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Convert st_ops->data to the shadow type of the struct_ops map. The shadow
type of a struct_ops type is a variant of the original struct type
providing a way to access/change the values in the maps of the struct_ops
type.
bpf_map__initial_value() will return st_ops->data for struct_ops types. The
skeleton is going to use it as the pointer to the shadow type of the
original struct type.
One of the main differences between the original struct type and the shadow
type is that all function pointers of the shadow type are converted to
pointers of struct bpf_program. Users can replace these bpf_program
pointers with other BPF programs. The st_ops->progs[] will be updated
before updating the value of a map to reflect the changes made by users.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240229064523.2091270-3-thinker.li@gmail.com
For a struct_ops map, btf_value_type_id is the type ID of it's struct
type. This value is required by bpftool to generate skeleton including
pointers of shadow types. The code generator gets the type ID from
bpf_map__btf_value_type_id() in order to get the type information of the
struct type of a map.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240229064523.2091270-2-thinker.li@gmail.com
The batch lookup and lookup_and_delete APIs have two parameters,
in_batch and out_batch, to facilitate iterative
lookup/lookup_and_deletion operations for supported maps. Except NULL
for in_batch at the start of these two batch operations, both parameters
need to point to memory equal or larger than the respective map key
size, except for various hashmaps (hash, percpu_hash, lru_hash,
lru_percpu_hash) where the in_batch/out_batch memory size should be
at least 4 bytes.
Document these semantics to clarify the API.
Signed-off-by: Martin Kelly <martin.kelly@crowdstrike.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240221211838.1241578-1-martin.kelly@crowdstrike.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
In some situations, if you fail to zero-initialize the
bpf_{prog,map,btf,link}_info structs supplied to the set of LIBBPF
helpers bpf_{prog,map,btf,link}_get_info_by_fd(), you can expect the
helper to return an error. This can possibly leave people in a
situation where they're scratching their heads for an unnnecessary
amount of time. Make an explicit remark about the requirement of
zero-initializing the supplied bpf_{prog,map,btf,link}_info structs
for the respective LIBBPF helpers.
Internally, LIBBPF helpers bpf_{prog,map,btf,link}_get_info_by_fd()
call into bpf_obj_get_info_by_fd() where the bpf(2)
BPF_OBJ_GET_INFO_BY_FD command is used. This specific command is
effectively backed by restrictions enforced by the
bpf_check_uarg_tail_zero() helper. This function ensures that if the
size of the supplied bpf_{prog,map,btf,link}_info structs are larger
than what the kernel can handle, trailing bits are zeroed. This can be
a problem when compiling against UAPI headers that don't necessarily
match the sizes of the same underlying types known to the kernel.
Signed-off-by: Matt Bobrowski <mattbobrowski@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/ZcyEb8x4VbhieWsL@google.com
Due to internal differences between LLVM and GCC the current
implementation for the CO-RE macros does not fit GCC parser, as it will
optimize those expressions even before those would be accessible by the
BPF backend.
As examples, the following would be optimized out with the original
definitions:
- As enums are converted to their integer representation during
parsing, the IR would not know how to distinguish an integer
constant from an actual enum value.
- Types need to be kept as temporary variables, as the existing type
casts of the 0 address (as expanded for LLVM), are optimized away by
the GCC C parser, never really reaching GCCs IR.
Although, the macros appear to add extra complexity, the expanded code
is removed from the compilation flow very early in the compilation
process, not really affecting the quality of the generated assembly.
Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240213173543.1397708-1-cupertino.miranda@oracle.com
When the feature_flags and xdp_zc_max_segs fields were added to the libbpf
bpf_xdp_query_opts, the code writing them did not use the OPTS_SET() macro.
This causes libbpf to write to those fields unconditionally, which means
that programs compiled against an older version of libbpf (with a smaller
size of the bpf_xdp_query_opts struct) will have its stack corrupted by
libbpf writing out of bounds.
The patch adding the feature_flags field has an early bail out if the
feature_flags field is not part of the opts struct (via the OPTS_HAS)
macro, but the patch adding xdp_zc_max_segs does not. For consistency, this
fix just changes the assignments to both fields to use the OPTS_SET()
macro.
Fixes: 13ce2daa25 ("xsk: add new netlink attribute dedicated for ZC max frags")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240206125922.1992815-1-toke@redhat.com
If PERF_EVENT program has __arg_ctx argument with matching
architecture-specific pt_regs/user_pt_regs/user_regs_struct pointer
type, libbpf should still perform type rewrite for old kernels, but not
emit the warning. Fix copy/paste from kernel code where 0 is meant to
signify "no error" condition. For libbpf we need to return "true" to
proceed with type rewrite (which for PERF_EVENT program will be
a canonical `struct bpf_perf_event_data *` type).
Fixes: 9eea8fafe3 ("libbpf: fix __arg_ctx type enforcement for perf_event programs")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240206002243.1439450-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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
LIBBPF_API annotation seems missing on libbpf_set_memlock_rlim API, so
add it to make this API callable from libbpf's shared library version.
Fixes: e542f2c4cd ("libbpf: Auto-bump RLIMIT_MEMLOCK if kernel needs it for BPF")
Fixes: ab9a5a05dc ("libbpf: fix up few libbpf.map problems")
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/20240201172027.604869-3-andrii@kernel.org
After recent changes, Coverity complained about inconsistent null checks
in kernel_supports() function:
kernel_supports(const struct bpf_object *obj, ...)
[...]
// var_compare_op: Comparing obj to null implies that obj might be null
if (obj && obj->gen_loader)
return true;
// var_deref_op: Dereferencing null pointer obj
if (obj->token_fd)
return feat_supported(obj->feat_cache, feat_id);
[...]
- The original null check was introduced by commit [0], which introduced
a call `kernel_supports(NULL, ...)` in function bump_rlimit_memlock();
- This call was refactored to use `feat_supported(NULL, ...)` in commit [1].
Looking at all places where kernel_supports() is called:
- There is either `obj->...` access before the call;
- Or `obj` comes from `prog->obj` expression, where `prog` comes from
enumeration of programs in `obj`;
- Or `obj` comes from `prog->obj`, where `prog` is a parameter to one
of the API functions:
- bpf_program__attach_kprobe_opts;
- bpf_program__attach_kprobe;
- bpf_program__attach_ksyscall.
Assuming correct API usage, it appears that `obj` can never be null when
passed to kernel_supports(). Silence the Coverity warning by removing
redundant null check.
[0] e542f2c4cd ("libbpf: Auto-bump RLIMIT_MEMLOCK if kernel needs it for BPF")
[1] d6dd1d4936 ("libbpf: Further decouple feature checking logic from bpf_object")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240131212615.20112-1-eddyz87@gmail.com
Add bpf_core_cast() macro that wraps bpf_rdonly_cast() kfunc. It's more
ergonomic than kfunc, as it automatically extracts btf_id with
bpf_core_type_id_kernel(), and works with type names. It also casts result
to (T *) pointer. See the definition of the macro, it's self-explanatory.
libbpf declares bpf_rdonly_cast() extern as __weak __ksym and should be
safe to not conflict with other possible declarations in user code.
