In the function btf__load_vmlinux_btf, the debug message incorrectly
refers to 'path' instead of 'sysfs_btf_path'.
Signed-off-by: Chen Shen <peterchenshen@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20240302062218.3587-1-peterchenshen@gmail.com
Another API that was declared in libbpf.map but actual implementation
was missing. btf_ext__get_raw_data() was intended as a discouraged alias
to consistently-named btf_ext__raw_data(), so make this an actuality.
Fixes: 20eccf29e2 ("libbpf: hide and discourage inconsistently named getters")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20240201172027.604869-5-andrii@kernel.org
Seems like original commit adding split BTF support intended to add
btf__new_split() API, and even declared it in libbpf.map, but never
added (trivial) implementation. Fix this.
Fixes: ba451366bf ("libbpf: Implement basic split BTF support")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20240201172027.604869-4-andrii@kernel.org
As CONFIG_DEBUG_INFO_BTF is default off the existing "failed to find
valid kernel BTF" message makes diagnosing the kernel build issue somewhat
cryptic. Add a little more detail with the hope of helping users.
Before:
```
libbpf: failed to find valid kernel BTF
libbpf: Error loading vmlinux BTF: -3
```
After not accessible:
```
libbpf: kernel BTF is missing at '/sys/kernel/btf/vmlinux', was CONFIG_DEBUG_INFO_BTF enabled?
libbpf: failed to find valid kernel BTF
libbpf: Error loading vmlinux BTF: -3
```
After not readable:
```
libbpf: failed to read kernel BTF from (/sys/kernel/btf/vmlinux): -1
```
Closes: https://lore.kernel.org/bpf/CAP-5=fU+DN_+Y=Y4gtELUsJxKNDDCOvJzPHvjUVaUoeFAzNnig@mail.gmail.com/
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240125231840.1647951-1-irogers@google.com
Add BPF token support to BPF object-level functionality.
BPF token is supported by BPF object logic either as an explicitly
provided BPF token from outside (through BPF FS path), or implicitly
(unless prevented through bpf_object_open_opts).
Implicit mode is assumed to be the most common one for user namespaced
unprivileged workloads. The assumption is that privileged container
manager sets up default BPF FS mount point at /sys/fs/bpf with BPF token
delegation options (delegate_{cmds,maps,progs,attachs} mount options).
BPF object during loading will attempt to create BPF token from
/sys/fs/bpf location, and pass it for all relevant operations
(currently, map creation, BTF load, and program load).
In this implicit mode, if BPF token creation fails due to whatever
reason (BPF FS is not mounted, or kernel doesn't support BPF token,
etc), this is not considered an error. BPF object loading sequence will
proceed with no BPF token.
In explicit BPF token mode, user provides explicitly custom BPF FS mount
point path. In such case, BPF object will attempt to create BPF token
from provided BPF FS location. If BPF token creation fails, that is
considered a critical error and BPF object load fails with an error.
Libbpf provides a way to disable implicit BPF token creation, if it
causes any troubles (BPF token is designed to be completely optional and
shouldn't cause any problems even if provided, but in the world of BPF
LSM, custom security logic can be installed that might change outcome
depending on the presence of BPF token). To disable libbpf's default BPF
token creation behavior user should provide either invalid BPF token FD
(negative), or empty bpf_token_path option.
BPF token presence can influence libbpf's feature probing, so if BPF
object has associated BPF token, feature probing is instructed to use
BPF object-specific feature detection cache and token FD.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-26-andrii@kernel.org
Make sure that libbpf code always gets FD with O_CLOEXEC flag set,
regardless if file is open through open() or fopen(). For the latter
this means to add "e" to mode string, which is supported since pretty
ancient glibc v2.7.
Also drop the outdated TODO comment in usdt.c, which was already completed.
Suggested-by: Lennart Poettering <lennart@poettering.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230525221311.2136408-1-andrii@kernel.org
As discussed before, return -ENODATA (No data available) would be more
meaningful than ENOENT (No such file or directory).
Suggested-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221231151436.6541-1-changbin.du@gmail.com
Show the real problem instead of just saying "No such file or directory".
