Em Thu, Apr 23, 2020 at 08:01:04PM +0900, Masami Hiramatsu escreveu:
> Fix to check kprobe blacklist address correctly with
> relocated address by adjusting debuginfo address.
>
> Since the address in the debuginfo is same as objdump,
> it is different from relocated kernel address with KASLR.
> Thus, the perf-probe always misses to catch the
> blacklisted addresses.
Thanks, applied, sorry for the delay,
- Arnaldo
> Without this patch, perf probe can not detect the blacklist
> addresses on KASLR enabled kernel.
>
> =========
> # perf probe kprobe_dispatcher
> Failed to write event: Invalid argument
> Error: Failed to add events.
> =========
>
> With this patch, it correctly shows the error message.
>
> =========
> # perf probe kprobe_dispatcher
> kprobe_dispatcher is blacklisted function, skip it.
> Probe point 'kprobe_dispatcher' not found.
> Error: Failed to add events.
> =========
>
> Fixes: 9aaf5a5f479b ("perf probe: Check kprobes blacklist when adding new
> events")
> Signed-off-by: Masami Hiramatsu <[email protected]>
> Cc: [email protected]
> ---
> tools/perf/util/probe-event.c | 21 +++++++++++++++------
> 1 file changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index eea132f512b0..f75df63309be 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -102,7 +102,7 @@ void exit_probe_symbol_maps(void)
> symbol__exit();
> }
>
> -static struct ref_reloc_sym *kernel_get_ref_reloc_sym(void)
> +static struct ref_reloc_sym *kernel_get_ref_reloc_sym(struct map **pmap)
> {
> /* kmap->ref_reloc_sym should be set if host_machine is initialized */
> struct kmap *kmap;
> @@ -114,6 +114,10 @@ static struct ref_reloc_sym
> *kernel_get_ref_reloc_sym(void)
> kmap = map__kmap(map);
> if (!kmap)
> return NULL;
> +
> + if (pmap)
> + *pmap = map;
> +
> return kmap->ref_reloc_sym;
> }
>
> @@ -125,7 +129,7 @@ static int kernel_get_symbol_address_by_name(const char
> *name, u64 *addr,
> struct map *map;
>
> /* ref_reloc_sym is just a label. Need a special fix*/
> - reloc_sym = kernel_get_ref_reloc_sym();
> + reloc_sym = kernel_get_ref_reloc_sym(NULL);
> if (reloc_sym && strcmp(name, reloc_sym->name) == 0)
> *addr = (reloc) ? reloc_sym->addr : reloc_sym->unrelocated_addr;
> else {
> @@ -745,6 +749,7 @@ post_process_kernel_probe_trace_events(struct
> probe_trace_event *tevs,
> int ntevs)
> {
> struct ref_reloc_sym *reloc_sym;
> + struct map *map;
> char *tmp;
> int i, skipped = 0;
>
> @@ -753,7 +758,7 @@ post_process_kernel_probe_trace_events(struct
> probe_trace_event *tevs,
> return post_process_offline_probe_trace_events(tevs, ntevs,
> symbol_conf.vmlinux_name);
>
> - reloc_sym = kernel_get_ref_reloc_sym();
> + reloc_sym = kernel_get_ref_reloc_sym(&map);
> if (!reloc_sym) {
> pr_warning("Relocated base symbol is not found!\n");
> return -EINVAL;
> @@ -764,9 +769,13 @@ post_process_kernel_probe_trace_events(struct
> probe_trace_event *tevs,
> continue;
> if (tevs[i].point.retprobe && !kretprobe_offset_is_supported())
> continue;
> - /* If we found a wrong one, mark it by NULL symbol */
> + /*
> + * If we found a wrong one, mark it by NULL symbol.
> + * Since addresses in debuginfo is same as objdump, we need
> + * to convert it to addresses on memory.
> + */
> if (kprobe_warn_out_range(tevs[i].point.symbol,
> - tevs[i].point.address)) {
> + map__objdump_2mem(map, tevs[i].point.address))) {
> tmp = NULL;
> skipped++;
> } else {
> @@ -2936,7 +2945,7 @@ static int find_probe_trace_events_from_map(struct
> perf_probe_event *pev,
> /* Note that the symbols in the kmodule are not relocated */
> if (!pev->uprobes && !pev->target &&
> (!pp->retprobe || kretprobe_offset_is_supported())) {
> - reloc_sym = kernel_get_ref_reloc_sym();
> + reloc_sym = kernel_get_ref_reloc_sym(NULL);
> if (!reloc_sym) {
> pr_warning("Relocated base symbol is not found!\n");
> ret = -EINVAL;
>
--
- Arnaldo