But we do have a conflict with current BPF selftests that declare their
externs with first argument as `void *obj`, while libbpf opts into more
permissive `const void *obj`. This causes conflict, so we fix up BPF
selftests uses in the same patch.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240130212023.183765-2-andrii@kernel.org
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Add __arg_trusted to annotate global func args that accept trusted
PTR_TO_BTF_ID arguments.
Also add __arg_nullable to combine with __arg_trusted (and maybe other
tags in the future) to force global subprog itself (i.e., callee) to do
NULL checks, as opposed to default non-NULL semantics (and thus caller's
responsibility to ensure non-NULL values).
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240130000648.2144827-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@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
Adjust PERF_EVENT type enforcement around __arg_ctx to match exactly
what kernel is doing.
Fixes: 76ec90a996 ("libbpf: warn on unexpected __arg_ctx type when rewriting BTF")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240125205510.3642094-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Now that feature detection code is in bpf-next tree, integrate __arg_ctx
kernel-side support into kernel_supports() framework.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240125205510.3642094-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2024-01-26
We've added 107 non-merge commits during the last 4 day(s) which contain
a total of 101 files changed, 6009 insertions(+), 1260 deletions(-).
The main changes are:
1) Add BPF token support to delegate a subset of BPF subsystem
functionality from privileged system-wide daemons such as systemd
through special mount options for userns-bound BPF fs to a trusted
& unprivileged application. With addressed changes from Christian
and Linus' reviews, from Andrii Nakryiko.
2) Support registration of struct_ops types from modules which helps
projects like fuse-bpf that seeks to implement a new struct_ops type,
from Kui-Feng Lee.
3) Add support for retrieval of cookies for perf/kprobe multi links,
from Jiri Olsa.
4) Bigger batch of prep-work for the BPF verifier to eventually support
preserving boundaries and tracking scalars on narrowing fills,
from Maxim Mikityanskiy.
5) Extend the tc BPF flavor to support arbitrary TCP SYN cookies to help
with the scenario of SYN floods, from Kuniyuki Iwashima.
6) Add code generation to inline the bpf_kptr_xchg() helper which
improves performance when stashing/popping the allocated BPF objects,
from Hou Tao.
7) Extend BPF verifier to track aligned ST stores as imprecise spilled
registers, from Yonghong Song.
8) Several fixes to BPF selftests around inline asm constraints and
unsupported VLA code generation, from Jose E. Marchesi.
9) Various updates to the BPF IETF instruction set draft document such
as the introduction of conformance groups for instructions,
from Dave Thaler.
10) Fix BPF verifier to make infinite loop detection in is_state_visited()
exact to catch some too lax spill/fill corner cases,
from Eduard Zingerman.
11) Refactor the BPF verifier pointer ALU check to allow ALU explicitly
instead of implicitly for various register types, from Hao Sun.
12) Fix the flaky tc_redirect_dtime BPF selftest due to slowness
in neighbor advertisement at setup time, from Martin KaFai Lau.
13) Change BPF selftests to skip callback tests for the case when the
JIT is disabled, from Tiezhu Yang.
14) Add a small extension to libbpf which allows to auto create
a map-in-map's inner map, from Andrey Grafin.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (107 commits)
selftests/bpf: Add missing line break in test_verifier
bpf, docs: Clarify definitions of various instructions
bpf: Fix error checks against bpf_get_btf_vmlinux().
bpf: One more maintainer for libbpf and BPF selftests
selftests/bpf: Incorporate LSM policy to token-based tests
selftests/bpf: Add tests for LIBBPF_BPF_TOKEN_PATH envvar
libbpf: Support BPF token path setting through LIBBPF_BPF_TOKEN_PATH envvar
selftests/bpf: Add tests for BPF object load with implicit token
selftests/bpf: Add BPF object loading tests with explicit token passing
libbpf: Wire up BPF token support at BPF object level
libbpf: Wire up token_fd into feature probing logic
libbpf: Move feature detection code into its own file
libbpf: Further decouple feature checking logic from bpf_object
libbpf: Split feature detectors definitions from cached results
selftests/bpf: Utilize string values for delegate_xxx mount options
bpf: Support symbolic BPF FS delegation mount options
bpf: Fail BPF_TOKEN_CREATE if no delegation option was set on BPF FS
bpf,selinux: Allocate bpf_security_struct per BPF token
selftests/bpf: Add BPF token-enabled tests
libbpf: Add BPF token support to bpf_prog_load() API
...
====================
Link: https://lore.kernel.org/r/20240126215710.19855-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
To allow external admin authority to override default BPF FS location
(/sys/fs/bpf) for implicit BPF token creation, teach libbpf to recognize
LIBBPF_BPF_TOKEN_PATH envvar. If it is specified and user application
didn't explicitly specify bpf_token_path option, it will be treated
exactly like bpf_token_path option, overriding default /sys/fs/bpf
location and making BPF token mandatory.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-29-andrii@kernel.org
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
Adjust feature probing callbacks to take into account optional token_fd.
In unprivileged contexts, some feature detectors would fail to detect
kernel support just because BPF program, BPF map, or BTF object can't be
loaded due to privileged nature of those operations. So when BPF object
is loaded with BPF token, this token should be used for feature probing.
This patch is setting support for this scenario, but we don't yet pass
non-zero token FD. This will be added in the next patch.
We also switched BPF cookie detector from using kprobe program to
tracepoint one, as tracepoint is somewhat less dangerous BPF program
type and has higher likelihood of being allowed through BPF token in the
future. This change has no effect on detection behavior.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-25-andrii@kernel.org
It's quite a lot of well isolated code, so it seems like a good
candidate to move it out of libbpf.c to reduce its size.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-24-andrii@kernel.org
Add feat_supported() helper that accepts feature cache instead of
bpf_object. This allows low-level code in bpf.c to not know or care
about higher-level concept of bpf_object, yet it will be able to utilize
custom feature checking in cases where BPF token might influence the
outcome.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-23-andrii@kernel.org
Split a list of supported feature detectors with their corresponding
callbacks from actual cached supported/missing values. This will allow
to have more flexible per-token or per-object feature detectors in
subsequent refactorings.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-22-andrii@kernel.org
Allow user to specify token_fd for bpf_btf_load() API that wraps
kernel's BPF_BTF_LOAD command. This allows loading BTF from unprivileged
process as long as it has BPF token allowing BPF_BTF_LOAD command, which
can be created and delegated by privileged process.
