Masami Hiramatsu
07d3698578
Since there are some DIE which has only ranges instead of the
combination of entrypc/highpc, address verification must use
dwarf_haspc() instead of dwarf_entrypc/dwarf_highpc.
Also, the ranges only DIE will have a partial code in different section
(e.g. unlikely code will be in text.unlikely as "FUNC.cold" symbol). In
that case, we can not use dwarf_entrypc() or die_entrypc(), because the
offset from original DIE can be a minus value.
Instead, this simply gets the symbol and offset from symtab.
Without this patch;
# perf probe -D clear_tasks_mm_cpumask:1
Failed to get entry address of clear_tasks_mm_cpumask
Error: Failed to add events.
And with this patch:
# perf probe -D clear_tasks_mm_cpumask:1
p:probe/clear_tasks_mm_cpumask clear_tasks_mm_cpumask+0
p:probe/clear_tasks_mm_cpumask_1 clear_tasks_mm_cpumask+5
p:probe/clear_tasks_mm_cpumask_2 clear_tasks_mm_cpumask+8
p:probe/clear_tasks_mm_cpumask_3 clear_tasks_mm_cpumask+16
p:probe/clear_tasks_mm_cpumask_4 clear_tasks_mm_cpumask+82
Committer testing:
I managed to reproduce the above:
[root@quaco ~]# perf probe -D clear_tasks_mm_cpumask:1
p:probe/clear_tasks_mm_cpumask _text+919968
p:probe/clear_tasks_mm_cpumask_1 _text+919973
p:probe/clear_tasks_mm_cpumask_2 _text+919976
[root@quaco ~]#
But then when trying to actually put the probe in place, it fails if I
use :0 as the offset:
[root@quaco ~]# perf probe -L clear_tasks_mm_cpumask | head -5
<clear_tasks_mm_cpumask@/usr/src/debug/kernel-5.2.fc30/linux-5.2.18-200.fc30.x86_64/kernel/cpu.c:0>
0 void clear_tasks_mm_cpumask(int cpu)
1 {
2 struct task_struct *p;
[root@quaco ~]# perf probe clear_tasks_mm_cpumask:0
Probe point 'clear_tasks_mm_cpumask' not found.
Error: Failed to add events.
[root@quaco
The next patch is needed to fix this case.
Fixes: 576b523721 ("perf probe: Fix probing symbols with optimization suffix")
Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lore.kernel.org/lkml/157199318513.8075.10463906803299647907.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.