f4f1c42953
Report possible permission error including kptr_restrict setting for map__load() failure. This can happen when non-superuser runs perf probe. With this patch, perf probe shows the following message. $ perf probe vfs_read Failed to load symbols from /proc/kallsyms Please ensure you can read the /proc/kallsyms symbol addresses. If the /proc/sys/kernel/kptr_restrict is '2', you can not read kernel symbol address even if you are a superuser. Please change it to '1'. If kptr_restrict is '1', the superuser can read the symbol addresses. In that case, please run this command again with sudo. Error: Failed to add events. Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Ian Rogers <irogers@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Link: http://lore.kernel.org/lkml/162282065877.448336.10047912688119745151.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.