kernel/tools/perf/util/probe-event.c, branch linux-4.3.y

perf probe: Use existing routine to look for a kernel module by dso->short_name

2015-09-25T13:41:31Z

We have map_groups__find_by_name() to look at the list of modules that are in place for a given machine, so use it instead of traversing the machine dso list, which also includes DSOs for userspace. When merging the user and kernel DSO lists a bug was introduced where 'perf probe' stopped being able to add probes to modules using its short name: # perf probe -m usbnet --add usbnet_start_xmit usbnet_start_xmit is out of .text, skip it. Error: Failed to add events. # With this fix it works again: # perf probe -m usbnet --add usbnet_start_xmit Added new event: probe:usbnet_start_xmit (on usbnet_start_xmit in usbnet) You can now use it in all perf tools, such as: perf record -e probe:usbnet_start_xmit -aR sleep 1 # Reported-by: Wang Nan Acked-by: Masami Hiramatsu Cc: Adrian Hunter Cc: Borislav Petkov Cc: David Ahern Cc: Frederic Weisbecker Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Fixes: 3d39ac538629 ("perf machine: No need to have two DSOs lists") Link: http://lkml.kernel.org/r/20150924015008.GE1897@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf probe: Support probing at absolute address

2015-08-26T13:41:12Z

It should be useful to allow 'perf probe' probe at absolute offset of a target. For example, when (u)probing at a instruction of a shared object in a embedded system where debuginfo is not avaliable but we know the offset of that instruction by manually digging. This patch enables following perf probe command syntax: # perf probe 0xffffffff811e6615 And # perf probe /lib/x86_64-linux-gnu/libc-2.19.so 0xeb860 In the above example, we don't need a anchor symbol, so it is possible to compute absolute addresses using other methods and then use 'perf probe' to create the probing points. v1 -> v2: Drop the leading '+' in cmdline; Allow uprobing at offset 0x0; Improve 'perf probe -l' result when uprobe at area without debuginfo. v2 -> v3: Split bugfix to a separated patch. Test result: # perf probe 0xffffffff8119d175 %ax # perf probe sys_write %ax # perf probe /lib64/libc-2.18.so 0x0 %ax # perf probe /lib64/libc-2.18.so 0x5 %ax # perf probe /lib64/libc-2.18.so 0xd8e40 %ax # perf probe /lib64/libc-2.18.so __write %ax # perf probe /lib64/libc-2.18.so 0xd8e49 %ax # cat /sys/kernel/debug/tracing/uprobe_events p:probe_libc/abs_0 /lib64/libc-2.18.so:0x (null) arg1=%ax p:probe_libc/abs_5 /lib64/libc-2.18.so:0x0000000000000005 arg1=%ax p:probe_libc/abs_d8e40 /lib64/libc-2.18.so:0x00000000000d8e40 arg1=%ax p:probe_libc/__write /lib64/libc-2.18.so:0x00000000000d8e40 arg1=%ax p:probe_libc/abs_d8e49 /lib64/libc-2.18.so:0x00000000000d8e49 arg1=%ax # cat /sys/kernel/debug/tracing/kprobe_events p:probe/abs_ffffffff8119d175 0xffffffff8119d175 arg1=%ax p:probe/sys_write _text+1692016 arg1=%ax # perf probe -l Failed to find debug information for address 5 probe:abs_ffffffff8119d175 (on sys_write+5 with arg1) probe:sys_write (on sys_write with arg1) probe_libc:__write (on @unix/syscall-template.S:81 in /lib64/libc-2.18.so with arg1) probe_libc:abs_0 (on 0x0 in /lib64/libc-2.18.so with arg1) probe_libc:abs_5 (on 0x5 in /lib64/libc-2.18.so with arg1) probe_libc:abs_d8e40 (on @unix/syscall-template.S:81 in /lib64/libc-2.18.so with arg1) probe_libc:abs_d8e49 (on __GI___libc_write+9 in /lib64/libc-2.18.so with arg1) Signed-off-by: Wang Nan Acked-by: Masami Hiramatsu Cc: Namhyung Kim Cc: Steven Rostedt Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1440586666-235233-7-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo

