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perf probe: Support SDT markers having reference counter (semaphore)

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With this, perf buildid-cache will save SDT markers with reference
counter in probe cache. Perf probe will be able to probe markers
having reference counter. Ex,

  # readelf -n /tmp/tick | grep -A1 loop2
    Name: loop2
    ... Semaphore: 0x0000000010020036

  # ./perf buildid-cache --add /tmp/tick
  # ./perf probe sdt_tick:loop2
  # ./perf stat -e sdt_tick:loop2 /tmp/tick
    hi: 0
    hi: 1
    hi: 2
    ^C
     Performance counter stats for '/tmp/tick':
                 3      sdt_tick:loop2
       2.561851452 seconds time elapsed

Link: http://lkml.kernel.org/r/20180820044250.11659-5-ravi.bangoria@linux.ibm.com

Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Song Liu <songliubraving@fb.com>
Tested-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Ravi Bangoria 2018-08-20 10:12:50 +05:30 committed by Steven Rostedt (VMware)
parent ccea8727dc
commit 5a5e3d3cea
6 changed files with 106 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
tools/perf/util/probe-event.c
View File

@ -1819,6 +1819,12 @@ int parse_probe_trace_command(const char *cmd, struct probe_trace_event *tev)
tp->offset = strtoul(fmt2_str, NULL, 10);
}
if (tev->uprobes) {
fmt2_str = strchr(p, '(');
if (fmt2_str)
tp->ref_ctr_offset = strtoul(fmt2_str + 1, NULL, 0);
}
tev->nargs = argc - 2;
tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
if (tev->args == NULL) {
@ -2012,6 +2018,22 @@ static int synthesize_probe_trace_arg(struct probe_trace_arg *arg,
return err;
}
static int
synthesize_uprobe_trace_def(struct probe_trace_event *tev, struct strbuf *buf)
{
struct probe_trace_point *tp = &tev->point;
int err;
err = strbuf_addf(buf, "%s:0x%lx", tp->module, tp->address);
if (err >= 0 && tp->ref_ctr_offset) {
if (!uprobe_ref_ctr_is_supported())
return -1;
err = strbuf_addf(buf, "(0x%lx)", tp->ref_ctr_offset);
}
return err >= 0 ? 0 : -1;
}
char *synthesize_probe_trace_command(struct probe_trace_event *tev)
{
struct probe_trace_point *tp = &tev->point;
@ -2041,15 +2063,17 @@ char *synthesize_probe_trace_command(struct probe_trace_event *tev)
}
/* Use the tp->address for uprobes */
if (tev->uprobes)
err = strbuf_addf(&buf, "%s:0x%lx", tp->module, tp->address);
else if (!strncmp(tp->symbol, "0x", 2))
if (tev->uprobes) {
err = synthesize_uprobe_trace_def(tev, &buf);
} else if (!strncmp(tp->symbol, "0x", 2)) {
/* Absolute address. See try_to_find_absolute_address() */
err = strbuf_addf(&buf, "%s%s0x%lx", tp->module ?: "",
tp->module ? ":" : "", tp->address);
else
} else {
err = strbuf_addf(&buf, "%s%s%s+%lu", tp->module ?: "",
tp->module ? ":" : "", tp->symbol, tp->offset);
}
if (err)
goto error;
@ -2633,6 +2657,13 @@ static void warn_uprobe_event_compat(struct probe_trace_event *tev)
{
int i;
char *buf = synthesize_probe_trace_command(tev);
struct probe_trace_point *tp = &tev->point;
if (tp->ref_ctr_offset && !uprobe_ref_ctr_is_supported()) {
pr_warning("A semaphore is associated with %s:%s and "
"seems your kernel doesn't support it.\n",
tev->group, tev->event);
}
/* Old uprobe event doesn't support memory dereference */
if (!tev->uprobes || tev->nargs == 0 || !buf)

1
tools/perf/util/probe-event.h
View File

@ -27,6 +27,7 @@ struct probe_trace_point {
char *symbol; /* Base symbol */
char *module; /* Module name */
unsigned long offset; /* Offset from symbol */
unsigned long ref_ctr_offset; /* SDT reference counter offset */
unsigned long address; /* Actual address of the trace point */
bool retprobe; /* Return probe flag */
};

34
tools/perf/util/probe-file.c
View File

@ -696,8 +696,16 @@ int probe_cache__add_entry(struct probe_cache *pcache,
#ifdef HAVE_GELF_GETNOTE_SUPPORT
static unsigned long long sdt_note__get_addr(struct sdt_note *note)
{
return note->bit32 ? (unsigned long long)note->addr.a32[0]
: (unsigned long long)note->addr.a64[0];
return note->bit32 ?
(unsigned long long)note->addr.a32[SDT_NOTE_IDX_LOC] :
(unsigned long long)note->addr.a64[SDT_NOTE_IDX_LOC];
}
static unsigned long long sdt_note__get_ref_ctr_offset(struct sdt_note *note)
{
return note->bit32 ?
(unsigned long long)note->addr.a32[SDT_NOTE_IDX_REFCTR] :
(unsigned long long)note->addr.a64[SDT_NOTE_IDX_REFCTR];
}
static const char * const type_to_suffix[] = {
@ -775,14 +783,21 @@ static char *synthesize_sdt_probe_command(struct sdt_note *note,
{
struct strbuf buf;
char *ret = NULL, **args;
int i, args_count;
int i, args_count, err;
unsigned long long ref_ctr_offset;
if (strbuf_init(&buf, 32) < 0)
return NULL;
if (strbuf_addf(&buf, "p:%s/%s %s:0x%llx",
sdtgrp, note->name, pathname,
sdt_note__get_addr(note)) < 0)
err = strbuf_addf(&buf, "p:%s/%s %s:0x%llx",
sdtgrp, note->name, pathname,
sdt_note__get_addr(note));
ref_ctr_offset = sdt_note__get_ref_ctr_offset(note);
if (ref_ctr_offset && err >= 0)
err = strbuf_addf(&buf, "(0x%llx)", ref_ctr_offset);
if (err < 0)
goto error;
if (!note->args)
@ -998,6 +1013,7 @@ int probe_cache__show_all_caches(struct strfilter *filter)
enum ftrace_readme {
FTRACE_README_PROBE_TYPE_X = 0,
FTRACE_README_KRETPROBE_OFFSET,
FTRACE_README_UPROBE_REF_CTR,
FTRACE_README_END,
};
@ -1009,6 +1025,7 @@ static struct {
[idx] = {.pattern = pat, .avail = false}
DEFINE_TYPE(FTRACE_README_PROBE_TYPE_X, "*type: * x8/16/32/64,*"),
DEFINE_TYPE(FTRACE_README_KRETPROBE_OFFSET, "*place (kretprobe): *"),
DEFINE_TYPE(FTRACE_README_UPROBE_REF_CTR, "*ref_ctr_offset*"),
};
static bool scan_ftrace_readme(enum ftrace_readme type)
@ -1064,3 +1081,8 @@ bool kretprobe_offset_is_supported(void)
{
return scan_ftrace_readme(FTRACE_README_KRETPROBE_OFFSET);
}
bool uprobe_ref_ctr_is_supported(void)
{
return scan_ftrace_readme(FTRACE_README_UPROBE_REF_CTR);
}

1
tools/perf/util/probe-file.h
View File

@ -69,6 +69,7 @@ struct probe_cache_entry *probe_cache__find_by_name(struct probe_cache *pcache,
int probe_cache__show_all_caches(struct strfilter *filter);
bool probe_type_is_available(enum probe_type type);
bool kretprobe_offset_is_supported(void);
bool uprobe_ref_ctr_is_supported(void);
#else /* ! HAVE_LIBELF_SUPPORT */
static inline struct probe_cache *probe_cache__new(const char *tgt __maybe_unused, struct nsinfo *nsi __maybe_unused)
{

