diff options
| -rw-r--r-- | arch/arm64/Kconfig | 1 | ||||
| -rw-r--r-- | arch/arm64/include/asm/debug-monitors.h | 5 | ||||
| -rw-r--r-- | arch/arm64/include/asm/kprobes.h | 62 | ||||
| -rw-r--r-- | arch/arm64/include/asm/probes.h | 50 | ||||
| -rw-r--r-- | arch/arm64/include/asm/ptrace.h | 3 | ||||
| -rw-r--r-- | arch/arm64/kernel/Makefile | 1 | ||||
| -rw-r--r-- | arch/arm64/kernel/debug-monitors.c | 33 | ||||
| -rw-r--r-- | arch/arm64/kernel/kprobes-arm64.c | 68 | ||||
| -rw-r--r-- | arch/arm64/kernel/kprobes-arm64.h | 28 | ||||
| -rw-r--r-- | arch/arm64/kernel/kprobes.c | 537 | ||||
| -rw-r--r-- | arch/arm64/kernel/kprobes.h | 24 | ||||
| -rw-r--r-- | arch/arm64/kernel/vmlinux.lds.S | 1 | ||||
| -rw-r--r-- | arch/arm64/mm/fault.c | 25 |
13 files changed, 828 insertions, 10 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 987a681af2f..8e06a033f09 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -68,6 +68,7 @@ config ARM64 select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_RCU_TABLE_FREE select HAVE_SYSCALL_TRACEPOINTS + select HAVE_KPROBES select IRQ_DOMAIN select MODULES_USE_ELF_RELA select NO_BOOTMEM diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h index 40ec68aa687..92d7ceac9ad 100644 --- a/arch/arm64/include/asm/debug-monitors.h +++ b/arch/arm64/include/asm/debug-monitors.h @@ -90,6 +90,11 @@ #define CACHE_FLUSH_IS_SAFE 1 +/* kprobes BRK opcodes with ESR encoding */ +#define BRK64_ESR_MASK 0xFFFF +#define BRK64_ESR_KPROBES 0x0004 +#define BRK64_OPCODE_KPROBES (AARCH64_BREAK_MON | (BRK64_ESR_KPROBES << 5)) + /* AArch32 */ #define DBG_ESR_EVT_BKPT 0x4 #define DBG_ESR_EVT_VECC 0x5 diff --git a/arch/arm64/include/asm/kprobes.h b/arch/arm64/include/asm/kprobes.h new file mode 100644 index 00000000000..af31c4d2823 --- /dev/null +++ b/arch/arm64/include/asm/kprobes.h @@ -0,0 +1,62 @@ +/* + * arch/arm64/include/asm/kprobes.h + * + * Copyright (C) 2013 Linaro Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + */ + +#ifndef _ARM_KPROBES_H +#define _ARM_KPROBES_H + +#include <linux/types.h> +#include <linux/ptrace.h> +#include <linux/percpu.h> + +#define __ARCH_WANT_KPROBES_INSN_SLOT +#define MAX_INSN_SIZE 1 +#define MAX_STACK_SIZE 128 + +#define flush_insn_slot(p) do { } while (0) +#define kretprobe_blacklist_size 0 + +#include <asm/probes.h> + +struct prev_kprobe { + struct kprobe *kp; + unsigned int status; +}; + +/* Single step context for kprobe */ +struct kprobe_step_ctx { +#define KPROBES_STEP_NONE 0x0 +#define KPROBES_STEP_PENDING 0x1 + unsigned long ss_status; + unsigned long match_addr; +}; + +/* per-cpu kprobe control block */ +struct kprobe_ctlblk { + unsigned int kprobe_status; + unsigned long saved_irqflag; + struct prev_kprobe prev_kprobe; + struct kprobe_step_ctx ss_ctx; + struct pt_regs jprobe_saved_regs; + char jprobes_stack[MAX_STACK_SIZE]; +}; + +void arch_remove_kprobe(struct kprobe *); +int kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr); +int kprobe_exceptions_notify(struct notifier_block *self, + unsigned long val, void *data); +int kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr); +int kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr); + +#endif /* _ARM_KPROBES_H */ diff --git a/arch/arm64/include/asm/probes.h b/arch/arm64/include/asm/probes.h new file mode 100644 index 00000000000..7f5a27fa071 --- /dev/null +++ b/arch/arm64/include/asm/probes.h @@ -0,0 +1,50 @@ +/* + * arch/arm64/include/asm/probes.h + * + * Copyright (C) 2013 Linaro Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + */ +#ifndef _ARM_PROBES_H +#define _ARM_PROBES_H + +struct kprobe; +struct arch_specific_insn; + +typedef u32 kprobe_opcode_t; +typedef unsigned long (kprobes_pstate_check_t)(unsigned long); +typedef unsigned long +(probes_condition_check_t)(struct kprobe *p, struct pt_regs *); +typedef void +(probes_prepare_t)(struct kprobe *, struct arch_specific_insn *); +typedef void (kprobes_handler_t) (u32 opcode, long addr, struct pt_regs *); + +enum pc_restore_type { + NO_RESTORE, + RESTORE_PC, +}; + +struct kprobe_pc_restore { + enum pc_restore_type type; + unsigned long addr; +}; + +/* architecture specific copy of original instruction */ +struct arch_specific_insn { + kprobe_opcode_t *insn; + kprobes_pstate_check_t *pstate_cc; + probes_condition_check_t *check_condn; + probes_prepare_t *prepare; + kprobes_handler_t *handler; + /* restore address after step xol */ + struct kprobe_pc_restore restore; +}; + +#endif diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h index 92186c0b28c..61dcc3fdbcd 100644 --- a/arch/arm64/include/asm/ptrace.h +++ b/arch/arm64/include/asm/ptrace.h @@ -187,7 +187,8 @@ static inline int valid_user_regs(struct user_pt_regs *regs) return 0; } -#define instruction_pointer(regs) ((unsigned long)(regs)->pc) +#define instruction_pointer(regs) ((regs)->pc) +#define stack_pointer(regs) ((regs)->sp) #ifdef CONFIG_SMP extern unsigned long profile_pc(struct pt_regs *regs); diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 5ee07eee80c..056b1a48a2c 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -32,6 +32,7 @@ arm64-obj-$(CONFIG_CPU_PM) += sleep.o suspend.o arm64-obj-$(CONFIG_CPU_IDLE) += cpuidle.o arm64-obj-$(CONFIG_JUMP_LABEL) += jump_label.o arm64-obj-$(CONFIG_KGDB) += kgdb.o +arm64-obj-$(CONFIG_KPROBES) += kprobes.o kprobes-arm64.o arm64-obj-$(CONFIG_EFI) += efi.o efi-stub.o efi-entry.o arm64-obj-$(CONFIG_PCI) += pci.o arm64-obj-$(CONFIG_ARMV8_DEPRECATED) += armv8_deprecated.o diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index b056369fd47..dae7bb45894 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -23,6 +23,7 @@ #include <linux/hardirq.h> #include <linux/init.h> #include <linux/ptrace.h> +#include <linux/kprobes.h> #include <linux/stat.h> #include <linux/uaccess.h> @@ -228,6 +229,7 @@ static int single_step_handler(unsigned long addr, unsigned int esr, struct pt_regs *regs) { siginfo_t info; + bool handler_found = false; /* * If we are stepping a pending breakpoint, call the hw_breakpoint @@ -251,15 +253,21 @@ static int single_step_handler(unsigned long addr, unsigned int esr, */ user_rewind_single_step(current); } else { +#ifdef CONFIG_KPROBES + if (kprobe_single_step_handler(regs, esr) == DBG_HOOK_HANDLED) + handler_found = true; +#endif if (call_step_hook(regs, esr) == DBG_HOOK_HANDLED) - return 0; - - pr_warning("Unexpected kernel single-step exception at EL1\n"); - /* - * Re-enable stepping since we know that we will be - * returning to regs. - */ - set_regs_spsr_ss(regs); + handler_found = true; + + if (!handler_found) { + pr_warning("Unexpected kernel single-step exception at EL1\n"); + /* + * Re-enable stepping since we know that we will be + * returning to regs. + */ + set_regs_spsr_ss(regs); + } } return 0; @@ -315,7 +323,14 @@ static int brk_handler(unsigned long addr, unsigned int esr, }; force_sig_info(SIGTRAP, &info, current); - } else