On 2015/05/24 17:28, He Kuang wrote:
> When probing at function entry, fallback $params to calling regs if no
> debuginfo is provided.
>
> Before this path:
> $ perf probe -v --add='generic_perform_write $params'
> ...
> Added new event:
> Writing event: p:probe/generic_perform_write _stext+1246632 $params
> [86152.161204] Parse error at argument[0]. (-22)
> Failed to write event: Invalid argument
> Error: Failed to add events. Reason: Invalid argument (Code: -22)
>
> After this patch:
> $ perf probe -v --add='generic_perform_write $params'
> ...
> Could not open debuginfo. Try to use symbols.
> ...
> Added new event:
> Writing event: p:probe/generic_perform_write _stext+1246632 %di %si %dx %cx
> %r8 %r9
> probe:generic_perform_write (on generic_perform_write with $params)
>
> You can now use it in all perf tools, such as:
>
> perf record -e probe:generic_perform_write -aR sleep 1
>
> $ perf record -e probe:generic_perform_write dd if=/dev/zero
> of=/mnt/data/test bs=4k count=3
NAK, this should not work on x86-32 and we don't know how many registers are
used.
I think $params special handler should be used only with debuginfo, since
$params
ensures user to save function parameters with its name. If we can't do that, we
should accept that.
If you need to handle register arguments, you should introduce new $regparams
instead
of $params. (however, that still not work correctly on x86-32)
Hmm, we also need $regs to record all registers.
Thank you,
>
> $ perf script
> dd 1149 [000] 18574.762652: probe:generic_perform_write:
> (ffffffff81130770) arg1=0xffff88007c37f600 arg2=0xffff88007ca87e70 arg3=0x0
> arg4=0x0 arg5=0x556062e3 arg6=0x12a8010
> dd 1149 [000] 18574.762652: probe:generic_perform_write:
> (ffffffff81130770) arg1=0xffff88007c37f600 arg2=0xffff88007ca87e70
> arg3=0x1000 arg4=0x0 arg5=0x556062e3 arg6=0x12a8010
> dd 1149 [000] 18574.762652: probe:generic_perform_write:
> (ffffffff81130770) arg1=0xffff88007c37f600 arg2=0xffff88007ca87e70
> arg3=0x2000 arg4=0x0 arg5=0x556062e3 arg6=0x12a8010
>
> Signed-off-by: He Kuang <heku...@huawei.com>
> ---
> tools/perf/util/probe-event.c | 42 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 42 insertions(+)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index d05b77c..7f9f431 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -46,6 +46,7 @@
> #include "probe-event.h"
> #include "probe-finder.h"
> #include "session.h"
> +#include <dwarf-regs.h>
>
> #define MAX_CMDLEN 256
> #define PERFPROBE_GROUP "probe"
> @@ -286,6 +287,14 @@ static void clear_probe_trace_events(struct
> probe_trace_event *tevs, int ntevs)
> clear_probe_trace_event(tevs + i);
> }
>
> +static bool perf_probe_is_function_entry(struct perf_probe_event *pev)
> +{
> + if (pev->point.file || pev->point.line || pev->point.lazy_line)
> + return false;
> +
> + return true;
> +}
> +
> #ifdef HAVE_DWARF_SUPPORT
> /*
> * Some binaries like glibc have special symbols which are on the symbol
> @@ -1225,6 +1234,33 @@ static int parse_perf_probe_point(char *arg, struct
> perf_probe_event *pev)
> return 0;
> }
>
> +static char *parse_perf_probe_param(void)
> +{
> + int i = 0;
> + struct strbuf sb;
> + bool first = true;
> + const char *reg_str;
> +
> + strbuf_init(&sb, 16);
> +
> + while (1) {
> + reg_str = get_arch_calling_reg_str(i++);
> + if (!reg_str)
> + break;
> +
> + if (first) {
> + strbuf_addf(&sb, "%s", reg_str);
> + first = false;
> + } else
> + strbuf_addf(&sb, " %s", reg_str);
> + }
> +
> + if (first)
> + strbuf_add(&sb, "", 1);
> +
> + return strbuf_detach(&sb, NULL);
> +}
> +
> /* Parse perf-probe event argument */
> static int parse_perf_probe_arg(char *str, struct perf_probe_arg *arg)
> {
> @@ -2543,6 +2579,12 @@ static int find_probe_trace_events_from_map(struct
> perf_probe_event *pev,
> goto nomem_out;
> }
> for (i = 0; i < tev->nargs; i++) {
> + if (perf_probe_is_function_entry(pev) &&
> + !strcmp(pev->args[i].var, "$params")) {
> + tev->args[i].value = parse_perf_probe_param();
> + continue;
> + }
> +
> if (pev->args[i].name)
> tev->args[i].name =
> strdup_or_goto(pev->args[i].name,
>
--
Masami HIRAMATSU
Linux Technology Research Center, System Productivity Research Dept.
Center for Technology Innovation - Systems Engineering
Hitachi, Ltd., Research & Development Group
E-mail: masami.hiramatsu...@hitachi.com
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