| /* |
| * 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, 2004 |
| * |
| * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel |
| * Probes initial implementation ( includes contributions from |
| * Rusty Russell). |
| * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes |
| * interface to access function arguments. |
| * 2004-Oct Jim Keniston <kenistoj@us.ibm.com> and Prasanna S Panchamukhi |
| * <prasanna@in.ibm.com> adapted for x86_64 |
| * 2005-Mar Roland McGrath <roland@redhat.com> |
| * Fixed to handle %rip-relative addressing mode correctly. |
| * 2005-May Rusty Lynch <rusty.lynch@intel.com> |
| * Added function return probes functionality |
| */ |
| |
| #include <linux/kprobes.h> |
| #include <linux/ptrace.h> |
| #include <linux/string.h> |
| #include <linux/slab.h> |
| #include <linux/preempt.h> |
| #include <linux/module.h> |
| #include <linux/kdebug.h> |
| |
| #include <asm/pgtable.h> |
| #include <asm/uaccess.h> |
| #include <asm/alternative.h> |
| |
| void jprobe_return_end(void); |
| static void __kprobes arch_copy_kprobe(struct kprobe *p); |
| |
| DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
| DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); |
| |
| struct kretprobe_blackpoint kretprobe_blacklist[] = { |
| {"__switch_to", }, /* This function switches only current task, but |
| doesn't switch kernel stack.*/ |
| {NULL, NULL} /* Terminator */ |
| }; |
| const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); |
| |
| /* |
| * returns non-zero if opcode modifies the interrupt flag. |
| */ |
| static int __kprobes is_IF_modifier(kprobe_opcode_t *insn) |
| { |
| switch (*insn) { |
| case 0xfa: /* cli */ |
| case 0xfb: /* sti */ |
| case 0xcf: /* iret/iretd */ |
| case 0x9d: /* popf/popfd */ |
| return 1; |
| } |
| |
| if (*insn >= 0x40 && *insn <= 0x4f && *++insn == 0xcf) |
| return 1; |
| return 0; |
| } |
| |
| int __kprobes arch_prepare_kprobe(struct kprobe *p) |
| { |
| /* insn: must be on special executable page on x86_64. */ |
| p->ainsn.insn = get_insn_slot(); |
| if (!p->ainsn.insn) { |
| return -ENOMEM; |
| } |
| arch_copy_kprobe(p); |
| return 0; |
| } |
| |
| /* |
| * Determine if the instruction uses the %rip-relative addressing mode. |
| * If it does, return the address of the 32-bit displacement word. |
| * If not, return null. |
| */ |
| static s32 __kprobes *is_riprel(u8 *insn) |
| { |
| #define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \ |
| (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ |
| (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ |
| (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ |
| (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ |
| << (row % 64)) |
| static const u64 onebyte_has_modrm[256 / 64] = { |
| /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
| /* ------------------------------- */ |
| W(0x00, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 00 */ |
| W(0x10, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 10 */ |
| W(0x20, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 20 */ |
| W(0x30, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0), /* 30 */ |
| W(0x40, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 40 */ |
| W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 50 */ |
| W(0x60, 0,0,1,1,0,0,0,0,0,1,0,1,0,0,0,0)| /* 60 */ |
| W(0x70, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 70 */ |
| W(0x80, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 80 */ |
| W(0x90, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 90 */ |
| W(0xa0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* a0 */ |
| W(0xb0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* b0 */ |
| W(0xc0, 1,1,0,0,1,1,1,1,0,0,0,0,0,0,0,0)| /* c0 */ |
| W(0xd0, 1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1)| /* d0 */ |
| W(0xe0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* e0 */ |
| W(0xf0, 0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1) /* f0 */ |
| /* ------------------------------- */ |
| /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
| }; |
| static const u64 twobyte_has_modrm[256 / 64] = { |
| /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
| /* ------------------------------- */ |
| W(0x00, 1,1,1,1,0,0,0,0,0,0,0,0,0,1,0,1)| /* 0f */ |
| W(0x10, 1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0)| /* 1f */ |
| W(0x20, 1,1,1,1,1,0,1,0,1,1,1,1,1,1,1,1)| /* 2f */ |
| W(0x30, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 3f */ |
| W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 4f */ |
