In 3f8aad340b ("elf_symtab: Handle SHN_XINDEX index in
elf_section_by_name()") we stopped using that argument as we switched to
using elf_getshdrstrndx() to get SHN_XINDEX.
So just remove that argument and fixup its callers, this will allow
removing a good chunk of calls and variables.
Cc: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
So that we handle const pointers, also zalloc() is much simpler just
calling calloc(1, size).
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Use elf_getshdrstrndx() to cover the case where the ELF header
'e_shstrndx' field contains the special value SHN_XINDEX so that we get
the proper string table index.
This is necessary to handle files with over 65536 sections, such as when
building the kernel with -f[function|data]-sections. Other cases may
include when using FG-ASLR, LTO.
With so many sections, ELF is using extended section index table, which
is used to hold values for some of the indexes and extra code is needed
to retrieve them.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Hao Luo <haoluo@google.com>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@chromium.org>
Cc: Mark Wieelard <mjw@redhat.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Add support to detect kernel module ftrace addresses and use
it as filter for detected functions.
For kernel modules the ftrace addresses are stored in __mcount_loc
section. Adding the code that detects this section and reads
its data into array, which is then processed as filter by
current code.
There's one tricky point with kernel modules wrt Elf object,
which we get from dwfl_module_getelf function. This function
performs all possible relocations, including __mcount_loc
section.
So addrs array contains relocated values, which we need take
into account when we compare them to functions values which
are relative to their sections.
With this change for example for xfs.ko module in my kernel
config, I'm getting slightly bigger number of functions:
before: 2373, after: 2601
The ftrace's available_filter_functions still shows 2701, but
it includes functions like:
suffix_kstrtoint.constprop.0
xchk_btree_check_minrecs.isra.0
xfs_ascii_ci_compname.part.0
which are not part of dwarf data, the rest matches BTF functions.
Because of the malfunction DWARF's declaration tag, the 'before'
functions contain also functions that are not part of the module.
The 'after' functions contain only functions that are traceable
and part of xfs.ko.
Despite filtering out some declarations, this change also adds
static functions, hence the total number of functions is bigger.
Committer notes:
Andrii test notes:
<quote>
I've tested locally on bpf_testmod that I'm adding to selftests in [0].
All worked well. I changed the test function from global to non-inlined
static, and BTF had it. And the tests passed. So LGTM.
[0] https://patchwork.kernel.org/user/todo/netdevbpf/?series=395715&delegate=121173&state=*
</>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Hao Luo <haoluo@google.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
I.e. when we do:
pahole -C a,b,c,d binary
We want that the 'a' type be processed first, etc. So add a list for
that.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
As Thomas Gleixner wisely pointed out, using 'self' is stupid, it
doesn't convey useful information, so use sensible names.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
I.e. the operation may fail because the string is already there or
because there wasn't enough memory.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Amazing how many crept up over time, should have set the
execute bit of .git/hooks/pre-commit already, duh.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Now at creation time we specify if the strings must be allocated or if using
the pointer directly.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Arnaldo Carvalho de Melo
Jiri Olsa
Domenico Andreoli