From da15bd9df4afd2f9f78cf29f85f013e3a38402b5 Mon Sep 17 00:00:00 2001 From: Wang Nan Date: Wed, 26 Aug 2015 10:57:45 +0000 Subject: perf probe: Support probing at absolute address 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 --- tools/perf/util/probe-event.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'tools/perf/util/probe-event.h') diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h index 83ee95e9743b..6e7ec68a4aa8 100644 --- a/tools/perf/util/probe-event.h +++ b/tools/perf/util/probe-event.h @@ -59,6 +59,7 @@ struct perf_probe_point { bool retprobe; /* Return probe flag */ char *lazy_line; /* Lazy matching pattern */ unsigned long offset; /* Offset from function entry */ + unsigned long abs_address; /* Absolute address of the point */ }; /* Perf probe probing argument field chain */ @@ -156,4 +157,7 @@ int e_snprintf(char *str, size_t size, const char *format, ...) /* Maximum index number of event-name postfix */ #define MAX_EVENT_INDEX 1024 +int copy_to_probe_trace_arg(struct probe_trace_arg *tvar, + struct perf_probe_arg *pvar); + #endif /*_PROBE_EVENT_H */ -- cgit v1.2.1