Wire through new btf_flags as well, so that user can provide
BPF_F_TOKEN_FD flag, if necessary.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-15-andrii@kernel.org
The commit 9e926acda0 ("libbpf: Find correct module BTFs for struct_ops maps and progs.")
sets a newly added field (value_type_btf_obj_fd) to -1 in libbpf when
the caller of the libbpf's bpf_map_create did not define this field by
passing a NULL "opts" or passing in a "opts" that does not cover this
new field. OPT_HAS(opts, field) is used to decide if the field is
defined or not:
((opts) && opts->sz >= offsetofend(typeof(*(opts)), field))
Once OPTS_HAS decided the field is not defined, that field should
be set to 0. For this particular new field (value_type_btf_obj_fd),
its corresponding map_flags "BPF_F_VTYPE_BTF_OBJ_FD" is not set.
Thus, the kernel does not treat it as an fd field.
Fixes: 9e926acda0 ("libbpf: Find correct module BTFs for struct_ops maps and progs.")
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240124224418.2905133-1-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Past commit ([0]) removed the last vestiges of struct bpf_field_reloc,
it's called struct bpf_core_relo now.
[0] 28b93c6449 ("libbpf: Clean up and improve CO-RE reloc logging")
Signed-off-by: Dima Tisnek <dimaqq@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20240121060126.15650-1-dimaqq@gmail.com
Locate the module BTFs for struct_ops maps and progs and pass them to the
kernel. This ensures that the kernel correctly resolves type IDs from the
appropriate module BTFs.
For the map of a struct_ops object, the FD of the module BTF is set to
bpf_map to keep a reference to the module BTF. The FD is passed to the
kernel as value_type_btf_obj_fd when the struct_ops object is loaded.
For a bpf_struct_ops prog, attach_btf_obj_fd of bpf_prog is the FD of a
module BTF in the kernel.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240119225005.668602-13-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
We've ran into issues with using dup2() API in production setting, where
libbpf is linked into large production environment and ends up calling
unintended custom implementations of dup2(). These custom implementations
don't provide atomic FD replacement guarantees of dup2() syscall,
leading to subtle and hard to debug issues.
To prevent this in the future and guarantee that no libc implementation
will do their own custom non-atomic dup2() implementation, call dup2()
syscall directly with syscall(SYS_dup2).
Note that some architectures don't seem to provide dup2 and have dup3
instead. Try to detect and pick best syscall.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240119210201.1295511-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch allows to auto create BPF_MAP_TYPE_ARRAY_OF_MAPS and
BPF_MAP_TYPE_HASH_OF_MAPS with values of BPF_MAP_TYPE_PERF_EVENT_ARRAY
by bpf_object__load().
Previous behaviour created a zero filled btf_map_def for inner maps and
tried to use it for a map creation but the linux kernel forbids to create
a BPF_MAP_TYPE_PERF_EVENT_ARRAY map with max_entries=0.
Fixes: 646f02ffdd ("libbpf: Add BTF-defined map-in-map support")
Signed-off-by: Andrey Grafin <conquistador@yandex-team.ru>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/bpf/20240117130619.9403-1-conquistador@yandex-team.ru
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- Add Namhyung Kim as tools/perf/ co-maintainer, we're taking turns processing
patches, switching roles from perf-tools to perf-tools-next at each Linux
release.
Data profiling:
- Associate samples that identify loads and stores with data structures. This
uses events available on Intel, AMD and others and DWARF info:
# To get memory access samples in kernel for 1 second (on Intel)
$ perf mem record -a -K --ldlat=4 -- sleep 1
# Similar for the AMD (but it requires 6.3+ kernel for BPF filters)
$ perf mem record -a --filter 'mem_op == load || mem_op == store, ip > 0x8000000000000000' -- sleep 1
Then, amongst several modes of post processing, one can do things like:
$ perf report -s type,typeoff --hierarchy --group --stdio
...
#
# Samples: 10K of events 'cpu/mem-loads,ldlat=4/P, cpu/mem-stores/P, dummy:u'
# Event count (approx.): 602758064
#
# Overhead Data Type / Data Type Offset
# ........................... ............................
#
26.09% 3.28% 0.00% long unsigned int
26.09% 3.28% 0.00% long unsigned int +0 (no field)
18.48% 0.73% 0.00% struct page
10.83% 0.02% 0.00% struct page +8 (lru.next)
3.90% 0.28% 0.00% struct page +0 (flags)
3.45% 0.06% 0.00% struct page +24 (mapping)
0.25% 0.28% 0.00% struct page +48 (_mapcount.counter)
0.02% 0.06% 0.00% struct page +32 (index)
0.02% 0.00% 0.00% struct page +52 (_refcount.counter)
0.02% 0.01% 0.00% struct page +56 (memcg_data)
0.00% 0.01% 0.00% struct page +16 (lru.prev)
15.37% 17.54% 0.00% (stack operation)
15.37% 17.54% 0.00% (stack operation) +0 (no field)
11.71% 50.27% 0.00% (unknown)
11.71% 50.27% 0.00% (unknown) +0 (no field)
$ perf annotate --data-type
...
Annotate type: 'struct cfs_rq' in [kernel.kallsyms] (13 samples):
============================================================================
samples offset size field
13 0 640 struct cfs_rq {
2 0 16 struct load_weight load {
2 0 8 unsigned long weight;
0 8 4 u32 inv_weight;
};
0 16 8 unsigned long runnable_weight;
0 24 4 unsigned int nr_running;
1 28 4 unsigned int h_nr_running;
...
$ perf annotate --data-type=page --group
Annotate type: 'struct page' in [kernel.kallsyms] (480 samples):
event[0] = cpu/mem-loads,ldlat=4/P
event[1] = cpu/mem-stores/P
event[2] = dummy:u
===================================================================================
samples offset size field
447 33 0 0 64 struct page {
108 8 0 0 8 long unsigned int flags;
319 13 0 8 40 union {
319 13 0 8 40 struct {
236 2 0 8 16 union {
236 2 0 8 16 struct list_head lru {
236 1 0 8 8 struct list_head* next;
0 1 0 16 8 struct list_head* prev;
};
236 2 0 8 16 struct {
236 1 0 8 8 void* __filler;
0 1 0 16 4 unsigned int mlock_count;
};
236 2 0 8 16 struct list_head buddy_list {
236 1 0 8 8 struct list_head* next;
0 1 0 16 8 struct list_head* prev;
};
236 2 0 8 16 struct list_head pcp_list {
236 1 0 8 8 struct list_head* next;
0 1 0 16 8 struct list_head* prev;
};
};
82 4 0 24 8 struct address_space* mapping;
1 7 0 32 8 union {
1 7 0 32 8 long unsigned int index;
1 7 0 32 8 long unsigned int share;
};
0 0 0 40 8 long unsigned int private;
};
This uses the existing annotate code, calling objdump to do the disassembly,
with improvements to avoid having this take too long, but longer term a
switch to a disassembler library, possibly reusing code in the kernel will
be pursued.
This is the initial implementation, please use it and report impressions and
bugs. Make sure the kernel-debuginfo packages match the running kernel. The
'perf report' phase for non short perf.data files may take a while.
