[SPARC64]: Add kretprobe support.
Passes the smoke tests at least, powerpc implementation was used as a guide. Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -480,8 +480,117 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
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return 0;
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}
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/* architecture specific initialization */
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int arch_init_kprobes(void)
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/* Called with kretprobe_lock held. The value stored in the return
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* address register is actually 2 instructions before where the
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* callee will return to. Sequences usually look something like this
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*
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* call some_function <--- return register points here
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* nop <--- call delay slot
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* whatever <--- where callee returns to
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*
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* To keep trampoline_probe_handler logic simpler, we normalize the
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* value kept in ri->ret_addr so we don't need to keep adjusting it
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* back and forth.
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*/
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void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
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struct pt_regs *regs)
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{
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ri->ret_addr = (kprobe_opcode_t *)(regs->u_regs[UREG_RETPC] + 8);
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/* Replace the return addr with trampoline addr */
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regs->u_regs[UREG_RETPC] =
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((unsigned long)kretprobe_trampoline) - 8;
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}
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/*
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* Called when the probe at kretprobe trampoline is hit
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*/
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int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
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{
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struct kretprobe_instance *ri = NULL;
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struct hlist_head *head, empty_rp;
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struct hlist_node *node, *tmp;
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unsigned long flags, orig_ret_address = 0;
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unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
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INIT_HLIST_HEAD(&empty_rp);
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spin_lock_irqsave(&kretprobe_lock, flags);
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head = kretprobe_inst_table_head(current);
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/*
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* It is possible to have multiple instances associated with a given
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* task either because an multiple functions in the call path
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* have a return probe installed on them, and/or more then one return
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* return probe was registered for a target function.
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*
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* We can handle this because:
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* - instances are always inserted at the head of the list
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* - when multiple return probes are registered for the same
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* function, the first instance's ret_addr will point to the
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* real return address, and all the rest will point to
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* kretprobe_trampoline
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*/
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hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
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if (ri->task != current)
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/* another task is sharing our hash bucket */
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continue;
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if (ri->rp && ri->rp->handler)
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ri->rp->handler(ri, regs);
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orig_ret_address = (unsigned long)ri->ret_addr;
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recycle_rp_inst(ri, &empty_rp);
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if (orig_ret_address != trampoline_address)
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/*
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* This is the real return address. Any other
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* instances associated with this task are for
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* other calls deeper on the call stack
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*/
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break;
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}
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kretprobe_assert(ri, orig_ret_address, trampoline_address);
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regs->tpc = orig_ret_address;
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regs->tnpc = orig_ret_address + 4;
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reset_current_kprobe();
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spin_unlock_irqrestore(&kretprobe_lock, flags);
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preempt_enable_no_resched();
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hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
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hlist_del(&ri->hlist);
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kfree(ri);
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}
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/*
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* By returning a non-zero value, we are telling
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* kprobe_handler() that we don't want the post_handler
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* to run (and have re-enabled preemption)
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*/
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return 1;
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}
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void kretprobe_trampoline_holder(void)
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{
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asm volatile(".global kretprobe_trampoline\n"
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"kretprobe_trampoline:\n"
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"\tnop\n"
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"\tnop\n");
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}
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static struct kprobe trampoline_p = {
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.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
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.pre_handler = trampoline_probe_handler
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};
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int __init arch_init_kprobes(void)
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{
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return register_kprobe(&trampoline_p);
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}
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int __kprobes arch_trampoline_kprobe(struct kprobe *p)
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{
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if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline)
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return 1;
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return 0;
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}
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@ -14,11 +14,15 @@ typedef u32 kprobe_opcode_t;
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#define arch_remove_kprobe(p) do {} while (0)
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#define ARCH_SUPPORTS_KRETPROBES
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#define flush_insn_slot(p) \
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do { flushi(&(p)->ainsn.insn[0]); \
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flushi(&(p)->ainsn.insn[1]); \
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} while (0)
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void kretprobe_trampoline(void);
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/* Architecture specific copy of original instruction*/
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struct arch_specific_insn {
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/* copy of the original instruction */
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