diff options
Diffstat (limited to 'arch/s390/kernel/kprobes.c')
| -rw-r--r-- | arch/s390/kernel/kprobes.c | 657 |
1 files changed, 657 insertions, 0 deletions
diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c new file mode 100644 index 000000000000..ca28fb0b3790 --- /dev/null +++ b/arch/s390/kernel/kprobes.c @@ -0,0 +1,657 @@ +/* + * 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); +} |