER)
+ regs->gprs[p->ainsn.reg] = ((unsigned long)p->addr +
+ (regs->gprs[p->ainsn.reg] -
+ (unsigned long)p->ainsn.insn))
+ | PSW_ADDR_AMODE;
+
+ regs->psw.addr |= PSW_ADDR_AMODE;
+ /* turn off PER mode */
+ regs->psw.mask &= ~PSW_MASK_PER;
+ /* Restore the original per control regs */
+ __ctl_load(kcb->kprobe_saved_ctl, 9, 11);
+ regs->psw.mask |= kcb->kprobe_saved_imask;
+}
+
+static int __kprobes post_kprobe_handler(struct pt_regs *regs)
+{
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ 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);
+ }
+
+ resume_execution(cur, regs);
+
+ /*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();
+
+ /*
+ * if somebody else is singlestepping across a probe point, psw mask
+ * will have PER set, in which case, continue the remaining processing
+ * of do_single_step, as if this is not a probe hit.
+ */
+ if (regs->psw.mask & PSW_MASK_PER) {
+ return 0;
+ }
+
+ return 1;
+}
+
+static int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
+{
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ const struct exception_table_entry *entry;
+
+ switch(kcb->kprobe_status) {
+ case KPROBE_SWAP_INST:
+ /* We are here because the instruction replacement failed */
+ return 0;
+ 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 and the nip points back to the probe address
+ * and allow the page fault handler to continue as a
+ * normal page fault.
+ */
+ regs->psw.addr = (unsigned long)cur->addr | PSW_ADDR_AMODE;
+ regs->psw.mask &= ~PSW_MASK_PER;
+ regs->psw.mask |= kcb->kprobe_saved_imask;
+ 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 accouting
+ * 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.
+ */
+ entry = search_exception_tables(regs->psw.addr & PSW_ADDR_INSN);
+ if (entry) {
+ regs->psw.addr = entry->fixup | PSW_ADDR_AMODE;
+ 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 die_args *args = (struct die_args *)data;
+ int ret = NOTIFY_DONE;
+
+ switch (val) {
+ case DIE_BPT:
+ if (kprobe_handler(args->regs))
+ ret = NOTIFY_STOP;
+ break;
+ case DIE_SSTEP:
+ if (post_kprobe_handler(args->regs))
+ ret = NOTIFY_STOP;
+ break;
+ case DIE_TRAP:
+ case DIE_PAGE_FAULT:
+ /* kprobe_running() needs smp_processor_id() */
+ preempt_disable();
+ if (kprobe_running() &&
+ kprobe_fault_handler(args->regs, args->trapnr))
+ ret = NOTIFY_STOP;
+ preempt_enable();
+ break;
+ default:
+ break;
+ }
+ 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();
+
+ memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs));
+
+ /* setup return addr to the jprobe handler routine */
+ regs->psw.addr = (unsigned long)(jp->entry) | PSW_ADDR_AMODE;
+
+ /* r14 is the function return address */
+ kcb->jprobe_saved_r14 = (unsigned long)regs->gprs[14];
+ /* r15 is the stack pointer */
+ kcb->jprobe_saved_r15 = (unsigned long)regs->gprs[15];
+ addr = (unsigned long)kcb->jprobe_saved_r15;
+
+ memcpy(kcb->jprobes_stack, (kprobe_opcode_t *) addr,
+ MIN_STACK_SIZE(addr));
+ return 1;
+}
+
+void __kprobes jprobe_return(void)
+{
+ asm volatile(".word 0x0002");
+}
+
+void __kprobes jprobe_return_end(void)
+{
+ asm volatile("bcr 0,0");
+}
+
+int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
+{
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_r15);
+
+ /* Put the regs back */
+ memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
+ /* put the stack back */
+ memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
+ MIN_STACK_SIZE(stack_addr));
+ preempt_enable_no_resched();
+ return 1;
+}
+
+static struct kprobe trampoline_p = {
+ .addr = (kprobe_opcode_t *) & kretprobe_trampoline,
+ .pre_handler = trampoline_probe_handler
+};
+
+int __init arch_init_kprobes(void)
+{
+ return register_kprobe(&trampoline_p);
+}
git.openpandora.org / pandora-kernel.git / commitdiff