There is a great article about it on LWN:
https://lwn.net/Articles/955709/ - "Data-type profiling for perf"
One last test I did while writing this text, on a AMD Ryzen 5950X, using a distro
kernel, while doing a simple 'find /' on an otherwise idle system resulted in:
# uname -r
6.6.9-100.fc38.x86_64
# perf -vv | grep BPF_
bpf: [ on ] # HAVE_LIBBPF_SUPPORT
bpf_skeletons: [ on ] # HAVE_BPF_SKEL
# rpm -qa | grep kernel-debuginfo
kernel-debuginfo-common-x86_64-6.6.9-100.fc38.x86_64
kernel-debuginfo-6.6.9-100.fc38.x86_64
#
# perf mem record -a --filter 'mem_op == load || mem_op == store, ip > 0x8000000000000000'
^C[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 2.199 MB perf.data (2913 samples) ]
#
# ls -la perf.data
-rw-------. 1 root root 2346486 Jan 9 18:36 perf.data
# perf evlist
ibs_op//
dummy:u
# perf evlist -v
ibs_op//: type: 11, size: 136, config: 0, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|ADDR|CPU|PERIOD|IDENTIFIER|DATA_SRC|WEIGHT, read_format: ID, disabled: 1, inherit: 1, freq: 1, sample_id_all: 1
dummy:u: type: 1 (PERF_TYPE_SOFTWARE), size: 136, config: 0x9 (PERF_COUNT_SW_DUMMY), { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|ADDR|CPU|IDENTIFIER|DATA_SRC|WEIGHT, read_format: ID, inherit: 1, exclude_kernel: 1, exclude_hv: 1, mmap: 1, comm: 1, task: 1, mmap_data: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1
#
# perf report -s type,typeoff --hierarchy --group --stdio
# Total Lost Samples: 0
#
# Samples: 2K of events 'ibs_op//, dummy:u'
# Event count (approx.): 1904553038
#
# Overhead Data Type / Data Type Offset
# ................... ............................
#
73.70% 0.00% (unknown)
73.70% 0.00% (unknown) +0 (no field)
3.01% 0.00% long unsigned int
3.00% 0.00% long unsigned int +0 (no field)
0.01% 0.00% long unsigned int +2 (no field)
2.73% 0.00% struct task_struct
1.71% 0.00% struct task_struct +52 (on_cpu)
0.38% 0.00% struct task_struct +2104 (rcu_read_unlock_special.b.blocked)
0.23% 0.00% struct task_struct +2100 (rcu_read_lock_nesting)
0.14% 0.00% struct task_struct +2384 ()
0.06% 0.00% struct task_struct +3096 (signal)
0.05% 0.00% struct task_struct +3616 (cgroups)
0.05% 0.00% struct task_struct +2344 (active_mm)
0.02% 0.00% struct task_struct +46 (flags)
0.02% 0.00% struct task_struct +2096 (migration_disabled)
0.01% 0.00% struct task_struct +24 (__state)
0.01% 0.00% struct task_struct +3956 (mm_cid_active)
0.01% 0.00% struct task_struct +1048 (cpus_ptr)
0.01% 0.00% struct task_struct +184 (se.group_node.next)
0.01% 0.00% struct task_struct +20 (thread_info.cpu)
0.00% 0.00% struct task_struct +104 (on_rq)
0.00% 0.00% struct task_struct +2456 (pid)
1.36% 0.00% struct module
0.59% 0.00% struct module +952 (kallsyms)
0.42% 0.00% struct module +0 (state)
0.23% 0.00% struct module +8 (list.next)
0.12% 0.00% struct module +216 (syms)
0.95% 0.00% struct inode
0.41% 0.00% struct inode +40 (i_sb)
0.22% 0.00% struct inode +0 (i_mode)
0.06% 0.00% struct inode +76 (i_rdev)
0.06% 0.00% struct inode +56 (i_security)
<SNIP>
perf top/report:
- Don't ignore job control, allowing control+Z + bg to work.
- Add s390 raw data interpretation for PAI (Processor Activity Instrumentation)
counters.
perf archive:
- Add new option '--all' to pack perf.data with DSOs.
- Add new option '--unpack' to expand tarballs.
Initialization speedups:
- Lazily initialize zstd streams to save memory when not using it.
- Lazily allocate/size mmap event copy.
- Lazy load kernel symbols in 'perf record'.
- Be lazier in allocating lost samples buffer in 'perf record'.
- Don't synthesize BPF events when disabled via the command line (perf record --no-bpf-event).
Assorted improvements:
- Show note on AMD systems that the :p, :pp, :ppp and :P are all the same, as
IBS (Instruction Based Sampling) is used and it is inherentely precise, not
having levels of precision like in Intel systems.
- When 'cycles' isn't available, fall back to the "task-clock" event when not
system wide, not to 'cpu-clock'.
- Add --debug-file option to redirect debug output, e.g.:
$ perf --debug-file /tmp/perf.log record -v true
- Shrink 'struct map' to under one cacheline by avoiding function pointers for
selecting if addresses are identity or DSO relative, and using just a byte for
some boolean struct members.
- Resolve the arch specific strerrno just once to use in perf_env__arch_strerrno().
- Reduce memory for recording PERF_RECORD_LOST_SAMPLES event.
Assorted fixes:
- Fix the default 'perf top' usage on Intel hybrid systems, now it starts with
a browser showing the number of samples for Efficiency (cpu_atom/cycles/P) and
Performance (cpu_core/cycles/P). This behaviour is similar on ARM64, with its
respective set of big.LITTLE processors.
- Fix segfault on build_mem_topology() error path.
- Fix 'perf mem' error on hybrid related to availability of mem event in a PMU.
- Fix missing reference count gets (map, maps) in the db-export code.
- Avoid recursively taking env->bpf_progs.lock in the 'perf_env' code.
- Use the newly introduced maps__for_each_map() to add missing locking around
iteration of 'struct map' entries.
- Parse NOTE segments until the build id is found, don't stop on the first one,
ELF files may have several such NOTE segments.
- Remove 'egrep' usage, its deprecated, use 'grep -E' instead.
- Warn first about missing libelf, not libbpf, that depends on libelf.
- Use alternative to 'find ... -printf' as this isn't supported in busybox.
- Address python 3.6 DeprecationWarning for string scapes.
- Fix memory leak in uniq() in libsubcmd.
- Fix man page formatting for 'perf lock'
- Fix some spelling mistakes.
perf tests:
- Fail shell tests that needs some symbol in perf itself if it is stripped.
These tests check if a symbol is resolved, if some hot function is indeed
detected by profiling, etc.
- The 'perf test sigtrap' test is currently failing on PREEMPT_RT, skip it if
sleeping spinlocks are detected (using BTF) and point to the mailing list
discussion about it. This test is also being skipped on several architectures
(powerpc, s390x, arm and aarch64) due to other pending issues with intruction
breakpoints.
- Adjust test case perf record offcpu profiling tests for s390.
- Fix 'Setup struct perf_event_attr' fails on s390 on z/VM guest, addressing
issues caused by the fallback from cycles to task-clock done in this release.
- Fix mask for VG register in the user-regs test.
