diff options
| -rw-r--r-- | arch/x86_64/kernel/kprobes.c | 129 | ||||
| -rw-r--r-- | include/asm-x86_64/kprobes.h | 19 |
2 files changed, 89 insertions, 59 deletions
diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c index ebfa2c9..6cb40d1 100644 --- a/arch/x86_64/kernel/kprobes.c +++ b/arch/x86_64/kernel/kprobes.c @@ -44,17 +44,10 @@ #include <asm/kdebug.h> static DECLARE_MUTEX(kprobe_mutex); - -static struct kprobe *current_kprobe; -static unsigned long kprobe_status, kprobe_old_rflags, kprobe_saved_rflags; -static struct kprobe *kprobe_prev; -static unsigned long kprobe_status_prev, kprobe_old_rflags_prev, kprobe_saved_rflags_prev; -static struct pt_regs jprobe_saved_regs; -static long *jprobe_saved_rsp; void jprobe_return_end(void); -/* copy of the kernel stack at the probe fire time */ -static kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE]; +DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; +DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); /* * returns non-zero if opcode modifies the interrupt flag. @@ -236,29 +229,30 @@ void __kprobes arch_remove_kprobe(struct kprobe *p) up(&kprobe_mutex); } -static inline void save_previous_kprobe(void) +static inline void save_previous_kprobe(struct kprobe_ctlblk *kcb) { - kprobe_prev = current_kprobe; - kprobe_status_prev = kprobe_status; - kprobe_old_rflags_prev = kprobe_old_rflags; - kprobe_saved_rflags_prev = kprobe_saved_rflags; + 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 inline void restore_previous_kprobe(void) +static inline void restore_previous_kprobe(struct kprobe_ctlblk *kcb) { - current_kprobe = kprobe_prev; - kprobe_status = kprobe_status_prev; - kprobe_old_rflags = kprobe_old_rflags_prev; - kprobe_saved_rflags = kprobe_saved_rflags_prev; + __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 inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs) +static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) { - current_kprobe = p; - kprobe_saved_rflags = kprobe_old_rflags + __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)) - kprobe_saved_rflags &= ~IF_MASK; + kcb->kprobe_saved_rflags &= ~IF_MASK; } static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) @@ -301,6 +295,7 @@ 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 = get_kprobe_ctlblk(); /* Check we're not actually recursing */ if (kprobe_running()) { @@ -308,13 +303,13 @@ int __kprobes kprobe_handler(struct pt_regs *regs) Disarm the probe we just hit, and ignore it. */ p = get_kprobe(addr); if (p) { - if (kprobe_status == KPROBE_HIT_SS && + if (kcb->kprobe_status == KPROBE_HIT_SS && *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { regs->eflags &= ~TF_MASK; - regs->eflags |= kprobe_saved_rflags; + regs->eflags |= kcb->kprobe_saved_rflags; unlock_kprobes(); goto no_kprobe; - } else if (kprobe_status == KPROBE_HIT_SSDONE) { + } 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 @@ -322,6 +317,7 @@ int __kprobes kprobe_handler(struct pt_regs *regs) */ arch_disarm_kprobe(p); regs->rip = (unsigned long)p->addr; + reset_current_kprobe(); ret = 1; } else { /* We have reentered the kprobe_handler(), since @@ -331,15 +327,15 @@ int __kprobes kprobe_handler(struct pt_regs *regs) * of the new probe without calling any user * handlers. */ - save_previous_kprobe(); - set_current_kprobe(p, regs); + save_previous_kprobe(kcb); + set_current_kprobe(p, regs, kcb); p->nmissed++; prepare_singlestep(p, regs); - kprobe_status = KPROBE_REENTER; + kcb->kprobe_status = KPROBE_REENTER; return 1; } } else { - p = current_kprobe; + p = __get_cpu_var(current_kprobe); if (p->break_handler && p->break_handler(p, regs)) { goto ss_probe; } @@ -374,8 +370,8 @@ int __kprobes kprobe_handler(struct pt_regs *regs) * in post_kprobe_handler() */ preempt_disable(); - kprobe_status = KPROBE_HIT_ACTIVE; - set_current_kprobe(p, regs); + 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 */ @@ -383,7 +379,7 @@ int __kprobes kprobe_handler(struct pt_regs *regs) ss_probe: prepare_singlestep(p, regs); - kprobe_status = KPROBE_HIT_SS; + kcb->kprobe_status = KPROBE_HIT_SS; return 1; no_kprobe: @@ -451,6 +447,7 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address)); regs->rip = orig_ret_address; + reset_current_kprobe(); unlock_kprobes(); preempt_enable_no_resched(); @@ -484,7 +481,8 @@ int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) * 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) +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; @@ -499,7 +497,7 @@ static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs) switch (*insn) { case 0x9c: /* pushfl */ *tos &= ~(TF_MASK | IF_MASK); - *tos |= kprobe_old_rflags; + *tos |= kcb->kprobe_old_rflags; break; case 0xc3: /* ret/lret */ case 0xcb: @@ -544,24 +542,28 @@ static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs) */ int __kprobes post_kprobe_handler(struct pt_regs *regs) { - if (!kprobe_running()) + struct kprobe *cur = kprobe_running(); + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + if (!cur) return 0; - if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) { - kprobe_status = KPROBE_HIT_SSDONE; - current_kprobe->post_handler(current_kprobe, regs, 0); + if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { + kcb->kprobe_status = KPROBE_HIT_SSDONE; + cur->post_handler(cur, regs, 0); } - resume_execution(current_kprobe, regs); - regs->eflags |= kprobe_saved_rflags; + resume_execution(cur, regs, kcb); + regs->eflags |= kcb->kprobe_saved_rflags; /* Restore the original saved kprobes variables and continue. */ - if (kprobe_status == KPROBE_REENTER) { - restore_previous_kprobe(); + if (kcb->kprobe_status == KPROBE_REENTER) { + restore_previous_kprobe(kcb); goto out; } else { unlock_kprobes(); } + reset_current_kprobe(); out: preempt_enable_no_resched(); @@ -579,14 +581,17 @@ out: /* Interrupts disabled, kprobe_lock held. */ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) { - if (current_kprobe->fault_handler - && current_kprobe->fault_handler(current_kprobe, regs, trapnr)) + struct kprobe *cur = kprobe_running(); + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + + if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) return 1; - if (kprobe_status & KPROBE_HIT_SS) { - resume_execution(current_kprobe, regs); - regs->eflags |= kprobe_old_rflags; + if (kcb->kprobe_status & KPROBE_HIT_SS) { + resume_execution(cur, regs, kcb); + regs->eflags |= kcb->kprobe_old_rflags; + reset_current_kprobe(); unlock_kprobes(); preempt_enable_no_resched(); } @@ -629,10 +634,11 @@ 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(); - jprobe_saved_regs = *regs; - jprobe_saved_rsp = (long *) regs->rsp; - addr = (unsigned long)jprobe_saved_rsp; + 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. @@ -640,7 +646,8 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) * we also save and restore enough stack bytes to cover * the argument area. */ - memcpy(jprobes_stack, (kprobe_opcode_t *) addr, MIN_STACK_SIZE(addr)); + memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, + MIN_STACK_SIZE(addr)); regs->eflags &= ~IF_MASK; regs->rip = (unsigned long)(jp->entry); return 1; @@ -648,34 +655,38 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) 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" - (jprobe_saved_rsp):"memory"); + (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)jprobe_saved_rsp; + 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 != jprobe_saved_rsp) { + if ((long *)regs->rsp != kcb->jprobe_saved_rsp) { struct pt_regs *saved_regs = - container_of(jprobe_saved_rsp, struct pt_regs, rsp); + container_of(kcb->jprobe_saved_rsp, + struct pt_regs, rsp); printk("current rsp %p does not match saved rsp %p\n", - (long *)regs->rsp, jprobe_saved_rsp); + (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 = jprobe_saved_regs; - memcpy((kprobe_opcode_t *) stack_addr, jprobes_stack, + *regs = kcb->jprobe_saved_regs; + memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack, MIN_STACK_SIZE(stack_addr)); return 1; } diff --git a/include/asm-x86_64/kprobes.h b/include/asm-x86_64/kprobes.h index 6d6d883..4dd7a7e 100644 --- a/include/asm-x86_64/kprobes.h +++ b/include/asm-x86_64/kprobes.h @@ -25,6 +25,7 @@ */ #include <linux/types.h> #include <linux/ptrace.h> +#include <linux/percpu.h> struct pt_regs; @@ -48,6 +49,24 @@ struct arch_specific_insn { kprobe_opcode_t *insn; }; +struct prev_kprobe { + struct kprobe *kp; + unsigned long status; + unsigned long old_rflags; + unsigned long saved_rflags; +}; + +/* per-cpu kprobe control block */ +struct kprobe_ctlblk { + unsigned long kprobe_status; + unsigned long kprobe_old_rflags; + unsigned long kprobe_saved_rflags; + long *jprobe_saved_rsp; + struct pt_regs jprobe_saved_regs; + kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE]; + struct prev_kprobe prev_kprobe; +}; + /* trap3/1 are intr gates for kprobes. So, restore the status of IF, * if necessary, before executing the original int3/1 (trap) handler. */ |