| W(0x50, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 5f */ |
| W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 6f */ |
| W(0x70, 1,1,1,1,1,1,1,0,0,0,0,0,1,1,1,1), /* 7f */ |
| W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 8f */ |
| W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 9f */ |
| W(0xa0, 0,0,0,1,1,1,1,1,0,0,0,1,1,1,1,1)| /* af */ |
| W(0xb0, 1,1,1,1,1,1,1,1,0,0,1,1,1,1,1,1), /* bf */ |
| W(0xc0, 1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0)| /* cf */ |
| W(0xd0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* df */ |
| W(0xe0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* ef */ |
| W(0xf0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0) /* ff */ |
| /* ------------------------------- */ |
| /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
| }; |
| #undef W |
| int need_modrm; |
| |
| /* Skip legacy instruction prefixes. */ |
| while (1) { |
| switch (*insn) { |
| case 0x66: |
| case 0x67: |
| case 0x2e: |
| case 0x3e: |
| case 0x26: |
| case 0x64: |
| case 0x65: |
| case 0x36: |
| case 0xf0: |
| case 0xf3: |
| case 0xf2: |
| ++insn; |
| continue; |
| } |
| break; |
| } |
| |
| /* Skip REX instruction prefix. */ |
| if ((*insn & 0xf0) == 0x40) |
| ++insn; |
| |
| if (*insn == 0x0f) { /* Two-byte opcode. */ |
| ++insn; |
| need_modrm = test_bit(*insn, twobyte_has_modrm); |
| } else { /* One-byte opcode. */ |
| need_modrm = test_bit(*insn, onebyte_has_modrm); |
| } |
| |
| if (need_modrm) { |
| u8 modrm = *++insn; |
| if ((modrm & 0xc7) == 0x05) { /* %rip+disp32 addressing mode */ |
| /* Displacement follows ModRM byte. */ |
| return (s32 *) ++insn; |
| } |
| } |
| |
| /* No %rip-relative addressing mode here. */ |
| return NULL; |
| } |
| |
| static void __kprobes arch_copy_kprobe(struct kprobe *p) |
| { |
| s32 *ripdisp; |
| memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE); |
| ripdisp = is_riprel(p->ainsn.insn); |
| if (ripdisp) { |
| /* |
| * The copied instruction uses the %rip-relative |
| * addressing mode. Adjust the displacement for the |
| * difference between the original location of this |
| * instruction and the location of the copy that will |
| * actually be run. The tricky bit here is making sure |
| * that the sign extension happens correctly in this |
| * calculation, since we need a signed 32-bit result to |
| * be sign-extended to 64 bits when it's added to the |
| * %rip value and yield the same 64-bit result that the |
| * sign-extension of the original signed 32-bit |
| * displacement would have given. |
| */ |
| s64 disp = (u8 *) p->addr + *ripdisp - (u8 *) p->ainsn.insn; |
| BUG_ON((s64) (s32) disp != disp); /* Sanity check. */ |
| *ripdisp = disp; |
| } |
| p->opcode = *p->addr; |
| } |
| |
| void __kprobes arch_arm_kprobe(struct kprobe *p) |
| { |
| text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
| } |
| |
| void __kprobes arch_disarm_kprobe(struct kprobe *p) |
| { |
| text_poke(p->addr, &p->opcode, 1); |
| } |
| |
| void __kprobes arch_remove_kprobe(struct kprobe *p) |
| { |
| mutex_lock(&kprobe_mutex); |
| free_insn_slot(p->ainsn.insn, 0); |
| mutex_unlock(&kprobe_mutex); |
| } |
| |
| 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.old_rflags = kcb->kprobe_old_rflags; |
| kcb->prev_kprobe.saved_rflags = kcb->kprobe_saved_rflags; |
| } |
| |
| 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_old_rflags = kcb->prev_kprobe.old_rflags; |
| kcb->kprobe_saved_rflags = kcb->prev_kprobe.saved_rflags; |
| } |
| |
| static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
| struct kprobe_ctlblk *kcb) |
| { |
| __get_cpu_var(current_kprobe) = p; |
| kcb->kprobe_saved_rflags = kcb->kprobe_old_rflags |
| = (regs->eflags & (TF_MASK | IF_MASK)); |
| if (is_IF_modifier(p->ainsn.insn)) |
| kcb->kprobe_saved_rflags &= ~IF_MASK; |
| } |
| |
| static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
| { |
| regs->eflags |= TF_MASK; |
| regs->eflags &= ~IF_MASK; |
| /*single step inline if the instruction is an int3*/ |
| if (p->opcode == BREAKPOINT_INSTRUCTION) |
| regs->rip = (unsigned long)p->addr; |
| else |
| regs->rip = (unsigned long)p->ainsn.insn; |
| } |
| |
| /* Called with kretprobe_lock held */ |
| void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
| struct pt_regs *regs) |
| { |
| unsigned long *sara = (unsigned long *)regs->rsp; |
| |
| ri->ret_addr = (kprobe_opcode_t *) *sara; |
| /* Replace the return addr with trampoline addr */ |
| *sara = (unsigned long) &kretprobe_trampoline; |
| } |
| |
| int __kprobes kprobe_handler(struct pt_regs *regs) |
