Skip to content

Commit

Permalink
perf probe: Fix to return error if no probe is added
Browse files Browse the repository at this point in the history 
Fix perf probe to return an error if no probe is added due to the given
probe point being on the blacklist.

To fix this problem, this moves the blacklist checking to right after
finding symbols/probe-points and marks them as skipped.

If all the symbols are skipped, "perf probe"  returns an error as it
fails to find the corresponding probe address.

E.g. currently if a blacklisted probe is given:

  # perf probe do_trap && echo 'succeed'
  Added new event:
  Warning: Skipped probing on blacklisted function: sync_regs
  succeed

No! It must fail! With this patch, it correctly fails:

  # perf probe do_trap && echo 'succeed'
  do_trap is blacklisted function, skip it.
  Probe point 'do_trap' not found.
    Error: Failed to add events.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Naohiro Aota <naota@elisp.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150616115055.19906.31359.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
  • Loading branch information
Masami Hiramatsu authored and Arnaldo Carvalho de Melo committed Jun 16, 2015
1 parent f005813 commit b031220
Showing 1 changed file with 71 additions and 42 deletions.
113 changes: 71 additions & 42 deletions tools/perf/util/probe-event.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -246,6 +246,20 @@ static void clear_probe_trace_events(struct probe_trace_event *tevs, int ntevs)
clear_probe_trace_event(tevs + i);
}

static bool kprobe_blacklist__listed(unsigned long address);
static bool kprobe_warn_out_range(const char *symbol, unsigned long address)
{
/* Get the address of _etext for checking non-probable text symbol */
if (kernel_get_symbol_address_by_name("_etext", false) < address)
pr_warning("%s is out of .text, skip it.\n", symbol);
else if (kprobe_blacklist__listed(address))
pr_warning("%s is blacklisted function, skip it.\n", symbol);
else
return false;

return true;
}

#ifdef HAVE_DWARF_SUPPORT

static int kernel_get_module_dso(const char *module, struct dso **pdso)
Expand Down Expand Up @@ -559,7 +573,6 @@ static int post_process_probe_trace_events(struct probe_trace_event *tevs,
bool uprobe)
{
struct ref_reloc_sym *reloc_sym;
u64 etext_addr;
char *tmp;
int i, skipped = 0;

Expand All @@ -575,31 +588,28 @@ static int post_process_probe_trace_events(struct probe_trace_event *tevs,
pr_warning("Relocated base symbol is not found!\n");
return -EINVAL;
}
/* Get the address of _etext for checking non-probable text symbol */
etext_addr = kernel_get_symbol_address_by_name("_etext", false);

for (i = 0; i < ntevs; i++) {
if (tevs[i].point.address && !tevs[i].point.retprobe) {
/* If we found a wrong one, mark it by NULL symbol */
if (etext_addr < tevs[i].point.address) {
pr_warning("%s+%lu is out of .text, skip it.\n",
tevs[i].point.symbol, tevs[i].point.offset);
tmp = NULL;
skipped++;
} else {
tmp = strdup(reloc_sym->name);
if (!tmp)
return -ENOMEM;
}
/* If we have no realname, use symbol for it */
if (!tevs[i].point.realname)
tevs[i].point.realname = tevs[i].point.symbol;
else
free(tevs[i].point.symbol);
tevs[i].point.symbol = tmp;
tevs[i].point.offset = tevs[i].point.address -
reloc_sym->unrelocated_addr;
if (!tevs[i].point.address || tevs[i].point.retprobe)
continue;
/* If we found a wrong one, mark it by NULL symbol */
if (kprobe_warn_out_range(tevs[i].point.symbol,
tevs[i].point.address)) {
tmp = NULL;
skipped++;
} else {
tmp = strdup(reloc_sym->name);
if (!tmp)
return -ENOMEM;
}
/* If we have no realname, use symbol for it */
if (!tevs[i].point.realname)
tevs[i].point.realname = tevs[i].point.symbol;
else
free(tevs[i].point.symbol);
tevs[i].point.symbol = tmp;
tevs[i].point.offset = tevs[i].point.address -
reloc_sym->unrelocated_addr;
}
return skipped;
}
Expand Down Expand Up @@ -2126,6 +2136,27 @@ kprobe_blacklist__find_by_address(struct list_head *blacklist,
return NULL;
}

