diff options
| -rw-r--r-- | arch/arm/kernel/kprobes.c | 122 | ||||
| -rw-r--r-- | arch/arm/kernel/kprobes.h | 7 |
2 files changed, 115 insertions, 14 deletions
diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c index 0df2d6d..a9050ba 100644 --- a/arch/arm/kernel/kprobes.c +++ b/arch/arm/kernel/kprobes.c @@ -34,10 +34,10 @@ min((unsigned long)MAX_STACK_SIZE, \ (unsigned long)current_thread_info() + THREAD_START_SP - (addr)) -#define flush_insns(addr, cnt) \ +#define flush_insns(addr, size) \ flush_icache_range((unsigned long)(addr), \ (unsigned long)(addr) + \ - sizeof(kprobe_opcode_t) * (cnt)) + (size)) /* Used as a marker in ARM_pc to note when we're in a jprobe. */ #define JPROBE_MAGIC_ADDR 0xffffffff @@ -86,7 +86,8 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) return -ENOMEM; for (is = 0; is < MAX_INSN_SIZE; ++is) p->ainsn.insn[is] = tmp_insn[is]; - flush_insns(p->ainsn.insn, MAX_INSN_SIZE); + flush_insns(p->ainsn.insn, + sizeof(p->ainsn.insn[0]) * MAX_INSN_SIZE); break; case INSN_GOOD_NO_SLOT: /* instruction doesn't need insn slot */ @@ -97,24 +98,82 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p) return 0; } +#ifdef CONFIG_THUMB2_KERNEL + +/* + * For a 32-bit Thumb breakpoint spanning two memory words we need to take + * special precautions to insert the breakpoint atomically, especially on SMP + * systems. This is achieved by calling this arming function using stop_machine. + */ +static int __kprobes set_t32_breakpoint(void *addr) +{ + ((u16 *)addr)[0] = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION >> 16; + ((u16 *)addr)[1] = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION & 0xffff; + flush_insns(addr, 2*sizeof(u16)); + return 0; +} + void __kprobes arch_arm_kprobe(struct kprobe *p) { - *p->addr = KPROBE_BREAKPOINT_INSTRUCTION; - flush_insns(p->addr, 1); + uintptr_t addr = (uintptr_t)p->addr & ~1; /* Remove any Thumb flag */ + + if (!is_wide_instruction(p->opcode)) { + *(u16 *)addr = KPROBE_THUMB16_BREAKPOINT_INSTRUCTION; + flush_insns(addr, sizeof(u16)); + } else if (addr & 2) { + /* A 32-bit instruction spanning two words needs special care */ + stop_machine(set_t32_breakpoint, (void *)addr, &cpu_online_map); + } else { + /* Word aligned 32-bit instruction can be written atomically */ + u32 bkp = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION; +#ifndef __ARMEB__ /* Swap halfwords for little-endian */ + bkp = (bkp >> 16) | (bkp << 16); +#endif + *(u32 *)addr = bkp; + flush_insns(addr, sizeof(u32)); + } } +#else /* !CONFIG_THUMB2_KERNEL */ + +void __kprobes arch_arm_kprobe(struct kprobe *p) +{ + *p->addr = KPROBE_ARM_BREAKPOINT_INSTRUCTION; + flush_insns(p->addr, sizeof(p->addr[0])); +} + +#endif /* !CONFIG_THUMB2_KERNEL */ + /* * The actual disarming is done here on each CPU and synchronized using * stop_machine. This synchronization is necessary on SMP to avoid removing * a probe between the moment the 'Undefined Instruction' exception is raised * and the moment the exception handler reads the faulting instruction from - * memory. + * memory. It is also needed to atomically set the two half-words of a 32-bit + * Thumb breakpoint. */ int __kprobes __arch_disarm_kprobe(void *p) { struct kprobe *kp = p; +#ifdef CONFIG_THUMB2_KERNEL + u16 *addr = (u16 *)((uintptr_t)kp->addr & ~1); + kprobe_opcode_t insn = kp->opcode; + unsigned int len; + + if (is_wide_instruction(insn)) { + ((u16 *)addr)[0] = insn>>16; + ((u16 *)addr)[1] = insn; + len = 2*sizeof(u16); + } else { + ((u16 *)addr)[0] = insn; + len = sizeof(u16); + } + flush_insns(addr, len); + +#else /* !CONFIG_THUMB2_KERNEL */ *kp->addr = kp->opcode; - flush_insns(kp->addr, 1); + flush_insns(kp->addr, sizeof(kp->addr[0])); +#endif return 0; } @@ -167,11 +226,23 @@ void __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p, *cur; struct kprobe_ctlblk *kcb; - kprobe_opcode_t *addr = (kprobe_opcode_t *)regs->ARM_pc; kcb = get_kprobe_ctlblk(); cur = kprobe_running(); - p = get_kprobe(addr); + +#ifdef CONFIG_THUMB2_KERNEL + /* + * First look for a probe which was registered using an address with + * bit 0 set, this is the usual situation for pointers to Thumb code. + * If not found, fallback to looking for one with bit 0 clear. + */ + p = get_kprobe((kprobe_opcode_t *)(regs->ARM_pc | 1)); + if (!p) + p = get_kprobe((kprobe_opcode_t *)regs->ARM_pc); + +#else /* ! CONFIG_THUMB2_KERNEL */ + p = get_kprobe((kprobe_opcode_t *)regs->ARM_pc); +#endif if (p) { if (cur) { @@ -511,17 +582,44 @@ int __kprobes arch_trampoline_kprobe(struct kprobe *p) return 0; } -static struct undef_hook kprobes_break_hook = { +#ifdef CONFIG_THUMB2_KERNEL + +static struct undef_hook kprobes_thumb16_break_hook = { + .instr_mask = 0xffff, + .instr_val = KPROBE_THUMB16_BREAKPOINT_INSTRUCTION, + .cpsr_mask = MODE_MASK, + .cpsr_val = SVC_MODE, + .fn = kprobe_trap_handler, +}; + +static struct undef_hook kprobes_thumb32_break_hook = { + .instr_mask = 0xffffffff, + .instr_val = KPROBE_THUMB32_BREAKPOINT_INSTRUCTION, + .cpsr_mask = MODE_MASK, + .cpsr_val = SVC_MODE, + .fn = kprobe_trap_handler, +}; + +#else /* !CONFIG_THUMB2_KERNEL */ + +static struct undef_hook kprobes_arm_break_hook = { .instr_mask = 0xffffffff, - .instr_val = KPROBE_BREAKPOINT_INSTRUCTION, + .instr_val = KPROBE_ARM_BREAKPOINT_INSTRUCTION, .cpsr_mask = MODE_MASK, .cpsr_val = SVC_MODE, .fn = kprobe_trap_handler, }; +#endif /* !CONFIG_THUMB2_KERNEL */ + int __init arch_init_kprobes() { arm_kprobe_decode_init(); - register_undef_hook(&kprobes_break_hook); +#ifdef CONFIG_THUMB2_KERNEL + register_undef_hook(&kprobes_thumb16_break_hook); + register_undef_hook(&kprobes_thumb32_break_hook); +#else + register_undef_hook(&kprobes_arm_break_hook); +#endif return 0; } diff --git a/arch/arm/kernel/kprobes.h b/arch/arm/kernel/kprobes.h index 86abfab..a84b14d8 100644 --- a/arch/arm/kernel/kprobes.h +++ b/arch/arm/kernel/kprobes.h @@ -18,10 +18,13 @@ #define _ARM_KERNEL_KPROBES_H /* - * This undefined instruction must be unique and + * These undefined instructions must be unique and * reserved solely for kprobes' use. */ -#define KPROBE_BREAKPOINT_INSTRUCTION 0xe7f001f8 +#define KPROBE_ARM_BREAKPOINT_INSTRUCTION 0xe7f001f8 +#define KPROBE_THUMB16_BREAKPOINT_INSTRUCTION 0xde18 +#define KPROBE_THUMB32_BREAKPOINT_INSTRUCTION 0xf7f0a018 + enum kprobe_insn { INSN_REJECTED, |
