[PATCH 4.19 266/267] perf probe: Check address correctness by map instead of _etext

Greg Kroah-Hartman
2020-06-19T15:04:38Z

From: Masami Hiramatsu <mhiramat@kernel.org>

commit 2ae5d0d7d8868df7c05c2013c0b9cddd4d40610e upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
tools/perf/util/probe-event.c | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)

--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -245,21 +245,22 @@ static void clear_probe_trace_events(str
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;
+ struct map *map;
+ bool ret = false;

- /* Get the address of _etext for checking non-probable text symbol */
- ret = kernel_get_symbol_address_by_name("_etext", &etext_addr,
- false, 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;
}

/*