perf probe: Fix error reported when offset without function

2015-08-26T13:40:34Z

This patch fixes a bug that, when offset is provided but function is lost, parse_perf_probe_point() will give a "" string as function name, so the checking code at the end of parse_perf_probe_point() become useless. For example: # perf probe +0x1234 Failed to find symbol in kernel Error: Failed to add events. After this patch: # perf probe +0x1234 Semantic error :Offset requires an entry function. Error: Command Parse Error. Signed-off-by: Wang Nan Acked-by: Masami Hiramatsu Cc: Namhyung Kim Cc: Steven Rostedt Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1440586666-235233-6-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo

perf probe: Fix list result when address is zero

2015-08-26T13:39:20Z

When manually added uprobe point with zero address, 'perf probe -l' reports error. For example: # echo p:probe_libc/abs_0 /path/to/lib.bin:0x0 arg1=%ax > \ /sys/kernel/debug/tracing/uprobe_events # perf probe -l Error: Failed to show event list. Probing at 0x0 is possible and useful when lib.bin is not a normal shared object but is manually mapped. However, in this case kernel report: # cat /sys/kernel/debug/tracing/uprobe_events p:probe_libc/abs_0 /path/to/lib.bin:0x (null) arg1=%ax This patch supports the above kernel output. Signed-off-by: Wang Nan Acked-by: Masami Hiramatsu Cc: Namhyung Kim Cc: Steven Rostedt Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1440586666-235233-5-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo

perf probe: Fix list result when symbol can't be found

2015-08-26T13:36:04Z

'perf probe -l' reports error if it is unable find symbol through address. Here is an example. # echo 'p:probe_libc/abs_5 /lib64/libc.so.6:0x5' > /sys/kernel/debug/tracing/uprobe_events # cat /sys/kernel/debug/tracing/uprobe_events p:probe_libc/abs_5 /lib64/libc.so.6:0x0000000000000005 # perf probe -l Error: Failed to show event list Also, this situation triggers a logical inconsistency in convert_to_perf_probe_point() that, it returns ENOMEM but actually it never try strdup(). This patch removes !tp->module && !is_kprobe condition, so it always uses address to build function name if symbol not found. Test result: # perf probe -l probe_libc:abs_5 (on 0x5 in /lib64/libc.so.6) Signed-off-by: Wang Nan Acked-by: Masami Hiramatsu Cc: Namhyung Kim Cc: Steven Rostedt Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1440586666-235233-4-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo

perf probe: Prevent segfault when reading probe point with absolute address

2015-08-26T13:34:11Z

'perf probe -l' panic if there is a manually inserted probing point with absolute address. For example: # echo 'p:probe/abs_ffffffff811e6615 0xffffffff811e6615' > /sys/kernel/debug/tracing/kprobe_events # perf probe -l Segmentation fault (core dumped) This patch fix this problem by considering the situation that "tp->symbol == NULL" in find_perf_probe_point_from_dwarf() and find_perf_probe_point_from_map(). After this patch: # perf probe -l probe:abs_ffffffff811e6615 (on SyS_write+5@fs/read_write.c) And when debug info is missing: # rm -rf ~/.debug # mv /lib/modules/4.2.0-rc1+/build/vmlinux /lib/modules/4.2.0-rc1+/build/vmlinux.bak # perf probe -l probe:abs_ffffffff811e6615 (on sys_write+5) Signed-off-by: Wang Nan Tested-by: Arnaldo Carvalho de Melo Acked-by: Masami Hiramatsu Cc: Namhyung Kim Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1440509256-193590-1-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo

