| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <50399556C9727B4D88A595C8584AAB37524EA491@GSjpTKYDCembx32.service.hitachi.net>
Date: Wed, 26 Aug 2015 00:02:40 +0000
From: 平松雅巳 / HIRAMATU，MASAMI
<masami.hiramatsu.pt@...achi.com>
To: "'Wang Nan'" <wangnan0@...wei.com>,
"acme@...nel.org" <acme@...nel.org>
CC: "mingo@...hat.com" <mingo@...hat.com>,
"namhyung@...nel.org" <namhyung@...nel.org>,
"pi3orama@....com" <pi3orama@....com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 2/2] perf probe: Support probing at absolute address
> From: Wang Nan [mailto:wangnan0@...wei.com]
>
> It should be useful to allow 'perf probe' probe at absolute offset of
> a target. For example, when (u)probing at a instruction of a shared
> object in a embedded system where debuginfo is not avaliable 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
Why do we need "+" for the absolute address?
It seems that we can do it if we find that the given probe point
starts with "0x".
Thanks,
>
> 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.
>
> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> ---
> 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 6c7e538..59de69a4 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 83ee95e..174a3cf 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 7b80f8c..29c43c068 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);
> --
> 1.8.3.4
Powered by blists - more mailing lists