| { |
| struct kprobe *p; |
| int ret = 0; |
| kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->rip - sizeof(kprobe_opcode_t)); |
| 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->eflags &= ~TF_MASK; |
| regs->eflags |= kcb->kprobe_saved_rflags; |
| goto no_kprobe; |
| } else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) { |
| /* TODO: Provide re-entrancy from |
| * post_kprobes_handler() and avoid exception |
| * stack corruption while single-stepping on |
| * the instruction of the new probe. |
| */ |
| arch_disarm_kprobe(p); |
| regs->rip = (unsigned long)p->addr; |
| reset_current_kprobe(); |
| ret = 1; |
| } else { |
| /* We have reentered the kprobe_handler(), since |
| * another probe was hit while within the |
| * handler. We here save the original kprobe |
| * variables and just single step on 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 { |
| if (*addr != BREAKPOINT_INSTRUCTION) { |
| /* The breakpoint instruction was removed by |
| * another cpu right after we hit, no further |
| * handling of this interrupt is appropriate |
| */ |
| regs->rip = (unsigned long)addr; |
| ret = 1; |
| goto no_kprobe; |
| } |
| 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. |
| * Back up over the (now missing) int3 and run |
| * the original instruction. |
| */ |
| regs->rip = (unsigned long)addr; |
| ret = 1; |
| } |
| /* Not one of ours: let kernel handle it */ |
| goto no_kprobe; |
| } |
| |
| set_current_kprobe(p, regs, kcb); |
| kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
| |
| 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; |
| } |
| |
| /* |
| * For function-return probes, init_kprobes() establishes a probepoint |
| * here. When a retprobed function returns, this probe is hit and |
| * trampoline_probe_handler() runs, calling the kretprobe's handler. |
| */ |
| void kretprobe_trampoline_holder(void) |
| { |
| asm volatile ( ".global kretprobe_trampoline\n" |
| "kretprobe_trampoline: \n" |
| "nop\n"); |
| } |
| |
| /* |
| * Called when we hit the probe point at kretprobe_trampoline |
| */ |
| int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) |
| { |
| struct kretprobe_instance *ri = NULL; |
| struct hlist_head *head, empty_rp; |
| struct hlist_node *node, *tmp; |
| unsigned long flags, orig_ret_address = 0; |
| unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; |
| |
| INIT_HLIST_HEAD(&empty_rp); |
| 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, &empty_rp); |
| |
| 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; |
| } |
| |
| kretprobe_assert(ri, orig_ret_address, trampoline_address); |
| regs->rip = orig_ret_address; |
| |
| reset_current_kprobe(); |
| spin_unlock_irqrestore(&kretprobe_lock, flags); |
| preempt_enable_no_resched(); |
| |
| hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
| hlist_del(&ri->hlist); |
| kfree(ri); |
| } |
| /* |
| * 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 "int 3" |
| * 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. |
| * |
| * This function prepares to return from the post-single-step |
| * interrupt. We have to fix up the stack as follows: |
| * |
| * 0) Except in the case of absolute or indirect jump or call instructions, |
| * the new rip is relative to the copied instruction. We need to make |
| * it relative to the original instruction. |
| * |
| * 1) If the single-stepped instruction was pushfl, then the TF and IF |
| * flags are set in the just-pushed eflags, and may need to be cleared. |
| * |
| * 2) If the single-stepped instruction was a call, the return address |
| * that is atop the stack is the address following the copied instruction. |
| * We need to make it the address following the original instruction. |
| */ |
| static void __kprobes resume_execution(struct kprobe *p, |
| struct pt_regs *regs, struct kprobe_ctlblk *kcb) |
| { |
| unsigned long *tos = (unsigned long *)regs->rsp; |
| unsigned long next_rip = 0; |
| unsigned long copy_rip = (unsigned long)p->ainsn.insn; |
| unsigned long orig_rip = (unsigned long)p->addr; |
| kprobe_opcode_t *insn = p->ainsn.insn; |
| |
| /*skip the REX prefix*/ |
| if (*insn >= 0x40 && *insn <= 0x4f) |
| insn++; |
| |
| switch (*insn) { |
| case 0x9c: /* pushfl */ |
| *tos &= ~(TF_MASK | IF_MASK); |
| *tos |= kcb->kprobe_old_rflags; |
| break; |
| case 0xc3: /* ret/lret */ |
| case 0xcb: |
| case 0xc2: |
| case 0xca: |
| regs->eflags &= ~TF_MASK; |
| /* rip is already adjusted, no more changes required*/ |
| return; |
| case 0xe8: /* call relative - Fix return addr */ |
| *tos = orig_rip + (*tos - copy_rip); |
