This reverts commit 77fa5e15c933a1ec812de61ad709c00aa51e96ae.

Since the upstream commit e792ff804f49720ce003b3e4c618b5d996256a18 depends on the generic kretprobe trampoline handler, which was introduced by commit 66ada2ccae4e ("kprobes: Add generic kretprobe trampoline handler") but that is not ported to the stable kernel because it is not a bugfix series. So revert this commit to fix a build error.

NOTE: I keep commit a7fe2378454c ("ia64: kprobes: Fix to pass correct trampoline address to the handler") on the tree, that seems just a cleanup without the original reverted commit, but it would be better to use dereference_function_descriptor() macro instead of accessing descriptor's field directly.

Fixes: 77fa5e15c933 ("ia64: kprobes: Use generic kretprobe trampoline handler") Reported-by: kernel test robot lkp@intel.com Signed-off-by: Masami Hiramatsu mhiramat@kernel.org --- Changes in v2: - fix the lack of type casting for dereference_function_descriptor(). --- arch/ia64/kernel/kprobes.c | 78 ++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 75 insertions(+), 3 deletions(-)

diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c index 8a223d0e4918..fa10d51f6217 100644 --- a/arch/ia64/kernel/kprobes.c +++ b/arch/ia64/kernel/kprobes.c @@ -396,10 +396,83 @@ 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 __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) { - regs->cr_iip = __kretprobe_trampoline_handler(regs, - dereference_function_descriptor(kretprobe_trampoline), NULL); + struct kretprobe_instance *ri = NULL; + struct hlist_head *head, empty_rp; + struct hlist_node *tmp; + unsigned long flags, orig_ret_address = 0; + unsigned long trampoline_address = + (unsigned long)dereference_function_descriptor(kretprobe_trampoline); + + INIT_HLIST_HEAD(&empty_rp); + kretprobe_hash_lock(current, &head, &flags); + + /* + * 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 than 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, tmp, head, hlist) { + if (ri->task != current) + /* another task is sharing our hash bucket */ + continue; + + orig_ret_address = (unsigned long)ri->ret_addr; + 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; + } + + regs->cr_iip = orig_ret_address; + + hlist_for_each_entry_safe(ri, 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); + + kretprobe_hash_unlock(current, &flags); + + hlist_for_each_entry_safe(ri, 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 @@ -412,7 +485,6 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) { ri->ret_addr = (kprobe_opcode_t *)regs->b0; - ri->fp = NULL;

/* Replace the return addr with trampoline addr */ regs->b0 = (unsigned long)dereference_function_descriptor(kretprobe_trampoline);