diff options
| -rw-r--r-- | arch/x86_64/kernel/kprobes.c | 98 | ||||
| -rw-r--r-- | arch/x86_64/kernel/process.c | 16 | ||||
| -rw-r--r-- | include/asm-x86_64/kprobes.h | 3 |
3 files changed, 116 insertions, 1 deletions
diff --git a/arch/x86_64/kernel/kprobes.c b/arch/x86_64/kernel/kprobes.c index f77f8a0ff18..203672ca740 100644 --- a/arch/x86_64/kernel/kprobes.c +++ b/arch/x86_64/kernel/kprobes.c @@ -27,6 +27,8 @@ * <prasanna@in.ibm.com> adapted for x86_64 * 2005-Mar Roland McGrath <roland@redhat.com> * Fixed to handle %rip-relative addressing mode correctly. + * 2005-May Rusty Lynch <rusty.lynch@intel.com> + * Added function return probes functionality */ #include <linux/config.h> @@ -240,6 +242,50 @@ static void prepare_singlestep(struct kprobe *p, struct pt_regs *regs) regs->rip = (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 *)regs->rsp; + 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. @@ -317,6 +363,55 @@ 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 *)regs->rsp - 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 *)regs->rsp) - 1; + + while ((ri = get_rp_inst(sara))) { + regs->rip = (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 @@ -404,7 +499,8 @@ int post_kprobe_handler(struct pt_regs *regs) if (current_kprobe->post_handler) 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_rflags; unlock_kprobes(); diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c index dce8bab4306..e59d1f9d616 100644 --- a/arch/x86_64/kernel/process.c +++ b/arch/x86_64/kernel/process.c @@ -34,6 +34,7 @@ #include <linux/ptrace.h> #include <linux/utsname.h> #include <linux/random.h> +#include <linux/kprobes.h> #include <asm/uaccess.h> #include <asm/pgtable.h> @@ -293,6 +294,14 @@ void exit_thread(void) { struct task_struct *me = current; struct thread_struct *t = &me->thread; + + /* + * Remove function-return probe instances associated with this task + * and put them back on the free list. Do not insert an exit probe for + * this function, it will be disabled by kprobe_flush_task if you do. + */ + kprobe_flush_task(me); + if (me->thread.io_bitmap_ptr) { struct tss_struct *tss = &per_cpu(init_tss, get_cpu()); @@ -312,6 +321,13 @@ void flush_thread(void) struct task_struct *tsk = current; struct thread_info *t = current_thread_info(); + /* + * Remove function-return probe instances associated with this task + * and put them back on the free list. Do not insert an exit probe for + * this function, it will be disabled by kprobe_flush_task if you do. + */ + kprobe_flush_task(tsk); + if (t->flags & _TIF_ABI_PENDING) t->flags ^= (_TIF_ABI_PENDING | _TIF_IA32); diff --git a/include/asm-x86_64/kprobes.h b/include/asm-x86_64/kprobes.h index bfea52d516f..6d6d883fdf6 100644 --- a/include/asm-x86_64/kprobes.h +++ b/include/asm-x86_64/kprobes.h @@ -38,6 +38,9 @@ typedef u8 kprobe_opcode_t; : (((unsigned long)current_thread_info()) + THREAD_SIZE - (ADDR))) #define JPROBE_ENTRY(pentry) (kprobe_opcode_t *)pentry +#define ARCH_SUPPORTS_KRETPROBES + +void kretprobe_trampoline(void); /* Architecture specific copy of original instruction*/ struct arch_specific_insn { |