- Use shellcheck on 'perf test' shell scripts automatically to make sure changes
don't introduce things it flags as problematic.
- Add option to change objdump binary and allow it to be set via 'perf config'.
- Add basic 'perf script', 'perf list --json" and 'perf diff' tests.
- Basic branch counter support.
- Make DSO tests a suite rather than individual.
- Remove atomics from test_loop to avoid test failures.
- Fix call chain match on powerpc for the record+probe_libc_inet_pton test.
- Improve Intel hybrid tests.
Vendor event files (JSON):
powerpc:
- Update datasource event name to fix duplicate events on IBM's Power10.
- Add PVN for HX-C2000 CPU with Power8 Architecture.
Intel:
- Alderlake/rocketlake metric fixes.
- Update emeraldrapids events to v1.02.
- Update icelakex events to v1.23.
- Update sapphirerapids events to v1.17.
- Add skx, clx, icx and spr upi bandwidth metric.
AMD:
- Add Zen 4 memory controller events.
RISC-V:
- Add StarFive Dubhe-80 and Dubhe-90 JSON files.
https://www.starfivetech.com/en/site/cpu-u
- Add T-HEAD C9xx JSON file.
https://github.com/riscv-software-src/opensbi/blob/master/docs/platform/thead-c9xx.md
ARM64:
- Remove UTF-8 characters from cmn.json, that were causing build failure in some
distros.
- Add core PMU events and metrics for Ampere One X.
- Rename Ampere One's BPU_FLUSH_MEM_FAULT to GPC_FLUSH_MEM_FAULT
libperf:
- Rename several perf_cpu_map constructor names to clarify what they really do.
- Ditto for some other methods, coping with some issues in their semantics,
like perf_cpu_map__empty() -> perf_cpu_map__has_any_cpu_or_is_empty().
- Document perf_cpu_map__nr()'s behavior
perf stat:
- Exit if parse groups fails.
- Combine the -A/--no-aggr and --no-merge options.
- Fix help message for --metric-no-threshold option.
Hardware tracing:
ARM64 CoreSight:
- Bump minimum OpenCSD version to ensure a bugfix is present.
- Add 'T' itrace option for timestamp trace
- Set start vm addr of exectable file to 0 and don't ignore first sample on the
arm-cs-trace-disasm.py 'perf script'.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Merge tag 'perf-tools-for-v6.8-1-2024-01-09' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools
Pull perf tools updates from Arnaldo Carvalho de Melo:
"Add Namhyung Kim as tools/perf/ co-maintainer, we're taking turns
processing patches, switching roles from perf-tools to perf-tools-next
at each Linux release.
Data profiling:
- Associate samples that identify loads and stores with data
structures. This uses events available on Intel, AMD and others and
DWARF info:
# To get memory access samples in kernel for 1 second (on Intel)
$ perf mem record -a -K --ldlat=4 -- sleep 1
# Similar for the AMD (but it requires 6.3+ kernel for BPF filters)
$ perf mem record -a --filter 'mem_op == load || mem_op == store, ip > 0x8000000000000000' -- sleep 1
Then, amongst several modes of post processing, one can do things like:
$ perf report -s type,typeoff --hierarchy --group --stdio
...
#
# Samples: 10K of events 'cpu/mem-loads,ldlat=4/P, cpu/mem-stores/P, dummy:u'
# Event count (approx.): 602758064
#
# Overhead Data Type / Data Type Offset
# ........................... ............................
#
26.09% 3.28% 0.00% long unsigned int
26.09% 3.28% 0.00% long unsigned int +0 (no field)
18.48% 0.73% 0.00% struct page
10.83% 0.02% 0.00% struct page +8 (lru.next)
3.90% 0.28% 0.00% struct page +0 (flags)
3.45% 0.06% 0.00% struct page +24 (mapping)
0.25% 0.28% 0.00% struct page +48 (_mapcount.counter)
0.02% 0.06% 0.00% struct page +32 (index)
0.02% 0.00% 0.00% struct page +52 (_refcount.counter)
0.02% 0.01% 0.00% struct page +56 (memcg_data)
0.00% 0.01% 0.00% struct page +16 (lru.prev)
15.37% 17.54% 0.00% (stack operation)
15.37% 17.54% 0.00% (stack operation) +0 (no field)
11.71% 50.27% 0.00% (unknown)
11.71% 50.27% 0.00% (unknown) +0 (no field)
$ perf annotate --data-type
...
Annotate type: 'struct cfs_rq' in [kernel.kallsyms] (13 samples):
============================================================================
samples offset size field
13 0 640 struct cfs_rq {
2 0 16 struct load_weight load {
2 0 8 unsigned long weight;
0 8 4 u32 inv_weight;
};
0 16 8 unsigned long runnable_weight;
0 24 4 unsigned int nr_running;
1 28 4 unsigned int h_nr_running;
...
$ perf annotate --data-type=page --group
Annotate type: 'struct page' in [kernel.kallsyms] (480 samples):
event[0] = cpu/mem-loads,ldlat=4/P
event[1] = cpu/mem-stores/P
event[2] = dummy:u
===================================================================================
samples offset size field
447 33 0 0 64 struct page {
108 8 0 0 8 long unsigned int flags;
319 13 0 8 40 union {
319 13 0 8 40 struct {
236 2 0 8 16 union {
236 2 0 8 16 struct list_head lru {
236 1 0 8 8 struct list_head* next;
0 1 0 16 8 struct list_head* prev;
};
236 2 0 8 16 struct {
236 1 0 8 8 void* __filler;
0 1 0 16 4 unsigned int mlock_count;
};
236 2 0 8 16 struct list_head buddy_list {
236 1 0 8 8 struct list_head* next;
0 1 0 16 8 struct list_head* prev;
};
236 2 0 8 16 struct list_head pcp_list {
236 1 0 8 8 struct list_head* next;
0 1 0 16 8 struct list_head* prev;
};
};
82 4 0 24 8 struct address_space* mapping;
1 7 0 32 8 union {
1 7 0 32 8 long unsigned int index;
1 7 0 32 8 long unsigned int share;
};
0 0 0 40 8 long unsigned int private;
};
This uses the existing annotate code, calling objdump to do the
disassembly, with improvements to avoid having this take too long,
but longer term a switch to a disassembler library, possibly
reusing code in the kernel will be pursued.
This is the initial implementation, please use it and report
impressions and bugs. Make sure the kernel-debuginfo packages match
the running kernel. The 'perf report' phase for non short perf.data
files may take a while.
