diff options
Diffstat (limited to 'arch/i386/kernel/kprobes.c')
| -rw-r--r-- | arch/i386/kernel/kprobes.c | 176 |
1 files changed, 160 insertions, 16 deletions
diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c index 59ff9b45506..3762f6b35ab 100644 --- a/arch/i386/kernel/kprobes.c +++ b/arch/i386/kernel/kprobes.c @@ -23,6 +23,9 @@ * Rusty Russell). * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes * interface to access function arguments. + * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston + * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi + * <prasanna@in.ibm.com> added function-return probes. */ #include <linux/config.h> @@ -30,15 +33,14 @@ #include <linux/ptrace.h> #include <linux/spinlock.h> #include <linux/preempt.h> +#include <asm/cacheflush.h> #include <asm/kdebug.h> #include <asm/desc.h> -/* kprobe_status settings */ -#define KPROBE_HIT_ACTIVE 0x00000001 -#define KPROBE_HIT_SS 0x00000002 - static struct kprobe *current_kprobe; static unsigned long kprobe_status, kprobe_old_eflags, kprobe_saved_eflags; +static struct kprobe *kprobe_prev; +static unsigned long kprobe_status_prev, kprobe_old_eflags_prev, kprobe_saved_eflags_prev; static struct pt_regs jprobe_saved_regs; static long *jprobe_saved_esp; /* copy of the kernel stack at the probe fire time */ @@ -68,16 +70,50 @@ int arch_prepare_kprobe(struct kprobe *p) void arch_copy_kprobe(struct kprobe *p) { memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); + p->opcode = *p->addr; } -void arch_remove_kprobe(struct kprobe *p) +void 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)); } -static inline void disarm_kprobe(struct kprobe *p, struct pt_regs *regs) +void arch_disarm_kprobe(struct kprobe *p) { *p->addr = p->opcode; - regs->eip = (unsigned long)p->addr; + flush_icache_range((unsigned long) p->addr, + (unsigned long) p->addr + sizeof(kprobe_opcode_t)); +} + +void arch_remove_kprobe(struct kprobe *p) +{ +} + +static inline void save_previous_kprobe(void) +{ + kprobe_prev = current_kprobe; + kprobe_status_prev = kprobe_status; + kprobe_old_eflags_prev = kprobe_old_eflags; + kprobe_saved_eflags_prev = kprobe_saved_eflags; +} + +static inline void restore_previous_kprobe(void) +{ + current_kprobe = kprobe_prev; + kprobe_status = kprobe_status_prev; + kprobe_old_eflags = kprobe_old_eflags_prev; + kprobe_saved_eflags = kprobe_saved_eflags_prev; +} + +static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs) +{ + current_kprobe = p; + kprobe_saved_eflags = kprobe_old_eflags + = (regs->eflags & (TF_MASK | IF_MASK)); + if (is_IF_modifier(p->opcode)) + kprobe_saved_eflags &= ~IF_MASK; } static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) @@ -91,6 +127,50 @@ static inline void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) regs->eip = (unsigned long)&p->ainsn.insn; } +struct task_struct *arch_get_kprobe_task(void *ptr) +{ + return ((struct thread_info *) (((unsigned long) ptr) & + (~(THREAD_SIZE -1))))->task; +} + +void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs) +{ + unsigned long *sara = (unsigned long *)®s->esp; + struct kretprobe_instance *ri; + static void *orig_ret_addr; + + /* + * Save the return address when the return probe hits + * the first time, and use it to populate the (krprobe + * instance)->ret_addr for subsequent return probes at + * the same addrress since stack address would have + * the kretprobe_trampoline by then. + */ + if (((void*) *sara) != kretprobe_trampoline) + orig_ret_addr = (void*) *sara; + + if ((ri = get_free_rp_inst(rp)) != NULL) { + ri->rp = rp; + ri->stack_addr = sara; + ri->ret_addr = orig_ret_addr; + add_rp_inst(ri); + /* Replace the return addr with trampoline addr */ + *sara = (unsigned long) &kretprobe_trampoline; + } else { + rp->nmissed++; + } +} + +void arch_kprobe_flush_task(struct task_struct *tk) +{ + struct kretprobe_instance *ri; + while ((ri = get_rp_inst_tsk(tk)) != NULL) { + *((unsigned long *)(ri->stack_addr)) = + (unsigned long) ri->ret_addr; + recycle_rp_inst(ri); + } +} + /* * Interrupts are disabled on entry as trap3 is an interrupt gate and they * remain disabled thorough out this function. @@ -127,8 +207,18 @@ static int kprobe_handler(struct pt_regs *regs) unlock_kprobes(); goto no_kprobe; } - disarm_kprobe(p, regs); - ret = 1; + /* We have reentered the kprobe_handler(), since + * another probe was hit while within the handler. + * We here save the original kprobes variables and + * just single step on the instruction of the new probe + * without calling any user handlers. + */ + save_previous_kprobe(); + set_current_kprobe(p, regs); + p->nmissed++; + prepare_singlestep(p, regs); + kprobe_status = KPROBE_REENTER; + return 1; } else { p = current_kprobe; if (p->break_handler && p->break_handler(p, regs)) { @@ -163,11 +253,7 @@ static int kprobe_handler(struct pt_regs *regs) } kprobe_status = KPROBE_HIT_ACTIVE; - current_kprobe = p; - kprobe_saved_eflags = kprobe_old_eflags - = (regs->eflags & (TF_MASK | IF_MASK)); - if (is_IF_modifier(p->opcode)) - kprobe_saved_eflags &= ~IF_MASK; + set_current_kprobe(p, regs); if (p->pre_handler && p->pre_handler(p, regs)) /* handler has already set things up, so skip ss setup */ @@ -184,6 +270,55 @@ no_kprobe: } /* + * 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 trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct task_struct *tsk; + struct kretprobe_instance *ri; + struct hlist_head *head; + struct hlist_node *node; + unsigned long *sara = ((unsigned long *) ®s->esp) - 1; + + tsk = arch_get_kprobe_task(sara); + head = kretprobe_inst_table_head(tsk); + + hlist_for_each_entry(ri, node, head, hlist) { + if (ri->stack_addr == sara && ri->rp) { + if (ri->rp->handler) + ri->rp->handler(ri, regs); + } + } + return 0; +} + +void trampoline_post_handler(struct kprobe *p, struct pt_regs *regs, + unsigned long flags) +{ + struct kretprobe_instance *ri; + /* RA already popped */ + unsigned long *sara = ((unsigned long *)®s->esp) - 1; + + while ((ri = get_rp_inst(sara))) { + regs->eip = (unsigned long)ri->ret_addr; + recycle_rp_inst(ri); + } + regs->eflags &= ~TF_MASK; +} + +/* * 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 @@ -263,13 +398,22 @@ static inline int post_kprobe_handler(struct pt_regs *regs) if (!kprobe_running()) return 0; - if (current_kprobe->post_handler) + if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) { + kprobe_status = KPROBE_HIT_SSDONE; current_kprobe->post_handler(current_kprobe, regs, 0); + } - resume_execution(current_kprobe, regs); + if (current_kprobe->post_handler != trampoline_post_handler) + resume_execution(current_kprobe, regs); regs->eflags |= kprobe_saved_eflags; + /*Restore back the original saved kprobes variables and continue. */ + if (kprobe_status == KPROBE_REENTER) { + restore_previous_kprobe(); + goto out; + } unlock_kprobes(); +out: preempt_enable_no_resched(); /* |