And that is where its passed, so just use the constructor argument, no
need to have it in the newly created object.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
As btf_elf__new() is only called from the BTF encoder, and that will not
be encoding from a BTF file, it'll be from a DWARF one.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This will allow us to stop using btfe->priv and eventually btf_elf
altogether for the BTF loader.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
So that we can get rid of that global base_btf and use the right way
to pass load configuration to the format loaders.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
We'll get rid of the 'base_btf' global variable in libbtf.c, so stop
using it in the BTF encoder.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
When loading a file, via btf__parse_split() libbtf will read the header
and have the endianness made available via the btf__endianness() API,
use it.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This way we use libbtf to transparently load both ELF files with a BTF
section as well as raw BTF files, such as those in /sys/kernel/btf/ or
the ones generated using 'pahole --btf_encode_detached'
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To fix the build in systems where this isn't defined.
Reported-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
To solve problems similar to _RH_KABI_REPLACE. The _RH_KABI_REPLACE(_orig, _new) macros perserve size alignment and kabi agreement between _orig and _new.Below is the definition of this macro:
union { \
_new; \
struct { \
_orig; \
} __UNIQUE_ID(rh_kabi_hide); \
__RH_KABI_CHECK_SIZE_ALIGN(_orig, _new); \
}
__UNIQUE_ID uses the __COUNTER__ macro, and the __COUNTER__ macro is automatically incremented by 1 every time it is precompiled. Therefore, in different compilation units, the same structure has different names.Here is a concrete example:
struct acpi_dev_node {
union {
struct acpi_device *companion;
struct {
void *handle;
} __UNIQUE_ID_rh_kabi_hide29;
union { };
};
};
struct acpi_dev_node {
union {
struct acpi_device *companion;
struct {
void *handle;
} __UNIQUE_ID_rh_kabi_hide31;
union { };
};
};
Finally, it will cause the btf algorithm to de-duplication efficiency is not high, and time-consuming. For example, running ./pahole -J vmlinux-3.10.0-1160.el7.x86_64 without --kabi_prefix flag, the running time is:
real 8m28.912s
user 8m27.271s
sys 0m1.471s
And the size of the generated btf segment is 30678240 bytes.
After adding the patch, running ./pahole --kabi_prefix=__UNIQUE_ID_rh_kabi_hide -J vmlinux-3.10.0-1160.el7.x86_64. The running time of the command is:
real 0m19.634s
user 0m18.457s
sys 0m1.169s
And the size of the generated btf segment is 3117719 bytes.
Signed-off-by: Shuyi Cheng <chengshuyi@linux.alibaba.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Wenan Mao <wenan.mao@linux.alibaba.com>
Cc: dwarves@vger.kernel.org
Link: https://lore.kernel.org/dwarves/482e5543-d7da-7bed-098d-cc879d8db253@linux.alibaba.com/
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
btf_encoder is ignoring zero-sized per-CPU ELF symbols, but the same has to be
done for DWARF variables when matching them with ELF symbols. This is due to
zero-sized DWARF variables matching unrelated (non-zero-sized) variable that
happens to be allocated at the exact same address, leading to a lot of
confusion in BTF.
See [0] for when this causes big problems.
[0] https://lore.kernel.org/bpf/CAEf4BzZ0-sihSL-UAm21JcaCCY92CqfNxycHRZYXcoj8OYb=wA@mail.gmail.com/
Committer notes:
Kept the {} around the if block with more than one line, which
simplifies the original patch by just removing that assignment
to the 'dwarf_name' variable.
Reported-by: Michal Suchánek <msuchanek@suse.de>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: bpf@vger.kernel.org
Cc: dwarves@vger.kernel.org
Cc: kernel-team@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Arnaldo Carvalho de Melo
Shuyi Cheng
Andrii Nakryiko