From: Masami Hiramatsu <mhiramat@kernel.org>

Date: Thu, 23 Apr 2020 20:01:13 +0900

Subject: perf probe: Check address correctness by map instead of _etext

Git-commit: 2ae5d0d7d8868df7c05c2013c0b9cddd4d40610e

References: git-fixes

​

Since commit 03db8b583d1c ("perf tools: Fix

maps__find_symbol_by_name()") introduced map address range check in

maps__find_symbol_by_name(), we can not get "_etext" from kernel map

because _etext is placed on the edge of the kernel .text section (=

kernel map in perf.)

​

To fix this issue, this checks the address correctness by map address

range information (map->start and map->end) instead of using _etext

address.

​

This can cause an error if the target inlined function is embedded in

both __init function and normal function.

​

For exaample, request_resource() is a normal function but also embedded

in __init reserve_setup(). In this case, the probe point in

reserve_setup() must be skipped.

​

However, without this fix, it failes to setup all probe points:

​

  # ./perf probe -v request_resource

  probe-definition(0): request_resource

  symbol:request_resource file:(null) line:0 offset:0 return:0 lazy:(null)

  0 arguments

  Looking at the vmlinux_path (8 entries long)

  Using /usr/lib/debug/lib/modules/5.5.17-200.fc31.x86_64/vmlinux for symbols

  Open Debuginfo file: /usr/lib/debug/lib/modules/5.5.17-200.fc31.x86_64/vmlinux

  Try to find probe point from debuginfo.

  Matched function: request_resource [15e29ad]

  found inline addr: 0xffffffff82fbf892

  Probe point found: reserve_setup+204

  found inline addr: 0xffffffff810e9790

  Probe point found: request_resource+0

  Found 2 probe_trace_events.

  Opening /sys/kernel/debug/tracing//kprobe_events write=1

  Opening /sys/kernel/debug/tracing//README write=0

  Writing event: p:probe/request_resource _text+33290386

  Failed to write event: Invalid argument

    Error: Failed to add events. Reason: Invalid argument (Code: -22)

  #

​

With this fix,

​

  # ./perf probe request_resource

  reserve_setup is out of .text, skip it.

  Added new events:

    (null):(null)        (on request_resource)

    probe:request_resource (on request_resource)

​

  You can now use it in all perf tools, such as:

​

    perf record -e probe:request_resource -aR sleep 1

​

  #

​

Fixes: 03db8b583d1c ("perf tools: Fix maps__find_symbol_by_name()")

Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>

Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Cc: Jiri Olsa <jolsa@kernel.org>

Cc: Namhyung Kim <namhyung@kernel.org>

Cc: stable@vger.kernel.org

Link: http://lore.kernel.org/lkml/158763967332.30755.4922496724365529088.stgit@devnote2

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Acked-by: Tony Jones <tonyj@suse.de>

---

 tools/perf/util/probe-event.c | 25 +++++++++++++------------

 1 file changed, 13 insertions(+), 12 deletions(-)

​

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c

index 63d936f6e993..a08f373d3305 100644

--- a/tools/perf/util/probe-event.c

+++ b/tools/perf/util/probe-event.c

@@ -236,21 +236,22 @@ static void clear_probe_trace_events(struct probe_trace_event *tevs, int ntevs)

 static bool kprobe_blacklist__listed(unsigned long address);

 static bool kprobe_warn_out_range(const char *symbol, unsigned long address)

 {

-   u64 etext_addr = 0;

-   int ret;

-

-   /* Get the address of _etext for checking non-probable text symbol */

-   ret = kernel_get_symbol_address_by_name("_etext", &etext_addr,

-                       false, false);

+   struct map *map;

+   bool ret = false;

-   if (ret == 0 && etext_addr < address)

-       pr_warning("%s is out of .text, skip it.\n", symbol);

-   else if (kprobe_blacklist__listed(address))

+   map = kernel_get_module_map(NULL);

+   if (map) {

+       ret = address <= map->start || map->end < address;

+       if (ret)

+           pr_warning("%s is out of .text, skip it.\n", symbol);

+       map__put(map);

+   }

+   if (!ret && kprobe_blacklist__listed(address)) {

        pr_warning("%s is blacklisted function, skip it.\n", symbol);

-   else

-       return false;

+       ret = true;

+   }

-   return true;

+   return ret;

 }

 /*

​

​