Now will print below info:
libbpf: failed to find '.BTF' ELF section in /home/changbin/work/linux/vmlinux
Error: failed to load BTF from /home/changbin/work/linux/vmlinux: No such file or directory
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221217223509.88254-2-changbin.du@gmail.com
btf__align_of() is supposed to be return alignment requirement of
a requested BTF type. For STRUCT/UNION it doesn't always return correct
value, because it calculates alignment only based on field types. But
for packed structs this is not enough, we need to also check field
offsets and struct size. If field offset isn't aligned according to
field type's natural alignment, then struct must be packed. Similarly,
if struct size is not a multiple of struct's natural alignment, then
struct must be packed as well.
This patch fixes this issue precisely by additionally checking these
conditions.
Fixes: 3d208f4ca1 ("libbpf: Expose btf__align_of() API")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221212211505.558851-5-andrii@kernel.org
Resolve forward declarations that don't take part in type graphs
comparisons if declaration name is unambiguous. Example:
CU #1:
struct foo; // standalone forward declaration
struct foo *some_global;
CU #2:
struct foo { int x; };
struct foo *another_global;
The `struct foo` from CU #1 is not a part of any definition that is
compared against another definition while `btf_dedup_struct_types`
processes structural types. The the BTF after `btf_dedup_struct_types`
the BTF looks as follows:
[1] STRUCT 'foo' size=4 vlen=1 ...
[2] INT 'int' size=4 ...
[3] PTR '(anon)' type_id=1
[4] FWD 'foo' fwd_kind=struct
[5] PTR '(anon)' type_id=4
This commit adds a new pass `btf_dedup_resolve_fwds`, that maps such
forward declarations to structs or unions with identical name in case
if the name is not ambiguous.
The pass is positioned before `btf_dedup_ref_types` so that types
[3] and [5] could be merged as a same type after [1] and [4] are merged.
The final result for the example above looks as follows:
[1] STRUCT 'foo' size=4 vlen=1
'x' type_id=2 bits_offset=0
[2] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED
[3] PTR '(anon)' type_id=1
For defconfig kernel with BTF enabled this removes 63 forward
declarations. Examples of removed declarations: `pt_regs`, `in6_addr`.
The running time of `btf__dedup` function is increased by about 3%.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221109142611.879983-3-eddyz87@gmail.com
An update for libbpf's hashmap interface from void* -> void* to a
polymorphic one, allowing both long and void* keys and values.
This simplifies many use cases in libbpf as hashmaps there are mostly
integer to integer.
Perf copies hashmap implementation from libbpf and has to be
updated as well.
Changes to libbpf, selftests/bpf and perf are packed as a single
commit to avoid compilation issues with any future bisect.
Polymorphic interface is acheived by hiding hashmap interface
functions behind auxiliary macros that take care of necessary
type casts, for example:
#define hashmap_cast_ptr(p) \
({ \
_Static_assert((p) == NULL || sizeof(*(p)) == sizeof(long),\
#p " pointee should be a long-sized integer or a pointer"); \
(long *)(p); \
})
bool hashmap_find(const struct hashmap *map, long key, long *value);
#define hashmap__find(map, key, value) \
hashmap_find((map), (long)(key), hashmap_cast_ptr(value))
- hashmap__find macro casts key and value parameters to long
and long* respectively
- hashmap_cast_ptr ensures that value pointer points to a memory
of appropriate size.
This hack was suggested by Andrii Nakryiko in [1].
This is a follow up for [2].
[1] https://lore.kernel.org/bpf/CAEf4BzZ8KFneEJxFAaNCCFPGqp20hSpS2aCj76uRk3-qZUH5xg@mail.gmail.com/
[2] https://lore.kernel.org/bpf/af1facf9-7bc8-8a3d-0db4-7b3f333589a2@meta.com/T/#m65b28f1d6d969fcd318b556db6a3ad499a42607d
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221109142611.879983-2-eddyz87@gmail.com
Changes de-duplication logic for enums in the following way:
- update btf_hash_enum to ignore size and kind fields to get
ENUM and ENUM64 types in a same hash bucket;
- update btf_compat_enum to consider enum fwd to be compatible with
full enum64 (and vice versa);
This allows BTF de-duplication in the following case:
// CU #1
enum foo;
struct s {
enum foo *a;
} *x;
// CU #2
enum foo {
x = 0xfffffffff // big enough to force enum64
};
struct s {
enum foo *a;
} *y;
De-duplicated BTF prior to this commit:
[1] ENUM64 'foo' encoding=UNSIGNED size=8 vlen=1
'x' val=68719476735ULL
[2] INT 'long unsigned int' size=8 bits_offset=0 nr_bits=64
encoding=(none)
[3] STRUCT 's' size=8 vlen=1
'a' type_id=4 bits_offset=0
[4] PTR '(anon)' type_id=1
[5] PTR '(anon)' type_id=3
[6] STRUCT 's' size=8 vlen=1
'a' type_id=8 bits_offset=0
[7] ENUM 'foo' encoding=UNSIGNED size=4 vlen=0
[8] PTR '(anon)' type_id=7
[9] PTR '(anon)' type_id=6
De-duplicated BTF after this commit:
[1] ENUM64 'foo' encoding=UNSIGNED size=8 vlen=1
'x' val=68719476735ULL
[2] INT 'long unsigned int' size=8 bits_offset=0 nr_bits=64
encoding=(none)
[3] STRUCT 's' size=8 vlen=1
'a' type_id=4 bits_offset=0
[4] PTR '(anon)' type_id=1
[5] PTR '(anon)' type_id=3
Enum forward declarations in C do not provide information about
enumeration values range. Thus the `btf_type->size` field is
meaningless for forward enum declarations. In fact, GCC does not
encode size in DWARF for forward enum declarations
(but dwarves sets enumeration size to a default value of `sizeof(int) * 8`
when size is not specified see dwarf_loader.c:die__create_new_enumeration).
