Arnaldo, I don't think we need "+". So, Nak it.
> -----Original Message----- > From: Arnaldo Carvalho de Melo [mailto:a...@kernel.org] > Sent: Wednesday, August 26, 2015 1:15 AM > To: Ingo Molnar > Cc: linux-kernel@vger.kernel.org; Wang Nan; 平松雅巳 / HIRAMATU，MASAMI; Namhyung > Kim; pi3or...@163.com; Arnaldo Carvalho > de Melo > Subject: [!][PATCH 16/16] perf probe: Support probing at absolute addresses > > From: Wang Nan <wangn...@huawei.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@glibc-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@glibc-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@glibc-2.20/malloc/malloc.c > in /lib64/libc-2.20.so) > [root@zoo ~]# > > Signed-off-by: Wang Nan <wangn...@huawei.com> > Tested-by: Arnaldo Carvalho de Melo <a...@redhat.com> > Cc: Masami Hiramatsu <masami.hiramatsu...@hitachi.com> > Cc: Namhyung Kim <namhy...@kernel.org> > Cc: pi3or...@163.com > Link: > http://lkml.kernel.org/r/1440509256-193590-2-git-send-email-wangn...@huawei.com > Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.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
