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Message-ID: <50399556C9727B4D88A595C8584AAB37524EA468@GSjpTKYDCembx32.service.hitachi.net>
Date: Wed, 26 Aug 2015 00:00:56 +0000
From: 平松雅巳 / HIRAMATU，MASAMI
<masami.hiramatsu.pt@...achi.com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
Ingo Molnar <mingo@...nel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Wang Nan <wangnan0@...wei.com>,
Namhyung Kim <namhyung@...nel.org>,
"pi3orama@....com" <pi3orama@....com>,
Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: RE: [PATCH 16/16] perf probe: Support probing at absolute
addresses
Arnaldo, I don't think we need "+".
So, Nak it.
> -----Original Message-----
> From: Arnaldo Carvalho de Melo [mailto:acme@...nel.org]
> Sent: Wednesday, August 26, 2015 1:15 AM
> To: Ingo Molnar
> Cc: linux-kernel@...r.kernel.org; Wang Nan; 平松雅巳 / HIRAMATU，MASAMI; Namhyung Kim; pi3orama@....com; Arnaldo Carvalho
> de Melo
> Subject: [!][PATCH 16/16] perf probe: Support probing at absolute addresses
>
> From: Wang Nan <wangnan0@...wei.com>
>
> It should be useful to allow 'perf probe' probe at absolute offsets of a
> target.
>
> For example, when (u)probing at a instruction of a shared object in an
> embedded system where debuginfo is not available but we know the offset
> of that instruction by manually digging.
>
> This patch enables following perf probe command syntax:
>
> # perf probe +0xffffffff811e6615
>
> And
>
> # perf probe /lib/x86_64-linux-gnu/libc-2.19.so +0xeb860
>
> In the above example, we don't need a anchor symbol, so it is possible
> to compute absolute addresses using other methods and then use 'perf
> probe' to create the probing points.
>
> Committer note:
>
> One can as well specify a name, so that the probe doesn't get assigned a
> generic one starting with abs_, i.e. if we use as described above we
> get:
>
> [root@zoo ~]# readelf -sW /lib64/libc-2.20.so | grep -w malloc
> 1175: 00000000000830f0 300 FUNC GLOBAL DEFAULT 12 malloc@@GLIBC_2.2.5
> 813: 0000000000000000 0 FILE LOCAL DEFAULT ABS malloc.c
> 5276: 00000000000830f0 300 FUNC GLOBAL DEFAULT 12 malloc
> [root@zoo ~]#
> [root@zoo ~]# perf probe /lib64/libc-2.20.so +0x830f0
> Added new event:
> probe_libc:abs_830f0 (on 0x830f0 in /lib64/libc-2.20.so)
>
> You can now use it in all perf tools, such as:
>
> perf record -e probe_libc:abs_830f0 -aR sleep 1
>
> [root@zoo ~]#
> [root@zoo ~]# perf probe -l
> probe_libc:abs_830f0 (on __libc_malloc@...bc-2.20/malloc/malloc.c in /lib64/libc-2.20.so)
> [root@zoo ~]#
>
> Whereas if we assign it a name it gets more manageable:
>
> [root@zoo ~]# perf probe /lib64/libc-2.20.so malloc=+0x830f0
> Added new event:
> probe_libc:malloc (on 0x830f0 in /lib64/libc-2.20.so)
>
> You can now use it in all perf tools, such as:
>
> perf record -e probe_libc:malloc -aR sleep 1
>
> [root@zoo ~]# perf probe -l
> probe_libc:malloc (on __libc_malloc@...bc-2.20/malloc/malloc.c in /lib64/libc-2.20.so)
> [root@zoo ~]#
>
> Both, of course, will produce the same results, and we can use a
> non canonical name, if the need arises:
>
> [root@zoo ~]# perf probe /lib64/libc-2.20.so memory_allocation=+0x830f0
> Added new event:
> probe_libc:memory_allocation (on 0x830f0 in /lib64/libc-2.20.so)
>
> You can now use it in all perf tools, such as:
>
> perf record -e probe_libc:memory_allocation -aR sleep 1
>
> [root@zoo ~]# perf probe -l
> probe_libc:memory_allocation (on __libc_malloc@...bc-2.20/malloc/malloc.c in /lib64/libc-2.20.so)
> [root@zoo ~]#
>
> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: pi3orama@....com
> Link: http://lkml.kernel.org/r/1440509256-193590-2-git-send-email-wangnan0@huawei.com
> Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
> ---
> tools/perf/util/probe-event.c | 144 +++++++++++++++++++++++++++++++++++++----