There is a great article about it on LWN:
https://lwn.net/Articles/955709/ - "Data-type profiling for perf"
One last test I did while writing this text, on a AMD Ryzen 5950X,
using a distro kernel, while doing a simple 'find /' on an
otherwise idle system resulted in:
# uname -r
6.6.9-100.fc38.x86_64
# perf -vv | grep BPF_
bpf: [ on ] # HAVE_LIBBPF_SUPPORT
bpf_skeletons: [ on ] # HAVE_BPF_SKEL
# rpm -qa | grep kernel-debuginfo
kernel-debuginfo-common-x86_64-6.6.9-100.fc38.x86_64
kernel-debuginfo-6.6.9-100.fc38.x86_64
#
# perf mem record -a --filter 'mem_op == load || mem_op == store, ip > 0x8000000000000000'
^C[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 2.199 MB perf.data (2913 samples) ]
#
# ls -la perf.data
-rw-------. 1 root root 2346486 Jan 9 18:36 perf.data
# perf evlist
ibs_op//
dummy:u
# perf evlist -v
ibs_op//: type: 11, size: 136, config: 0, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|ADDR|CPU|PERIOD|IDENTIFIER|DATA_SRC|WEIGHT, read_format: ID, disabled: 1, inherit: 1, freq: 1, sample_id_all: 1
dummy:u: type: 1 (PERF_TYPE_SOFTWARE), size: 136, config: 0x9 (PERF_COUNT_SW_DUMMY), { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|ADDR|CPU|IDENTIFIER|DATA_SRC|WEIGHT, read_format: ID, inherit: 1, exclude_kernel: 1, exclude_hv: 1, mmap: 1, comm: 1, task: 1, mmap_data: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1
#
# perf report -s type,typeoff --hierarchy --group --stdio
# Total Lost Samples: 0
#
# Samples: 2K of events 'ibs_op//, dummy:u'
# Event count (approx.): 1904553038
#
# Overhead Data Type / Data Type Offset
# ................... ............................
#
73.70% 0.00% (unknown)
73.70% 0.00% (unknown) +0 (no field)
3.01% 0.00% long unsigned int
3.00% 0.00% long unsigned int +0 (no field)
0.01% 0.00% long unsigned int +2 (no field)
2.73% 0.00% struct task_struct
1.71% 0.00% struct task_struct +52 (on_cpu)
0.38% 0.00% struct task_struct +2104 (rcu_read_unlock_special.b.blocked)
0.23% 0.00% struct task_struct +2100 (rcu_read_lock_nesting)
0.14% 0.00% struct task_struct +2384 ()
0.06% 0.00% struct task_struct +3096 (signal)
0.05% 0.00% struct task_struct +3616 (cgroups)
0.05% 0.00% struct task_struct +2344 (active_mm)
0.02% 0.00% struct task_struct +46 (flags)
0.02% 0.00% struct task_struct +2096 (migration_disabled)
0.01% 0.00% struct task_struct +24 (__state)
0.01% 0.00% struct task_struct +3956 (mm_cid_active)
0.01% 0.00% struct task_struct +1048 (cpus_ptr)
0.01% 0.00% struct task_struct +184 (se.group_node.next)
0.01% 0.00% struct task_struct +20 (thread_info.cpu)
0.00% 0.00% struct task_struct +104 (on_rq)
0.00% 0.00% struct task_struct +2456 (pid)
1.36% 0.00% struct module
0.59% 0.00% struct module +952 (kallsyms)
0.42% 0.00% struct module +0 (state)
0.23% 0.00% struct module +8 (list.next)
0.12% 0.00% struct module +216 (syms)
0.95% 0.00% struct inode
0.41% 0.00% struct inode +40 (i_sb)
0.22% 0.00% struct inode +0 (i_mode)
0.06% 0.00% struct inode +76 (i_rdev)
0.06% 0.00% struct inode +56 (i_security)
<SNIP>
perf top/report:
- Don't ignore job control, allowing control+Z + bg to work.
- Add s390 raw data interpretation for PAI (Processor Activity
Instrumentation) counters.
perf archive:
- Add new option '--all' to pack perf.data with DSOs.
- Add new option '--unpack' to expand tarballs.
Initialization speedups:
- Lazily initialize zstd streams to save memory when not using it.
- Lazily allocate/size mmap event copy.
- Lazy load kernel symbols in 'perf record'.
- Be lazier in allocating lost samples buffer in 'perf record'.
- Don't synthesize BPF events when disabled via the command line
(perf record --no-bpf-event).
Assorted improvements:
- Show note on AMD systems that the :p, :pp, :ppp and :P are all the
same, as IBS (Instruction Based Sampling) is used and it is
inherentely precise, not having levels of precision like in Intel
systems.
- When 'cycles' isn't available, fall back to the "task-clock" event
when not system wide, not to 'cpu-clock'.
- Add --debug-file option to redirect debug output, e.g.:
$ perf --debug-file /tmp/perf.log record -v true
- Shrink 'struct map' to under one cacheline by avoiding function
pointers for selecting if addresses are identity or DSO relative,
and using just a byte for some boolean struct members.
- Resolve the arch specific strerrno just once to use in
perf_env__arch_strerrno().
- Reduce memory for recording PERF_RECORD_LOST_SAMPLES event.
Assorted fixes:
- Fix the default 'perf top' usage on Intel hybrid systems, now it
starts with a browser showing the number of samples for Efficiency
(cpu_atom/cycles/P) and Performance (cpu_core/cycles/P). This
behaviour is similar on ARM64, with its respective set of
big.LITTLE processors.
- Fix segfault on build_mem_topology() error path.
- Fix 'perf mem' error on hybrid related to availability of mem event
in a PMU.
- Fix missing reference count gets (map, maps) in the db-export code.
- Avoid recursively taking env->bpf_progs.lock in the 'perf_env'
code.
- Use the newly introduced maps__for_each_map() to add missing
locking around iteration of 'struct map' entries.
- Parse NOTE segments until the build id is found, don't stop on the
first one, ELF files may have several such NOTE segments.
- Remove 'egrep' usage, its deprecated, use 'grep -E' instead.
- Warn first about missing libelf, not libbpf, that depends on
libelf.
- Use alternative to 'find ... -printf' as this isn't supported in
busybox.
- Address python 3.6 DeprecationWarning for string scapes.
- Fix memory leak in uniq() in libsubcmd.
- Fix man page formatting for 'perf lock'
- Fix some spelling mistakes.
perf tests:
- Fail shell tests that needs some symbol in perf itself if it is
stripped. These tests check if a symbol is resolved, if some hot
function is indeed detected by profiling, etc.
- The 'perf test sigtrap' test is currently failing on PREEMPT_RT,
skip it if sleeping spinlocks are detected (using BTF) and point to
the mailing list discussion about it. This test is also being
skipped on several architectures (powerpc, s390x, arm and aarch64)
due to other pending issues with intruction breakpoints.
- Adjust test case perf record offcpu profiling tests for s390.
- Fix 'Setup struct perf_event_attr' fails on s390 on z/VM guest,
addressing issues caused by the fallback from cycles to task-clock
done in this release.
- Fix mask for VG register in the user-regs test.
- Use shellcheck on 'perf test' shell scripts automatically to make
sure changes don't introduce things it flags as problematic.
- Add option to change objdump binary and allow it to be set via
'perf config'.
- Add basic 'perf script', 'perf list --json" and 'perf diff' tests.