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221101235413.1824260-1-eddyz87@gmail.com
When examining module BTF, it is common to see core kernel structures
such as sk_buff, net_device duplicated in the module. After adding
debug messaging to BTF it turned out that much of the problem
was down to the identical struct test failing during deduplication;
sometimes the compiler adds identical structs. However
it turns out sometimes that type ids of identical struct members
can also differ, even when the containing structs are still identical.
To take an example, for struct sk_buff, debug messaging revealed
that the identical struct matching was failing for the anon
struct "headers"; specifically for the first field:
__u8 __pkt_type_offset[0]; /* 128 0 */
Looking at the code in BTF deduplication, we have code that guards
against the possibility of identical struct definitions, down to
type ids, and identical array definitions. However in this case
we have a struct which is being defined twice but does not have
identical type ids since each duplicate struct has separate type
ids for the above array member. A similar problem (though not
observed) could occur for struct-in-struct.
The solution is to make the "identical struct" test check members
not just for matching ids, but to also check if they in turn are
identical structs or arrays.
The results of doing this are quite dramatic (for some modules
at least); I see the number of type ids drop from around 10000
to just over 1000 in one module for example.
For testing use latest pahole or apply [1], otherwise dedups
can fail for the reasons described there.
Also fix return type of btf_dedup_identical_arrays() as
suggested by Andrii to match boolean return type used
elsewhere.
Fixes: efdd3eb801 ("libbpf: Accommodate DWARF/compiler bug with duplicated structs")
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1666622309-22289-1-git-send-email-alan.maguire@oracle.com
[1] https://lore.kernel.org/bpf/1666364523-9648-1-git-send-email-alan.maguire
When running rootless with special capabilities like:
FOWNER / DAC_OVERRIDE / DAC_READ_SEARCH
The "access" API will not make the proper check if there is really
access to a file or not.
>From the access man page:
"
The check is done using the calling process's real UID and GID, rather
than the effective IDs as is done when actually attempting an operation
(e.g., open(2)) on the file. Similarly, for the root user, the check
uses the set of permitted capabilities rather than the set of effective
capabilities; ***and for non-root users, the check uses an empty set of
capabilities.***
"
What that means is that for non-root user the access API will not do the
proper validation if the process really has permission to a file or not.
To resolve this this patch replaces all the access API calls with
faccessat with AT_EACCESS flag.
Signed-off-by: Jon Doron <jond@wiz.io>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220925070431.1313680-1-arilou@gmail.com
Currently, the default vmlinux files at '/boot/vmlinux-*',
'/lib/modules/*/vmlinux-*' etc. are parsed with 'btf__parse_elf()' to
extract BTF. It is possible that these files are actually raw BTF files
similar to /sys/kernel/btf/vmlinux. So parse these files with
'btf__parse' which tries both raw format and ELF format.
This might be useful in some scenarios where users put their custom BTF
into known locations and don't want to specify btf_custom_path option.
Signed-off-by: Tao Chen <chentao.kernel@linux.alibaba.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/3f59fb5a345d2e4f10e16fe9e35fbc4c03ecaa3e.1662999860.git.chentao.kernel@linux.alibaba.com
Remove three missed deprecated APIs that were aliased to new APIs:
bpf_object__unload, bpf_prog_attach_xattr and btf__load.
