1a86f4ba5c
On anARM machine, kernel symbols from modules can be resolved to $a instead of printing the actual symbol name. Ignore symbols starting with "$" when building kallsyms rbtree. A sample stacktrace is shown as follows: c0f2e39c schedule_hrtimeout+0x14 ([kernel.kallsyms]) bf4a66d8 $a+0x78 ([test_module]) c0a4f5f4 kthread+0x15c ([kernel.kallsyms]) c0a001f8 ret_from_fork+0x14 ([kernel.kallsyms]) On an ARM machine, $a/$d symbols are used by the compiler to mark the beginning of code/data part in code section. These symbols are filtered out when linking vmlinux(see scripts/kallsyms.c ignored_prefixes), but are left on modules. So there are $a symbols in /proc/kallsyms which share the same addresses with the actual module symbols and confuses perf when resolving symbols. After this patch, the module symbol name is printed: c0f2e39c schedule_hrtimeout+0x14 ([kernel.kallsyms]) bf4a66d8 test_func+0x78 ([test_module]) c0a4f5f4 kthread+0x15c ([kernel.kallsyms]) c0a001f8 ret_from_fork+0x14 ([kernel.kallsyms]) Reviewed-by: James Clark <james.clark@arm.com> Signed-off-by: Lexi Shao <shaolexi@huawei.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jessica Yu <jeyu@kernel.org> Cc: Jiri Olsa <jolsa@redhat.com> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Martin KaFai Lau <kafai@fb.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Nathan Chancellor <natechancellor@gmail.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: QiuXi <qiuxi1@huawei.com> Cc: Song Liu <songliubraving@fb.com> Cc: Wangbing <wangbing6@huawei.com> Cc: Xiaoming Ni <nixiaoming@huawei.com> Cc: Yonghong Song <yhs@fb.com> Cc: bpf@vger.kernel.org Cc: clang-built-linux@googlegroups.com Link: https://lore.kernel.org/r/20211029065038.39449-2-shaolexi@huawei.com 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.