diff options
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/ia64/kernel/kprobes.c | 103 | ||||
| -rw-r--r-- | arch/ia64/kernel/process.c | 16 |
2 files changed, 117 insertions, 2 deletions
diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c index 5978823d5c6..c97e18e634c 100644 --- a/arch/ia64/kernel/kprobes.c +++ b/arch/ia64/kernel/kprobes.c @@ -290,6 +290,94 @@ static inline void set_current_kprobe(struct kprobe *p) current_kprobe = p; } +static void kretprobe_trampoline(void) +{ +} + +/* + * At this point the target function has been tricked into + * returning into our trampoline. Lookup the associated instance + * and then: + * - call the handler function + * - cleanup by marking the instance as unused + * - long jump back to the original return address + */ +int 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 trampoline_address = + ((struct fnptr *)kretprobe_trampoline)->ip; + + head = kretprobe_inst_table_head(current); + + /* + * It is possible to have multiple instances associated with a given + * task either because an multiple functions in the call path + * have a return probe installed on them, and/or more then one return + * return probe was registered for a target function. + * + * We can handle this because: + * - instances are always inserted at the head of the list + * - when multiple return probes are registered for the same + * function, the first instance's ret_addr will point to the + * real return address, and all the rest will point to + * kretprobe_trampoline + */ + hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { + if (ri->task != current) + /* another task is sharing our hash bucket */ + continue; + + if (ri->rp && ri->rp->handler) + ri->rp->handler(ri, regs); + + orig_ret_address = (unsigned long)ri->ret_addr; + recycle_rp_inst(ri); + + if (orig_ret_address != trampoline_address) + /* + * This is the real return address. Any other + * instances associated with this task are for + * other calls deeper on the call stack + */ + break; + } + + BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address)); + regs->cr_iip = orig_ret_address; + + unlock_kprobes(); + preempt_enable_no_resched(); + + /* + * By returning a non-zero value, we are telling + * kprobe_handler() that we have handled unlocking + * and re-enabling preemption. + */ + return 1; +} + +void arch_prepare_kretprobe(struct kretprobe *rp, struct pt_regs *regs) +{ + struct kretprobe_instance *ri; + + if ((ri = get_free_rp_inst(rp)) != NULL) { + ri->rp = rp; + ri->task = current; + ri->ret_addr = (kprobe_opcode_t *)regs->b0; + + /* Replace the return addr with trampoline addr */ + regs->b0 = ((struct fnptr *)kretprobe_trampoline)->ip; + + add_rp_inst(ri); + } else { + rp->nmissed++; + } +} + int arch_prepare_kprobe(struct kprobe *p) { unsigned long addr = (unsigned long) p->addr; @@ -492,8 +580,8 @@ static int pre_kprobes_handler(struct die_args *args) if (p->pre_handler && p->pre_handler(p, regs)) /* * Our pre-handler is specifically requesting that we just - * do a return. This is handling the case where the - * pre-handler is really our special jprobe pre-handler. + * do a return. This is used for both the jprobe pre-handler + * and the kretprobe trampoline */ return 1; @@ -599,3 +687,14 @@ int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) *regs = jprobe_saved_regs; return 1; } + +static struct kprobe trampoline_p = { + .pre_handler = trampoline_probe_handler +}; + +int __init arch_init(void) +{ + trampoline_p.addr = + (kprobe_opcode_t *)((struct fnptr *)kretprobe_trampoline)->ip; + return register_kprobe(&trampoline_p); +} diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c index ebb71f3d6d1..6e35bff05d5 100644 --- a/arch/ia64/kernel/process.c +++ b/arch/ia64/kernel/process.c @@ -27,6 +27,7 @@ #include <linux/efi.h> #include <linux/interrupt.h> #include <linux/delay.h> +#include <linux/kprobes.h> #include <asm/cpu.h> #include <asm/delay.h> @@ -707,6 +708,13 @@ kernel_thread_helper (int (*fn)(void *), void *arg) void flush_thread (void) { + /* + * 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(current); + /* drop floating-point and debug-register state if it exists: */ current->thread.flags &= ~(IA64_THREAD_FPH_VALID | IA64_THREAD_DBG_VALID); ia64_drop_fpu(current); @@ -721,6 +729,14 @@ flush_thread (void) void exit_thread (void) { + + /* + * 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(current); + ia64_drop_fpu(current); #ifdef CONFIG_PERFMON /* if needed, stop monitoring and flush state to perfmon context */ |