Also move legacy API libbpf_find_kernel_btf (aliased to
btf__load_vmlinux_btf) into libbpf_legacy.h.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/bpf/20220816001929.369487-4-andrii@kernel.org
Add enum64 deduplication support. BTF_KIND_ENUM64 handling
is very similar to BTF_KIND_ENUM.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220607062626.3720166-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add enum64 parsing support and two new enum64 public APIs:
btf__add_enum64
btf__add_enum64_value
Also add support of signedness for BTF_KIND_ENUM. The
BTF_KIND_ENUM API signatures are not changed. The signedness
will be changed from unsigned to signed if btf__add_enum_value()
finds any negative values.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220607062621.3719391-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Refactor btf__add_enum() function to create a separate
function btf_add_enum_common() so later the common function
can be used to add enum64 btf type. There is no functionality
change for this patch.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220607062615.3718063-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This change fixes a couple of typos that were encountered while studying
the source code.
Signed-off-by: Daniel Müller <deso@posteo.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220601154025.3295035-1-deso@posteo.net
One strategy employed by libbpf to guess the pointer size is by finding
the size of "unsigned long" type. This is achieved by looking for a type
of with the expected name and checking its size.
Unfortunately, the C syntax is friendlier to humans than to computers
as there is some variety in how such a type can be named. Specifically,
gcc and clang do not use the same names for integer types in debug info:
- clang uses "unsigned long"
- gcc uses "long unsigned int"
Lookup all the names for such a type so that libbpf can hope to find the
information it wants.
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220524094447.332186-1-douglas.raillard@arm.com
Instead of using ELF section names as a joining key between .BTF.ext and
corresponding BPF programs, pre-build .BTF.ext section number to ELF
section index mapping during bpf_object__open() and use it later for
matching .BTF.ext information (func/line info or CO-RE relocations) to
their respective BPF programs and subprograms.
This simplifies corresponding joining logic and let's libbpf do
manipulations with BPF program's ELF sections like dropping leading '?'
character for non-autoloaded programs. Original joining logic in
bpf_object__relocate_core() (see relevant comment that's now removed)
was never elegant, so it's a good improvement regardless. But it also
avoids unnecessary internal assumptions about preserving original ELF
section name as BPF program's section name (which was broken when
SEC("?abc") support was added).
Fixes: a3820c4811 ("libbpf: Support opting out from autoloading BPF programs declaratively")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220426004511.2691730-5-andrii@kernel.org
Since core relos is an optional part of the .BTF.ext ELF section, we should
skip parsing it instead of returning -EINVAL if header size is less than
offsetofend(struct btf_ext_header, core_relo_len).
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220404005320.1723055-1-ytcoode@gmail.com
Add a hashmap to map the string offsets from a source btf to the
string offsets from a target btf to reduce overheads.
btf__add_btf() calls btf__add_str() to add strings from a source to a
target btf. It causes many string comparisons, and it is a major
hotspot when adding a big btf. btf__add_str() uses strcmp() to check
if a hash entry is the right one. The extra hashmap here compares
offsets of strings, that are much cheaper. It remembers the results
of btf__add_str() for later uses to reduce the cost.
We are parallelizing BTF encoding for pahole by creating separated btf
instances for worker threads. These per-thread btf instances will be
added to the btf instance of the main thread by calling btf__add_str()
to deduplicate and write out. With this patch and -j4, the running
time of pahole drops to about 6.0s from 6.6s.
The following lines are the summary of 'perf stat' w/o the change.
6.668126396 seconds time elapsed
13.451054000 seconds user
0.715520000 seconds sys
The following lines are the summary w/ the change.
5.986973919 seconds time elapsed
12.939903000 seconds user
0.724152000 seconds sys
V4 fixes a bug of error checking against the pointer returned by
hashmap__new().
[v3] https://lore.kernel.org/bpf/20220118232053.2113139-1-kuifeng@fb.com/
[v2] https://lore.kernel.org/bpf/20220114193713.461349-1-kuifeng@fb.com/
Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220119180214.255634-1-kuifeng@fb.com
The btf__dedup_deprecated name was misspelled in the definition of the
compat symbol for btf__dedup. This leads it to be missing from the
shared library.
This fixes it.