> tools/perf/util/probe-event.h | 3 +
> tools/perf/util/probe-finder.c | 21 +-----
> 3 files changed, 138 insertions(+), 30 deletions(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 6c7e538c9b8b..59de69a4e3ac 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1194,9 +1194,13 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> *ptr++ = '\0';
> }
>
> - tmp = strdup(arg);
> - if (tmp == NULL)
> - return -ENOMEM;
> + if (arg[0] == '\0')
> + tmp = NULL;
> + else {
> + tmp = strdup(arg);
> + if (tmp == NULL)
> + return -ENOMEM;
> + }
>
> if (file_spec)
> pp->file = tmp;
> @@ -1283,11 +1287,6 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> return -EINVAL;
> }
>
> - if (pp->offset && !pp->function) {
> - semantic_error("Offset requires an entry function.\n");
> - return -EINVAL;
> - }
> -
> if (pp->retprobe && !pp->function) {
> semantic_error("Return probe requires an entry function.\n");
> return -EINVAL;
> @@ -1299,6 +1298,11 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> return -EINVAL;
> }
>
> + if (!pp->function && !pp->offset && !pp->file) {
> + semantic_error("Absolute address should not be zero.\n");
> + return -EINVAL;
> + }
> +
> pr_debug("symbol:%s file:%s line:%d offset:%lu return:%d lazy:%s\n",
> pp->function, pp->file, pp->line, pp->offset, pp->retprobe,
> pp->lazy_line);
> @@ -1609,7 +1613,7 @@ error:
> static char *synthesize_perf_probe_point(struct perf_probe_point *pp)
> {
> char *buf, *tmp;
> - char offs[32] = "", line[32] = "", file[32] = "";
> + char offs[32] = "", line[32] = "", file[32] = "", addr[32] = "";
> int ret, len;
>
> buf = zalloc(MAX_CMDLEN);
> @@ -1622,6 +1626,11 @@ static char *synthesize_perf_probe_point(struct perf_probe_point *pp)
> if (ret <= 0)
> goto error;
> }
> + if (!pp->function) {
> + ret = e_snprintf(addr, 32, "0x%lx", pp->offset);
> + if (ret <= 0)
> + goto error;
> + }
> if (pp->line) {
> ret = e_snprintf(line, 32, ":%d", pp->line);
> if (ret <= 0)
> @@ -1639,9 +1648,11 @@ static char *synthesize_perf_probe_point(struct perf_probe_point *pp)
> goto error;
> }
>
> - if (pp->function)
> - ret = e_snprintf(buf, MAX_CMDLEN, "%s%s%s%s%s", pp->function,
> - offs, pp->retprobe ? "%return" : "", line,
> + if (pp->function || pp->offset)
> + ret = e_snprintf(buf, MAX_CMDLEN, "%s%s%s%s%s",
> + pp->function ? : addr,
> + pp->function ? offs : "",
> + pp->retprobe ? "%return" : "", line,
> file);
> else
> ret = e_snprintf(buf, MAX_CMDLEN, "%s%s", file, line);
> @@ -1786,6 +1797,11 @@ char *synthesize_probe_trace_command(struct probe_trace_event *tev)
> if (tev->uprobes)
> ret = e_snprintf(buf + len, MAX_CMDLEN - len, "%s:0x%lx",
> tp->module, tp->address);
> + else if (tp->symbol[0] == '0' && tp->symbol[1] == 'x')
> + /* Absolute address. See try_to_find_absolute_address() */
> + ret = e_snprintf(buf + len, MAX_CMDLEN - len, "%s%s0x%lx",
> + tp->module ?: "", tp->module ? ":" : "",
> + tp->address);
> else
> ret = e_snprintf(buf + len, MAX_CMDLEN - len, "%s%s%s+%lu",
> tp->module ?: "", tp->module ? ":" : "",
> @@ -2572,6 +2588,87 @@ err_out:
> goto out;
> }
>
> +static int try_to_find_absolute_address(struct perf_probe_event *pev,
> + struct probe_trace_event **tevs)
> +{
> + struct perf_probe_point *pp = &pev->point;
> + struct probe_trace_event *tev;
> + struct probe_trace_point *tp;
> + int i, err;
> +
> + if (perf_probe_event_need_dwarf(pev) || pev->point.function)
> + return -EINVAL;
> +
> + /*
> + * This is 'perf probe /lib/libc.so +0xabcd'. Try to probe at
> + * absolute address.
> + *
> + * Only one tev can be generated by this.
> + */
> + *tevs = zalloc(sizeof(*tev));
> + if (!*tevs)
> + return -ENOMEM;
> +
> + tev = *tevs;
> + tp = &tev->point;
> +
> + /*
> + * Don't use tp->offset, use address directly, because
> + * in synthesize_probe_trace_command() address cannot be
> + * zero.