| break; |
| case 0xff: |
| if ((insn[1] & 0x30) == 0x10) { |
| /* call absolute, indirect */ |
| /* Fix return addr; rip is correct. */ |
| next_rip = regs->rip; |
| *tos = orig_rip + (*tos - copy_rip); |
| } else if (((insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */ |
| ((insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */ |
| /* rip is correct. */ |
| next_rip = regs->rip; |
| } |
| break; |
| case 0xea: /* jmp absolute -- rip is correct */ |
| next_rip = regs->rip; |
| break; |
| default: |
| break; |
| } |
| |
| regs->eflags &= ~TF_MASK; |
| if (next_rip) { |
| regs->rip = next_rip; |
| } else { |
| regs->rip = orig_rip + (regs->rip - copy_rip); |
| } |
| } |
| |
| 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, kcb); |
| regs->eflags |= kcb->kprobe_saved_rflags; |
| trace_hardirqs_fixup_flags(regs->eflags); |
| |
| /* Restore 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, eflags |
| * will have TF set, in which case, continue the remaining processing |
| * of do_debug, as if this is not a probe hit. |
| */ |
| if (regs->eflags & TF_MASK) |
| return 0; |
| |
| return 1; |
| } |
| |
| 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 *fixup; |
| |
| switch(kcb->kprobe_status) { |
| case KPROBE_HIT_SS: |
| case KPROBE_REENTER: |
| /* |
| * We are here because the instruction being single |
| * stepped caused a page fault. We reset the current |
| * kprobe and the rip points back to the probe address |
| * and allow the page fault handler to continue as a |
| * normal page fault. |
| */ |
| regs->rip = (unsigned long)cur->addr; |
| regs->eflags |= kcb->kprobe_old_rflags; |
| 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. |
| */ |
| fixup = search_exception_tables(regs->rip); |
| if (fixup) { |
| regs->rip = fixup->fixup; |
| return 1; |
| } |
| |
| /* |
| * fixup() could not handle it, |
| * Let do_page_fault() fix it. |
| */ |
| break; |
| default: |
| break; |
| } |
| return 0; |
| } |
| |
| /* |
| * Wrapper routine 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; |
| |
| if (args->regs && user_mode(args->regs)) |
| return ret; |
| |
| switch (val) { |
| case DIE_INT3: |
| if (kprobe_handler(args->regs)) |
| ret = NOTIFY_STOP; |
| break; |
| case DIE_DEBUG: |
| if (post_kprobe_handler(args->regs)) |
| ret = NOTIFY_STOP; |
| break; |
| case DIE_GPF: |
| /* 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(); |
| |
| kcb->jprobe_saved_regs = *regs; |
| kcb->jprobe_saved_rsp = (long *) regs->rsp; |
| addr = (unsigned long)(kcb->jprobe_saved_rsp); |
| /* |
| * As Linus pointed out, gcc assumes that the callee |
| * owns the argument space and could overwrite it, e.g. |
| * tailcall optimization. So, to be absolutely safe |
| * we also save and restore enough stack bytes to cover |
| * the argument area. |
| */ |
| memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
| MIN_STACK_SIZE(addr)); |
| regs->eflags &= ~IF_MASK; |
| trace_hardirqs_off(); |
| regs->rip = (unsigned long)(jp->entry); |
| return 1; |
| } |
| |
| void __kprobes jprobe_return(void) |
| { |
| struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| |
| asm volatile (" xchg %%rbx,%%rsp \n" |
| " int3 \n" |
| " .globl jprobe_return_end \n" |
| " jprobe_return_end: \n" |
| " nop \n"::"b" |
| (kcb->jprobe_saved_rsp):"memory"); |
| } |
| |
| int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
| { |
| struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| u8 *addr = (u8 *) (regs->rip - 1); |
| unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_rsp); |
| struct jprobe *jp = container_of(p, struct jprobe, kp); |
| |
| if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) { |
| if ((long *)regs->rsp != kcb->jprobe_saved_rsp) { |
| struct pt_regs *saved_regs = |
| container_of(kcb->jprobe_saved_rsp, |
| struct pt_regs, rsp); |
| printk("current rsp %p does not match saved rsp %p\n", |
| (long *)regs->rsp, kcb->jprobe_saved_rsp); |
| printk("Saved registers for jprobe %p\n", jp); |
| show_registers(saved_regs); |
| printk("Current registers\n"); |
| show_registers(regs); |
| BUG(); |
| } |
| *regs = kcb->jprobe_saved_regs; |
| memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack, |
| MIN_STACK_SIZE(stack_addr)); |
| preempt_enable_no_resched(); |
| 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) |
| { |
| return register_kprobe(&trampoline_p); |
| } |
| |
| int __kprobes arch_trampoline_kprobe(struct kprobe *p) |
| { |
| if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline) |
| return 1; |
| |
| return 0; |
| } |