if (call_break_hook(regs, esr) != DBG_HOOK_HANDLED) { + } +#ifdef CONFIG_KPROBES + else if ((esr & BRK64_ESR_MASK) == BRK64_ESR_KPROBES) { + if (kprobe_breakpoint_handler(regs, esr) != DBG_HOOK_HANDLED) + return -EFAULT; + } +#endif + else if (call_break_hook(regs, esr) != DBG_HOOK_HANDLED) { pr_warning("Unexpected kernel BRK exception at EL1\n"); return -EFAULT; } diff --git a/arch/arm64/kernel/kprobes-arm64.c b/arch/arm64/kernel/kprobes-arm64.c new file mode 100644 index 00000000000..f958c525600 --- /dev/null +++ b/arch/arm64/kernel/kprobes-arm64.c @@ -0,0 +1,68 @@ +/* + * arch/arm64/kernel/kprobes-arm64.c + * + * Copyright (C) 2013 Linaro Limited. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + */ + +#include <linux/kernel.h> +#include <linux/kprobes.h> +#include <linux/module.h> +#include <asm/kprobes.h> +#include <asm/insn.h> + +#include "kprobes-arm64.h" + +static bool __kprobes aarch64_insn_is_steppable(u32 insn) +{ + if (aarch64_get_insn_class(insn) == AARCH64_INSN_CLS_BR_SYS) { + if (aarch64_insn_is_branch(insn)) + return false; + + /* modification of daif creates issues */ + if (aarch64_insn_is_daif_access(insn)) + return false; + + if (aarch64_insn_is_exception(insn)) + return false; + + if (aarch64_insn_is_hint(insn)) + return aarch64_insn_is_nop(insn); + + return true; + } + + if (aarch64_insn_uses_literal(insn)) + return false; + + if (aarch64_insn_is_exclusive(insn)) + return false; + + return true; +} + +/* Return: + * INSN_REJECTED If instruction is one not allowed to kprobe, + * INSN_GOOD If instruction is supported and uses instruction slot, + * INSN_GOOD_NO_SLOT If instruction is supported but doesn't use its slot. + */ +enum kprobe_insn __kprobes +arm_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi) +{ + /* + * Instructions reading or modifying the PC won't work from the XOL + * slot. + */ + if (aarch64_insn_is_steppable(insn)) + return INSN_GOOD; + else + return INSN_REJECTED; +} diff --git a/arch/arm64/kernel/kprobes-arm64.h b/arch/arm64/kernel/kprobes-arm64.h new file mode 100644 index 00000000000..87e789128e8 --- /dev/null +++ b/arch/arm64/kernel/kprobes-arm64.h @@ -0,0 +1,28 @@ +/* + * arch/arm64/kernel/kprobes-arm64.h + * + * Copyright (C) 2013 Linaro Limited. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + */ + +#ifndef _ARM_KERNEL_KPROBES_ARM64_H +#define _ARM_KERNEL_KPROBES_ARM64_H + +enum kprobe_insn { + INSN_REJECTED, + INSN_GOOD_NO_SLOT, + INSN_GOOD, +}; + +enum kprobe_insn __kprobes +arm_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi); + +#endif /* _ARM_KERNEL_KPROBES_ARM64_H */ diff --git a/arch/arm64/kernel/kprobes.c b/arch/arm64/kernel/kprobes.c new file mode 100644 index 00000000000..601d2c6f196 --- /dev/null +++ b/arch/arm64/kernel/kprobes.c @@ -0,0 +1,537 @@ +/* + * arch/arm64/kernel/kprobes.c + * + * Kprobes support for ARM64 + * + * Copyright (C) 2013 Linaro Limited. + * Author: Sandeepa Prabhu <sandeepa.prabhu@linaro.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + * + */ +#include <linux/kernel.h> +#include <linux/kprobes.