Fixes: 957d350a8b ("libbpf: Turn btf_dedup_opts into OPTS-based struct")
Signed-off-by: Vincent Minet <vincent@vincent-minet.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211210063112.80047-1-vincent@vincent-minet.net
Add libbpf-internal btf_load_into_kernel() that allows to pass
preallocated log_buf and custom log_level to be passed into kernel
during BPF_BTF_LOAD call. When custom log_buf is provided,
btf_load_into_kernel() won't attempt an retry with automatically
allocated internal temporary buffer to capture BTF validation log.
It's important to note the relation between log_buf and log_level, which
slightly deviates from stricter kernel logic. From kernel's POV, if
log_buf is specified, log_level has to be > 0, and vice versa. While
kernel has good reasons to request such "sanity, this, in practice, is
a bit unconvenient and restrictive for libbpf's high-level bpf_object APIs.
So libbpf will allow to set non-NULL log_buf and log_level == 0. This is
fine and means to attempt to load BTF without logging requested, but if
it failes, retry the load with custom log_buf and log_level 1. Similar
logic will be implemented for program loading. In practice this means
that users can provide custom log buffer just in case error happens, but
not really request slower verbose logging all the time. This is also
consistent with libbpf behavior when custom log_buf is not set: libbpf
first tries to load everything with log_level=0, and only if error
happens allocates internal log buffer and retries with log_level=1.
Also, while at it, make BTF validation log more obvious and follow the log
pattern libbpf is using for dumping BPF verifier log during
BPF_PROG_LOAD. BTF loading resulting in an error will look like this:
libbpf: BTF loading error: -22
libbpf: -- BEGIN BTF LOAD LOG ---
magic: 0xeb9f
version: 1
flags: 0x0
hdr_len: 24
type_off: 0
type_len: 1040
str_off: 1040
str_len: 2063598257
btf_total_size: 1753
Total section length too long
-- END BTF LOAD LOG --
libbpf: Error loading .BTF into kernel: -22. BTF is optional, ignoring.
This makes it much easier to find relevant parts in libbpf log output.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211209193840.1248570-4-andrii@kernel.org
To prepare relo_core.c to be compiled in the kernel and the user space
replace btf__type_by_id with btf_type_by_id.
In libbpf btf__type_by_id and btf_type_by_id have different behavior.
bpf_core_apply_relo_insn() needs behavior of uapi btf__type_by_id
vs internal btf_type_by_id, but type_id range check is already done
in bpf_core_apply_relo(), so it's safe to replace it everywhere.
The kernel btf_type_by_id() does the check anyway. It doesn't hurt.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-2-alexei.starovoitov@gmail.com
Perform a memory copy before we do the sanity checks of btf_ext_hdr.
This prevents misaligned memory access if raw btf_ext data is not 4-byte
aligned ([0]).
While at it, also add missing const qualifier.
[0] Closes: https://github.com/libbpf/libbpf/issues/391
Fixes: 2993e0515b ("tools/bpf: add support to read .BTF.ext sections")
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211124002325.1737739-3-andrii@kernel.org
According to [0], compilers sometimes might produce duplicate DWARF
definitions for exactly the same struct/union within the same
compilation unit (CU). We've had similar issues with identical arrays
and handled them with a similar workaround in 6b6e6b1d09 ("libbpf:
Accomodate DWARF/compiler bug with duplicated identical arrays"). Do the
same for struct/union by ensuring that two structs/unions are exactly
the same, down to the integer values of field referenced type IDs.
Solving this more generically (allowing referenced types to be
equivalent, but using different type IDs, all within a single CU)
requires a huge complexity increase to handle many-to-many mappings
between canonidal and candidate type graphs. Before we invest in that,
let's see if this approach handles all the instances of this issue in
practice. Thankfully it's pretty rare, it seems.
[0] https://lore.kernel.org/bpf/YXr2NFlJTAhHdZqq@krava/
Reported-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211117194114.347675-1-andrii@kernel.org
Commit 2dc1e488e5 ("libbpf: Support BTF_KIND_TYPE_TAG") added the
BTF_KIND_TYPE_TAG support. But to test vmlinux build with ...
#define __user __attribute__((btf_type_tag("user")))
... I needed to sync libbpf repo and manually copy libbpf sources to
pahole. To simplify process, I used BTF_KIND_RESTRICT to simulate the
BTF_KIND_TYPE_TAG with vmlinux build as "restrict" modifier is barely
used in kernel.
