RE: [PATCH v3 3/6] perf probe: Fix list result when address is zero

From: åæéå / HIRAMATUïMASAMI
Date: Wed Aug 26 2015 - 08:14:36 EST


> From: Wang Nan [mailto:wangnan0@xxxxxxxxxx]
>
> When manually added uprobe point with zero address, 'perf probe -l'
> reports error. For example:
>
> # echo p:probe_libc/abs_0 /path/to/lib.bin:0x0 arg1=%ax > \
> /sys/kernel/debug/tracing/uprobe_events
>
> # perf probe -l
> Error: Failed to show event list.
>
> Probing at 0x0 is possible and useful when lib.bin is not a normal
> shared object but is manually mapped. However, in this case kernel
> report:
>
> # cat /sys/kernel/debug/tracing/uprobe_events
> p:probe_libc/abs_0 /path/to/lib.bin:0x (null) arg1=%ax
>
> This patch supports the above kernel output.

OK, Looks good to me:)


Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>

Thanks!


>
> Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
> Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> ---
> tools/perf/util/probe-event.c | 28 +++++++++++++++++++++++++---
> 1 file changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index f7bacbb..926bcec 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1519,9 +1519,31 @@ int parse_probe_trace_command(const char *cmd, struct probe_trace_event *tev)
> } else
> p = argv[1];
> fmt1_str = strtok_r(p, "+", &fmt);
> - if (fmt1_str[0] == '0') /* only the address started with 0x */
> - tp->address = strtoul(fmt1_str, NULL, 0);
> - else {
> + /* only the address started with 0x */
> + if (fmt1_str[0] == '0') {
> + /*
> + * Fix a special case:
> + * if address == 0, kernel reports something like:
> + * p:probe_libc/abs_0 /lib/libc-2.18.so:0x (null) arg1=%ax
> + * Newer kernel may fix that, but we want to
> + * support old kernel also.
> + */
> + if (strcmp(fmt1_str, "0x") == 0) {
> + if (!argv[2] || strcmp(argv[2], "(null)")) {
> + ret = -EINVAL;
> + goto out;
> + }
> + tp->address = 0;
> +
> + free(argv[2]);
> + for (i = 2; argv[i + 1] != NULL; i++)
> + argv[i] = argv[i + 1];
> +
> + argv[i] = NULL;
> + argc -= 1;
> + } else
> + tp->address = strtoul(fmt1_str, NULL, 0);
> + } else {
> /* Only the symbol-based probe has offset */
> tp->symbol = strdup(fmt1_str);
> if (tp->symbol == NULL) {
> --
> 1.8.3.4