On Tue, Sep 23, 2025 at 09:34:20PM +0800, Menglong Dong wrote: > On 2025/9/23 20:25, Jiri Olsa wrote: > > On Tue, Sep 23, 2025 at 07:16:55PM +0800, [email protected] wrote: > > > On 2025/9/23 19:10 Jiri Olsa <[email protected]> write: > > > > On Tue, Sep 23, 2025 at 05:20:01PM +0800, Menglong Dong wrote: > > > > > For now, fgraph is used for the fprobe, even if we need trace the > > > > > entry > > > > > only. However, the performance of ftrace is better than fgraph, and we > > > > > can use ftrace_ops for this case. > > > > > > > > > > Then performance of kprobe-multi increases from 54M to 69M. Before > > > > > this > > > > > commit: > > > > > > > > > > $ ./benchs/run_bench_trigger.sh kprobe-multi > > > > > kprobe-multi : 54.663 ± 0.493M/s > > > > > > > > > > After this commit: > > > > > > > > > > $ ./benchs/run_bench_trigger.sh kprobe-multi > > > > > kprobe-multi : 69.447 ± 0.143M/s > > > > > > > > > > Mitigation is disable during the bench testing above. > > > > > > > > > > Signed-off-by: Menglong Dong <[email protected]> > > > > > --- > > > > > kernel/trace/fprobe.c | 88 > > > > > +++++++++++++++++++++++++++++++++++++++---- > > > > > 1 file changed, 81 insertions(+), 7 deletions(-) > > > > > > > > > > diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c > > > > > index 1785fba367c9..de4ae075548d 100644 > > > > > --- a/kernel/trace/fprobe.c > > > > > +++ b/kernel/trace/fprobe.c > > > > > @@ -292,7 +292,7 @@ static int fprobe_fgraph_entry(struct > > > > > ftrace_graph_ent *trace, struct fgraph_ops > > > > > if (node->addr != func) > > > > > continue; > > > > > fp = READ_ONCE(node->fp); > > > > > - if (fp && !fprobe_disabled(fp)) > > > > > + if (fp && !fprobe_disabled(fp) && > > > > > fp->exit_handler) > > > > > fp->nmissed++; > > > > > } > > > > > return 0; > > > > > @@ -312,11 +312,11 @@ static int fprobe_fgraph_entry(struct > > > > > ftrace_graph_ent *trace, struct fgraph_ops > > > > > if (node->addr != func) > > > > > continue; > > > > > fp = READ_ONCE(node->fp); > > > > > - if (!fp || fprobe_disabled(fp)) > > > > > + if (unlikely(!fp || fprobe_disabled(fp) || > > > > > !fp->exit_handler)) > > > > > continue; > > > > > > > > > > data_size = fp->entry_data_size; > > > > > - if (data_size && fp->exit_handler) > > > > > + if (data_size) > > > > > data = fgraph_data + used + > > > > > FPROBE_HEADER_SIZE_IN_LONG; > > > > > else > > > > > data = NULL; > > > > > @@ -327,7 +327,7 @@ static int fprobe_fgraph_entry(struct > > > > > ftrace_graph_ent *trace, struct fgraph_ops > > > > > ret = __fprobe_handler(func, ret_ip, fp, fregs, > > > > > data); > > > > > > > > > > /* If entry_handler returns !0, nmissed is not counted > > > > > but skips exit_handler. */ > > > > > - if (!ret && fp->exit_handler) { > > > > > + if (!ret) { > > > > > int size_words = SIZE_IN_LONG(data_size); > > > > > > > > > > if (write_fprobe_header(&fgraph_data[used], fp, > > > > > size_words)) > > > > > @@ -384,6 +384,70 @@ static struct fgraph_ops fprobe_graph_ops = { > > > > > }; > > > > > static int fprobe_graph_active; > > > > > > > > > > +/* ftrace_ops backend (entry-only) */ > > > > > +static void fprobe_ftrace_entry(unsigned long ip, unsigned long > > > > > parent_ip, > > > > > + struct ftrace_ops *ops, struct ftrace_regs *fregs) > > > > > +{ > > > > > + struct fprobe_hlist_node *node; > > > > > + struct rhlist_head *head, *pos; > > > > > + struct fprobe *fp; > > > > > + > > > > > + guard(rcu)(); > > > > > + head = rhltable_lookup(&fprobe_ip_table, &ip, > > > > > fprobe_rht_params); > > > > > > > > hi, > > > > so this is based on yout previous patch, right? > > > > fprobe: use rhltable for fprobe_ip_table > > > > > > > > would be better to mention that.. is there latest version of that > > > > somewhere? > > > > > > Yeah, this is based on that version. That patch is applied > > > to: > > > https://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git/log/?h=probes%2Ffor-next > > > > > > And I do the testing on that branches. > > > > did you run 'test_progs -t kprobe_multi' ? it silently crashes the > > kernel for me.. attaching config > > Hi. I have tested the whole test_progs and it passed. > > In fact, your config will panic even without this patch. > Please don't enable CONFIG_X86_KERNEL_IBT, the recursion > of the is_endbr() still exist until this series apply: > > tracing: fprobe: Protect return handler from recursion loop
ugh, I thought it's there already, thanks jirka
