diff options
| -rw-r--r-- | arch/sparc64/kernel/kprobes.c | 113 | ||||
| -rw-r--r-- | include/asm-sparc64/kprobes.h | 4 |
2 files changed, 115 insertions, 2 deletions
diff --git a/arch/sparc64/kernel/kprobes.c b/arch/sparc64/kernel/kprobes.c index d94f901d321..34fc3ddd500 100644 --- a/arch/sparc64/kernel/kprobes.c +++ b/arch/sparc64/kernel/kprobes.c @@ -480,8 +480,117 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) return 0; } -/* architecture specific initialization */ -int arch_init_kprobes(void) +/* Called with kretprobe_lock held. The value stored in the return + * address register is actually 2 instructions before where the + * callee will return to. Sequences usually look something like this + * + * call some_function <--- return register points here + * nop <--- call delay slot + * whatever <--- where callee returns to + * + * To keep trampoline_probe_handler logic simpler, we normalize the + * value kept in ri->ret_addr so we don't need to keep adjusting it + * back and forth. + */ +void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, + struct pt_regs *regs) +{ + ri->ret_addr = (kprobe_opcode_t *)(regs->u_regs[UREG_RETPC] + 8); + + /* Replace the return addr with trampoline addr */ + regs->u_regs[UREG_RETPC] = + ((unsigned long)kretprobe_trampoline) - 8; +} + +/* + * Called when the probe at kretprobe trampoline is hit + */ +int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) +{ + struct kretprobe_instance *ri = NULL; + struct hlist_head *head, empty_rp; + struct hlist_node *node, *tmp; + unsigned long flags, orig_ret_address = 0; + unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; + + INIT_HLIST_HEAD(&empty_rp); + spin_lock_irqsave(&kretprobe_lock, flags); + 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, &empty_rp); + + 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; + } + + kretprobe_assert(ri, orig_ret_address, trampoline_address); + regs->tpc = orig_ret_address; + regs->tnpc = orig_ret_address + 4; + + reset_current_kprobe(); + spin_unlock_irqrestore(&kretprobe_lock, flags); + preempt_enable_no_resched(); + + hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { + hlist_del(&ri->hlist); + kfree(ri); + } + /* + * By returning a non-zero value, we are telling + * kprobe_handler() that we don't want the post_handler + * to run (and have re-enabled preemption) + */ + return 1; +} + +void kretprobe_trampoline_holder(void) +{ + asm volatile(".global kretprobe_trampoline\n" + "kretprobe_trampoline:\n" + "\tnop\n" + "\tnop\n"); +} +static struct kprobe trampoline_p = { + .addr = (kprobe_opcode_t *) &kretprobe_trampoline, + .pre_handler = trampoline_probe_handler +}; + +int __init arch_init_kprobes(void) { + return register_kprobe(&trampoline_p); +} + +int __kprobes arch_trampoline_kprobe(struct kprobe *p) +{ + if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline) + return 1; + return 0; } diff --git a/include/asm-sparc64/kprobes.h b/include/asm-sparc64/kprobes.h index 5020eaf67c2..7237dd87663 100644 --- a/include/asm-sparc64/kprobes.h +++ b/include/asm-sparc64/kprobes.h @@ -14,11 +14,15 @@ typedef u32 kprobe_opcode_t; #define arch_remove_kprobe(p) do {} while (0) +#define ARCH_SUPPORTS_KRETPROBES + #define flush_insn_slot(p) \ do { flushi(&(p)->ainsn.insn[0]); \ flushi(&(p)->ainsn.insn[1]); \ } while (0) +void kretprobe_trampoline(void); + /* Architecture specific copy of original instruction*/ struct arch_specific_insn { /* copy of the original instruction */ |