46
tools/perf/util/symbol-elf.c
View File

@ -1947,6 +1947,34 @@ void kcore_extract__delete(struct kcore_extract *kce)
}
#ifdef HAVE_GELF_GETNOTE_SUPPORT
static void sdt_adjust_loc(struct sdt_note *tmp, GElf_Addr base_off)
{
if (!base_off)
return;
if (tmp->bit32)
tmp->addr.a32[SDT_NOTE_IDX_LOC] =
tmp->addr.a32[SDT_NOTE_IDX_LOC] + base_off -
tmp->addr.a32[SDT_NOTE_IDX_BASE];
else
tmp->addr.a64[SDT_NOTE_IDX_LOC] =
tmp->addr.a64[SDT_NOTE_IDX_LOC] + base_off -
tmp->addr.a64[SDT_NOTE_IDX_BASE];
}
static void sdt_adjust_refctr(struct sdt_note *tmp, GElf_Addr base_addr,
GElf_Addr base_off)
{
if (!base_off)
return;
if (tmp->bit32 && tmp->addr.a32[SDT_NOTE_IDX_REFCTR])
tmp->addr.a32[SDT_NOTE_IDX_REFCTR] -= (base_addr - base_off);
else if (tmp->addr.a64[SDT_NOTE_IDX_REFCTR])
tmp->addr.a64[SDT_NOTE_IDX_REFCTR] -= (base_addr - base_off);
}
/**
* populate_sdt_note : Parse raw data and identify SDT note
* @elf: elf of the opened file
@ -1964,7 +1992,6 @@ static int populate_sdt_note(Elf **elf, const char *data, size_t len,
const char *provider, *name, *args;
struct sdt_note *tmp = NULL;
GElf_Ehdr ehdr;
GElf_Addr base_off = 0;
GElf_Shdr shdr;
int ret = -EINVAL;
@ -2060,17 +2087,12 @@ static int populate_sdt_note(Elf **elf, const char *data, size_t len,
* base address in the description of the SDT note. If its different,
* then accordingly, adjust the note location.
*/
if (elf_section_by_name(*elf, &ehdr, &shdr, SDT_BASE_SCN, NULL)) {
base_off = shdr.sh_offset;
if (base_off) {
if (tmp->bit32)
tmp->addr.a32[0] = tmp->addr.a32[0] + base_off -
tmp->addr.a32[1];
else
tmp->addr.a64[0] = tmp->addr.a64[0] + base_off -
tmp->addr.a64[1];
}
}
if (elf_section_by_name(*elf, &ehdr, &shdr, SDT_BASE_SCN, NULL))
sdt_adjust_loc(tmp, shdr.sh_offset);
/* Adjust reference counter offset */
if (elf_section_by_name(*elf, &ehdr, &shdr, SDT_PROBES_SCN, NULL))
sdt_adjust_refctr(tmp, shdr.sh_addr, shdr.sh_offset);
list_add_tail(&tmp->note_list, sdt_notes);
return 0;

7
tools/perf/util/symbol.h
View File

@ -379,12 +379,19 @@ int get_sdt_note_list(struct list_head *head, const char *target);
int cleanup_sdt_note_list(struct list_head *sdt_notes);
int sdt_notes__get_count(struct list_head *start);
#define SDT_PROBES_SCN ".probes"
#define SDT_BASE_SCN ".stapsdt.base"
#define SDT_NOTE_SCN ".note.stapsdt"
#define SDT_NOTE_TYPE 3
#define SDT_NOTE_NAME "stapsdt"
#define NR_ADDR 3
enum {
SDT_NOTE_IDX_LOC = 0,
SDT_NOTE_IDX_BASE,
SDT_NOTE_IDX_REFCTR,
};
struct mem_info *mem_info__new(void);
struct mem_info *mem_info__get(struct mem_info *mi);
void mem_info__put(struct mem_info *mi);