But this approach missed one case in dedup with structures where
BTF_KIND_RESTRICT is handled and BTF_KIND_TYPE_TAG is not handled in
btf_dedup_is_equiv(), and this will result in a pahole dedup failure.
This patch fixed this issue and a selftest is added in the subsequent
patch to test this scenario.
The other missed handling is in btf__resolve_size(). Currently the compiler
always emit like PTR->TYPE_TAG->... so in practice we don't hit the missing
BTF_KIND_TYPE_TAG handling issue with compiler generated code. But lets
add case BTF_KIND_TYPE_TAG in the switch statement to be future proof.
Fixes: 2dc1e488e5 ("libbpf: Support BTF_KIND_TYPE_TAG")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211115163937.3922235-1-yhs@fb.com
btf__dedup() and struct btf_dedup_opts were added before we figured out
OPTS mechanism. As such, btf_dedup_opts is non-extensible without
breaking an ABI and potentially crashing user application.
Unfortunately, btf__dedup() and btf_dedup_opts are short and succinct
names that would be great to preserve and use going forward. So we use
___libbpf_override() macro approach, used previously for bpf_prog_load()
API, to define a new btf__dedup() variant that accepts only struct btf *
and struct btf_dedup_opts * arguments, and rename the old btf__dedup()
implementation into btf__dedup_deprecated(). This keeps both source and
binary compatibility with old and new applications.
The biggest problem was struct btf_dedup_opts, which wasn't OPTS-based,
and as such doesn't have `size_t sz;` as a first field. But btf__dedup()
is a pretty rarely used API and I believe that the only currently known
users (besides selftests) are libbpf's own bpf_linker and pahole.
Neither use case actually uses options and just passes NULL. So instead
of doing extra hacks, just rewrite struct btf_dedup_opts into OPTS-based
one, move btf_ext argument into those opts (only bpf_linker needs to
dedup btf_ext, so it's not a typical thing to specify), and drop never
used `dont_resolve_fwds` option (it was never used anywhere, AFAIK, it
makes BTF dedup much less useful and efficient).
Just in case, for old implementation, btf__dedup_deprecated(), detect
non-NULL options and error out with helpful message, to help users
migrate, if there are any user playing with btf__dedup().
The last remaining piece is dedup_table_size, which is another
anachronism from very early days of BTF dedup. Since then it has been
reduced to the only valid value, 1, to request forced hash collisions.
This is only used during testing. So instead introduce a bool flag to
force collisions explicitly.
This patch also adapts selftests to new btf__dedup() and btf_dedup_opts
use to avoid selftests breakage.
[0] Closes: https://github.com/libbpf/libbpf/issues/281
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211111053624.190580-4-andrii@kernel.org
There are some instances where we don't use O_CLOEXEC when opening an
fd, fix these up. Otherwise, it is possible that a parallel fork causes
these fds to leak into a child process on execve.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211028063501.2239335-6-memxor@gmail.com
Use the compiler-defined __BYTE_ORDER__ instead of the libc-defined
__BYTE_ORDER for consistency.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211026010831.748682-3-iii@linux.ibm.com
Original code assumed fixed and correct BTF header length. That's not
always the case, though, so fix this bug with a proper additional check.
And use actual header length instead of sizeof(struct btf_header) in
sanity checks.
Fixes: 8a138aed4a ("bpf: btf: Add BTF support to libbpf")
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211023003157.726961-2-andrii@kernel.org
btf_header's str_off+str_len or type_off+type_len can overflow as they
are u32s. This will lead to bypassing the sanity checks during BTF
parsing, resulting in crashes afterwards. Fix by using 64-bit signed
integers for comparison.
Fixes: d812362450 ("libbpf: Fix BTF data layout checks and allow empty BTF")
Reported-by: Evgeny Vereshchagin <evvers@ya.ru>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211023003157.726961-1-andrii@kernel.org
Add btf__type_cnt() and btf__raw_data() APIs and deprecate
btf__get_nr_type() and btf__get_raw_data() since the old APIs
don't follow the libbpf naming convention for getters which
omit 'get' in the name (see [0]). btf__raw_data() is just an
alias to the existing btf__get_raw_data(). btf__type_cnt()
now returns the number of all types of the BTF object
including 'void'.
