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

    /*

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