Messages in this thread | | | Date | Sun, 24 May 2015 17:49:46 +0900 | From | Masami Hiramatsu <> | Subject | Re: [RFC PATCH v2 09/15] perf probe: Support $params without debuginfo |
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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 <hekuang@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.pt@hitachi.com
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