• Masami Hiramatsu's avatar
    perf probe: Check address correctness by map instead of _etext · 2ae5d0d7
    Masami Hiramatsu authored
    Since commit 03db8b58 ("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: 03db8b58 ("perf tools: Fix maps__find_symbol_by_name()")
    Reported-by: default avatarArnaldo Carvalho de Melo <acme@kernel.org>
    Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
    Tested-by: default avatarArnaldo 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@devnote2Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    2ae5d0d7
probe-event.c 81.4 KB