perf probe: Try to use symbol table if searching debug info failed

2015-08-21T15:57:20Z

A problem can occur in a statically linked perf when vmlinux can be found: # perf probe --add sys_epoll_pwait probe-definition(0): sys_epoll_pwait symbol:sys_epoll_pwait file:(null) line:0 offset:0 return:0 lazy:(null) 0 arguments Looking at the vmlinux_path (7 entries long) Using /lib/modules/4.2.0-rc1+/build/vmlinux for symbols Open Debuginfo file: /lib/modules/4.2.0-rc1+/build/vmlinux Try to find probe point from debuginfo. Symbol sys_epoll_pwait address found : ffffffff8122bd40 Matched function: SyS_epoll_pwait Failed to get call frame on 0xffffffff8122bd40 An error occurred in debuginfo analysis (-2). Error: Failed to add events. Reason: No such file or directory (Code: -2) The reason is caused by libdw that, if libdw is statically linked, it can't load libebl_{arch}.so reliable. In this case it is still possible to get the address from /proc/kalksyms. However, perf tries that only when libdw returns -EBADF. This patch gives it another chance to utilize symbol table, even if libdw returns an error code other than -EBADF. After applying this patch: # perf probe -nv --add sys_epoll_pwait probe-definition(0): sys_epoll_pwait symbol:sys_epoll_pwait file:(null) line:0 offset:0 return:0 lazy:(null) 0 arguments Looking at the vmlinux_path (7 entries long) Using /lib/modules/4.2.0-rc1+/build/vmlinux for symbols Open Debuginfo file: /lib/modules/4.2.0-rc1+/build/vmlinux Try to find probe point from debuginfo. Symbol sys_epoll_pwait address found : ffffffff8122bd40 Matched function: SyS_epoll_pwait Failed to get call frame on 0xffffffff8122bd40 An error occurred in debuginfo analysis (-2). Trying to use symbols. Opening /sys/kernel/debug/tracing/kprobe_events write=1 Added new event: Writing event: p:probe/sys_epoll_pwait _text+2276672 probe:sys_epoll_pwait (on sys_epoll_pwait) You can now use it in all perf tools, such as: perf record -e probe:sys_epoll_pwait -aR sleep 1 Although libdw returns an error (Failed to get call frame), perf tries symbol table and finally gets correct address. Signed-off-by: Wang Nan Cc: Alexei Starovoitov Cc: Brendan Gregg Cc: Daniel Borkmann Cc: David Ahern Cc: He Kuang Cc: Jiri Olsa Cc: Kaixu Xia Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Zefan Li Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1440151770-129878-2-git-send-email-wangnan0@huawei.com Signed-off-by: Arnaldo Carvalho de Melo

perf probe: Move ftrace probe-event operations to probe-file.c

2015-07-20T20:49:49Z

Move ftrace probe-event operations to probe-file.c from probe-event.c. Signed-off-by: Masami Hiramatsu Cc: Adrian Hunter Cc: Borislav Petkov Cc: Hemant Kumar Cc: Jiri Olsa Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20150715091407.8915.14316.stgit@localhost.localdomain [ Fixed up strlist__new() calls wrt 4a77e2183fc0 ("perf strlist: Make dupstr be the...") ] Signed-off-by: Arnaldo Carvalho de Melo

perf probe: Simplify __add_probe_trace_events code

2015-07-20T20:49:49Z

Simplify the __add_probe_trace_events() code by taking out the probe_trace_event__set_name() and updating show_perf_probe_event() Signed-off-by: Masami Hiramatsu Cc: Adrian Hunter Cc: Borislav Petkov Cc: Hemant Kumar Cc: Jiri Olsa Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20150715091400.8915.85501.stgit@localhost.localdomain Signed-off-by: Arnaldo Carvalho de Melo

perf strlist: Make dupstr be the default and part of an extensible config parm

2015-07-20T15:13:34Z

So that we can pass more info to strlist__new() without having to change its function signature, just adding entries to the strlist_config struct with sensible defaults for when those fields are not specified. Cc: Adrian Hunter Cc: Borislav Petkov Cc: David Ahern Cc: Frederic Weisbecker Cc: Jiri Olsa Cc: Namhyung Kim Cc: Stephane Eranian Link: http://lkml.kernel.org/n/tip-5uaaler4931i0s9sedxjquhq@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo