On Wed, 25 Apr 2018 21:16:06 +0900 Masami Hiramatsu <[email protected]> wrote:
> Hi, > > This is the 7th version of the fetch-arg improvement series. > This includes variable changes on fetcharg framework like, > > - Add fetcharg testcases (syntax, argN, symbol, string and array) > and probepoint testcase. > - Rewrite fetcharg framework with fetch_insn, switch-case based > instead of function pointer. > - Add "symbol" type support, which shows symbol+offset instead of > address value. > - Add "$argN" fetcharg, which fetches function parameters. > (currently only for x86-64) > - Add array type support (including string arrary :) ) , > which enables to get fixed length array from probe-events. > - Add array type support for perf-probe, so that user can > dump partial array entries. > > V6 is here: > https://lkml.org/lkml/2018/3/17/75 > > Changes from the v6 are here: > [6/16] - Fix to return an error if failed to fetch string and > fill zero-length data_loc in error case. > [11/16] - Update document for restructured text. > [15/16] - Fix README test. > [16/16] - Add type-casting description (and note) to documentation. > > And rebased on the latest Steve's ftrace/core branch. > Hi Masami, I skimmed through the patches and it they appear fine. I've applied them and started playing a little. I've been thinking my function based events, and thought instead I would make them part of the kprobe infrastructure. Just have a slightly different format, and instead of being p: or r: be f: And keep the format I was suggesting. What do you think? Also, when looking at the kprobe code, I was looking at this function: > /* Ftrace callback handler for kprobes -- called under preepmt disabed */ > void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, > struct ftrace_ops *ops, struct pt_regs *regs) > { > struct kprobe *p; > struct kprobe_ctlblk *kcb; > > /* Preempt is disabled by ftrace */ > p = get_kprobe((kprobe_opcode_t *)ip); > if (unlikely(!p) || kprobe_disabled(p)) > return; > > kcb = get_kprobe_ctlblk(); > if (kprobe_running()) { > kprobes_inc_nmissed_count(p); > } else { > unsigned long orig_ip = regs->ip; > /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */ > regs->ip = ip + sizeof(kprobe_opcode_t); > > /* To emulate trap based kprobes, preempt_disable here */ > preempt_disable(); > __this_cpu_write(current_kprobe, p); > kcb->kprobe_status = KPROBE_HIT_ACTIVE; > if (!p->pre_handler || !p->pre_handler(p, regs)) { > __skip_singlestep(p, regs, kcb, orig_ip); > preempt_enable_no_resched(); This preemption disabling and enabling looks rather strange. Looking at git blame, it appears this was added for jprobes. Can we remove it now that jprobes is going away? > } > /* > * If pre_handler returns !0, it sets regs->ip and > * resets current kprobe, and keep preempt count +1. > */ > } > } -- Steve
