Hi, On Fri, 27 Oct 2023 16:31:26 -0700 Andrii Nakryiko <[email protected]> wrote:
> Recent changes to count number of matching symbols when creating > a kprobe event failed to take into account kernel modules. As such, it > breaks kprobes on kernel module symbols, by assuming there is no match. > > Fix this my calling module_kallsyms_on_each_symbol() in addition to > kallsyms_on_each_match_symbol() to perform a proper counting. > > Cc: Francis Laniel <[email protected]> > Cc: [email protected] > Cc: Masami Hiramatsu <[email protected]> > Cc: Steven Rostedt <[email protected]> > Fixes: b022f0c7e404 ("tracing/kprobes: Return EADDRNOTAVAIL when func matches > several symbols") > Signed-off-by: Andrii Nakryiko <[email protected]> This fixes "BPF" kprobe event, but not ftrace kprobe events. ftrace kprobe events only checks this if it is in the vmlinux not modules and that's why my selftest passed the original one. Hmm, I need another enhancement like this for the events on offline modules. Thank you, > --- > kernel/trace/trace_kprobe.c | 24 ++++++++++++++++++++---- > 1 file changed, 20 insertions(+), 4 deletions(-) > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index effcaede4759..1efb27f35963 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -714,14 +714,30 @@ static int count_symbols(void *data, unsigned long > unused) > return 0; > } > > +struct sym_count_ctx { > + unsigned int count; > + const char *name; > +}; > + > +static int count_mod_symbols(void *data, const char *name, unsigned long > unused) > +{ > + struct sym_count_ctx *ctx = data; > + > + if (strcmp(name, ctx->name) == 0) > + ctx->count++; > + > + return 0; > +} > + > static unsigned int number_of_same_symbols(char *func_name) > { > - unsigned int count; > + struct sym_count_ctx ctx = { .count = 0, .name = func_name }; > + > + kallsyms_on_each_match_symbol(count_symbols, func_name, &ctx.count); > > - count = 0; > - kallsyms_on_each_match_symbol(count_symbols, func_name, &count); > + module_kallsyms_on_each_symbol(NULL, count_mod_symbols, &ctx); > > - return count; > + return ctx.count; > } > > static int __trace_kprobe_create(int argc, const char *argv[]) > -- > 2.34.1 > -- Masami Hiramatsu (Google) <[email protected]>
