X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=arch%2Fx86_64%2Fkernel%2Fkprobes.c;h=9bef2c8dc12ca729853142a105cc201dba899dd7;hb=991a51d83a3d9bebfafdd1e692cf310899d60791;hp=5c6dc705148299e5cede75693244e10ebe367410;hpb=c514720716c7b109ff980f8b3cb93f9af872c91c;p=linux-2.6 diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c index 5c6dc70514..9bef2c8dc1 100644 --- a/arch/x86_64/kernel/kprobes.c +++ b/arch/x86_64/kernel/kprobes.c @@ -34,7 +34,6 @@ #include #include #include -#include #include #include #include @@ -44,17 +43,10 @@ #include 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. @@ -74,12 +66,12 @@ static inline int is_IF_modifier(kprobe_opcode_t *insn) return 0; } -int arch_prepare_kprobe(struct kprobe *p) +int __kprobes arch_prepare_kprobe(struct kprobe *p) { /* insn: must be on special executable page on x86_64. */ - up(&kprobe_mutex); - p->ainsn.insn = get_insn_slot(); down(&kprobe_mutex); + p->ainsn.insn = get_insn_slot(); + up(&kprobe_mutex); if (!p->ainsn.insn) { return -ENOMEM; } @@ -189,7 +181,7 @@ static inline s32 *is_riprel(u8 *insn) return NULL; } -void arch_copy_kprobe(struct kprobe *p) +void __kprobes arch_copy_kprobe(struct kprobe *p) { s32 *ripdisp; memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE); @@ -215,53 +207,54 @@ void arch_copy_kprobe(struct kprobe *p) p->opcode = *p->addr; } -void arch_arm_kprobe(struct kprobe *p) +void __kprobes arch_arm_kprobe(struct kprobe *p) { *p->addr = BREAKPOINT_INSTRUCTION; flush_icache_range((unsigned long) p->addr, (unsigned long) p->addr + sizeof(kprobe_opcode_t)); } -void arch_disarm_kprobe(struct kprobe *p) +void __kprobes arch_disarm_kprobe(struct kprobe *p) { *p->addr = p->opcode; flush_icache_range((unsigned long) p->addr, (unsigned long) p->addr + sizeof(kprobe_opcode_t)); } -void arch_remove_kprobe(struct kprobe *p) +void __kprobes arch_remove_kprobe(struct kprobe *p) { - up(&kprobe_mutex); - free_insn_slot(p->ainsn.insn); down(&kprobe_mutex); + free_insn_slot(p->ainsn.insn); + 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 prepare_singlestep(struct kprobe *p, struct pt_regs *regs) +static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) { regs->eflags |= TF_MASK; regs->eflags &= ~IF_MASK; @@ -272,7 +265,9 @@ static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) regs->rip = (unsigned long)p->ainsn.insn; } -void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs) +/* Called with kretprobe_lock held */ +void __kprobes arch_prepare_kretprobe(struct kretprobe *rp, + struct pt_regs *regs) { unsigned long *sara = (unsigned long *)regs->rsp; struct kretprobe_instance *ri; @@ -295,27 +290,23 @@ void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs) * Interrupts are disabled on entry as trap3 is an interrupt gate and they * remain disabled thorough out this function. */ -int kprobe_handler(struct pt_regs *regs) +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)); - - /* We're in an interrupt, but this is clear and BUG()-safe. */ - preempt_disable(); + struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); /* Check we're not actually recursing */ if (kprobe_running()) { - /* We *are* holding lock here, so this is safe. - 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; - unlock_kprobes(); + regs->eflags |= kcb->kprobe_saved_rflags; 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 @@ -323,6 +314,7 @@ int 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 @@ -332,27 +324,24 @@ int 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; } } - /* If it's not ours, can't be delete race, (we hold lock). */ goto no_kprobe; } - lock_kprobes(); p = get_kprobe(addr); if (!p) { - unlock_kprobes(); if (*addr != BREAKPOINT_INSTRUCTION) { /* * The breakpoint instruction was removed right @@ -360,15 +349,23 @@ int kprobe_handler(struct pt_regs *regs) * 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; } - kprobe_status = KPROBE_HIT_ACTIVE; - set_current_kprobe(p, regs); + /* + * This preempt_disable() matches the preempt_enable_no_resched() + * in post_kprobe_handler() + */ + preempt_disable(); + 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 */ @@ -376,11 +373,10 @@ int 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: - preempt_enable_no_resched(); return ret; } @@ -399,14 +395,15 @@ no_kprobe: /* * Called when we hit the probe point at kretprobe_trampoline */ -int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) +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 orig_ret_address = 0; + 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); /* @@ -445,13 +442,14 @@ int 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; - unlock_kprobes(); + 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 have handled unlocking - * and re-enabling preemption. + * and re-enabling preemption */ return 1; } @@ -478,7 +476,8 @@ int 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 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; @@ -493,7 +492,7 @@ static void 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: @@ -532,30 +531,28 @@ static void resume_execution(struct kprobe *p, struct pt_regs *regs) } } -/* - * Interrupts are disabled on entry as trap1 is an interrupt gate and they - * remain disabled thoroughout this function. And we hold kprobe lock. - */ -int post_kprobe_handler(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(); @@ -570,18 +567,19 @@ out: return 1; } -/* Interrupts disabled, kprobe_lock held. */ -int kprobe_fault_handler(struct pt_regs *regs, int trapnr) +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; - unlock_kprobes(); + reset_current_kprobe(); preempt_enable_no_resched(); } return 0; @@ -590,43 +588,44 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr) /* * Wrapper routine for handling exceptions. */ -int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, - void *data) +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; + + rcu_read_lock(); switch (val) { case DIE_INT3: if (kprobe_handler(args->regs)) - return NOTIFY_STOP; + ret = NOTIFY_STOP; break; case DIE_DEBUG: if (post_kprobe_handler(args->regs)) - return NOTIFY_STOP; + ret = NOTIFY_STOP; break; case DIE_GPF: - if (kprobe_running() && - kprobe_fault_handler(args->regs, args->trapnr)) - return NOTIFY_STOP; - break; case DIE_PAGE_FAULT: if (kprobe_running() && kprobe_fault_handler(args->regs, args->trapnr)) - return NOTIFY_STOP; + ret = NOTIFY_STOP; break; default: break; } - return NOTIFY_DONE; + rcu_read_unlock(); + return ret; } -int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) +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. @@ -634,43 +633,47 @@ int 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; } -void jprobe_return(void) +void __kprobes jprobe_return(void) { - preempt_enable_no_resched(); + 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 longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) +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; }