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/stop_machine.h> +#include <linux/stringify.h> +#include <asm/traps.h> +#include <asm/ptrace.h> +#include <asm/cacheflush.h> +#include <asm/debug-monitors.h> +#include <asm/system_misc.h> +#include <asm/insn.h> + +#include "kprobes.h" +#include "kprobes-arm64.h" + +#define MIN_STACK_SIZE(addr) min((unsigned long)MAX_STACK_SIZE, \ + (unsigned long)current_thread_info() + THREAD_START_SP - (addr)) + +DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); + +static void __kprobes arch_prepare_ss_slot(struct kprobe *p) +{ + /* prepare insn slot */ + p->ainsn.insn[0] = p->opcode; + + flush_icache_range((uintptr_t) (p->ainsn.insn), + (uintptr_t) (p->ainsn.insn) + MAX_INSN_SIZE); + + /* + * Needs restoring of return address after stepping xol. + */ + p->ainsn.restore.addr = (unsigned long) p->addr + + sizeof(kprobe_opcode_t); + p->ainsn.restore.type = RESTORE_PC; +} + +int __kprobes arch_prepare_kprobe(struct kprobe *p) +{ + kprobe_opcode_t insn; + unsigned long probe_addr = (unsigned long)p->addr; + + /* copy instruction */ + insn = *p->addr; + p->opcode = insn; + + if (in_exception_text(probe_addr)) + return -EINVAL; + + /* decode instruction */ + switch (arm_kprobe_decode_insn(insn, &p->ainsn)) { + case INSN_REJECTED: /* insn not supported */ + return -EINVAL; + + case INSN_GOOD_NO_SLOT: /* insn need simulation */ + return -EINVAL; + + case INSN_GOOD: /* instruction uses slot */ + p->ainsn.insn = get_insn_slot(); + if (!p->ainsn.insn) + return -ENOMEM; + break; + }; + + /* prepare the instruction */ + arch_prepare_ss_slot(p); + + return 0; +} + +static int __kprobes patch_text(kprobe_opcode_t *addr, u32 opcode) +{ + void *addrs[1]; + u32 insns[1]; + + addrs[0] = (void *)addr; + insns[0] = (u32)opcode; + + return aarch64_insn_patch_text_sync(addrs, insns, 1); +} + +/* arm kprobe: install breakpoint in text */ +void __kprobes arch_arm_kprobe(struct kprobe *p) +{ + patch_text(p->addr, BRK64_OPCODE_KPROBES); +} + +/* disarm kprobe: remove breakpoint from text */ +void __kprobes arch_disarm_kprobe(struct kprobe *p) +{ + patch_text(p->addr, p->opcode); +} + +void __kprobes arch_remove_kprobe(struct kprobe *p) +{ + if (p->ainsn.insn) { + free_insn_slot(p->ainsn.insn, 0); + p->ainsn.insn = NULL; + } +} + +static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + kcb->prev_kprobe.kp = kprobe_running(); + kcb->prev_kprobe.status = kcb->kprobe_status; +} + +static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) +{ + __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); + kcb->kprobe_status = kcb->prev_kprobe.status; +} + +static void __kprobes set_current_kprobe(struct kprobe *p) +{ + __this_cpu_write(current_kprobe, p); +} + +/* + * The D-flag (Debug mask) is set (masked) upon exception entry. + * Kprobes needs to clear (unmask) D-flag -ONLY- in case of recursive + * probe i.e. when probe hit from kprobe handler context upon + * executing the pre/post handlers. In this case we return with + * D-flag clear so that single-stepping can be carried-out. + * + * Leave D-flag set in all other cases. + */ +static void __kprobes +spsr_set_debug_flag(struct pt_regs *regs, int mask) +{ + unsigned long spsr = regs->pstate; + + if (mask) + spsr |= PSR_D_BIT; + else + spsr &= ~PSR_D_BIT; + + regs->pstate = spsr; +} + +/* + * Interrupts need to be disabled before single-step mode is set, and not + * reenabled until after single-step mode ends. + * Without disabling interrupt on local CPU, there is a chance of + * interrupt occurrence in the period of exception return and start of + * out-of-line single-step, that result in wrongly single stepping + * the interrupt handler. + */ +static void __kprobes kprobes_save_local_irqflag(struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + kcb->saved_irqflag = regs->pstate; + regs->pstate |= PSR_I_BIT; +} + +static void __kprobes kprobes_restore_local_irqflag(struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + if (kcb->saved_irqflag & PSR_I_BIT) + regs->pstate |= PSR_I_BIT; + else + regs->pstate &= ~PSR_I_BIT; +} + +static void __kprobes +set_ss_context(struct kprobe_ctlblk *kcb, unsigned long addr) +{ + kcb->ss_ctx.ss_status = KPROBES_STEP_PENDING; + kcb->ss_ctx.match_addr = addr + sizeof(kprobe_opcode_t); +} + +static void __kprobes clear_ss_context(struct kprobe_ctlblk *kcb) +{ + kcb->ss_ctx.ss_status = KPROBES_STEP_NONE; + kcb->ss_ctx.match_addr = 0; +} + +static void __kprobes +skip_singlestep_missed(struct kprobe_ctlblk *kcb, struct pt_regs *regs) +{ + /* set return addr to next pc to continue */ + instruction_pointer(regs) += sizeof(kprobe_opcode_t); +} + +static void __kprobes setup_singlestep(struct kprobe *p, + struct pt_regs *regs, + struct kprobe_ctlblk *kcb, int reenter) +{ + unsigned long slot; + + if (reenter) { + save_previous_kprobe(kcb); + set_current_kprobe(p); + kcb->kprobe_status = KPROBE_REENTER; + } else { + kcb->kprobe_status = KPROBE_HIT_SS; + } + + if (p->ainsn.insn) { + /* prepare for single stepping */ + slot = (unsigned long)p->ainsn.insn; + + set_ss_context(kcb, slot); /* mark pending ss */ + + if (kcb->kprobe_status == KPROBE_REENTER) + spsr_set_debug_flag(regs, 0); + + /* IRQs and single stepping do not mix well. */ + kprobes_save_local_irqflag(regs); + kernel_enable_single_step(regs); + instruction_pointer(regs) = slot; + } else { + BUG(); + } +} + +static int __kprobes reenter_kprobe(struct kprobe *p, + struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + switch (kcb->kprobe_status) { + case KPROBE_HIT_SSDONE: + case KPROBE_HIT_ACTIVE: + if (!p->ainsn.check_condn || p->ainsn.check_condn(p, regs)) { + kprobes_inc_nmissed_count(p); + setup_singlestep(p, regs, kcb, 1); + } else { + /* condition check failed, skip stepping */ + skip_singlestep_missed(kcb, regs); + } + break; + case KPROBE_HIT_SS: + case KPROBE_REENTER: + pr_warn("Unrecoverable kprobe detected at %p.\n", p->addr); + dump_kprobe(p); + BUG(); + break; + default: + WARN_ON(1); + return 0; + } + + return 1; +} + +static void __kprobes +post_kprobe_handler(struct kprobe_ctlblk *kcb, struct pt_regs *regs) +{ + struct kprobe *cur = kprobe_running(); + + if (!cur) + return; + + /* return addr restore if non-branching insn */ + if (cur->ainsn.restore.type == RESTORE_PC) { + instruction_pointer(regs) = cur->ainsn.restore.addr; + if (!instruction_pointer(regs)) + BUG(); + } + + /* restore back original saved kprobe variables and continue */ + if (kcb->kprobe_status == KPROBE_REENTER) { + restore_previous_kprobe(kcb); + return; + } + /* call post handler */ + kcb->kprobe_status = KPROBE_HIT_SSDONE; + if (cur->post_handler) { + /* post_handler can hit breakpoint and single step + * again, so we enable D-flag for recursive exception. + */ + cur->post_handler(cur, regs, 0); + } + + reset_current_kprobe(); +} + +int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr) +{ + struct kprobe *cur = kprobe_running(); + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + 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 ip points back to the probe address + * and allow the page fault handler to continue as a + * normal page fault. + */ + instruction_pointer(regs) = (unsigned long)cur->addr; + if (!instruction_pointer(regs)) + BUG(); + if (kcb->kprobe_status == KPROBE_REENTER) + restore_previous_kprobe(kcb); + else + reset_current_kprobe(); + + break; + case KPROBE_HIT_ACTIVE: + case KPROBE_HIT_SSDONE: + /* + * We increment the nmissed count for accounting, + * we can also use npre/npostfault count for accounting + * 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, fsr)) + return 1; + + /* + * In case the user-specified fault handler returned + * zero, try to fix up. + */ + if (fixup_exception(regs)) + return 1; + + break; + } + return 0; +} + +int __kprobes kprobe_exceptions_notify(struct notifier_block *self, + unsigned long val, void *data) +{ + return NOTIFY_DONE; +} + +void __kprobes kprobe_handler(struct pt_regs *regs) +{ + struct kprobe *p, *cur; + struct kprobe_ctlblk *kcb; + unsigned long addr = instruction_pointer(regs); + + kcb = get_kprobe_ctlblk(); + cur = kprobe_running(); + + p = get_kprobe((kprobe_opcode_t *) addr); + + if (p) { + if (cur) { + if (reenter_kprobe(p, regs, kcb)) + return; + } else if (!p->ainsn.check_condn || + p->ainsn.check_condn(p, regs)) { + /* Probe hit and conditional execution check ok. */ + set_current_kprobe(p); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + + /* + * If we have no pre-handler or it returned 0, we + * continue with normal processing. If we have a + * pre-handler and it returned non-zero, it prepped + * for calling the break_handler below on re-entry, + * so get out doing nothing more here. + * + * pre_handler can hit a breakpoint and can step thru + * before return, keep PSTATE D-flag enabled until + * pre_handler return back. + */ + if (!p->pre_handler || !p->pre_handler(p, regs)) { + kcb->kprobe_status = KPROBE_HIT_SS; + setup_singlestep(p, regs, kcb, 0); + return; + } + } else { + /* + * Breakpoint hit but conditional check failed, + * so just skip the instruction (NOP behaviour) + */ + skip_singlestep_missed(kcb, regs); + return; + } + } else if (*(kprobe_opcode_t *) addr != BRK64_OPCODE_KPROBES) { + /* + * 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. + * Return back to original instruction, and continue. + */ + return; + } else if (cur) { + /* We probably hit a jprobe. Call its break handler. */ + if (cur->break_handler && cur->break_handler(cur, regs)) { + kcb->kprobe_status = KPROBE_HIT_SS; + setup_singlestep(cur, regs, kcb, 0); + return; + } + } else { + /* breakpoint is removed, now in a race + * Return back to original instruction & continue. + */ + } +} + +static int __kprobes +kprobe_ss_hit(struct kprobe_ctlblk *kcb, unsigned long addr) +{ + if ((kcb->ss_ctx.ss_status == KPROBES_STEP_PENDING) + && (kcb->ss_ctx.match_addr == addr)) { + clear_ss_context(kcb); /* clear pending ss */ + return DBG_HOOK_HANDLED; + } + /* not ours, kprobes should ignore it */ + return DBG_HOOK_ERROR; +} + +int __kprobes +kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + int retval; + + /* return error if this is not our step */ + retval = kprobe_ss_hit(kcb, instruction_pointer(regs)); + + if (retval == DBG_HOOK_HANDLED) { + kprobes_restore_local_irqflag(regs); + kernel_disable_single_step(); + + if (kcb->kprobe_status == KPROBE_REENTER) + spsr_set_debug_flag(regs, 1); + + post_kprobe_handler(kcb, regs); + } + + return retval; +} + +int __kprobes +kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr) +{ + kprobe_handler(regs); + return DBG_HOOK_HANDLED; +} + +int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct jprobe *jp = container_of(p, struct jprobe, kp); + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + long stack_ptr = stack_pointer(regs); + + kcb->jprobe_saved_regs = *regs; + memcpy(kcb->jprobes_stack, (void *)stack_ptr, + MIN_STACK_SIZE(stack_ptr)); + + instruction_pointer(regs) = (long)jp->entry; + preempt_disable(); + return 1; +} + +void __kprobes jprobe_return(void) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + /* + * Jprobe handler return by entering break exception, + * encoded same as kprobe, but with following conditions + * -a magic number in x0 to identify from rest of other kprobes. + * -restore stack addr to original saved pt_regs + */ + asm volatile ("ldr x0, [%0]\n\t" + "mov sp, x0\n\t" + "ldr x0, =" __stringify(JPROBES_MAGIC_NUM) "\n\t" + "BRK %1\n\t" + "NOP\n\t" + : + : "r"(&kcb->jprobe_saved_regs.sp), + "I"(BRK64_ESR_KPROBES) + : "memory"); +} + +int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + long stack_addr = kcb->jprobe_saved_regs.sp; + long orig_sp = stack_pointer(regs); + struct jprobe *jp = container_of(p, struct jprobe, kp); + + if (regs->regs[0] == JPROBES_MAGIC_NUM) { + if (orig_sp != stack_addr) { + struct pt_regs *saved_regs = + (struct pt_regs *)kcb->jprobe_saved_regs.sp; + pr_err("current sp %lx does not match saved sp %lx\n", + orig_sp, stack_addr); + pr_err("Saved registers for jprobe %p\n", jp); + show_regs(saved_regs); + pr_err("Current registers\n"); + show_regs(regs); + BUG(); + } + *regs = kcb->jprobe_saved_regs; + memcpy((void *)stack_addr, kcb->jprobes_stack, + MIN_STACK_SIZE(stack_addr)); + preempt_enable_no_resched(); + return 1; + } + return 0; +} + +int __init arch_init_kprobes(void) +{ + return 0; +} diff --git a/arch/arm64/kernel/kprobes.h b/arch/arm64/kernel/kprobes.h new file mode 100644 index 00000000000..e98ad601506 --- /dev/null +++ b/arch/arm64/kernel/kprobes.h @@ -0,0 +1,24 @@ +/* + * arch/arm64/kernel/kprobes.h + * + * Copyright (C) 2013 Linaro Limited. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * 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. + */ + +#ifndef _ARM_KERNEL_KPROBES_H +#define _ARM_KERNEL_KPROBES_H + +#define JPROBES_MAGIC_NUM 0xa5a5a5a5a5a5a5a5 + +/* Move this out to appropriate header file */ +int fixup_exception(struct pt_regs *regs); + +#endif /* _ARM_KERNEL_KPROBES_H */ diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 5d9d2dca530..2e515103995 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -90,6 +90,7 @@ SECTIONS TEXT_TEXT SCHED_TEXT LOCK_TEXT + KPROBES_TEXT HYPERVISOR_TEXT *(.fixup) *(.gnu.warning) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 96da13167d4..4c13dfb450c 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -39,6 +39,28 @@ static const char *fault_name(unsigned int esr); +#ifdef CONFIG_KPROBES +static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr) +{ + int ret = 0; + + /* kprobe_running() needs smp_processor_id() */ + if (!user_mode(regs)) { + preempt_disable(); + if (kprobe_running() && kprobe_fault_handler(regs, esr)) + ret = 1; + preempt_enable(); + } + + return ret; +} +#else +static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr) +{ + return 0; +} +#endif + /* * Dump out the page tables associated with 'addr' in mm 'mm'. */ @@ -200,6 +222,9 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC; unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; + if (notify_page_fault(regs, esr)) + return 0; + tsk = current; mm = tsk->mm; |