static LIST_HEAD(kprobe_blacklist);

static void kprobe_blacklist__init(void)
{
if (!list_empty(&kprobe_blacklist))
return;

if (kprobe_blacklist__load(&kprobe_blacklist) < 0)
pr_debug("No kprobe blacklist support, ignored\n");
}

static void kprobe_blacklist__release(void)
{
kprobe_blacklist__delete(&kprobe_blacklist);
}

static bool kprobe_blacklist__listed(unsigned long address)
{
return !!kprobe_blacklist__find_by_address(&kprobe_blacklist, address);
}

static int perf_probe_event__sprintf(struct perf_probe_event *pev,
const char *module,
struct strbuf *result)
Expand Down Expand Up @@ -2409,8 +2440,6 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
char buf[64];
const char *event, *group;
struct strlist *namelist;
LIST_HEAD(blacklist);
struct kprobe_blacklist_node *node;
bool safename;

if (pev->uprobes)
Expand All @@ -2430,28 +2459,15 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
ret = -ENOMEM;
goto close_out;
}
/* Get kprobe blacklist if exists */
if (!pev->uprobes) {
ret = kprobe_blacklist__load(&blacklist);
if (ret < 0)
pr_debug("No kprobe blacklist support, ignored\n");
}

safename = (pev->point.function && !strisglob(pev->point.function));
ret = 0;
pr_info("Added new event%s\n", (ntevs > 1) ? "s:" : ":");
for (i = 0; i < ntevs; i++) {
tev = &tevs[i];
/* Skip if the symbol is out of .text (marked previously) */
/* Skip if the symbol is out of .text or blacklisted */
if (!tev->point.symbol)
continue;
/* Ensure that the address is NOT blacklisted */
node = kprobe_blacklist__find_by_address(&blacklist,
tev->point.address);
if (node) {
pr_warning("Warning: Skipped probing on blacklisted function: %s\n", node->symbol);
continue;
}

if (pev->event)
event = pev->event;
Expand Down Expand Up @@ -2513,7 +2529,6 @@ static int __add_probe_trace_events(struct perf_probe_event *pev,
tev->event);
}

kprobe_blacklist__delete(&blacklist);
strlist__delete(namelist);
close_out:
close(fd);
Expand Down Expand Up @@ -2563,7 +2578,7 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev,
struct perf_probe_point *pp = &pev->point;
struct probe_trace_point *tp;
int num_matched_functions;
int ret, i, j;
int ret, i, j, skipped = 0;

map = get_target_map(pev->target, pev->uprobes);
if (!map) {
Expand Down Expand Up @@ -2631,7 +2646,12 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev,
}
/* Add one probe point */
tp->address = map->unmap_ip(map, sym->start) + pp->offset;
if (reloc_sym) {
/* If we found a wrong one, mark it by NULL symbol */
if (!pev->uprobes &&
kprobe_warn_out_range(sym->name, tp->address)) {
tp->symbol = NULL; /* Skip it */
skipped++;
} else if (reloc_sym) {
tp->symbol = strdup_or_goto(reloc_sym->name, nomem_out);
tp->offset = tp->address - reloc_sym->addr;
} else {
Expand Down Expand Up @@ -2667,6 +2687,10 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev,
}
arch__fix_tev_from_maps(pev, tev, map);
}
if (ret == skipped) {
ret = -ENOENT;
goto err_out;
}

out:
put_target_map(map, pev->uprobes);
Expand Down Expand Up @@ -2737,13 +2761,18 @@ int add_perf_probe_events(struct perf_probe_event *pevs, int npevs)
/* Loop 1: convert all events */
for (i = 0; i < npevs; i++) {
pkgs[i].pev = &pevs[i];
/* Init kprobe blacklist if needed */
if (!pkgs[i].pev->uprobes)
kprobe_blacklist__init();
/* Convert with or without debuginfo */
ret = convert_to_probe_trace_events(pkgs[i].pev,
&pkgs[i].tevs);
if (ret < 0)
goto end;
pkgs[i].ntevs = ret;
}
/* This just release blacklist only if allocated */
kprobe_blacklist__release();

/* Loop 2: add all events */
for (i = 0; i < npevs; i++) {
Expand Down

0 comments on commit b031220

Please sign in to comment.