> + */
> + tp->address = pev->point.offset;
> + tp->retprobe = pp->retprobe;
> + tev->uprobes = pev->uprobes;
> +
> + err = -ENOMEM;
> + /* Give it a '0x' leading symbol name */
> + if (asprintf(&tp->symbol, "0x%lx", tp->address) < 0)
> + goto errout;
> +
> + /* For kprobe, check range */
> + if ((!tev->uprobes) &&
> + (kprobe_warn_out_range(tev->point.symbol,
> + tev->point.address))) {
> + err = -EACCES;
> + goto errout;
> + }
> +
> + if (asprintf(&tp->realname, "abs_%lx", tp->address) < 0)
> + goto errout;
> +
> + if (pev->target) {
> + tp->module = strdup(pev->target);
> + if (!tp->module)
> + goto errout;
> + }
> +
> + if (tev->group) {
> + tev->group = strdup(pev->group);
> + if (!tev->group)
> + goto errout;
> + }
> +
> + if (pev->event) {
> + tev->event = strdup(pev->event);
> + if (!tev->event)
> + goto errout;
> + }
> +
> + tev->nargs = pev->nargs;
> + for (i = 0; i < tev->nargs; i++)
> + copy_to_probe_trace_arg(&tev->args[i], &pev->args[i]);
> +
> + return 1;
> +
> +errout:
> + if (*tevs) {
> + clear_probe_trace_events(*tevs, 1);
> + *tevs = NULL;
> + }
> + return err;
> +}
> +
> bool __weak arch__prefers_symtab(void) { return false; }
>
> static int convert_to_probe_trace_events(struct perf_probe_event *pev,
> @@ -2588,6 +2685,10 @@ static int convert_to_probe_trace_events(struct perf_probe_event *pev,
> }
> }
>
> + ret = try_to_find_absolute_address(pev, tevs);
> + if (ret > 0)
> + return ret;
> +
> if (arch__prefers_symtab() && !perf_probe_event_need_dwarf(pev)) {
> ret = find_probe_trace_events_from_map(pev, tevs);
> if (ret > 0)
> @@ -2758,3 +2859,22 @@ end:
> return ret;
> }
>
> +int copy_to_probe_trace_arg(struct probe_trace_arg *tvar,
> + struct perf_probe_arg *pvar)
> +{
> + tvar->value = strdup(pvar->var);
> + if (tvar->value == NULL)
> + return -ENOMEM;
> + if (pvar->type) {
> + tvar->type = strdup(pvar->type);
> + if (tvar->type == NULL)
> + return -ENOMEM;
> + }
> + if (pvar->name) {
> + tvar->name = strdup(pvar->name);
> + if (tvar->name == NULL)
> + return -ENOMEM;
> + } else
> + tvar->name = NULL;
> + return 0;
> +}
> diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
> index 83ee95e9743b..174a3cf6c03d 100644
> --- a/tools/perf/util/probe-event.h
> +++ b/tools/perf/util/probe-event.h
> @@ -156,4 +156,7 @@ int e_snprintf(char *str, size_t size, const char *format, ...)
> /* Maximum index number of event-name postfix */
> #define MAX_EVENT_INDEX 1024
>
> +int copy_to_probe_trace_arg(struct probe_trace_arg *tvar,
> + struct perf_probe_arg *pvar);
> +
> #endif /*_PROBE_EVENT_H */
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index 7b80f8cb62b9..29c43c0680a8 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -553,24 +553,9 @@ static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf)
> char buf[32], *ptr;
> int ret = 0;
>
> - if (!is_c_varname(pf->pvar->var)) {
> - /* Copy raw parameters */
> - pf->tvar->value = strdup(pf->pvar->var);
> - if (pf->tvar->value == NULL)
> - return -ENOMEM;
> - if (pf->pvar->type) {
> - pf->tvar->type = strdup(pf->pvar->type);
> - if (pf->tvar->type == NULL)
> - return -ENOMEM;
> - }
> - if (pf->pvar->name) {
> - pf->tvar->name = strdup(pf->pvar->name);
> - if (pf->tvar->name == NULL)
> - return -ENOMEM;
> - } else
> - pf->tvar->name = NULL;
> - return 0;
> - }
> + /* Copy raw parameters */
> + if (!is_c_varname(pf->pvar->var))
> + return copy_to_probe_trace_arg(pf->tvar, pf->pvar);
>
> if (pf->pvar->name)
> pf->tvar->name = strdup(pf->pvar->name);
> --
> 2.1.0
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