Em Thu, Apr 23, 2020 at 08:01:13PM +0900, Masami Hiramatsu escreveu:
> 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)
But what is this (null):(null) probe? Confusing :-)
Thanks for working on this!
- Arnaldo
> 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@xxxxxxxxxx>
> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> ---
> 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 f75df63309be..a5387e03e365 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;
> }
>
> /*
>
--
- Arnaldo