[0] Closes: https://github.com/libbpf/libbpf/issues/279
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211022130623.1548429-2-hengqi.chen@gmail.com
There isn't a good use case where anyone but libbpf itself needs to call
btf__finalize_data(). It was implemented for internal use and it's not
clear why it was made into public API in the first place. To function, it
requires active ELF data, which is stored inside bpf_object for the
duration of opening phase only. But the only BTF that needs bpf_object's
ELF is that bpf_object's BTF itself, which libbpf fixes up automatically
during bpf_object__open() operation anyways. There is no need for any
additional fix up and no reasonable scenario where it's useful and
appropriate.
Thus, btf__finalize_data() is just an API atavism and is better removed.
So this patch marks it as deprecated immediately (v0.6+) and moves the
code from btf.c into libbpf.c where it's used in the context of
bpf_object opening phase. Such code co-location allows to make code
structure more straightforward and remove bpf_object__section_size() and
bpf_object__variable_offset() internal helpers from libbpf_internal.h,
making them static. Their naming is also adjusted to not create
a wrong illusion that they are some sort of method of bpf_object. They
are internal helpers and are called appropriately.
This is part of libbpf 1.0 effort ([0]).
[0] Closes: https://github.com/libbpf/libbpf/issues/276
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211021014404.2635234-2-andrii@kernel.org
Patch set [1] introduced BTF_KIND_TAG to allow tagging
declarations for struct/union, struct/union field, var, func
and func arguments and these tags will be encoded into
dwarf. They are also encoded to btf by llvm for the bpf target.
After BTF_KIND_TAG is introduced, we intended to use it
for kernel __user attributes. But kernel __user is actually
a type attribute. Upstream and internal discussion showed
it is not a good idea to mix declaration attribute and
type attribute. So we proposed to introduce btf_type_tag
as a type attribute and existing btf_tag renamed to
btf_decl_tag ([2]).
This patch renamed BTF_KIND_TAG to BTF_KIND_DECL_TAG and some
other declarations with *_tag to *_decl_tag to make it clear
the tag is for declaration. In the future, BTF_KIND_TYPE_TAG
might be introduced per [3].
[1] https://lore.kernel.org/bpf/20210914223004.244411-1-yhs@fb.com/
[2] https://reviews.llvm.org/D111588
[3] https://reviews.llvm.org/D111199
Fixes: b5ea834dde ("bpf: Support for new btf kind BTF_KIND_TAG")
Fixes: 5b84bd1036 ("libbpf: Add support for BTF_KIND_TAG")
Fixes: 5c07f2fec0 ("bpftool: Add support for BTF_KIND_TAG")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211012164838.3345699-1-yhs@fb.com
Add a bulk copying api, btf__add_btf(), that speeds up and simplifies
appending entire contents of one BTF object to another one, taking care
of copying BTF type data, adjusting resulting BTF type IDs according to
their new locations in the destination BTF object, as well as copying
and deduplicating all the referenced strings and updating all the string
offsets in new BTF types as appropriate.
This API is intended to be used from tools that are generating and
otherwise manipulating BTFs generically, such as pahole. In pahole's
case, this API is useful for speeding up parallelized BTF encoding, as
it allows pahole to offload all the intricacies of BTF type copying to
libbpf and handle the parallelization aspects of the process.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Link: https://lore.kernel.org/bpf/20211006051107.17921-2-andrii@kernel.org
This patch adds libbpf support for kernel module function call support.
The fd_array parameter is used during BPF program load to pass module
BTFs referenced by the program. insn->off is set to index into this
array, but starts from 1, because insn->off as 0 is reserved for
btf_vmlinux.
We try to use existing insn->off for a module, since the kernel limits
the maximum distinct module BTFs for kfuncs to 256, and also because
index must never exceed the maximum allowed value that can fit in
insn->off (INT16_MAX). In the future, if kernel interprets signed offset
as unsigned for kfunc calls, this limit can be increased to UINT16_MAX.
Also introduce a btf__find_by_name_kind_own helper to start searching
from module BTF's start id when we know that the BTF ID is not present
in vmlinux BTF (in find_ksym_btf_id).
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211002011757.311265-7-memxor@gmail.com
Add BTF_KIND_TAG support for parsing and dedup.
Also added sanitization for BTF_KIND_TAG. If BTF_KIND_TAG is not
supported in the kernel, sanitize it to INTs.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210914223025.246687-1-yhs@fb.com
This patch renames functions btf_{hash,equal}_int() to
btf_{hash,equal}_int_tag() so they can be reused for
BTF_KIND_TAG support. There is no functionality change for
this patch.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210914223020.245829-1-yhs@fb.com
Chen Shen