On Wed, 13 Dec 2023 20:09:14 +0530 Naveen N Rao <[email protected]> wrote:
> Trying to probe update_sd_lb_stats() using perf results in the below > message in the kernel log: > trace_kprobe: Could not probe notrace function _text > > This is because 'perf probe' specifies the kprobe location as an offset > from '_text': > $ sudo perf probe -D update_sd_lb_stats > p:probe/update_sd_lb_stats _text+1830728 > > However, the error message is misleading and doesn't help convey the > actual notrace function that is being probed. Fix this by looking up the > actual function name that is being probed. With this fix, we now get the > below message in the kernel log: > trace_kprobe: Could not probe notrace function > update_sd_lb_stats.constprop.0 > > Signed-off-by: Naveen N Rao <[email protected]> > --- > v3: Remove tk parameter from within_notrace_func() as suggested by > Masami > > kernel/trace/trace_kprobe.c | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index 3d7a180a8427..dc36c6ed6131 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -449,9 +449,8 @@ static bool __within_notrace_func(unsigned long addr) > return !ftrace_location_range(addr, addr + size - 1); > } > > -static bool within_notrace_func(struct trace_kprobe *tk) > +static bool within_notrace_func(unsigned long addr) > { > - unsigned long addr = trace_kprobe_address(tk); > char symname[KSYM_NAME_LEN], *p; > > if (!__within_notrace_func(addr)) > @@ -471,12 +470,14 @@ static bool within_notrace_func(struct trace_kprobe *tk) > return true; > } > #else > -#define within_notrace_func(tk) (false) > +#define within_notrace_func(addr) (false) > #endif > > /* Internal register function - just handle k*probes and flags */ > static int __register_trace_kprobe(struct trace_kprobe *tk) > { > + unsigned long addr = trace_kprobe_address(tk); > + char symname[KSYM_NAME_LEN]; > int i, ret; > > ret = security_locked_down(LOCKDOWN_KPROBES); > @@ -486,9 +487,9 @@ static int __register_trace_kprobe(struct trace_kprobe > *tk) > if (trace_kprobe_is_registered(tk)) > return -EINVAL; > > - if (within_notrace_func(tk)) { > + if (within_notrace_func(addr)) { > pr_warn("Could not probe notrace function %s\n", > - trace_kprobe_symbol(tk)); > + lookup_symbol_name(addr, symname) ? > trace_kprobe_symbol(tk) : symname); Can we just use %ps and (void *)trace_kprobe_address(tk) here? That will be simpler. Thank you, > return -EINVAL; > } > > > base-commit: 4758560fa268cecfa1144f015aa9f2525d164b7e > -- > 2.43.0 > -- Masami Hiramatsu (Google) <[email protected]>