- Basic branch counter support.
- Make DSO tests a suite rather than individual.
- Remove atomics from test_loop to avoid test failures.
- Fix call chain match on powerpc for the record+probe_libc_inet_pton
test.
- Improve Intel hybrid tests.
Vendor event files (JSON):
powerpc:
- Update datasource event name to fix duplicate events on IBM's
Power10.
- Add PVN for HX-C2000 CPU with Power8 Architecture.
Intel:
- Alderlake/rocketlake metric fixes.
- Update emeraldrapids events to v1.02.
- Update icelakex events to v1.23.
- Update sapphirerapids events to v1.17.
- Add skx, clx, icx and spr upi bandwidth metric.
AMD:
- Add Zen 4 memory controller events.
RISC-V:
- Add StarFive Dubhe-80 and Dubhe-90 JSON files.
https://www.starfivetech.com/en/site/cpu-u
- Add T-HEAD C9xx JSON file.
https://github.com/riscv-software-src/opensbi/blob/master/docs/platform/thead-c9xx.md
ARM64:
- Remove UTF-8 characters from cmn.json, that were causing build
failure in some distros.
- Add core PMU events and metrics for Ampere One X.
- Rename Ampere One's BPU_FLUSH_MEM_FAULT to GPC_FLUSH_MEM_FAULT
libperf:
- Rename several perf_cpu_map constructor names to clarify what they
really do.
- Ditto for some other methods, coping with some issues in their
semantics, like perf_cpu_map__empty() ->
perf_cpu_map__has_any_cpu_or_is_empty().
- Document perf_cpu_map__nr()'s behavior
perf stat:
- Exit if parse groups fails.
- Combine the -A/--no-aggr and --no-merge options.
- Fix help message for --metric-no-threshold option.
Hardware tracing:
ARM64 CoreSight:
- Bump minimum OpenCSD version to ensure a bugfix is present.
- Add 'T' itrace option for timestamp trace
- Set start vm addr of exectable file to 0 and don't ignore first
sample on the arm-cs-trace-disasm.py 'perf script'"
* tag 'perf-tools-for-v6.8-1-2024-01-09' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools: (179 commits)
MAINTAINERS: Add Namhyung as tools/perf/ co-maintainer
perf test: test case 'Setup struct perf_event_attr' fails on s390 on z/vm
perf db-export: Fix missing reference count get in call_path_from_sample()
perf tests: Add perf script test
libsubcmd: Fix memory leak in uniq()
perf TUI: Don't ignore job control
perf vendor events intel: Update sapphirerapids events to v1.17
perf vendor events intel: Update icelakex events to v1.23
perf vendor events intel: Update emeraldrapids events to v1.02
perf vendor events intel: Alderlake/rocketlake metric fixes
perf x86 test: Add hybrid test for conflicting legacy/sysfs event
perf x86 test: Update hybrid expectations
perf vendor events amd: Add Zen 4 memory controller events
perf stat: Fix hard coded LL miss units
perf record: Reduce memory for recording PERF_RECORD_LOST_SAMPLES event
perf env: Avoid recursively taking env->bpf_progs.lock
perf annotate: Add --insn-stat option for debugging
perf annotate: Add --type-stat option for debugging
perf annotate: Support event group display
perf annotate: Add --data-type option
...
On kernel that don't support arg:ctx tag, before adjusting global
subprog BTF information to match kernel's expected canonical type names,
make sure that types used by user are meaningful, and if not, warn and
don't do BTF adjustments.
This is similar to checks that kernel performs, but narrower in scope,
as only a small subset of BPF program types can be accommodated by
libbpf using canonical type names.
Libbpf unconditionally allows `struct pt_regs *` for perf_event program
types, unlike kernel, which supports that conditionally on architecture.
This is done to keep things simple and not cause unnecessary false
positives. This seems like a minor and harmless deviation, which in
real-world programs will be caught by kernels with arg:ctx tag support
anyways. So KISS principle.
This logic is hard to test (especially on latest kernels), so manual
testing was performed instead. Libbpf emitted the following warning for
perf_event program with wrong context argument type:
libbpf: prog 'arg_tag_ctx_perf': subprog 'subprog_ctx_tag' arg#0 is expected to be of `struct bpf_perf_event_data *` type
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240118033143.3384355-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add feature detector of kernel-side arg:ctx (__arg_ctx) tag support. If
this is detected, libbpf will avoid doing any __arg_ctx-related BTF
rewriting and checks in favor of letting kernel handle this completely.
test_global_funcs/ctx_arg_rewrite subtest is adjusted to do the same
feature detection (albeit in much simpler, though round-about and
inefficient, way), and skip the tests. This is done to still be able to
execute this test on older kernels (like in libbpf CI).
Note, BPF token series ([0]) does a major refactor and code moving of
libbpf-internal feature detection "framework", so to avoid unnecessary
conflicts we keep newly added feature detection stand-alone with ad-hoc
result caching. Once things settle, there will be a small follow up to
re-integrate everything back and move code into its final place in
newly-added (by BPF token series) features.c file.
[0] https://patchwork.kernel.org/project/netdevbpf/list/?series=814209&state=*
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240118033143.3384355-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
uniq() will write one command name over another causing the overwritten
string to be leaked. Fix by doing a pass that removes duplicates and a
second that removes the holes.
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Chenyuan Mi <cymi20@fudan.edu.cn>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20231208000515.1693746-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Out of all special global func arg tag annotations, __arg_ctx is
practically is the most immediately useful and most critical to have
working across multitude kernel version, if possible. This would allow
end users to write much simpler code if __arg_ctx semantics worked for
older kernels that don't natively understand btf_decl_tag("arg:ctx") in
verifier logic.
Luckily, it is possible to ensure __arg_ctx works on old kernels through
a bit of extra work done by libbpf, at least in a lot of common cases.
To explain the overall idea, we need to go back at how context argument
was supported in global funcs before __arg_ctx support was added. This
was done based on special struct name checks in kernel. E.g., for
BPF_PROG_TYPE_PERF_EVENT the expectation is that argument type `struct
bpf_perf_event_data *` mark that argument as PTR_TO_CTX. This is all
good as long as global function is used from the same BPF program types
only, which is often not the case. If the same subprog has to be called
from, say, kprobe and perf_event program types, there is no single
definition that would satisfy BPF verifier. Subprog will have context
argument either for kprobe (if using bpf_user_pt_regs_t struct name) or
perf_event (with bpf_perf_event_data struct name), but not both.
This limitation was the reason to add btf_decl_tag("arg:ctx"), making
the actual argument type not important, so that user can just define
"generic" signature:
__noinline int global_subprog(void *ctx __arg_ctx) { ... }
I won't belabor how libbpf is implementing subprograms, see a huge
comment next to bpf_object_relocate_calls() function. The idea is that
each main/entry BPF program gets its own copy of global_subprog's code
appended.
This per-program copy of global subprog code *and* associated func_info
.BTF.ext information, pointing to FUNC -> FUNC_PROTO BTF type chain
allows libbpf to simulate __arg_ctx behavior transparently, even if the
kernel doesn't yet support __arg_ctx annotation natively.
The idea is straightforward: each time we append global subprog's code
and func_info information, we adjust its FUNC -> FUNC_PROTO type
information, if necessary (that is, libbpf can detect the presence of
btf_decl_tag("arg:ctx") just like BPF verifier would do it).
The rest is just mechanical and somewhat painful BTF manipulation code.
It's painful because we need to clone FUNC -> FUNC_PROTO, instead of
reusing it, as same FUNC -> FUNC_PROTO chain might be used by another
main BPF program within the same BPF object, so we can't just modify it
in-place (and cloning BTF types within the same struct btf object is
painful due to constant memory invalidation, see comments in code).
Uploaded BPF object's BTF information has to work for all BPF
programs at the same time.
Once we have FUNC -> FUNC_PROTO clones, we make sure that instead of
using some `void *ctx` parameter definition, we have an expected `struct
bpf_perf_event_data *ctx` definition (as far as BPF verifier and kernel
is concerned), which will mark it as context for BPF verifier. Same
global subprog relocated and copied into another main BPF program will
get different type information according to main program's type. It all
works out in the end in a completely transparent way for end user.
Libbpf maintains internal program type -> expected context struct name
mapping internally. Note, not all BPF program types have named context
struct, so this approach won't work for such programs (just like it
didn't before __arg_ctx). So native __arg_ctx is still important to have
in kernel to have generic context support across all BPF program types.
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240104013847.3875810-8-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
With all the preparations in previous patches done we are ready to
postpone BTF loading and sanitization step until after all the
relocations are performed.
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240104013847.3875810-7-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Move the logic of finding and assigning exception callback indices from
BTF sanitization step to program relocations step, which seems more
logical and will unblock moving BTF loading to after relocation step.
Exception callbacks discovery and assignment has no dependency on BTF
being loaded into the kernel, it only uses BTF information. It does need
to happen before subprogram relocations happen, though. Which is why the
split.
No functional changes.
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240104013847.3875810-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Move map creation to later during BPF object loading by pre-creating
stable placeholder FDs (utilizing memfd_create()). Use dup2()
syscall to then atomically make those placeholder FDs point to real
kernel BPF map objects.
This change allows to delay BPF map creation to after all the BPF
program relocations. That, in turn, allows to delay BTF finalization and
loading into kernel to after all the relocations as well. We'll take
advantage of the latter in subsequent patches to allow libbpf to adjust
BTF in a way that helps with BPF global function usage.
Clean up a few places where we close map->fd, which now shouldn't
happen, because map->fd should be a valid FD regardless of whether map
was created or not. Surprisingly and nicely it simplifies a bunch of
error handling code. If this change doesn't backfire, I'm tempted to
pre-create such stable FDs for other entities (progs, maybe even BTF).
We previously did some manipulations to make gen_loader work with fake
map FDs, with stable map FDs this hack is not necessary for maps (we
still have it for BTF, but I left it as is for now).
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240104013847.3875810-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
With the upcoming switch to preallocated placeholder FDs for maps,
switch various getters/setter away from checking map->fd. Use
map_is_created() helper that detect whether BPF map can be modified based
on map->obj->loaded state, with special provision for maps set up with
bpf_map__reuse_fd().
For backwards compatibility, we take map_is_created() into account in
bpf_map__fd() getter as well. This way before bpf_object__load() phase
bpf_map__fd() will always return -1, just as before the changes in
subsequent patches adding stable map->fd placeholders.
We also get rid of all internal uses of bpf_map__fd() getter, as it's
more oriented for uses external to libbpf. The above map_is_created()
check actually interferes with some of the internal uses, if map FD is
fetched through bpf_map__fd().
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240104013847.3875810-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Instead of inferring whether map already point to previously
created/pinned BPF map (which user can specify with bpf_map__reuse_fd()) API),
use explicit map->reused flag that is set in such case.
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240104013847.3875810-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
It makes future grepping and code analysis a bit easier.
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240104013847.3875810-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
An issue occurred while reading an ELF file in libbpf.c during fuzzing:
Program received signal SIGSEGV, Segmentation fault.
0x0000000000958e97 in bpf_object.collect_prog_relos () at libbpf.c:4206
4206 in libbpf.c
(gdb) bt
#0 0x0000000000958e97 in bpf_object.collect_prog_relos () at libbpf.c:4206
#1 0x000000000094f9d6 in bpf_object.collect_relos () at libbpf.c:6706
#2 0x000000000092bef3 in bpf_object_open () at libbpf.c:7437
#3 0x000000000092c046 in bpf_object.open_mem () at libbpf.c:7497
#4 0x0000000000924afa in LLVMFuzzerTestOneInput () at fuzz/bpf-object-fuzzer.c:16
#5 0x000000000060be11 in testblitz_engine::fuzzer::Fuzzer::run_one ()
#6 0x000000000087ad92 in tracing::span::Span::in_scope ()
#7 0x00000000006078aa in testblitz_engine::fuzzer::util::walkdir ()
#8 0x00000000005f3217 in testblitz_engine::entrypoint::main::{{closure}} ()
#9 0x00000000005f2601 in main ()
(gdb)
scn_data was null at this code(tools/lib/bpf/src/libbpf.c):
if (rel->r_offset % BPF_INSN_SZ || rel->r_offset >= scn_data->d_size) {
The scn_data is derived from the code above:
scn = elf_sec_by_idx(obj, sec_idx);
scn_data = elf_sec_data(obj, scn);
relo_sec_name = elf_sec_str(obj, shdr->sh_name);
sec_name = elf_sec_name(obj, scn);
if (!relo_sec_name || !sec_name)// don't check whether scn_data is NULL
return -EINVAL;
In certain special scenarios, such as reading a malformed ELF file,
it is possible that scn_data may be a null pointer
Signed-off-by: Mingyi Zhang <zhangmingyi5@huawei.com>
Signed-off-by: Xin Liu <liuxin350@huawei.com>
Signed-off-by: Changye Wu <wuchangye@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231221033947.154564-1-liuxin350@huawei.com
clang can generate (with -g -Wa,--compress-debug-sections) 4-byte
aligned DWARF sections that declare themselves to be 8-byte aligned in
the section header. Since DWARF sections are dropped during linking
anyway, just skip running the sanity checks on them.
Reported-by: Sergei Trofimovich <slyich@gmail.com>
Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Alyssa Ross <hi@alyssa.is>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Closes: https://lore.kernel.org/bpf/ZXcFRJVKbKxtEL5t@nz.home/
Link: https://lore.kernel.org/bpf/20231219110324.8989-1-hi@alyssa.is
Add a set of __arg_xxx macros which can be used to augment BPF global
subprogs/functions with extra information for use by BPF verifier.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-9-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
To pick up fixes that went thru perf-tools for v6.7 and to get in sync
with upstream to check for drift in the copies of headers, etc.
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
