| Age | Commit message (Collapse) | Author |
|---|
|
Commit 728ff167910e uses a PROG_TYPE_TRACEPOINT BPF test program to
check whether the running kernel supports large LDIMM64 offsets. The
feature gate incorrectly assumes that the program will fail at
verification time with one of two messages, depending on whether the
feature is supported by the running kernel. However,
PROG_TYPE_TRACEPOINT programs may fail to load before verification even
starts, e.g., if the shell does not have the appropriate capabilities.
Use a BPF_PROG_TYPE_SOCKET_FILTER program for the feature gate instead.
Also fix two minor issues. First, ensure the log buffer for the test is
initialized: Failing program load before verification led to libbpf dumping
uninitialized data to stdout. Also, ensure that close() is only called
for program_fd in the probe if the program load actually succeeded. The
call was currently failing silently with -EBADF most of the time.
Fixes: 728ff167910e ("libbpf: Add gating for arena globals relocation feature")
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260217204345.548648-2-emil@etsalapatis.com
|
|
Add feature gating for the arena globals relocation introduced in
commit c1f61171d44b. The commit depends on a previous commit in the
same patchset that is absent from older kernels
(12a1fe6e12db "bpf/verifier: Do not limit maximum direct offset into arena map").
Without this commit, arena globals relocation with arenas >= 512MiB
fails to load and breaks libbpf's backwards compatibility.
Introduce a libbpf feature to check whether the running kernel allows for
full range ldimm64 offset, and only relocate arena globals if it does.
Fixes: c1f61171d44b ("libbpf: Move arena globals to the end of the arena")
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260210184532.255475-1-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Get rid of str_err.{c,h} by moving implementation of libbpf_errstr()
into libbpf_utils.c and declarations into libbpf_internal.h.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20251001171326.3883055-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
|
|
Convert numeric error codes into the string representations in log
messages in the rest of libbpf source files.
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20241111212919.368971-5-mykyta.yatsenko5@gmail.com
|
|
Guard close(link_fd) with extra link_fd >= 0 check to prevent close(-1).
Detected by Coverity static analysis.
Fixes: 04d939a2ab22 ("libbpf: detect broken PID filtering logic for multi-uprobe")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20240529231212.768828-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Libbpf is automatically (and transparently to user) detecting
multi-uprobe support in the kernel, and, if supported, uses
multi-uprobes to improve USDT attachment speed.
USDTs can be attached system-wide or for the specific process by PID. In
the latter case, we rely on correct kernel logic of not triggering USDT
for unrelated processes.
As such, on older kernels that do support multi-uprobes, but still have
broken PID filtering logic, we need to fall back to singular uprobes.
Unfortunately, whether user is using PID filtering or not is known at
the attachment time, which happens after relevant BPF programs were
loaded into the kernel. Also unfortunately, we need to make a call
whether to use multi-uprobes or singular uprobe for SEC("usdt") programs
during BPF object load time, at which point we have no information about
possible PID filtering.
The distinction between single and multi-uprobes is small, but important
for the kernel. Multi-uprobes get BPF_TRACE_UPROBE_MULTI attach type,
and kernel internally substitiute different implementation of some of
BPF helpers (e.g., bpf_get_attach_cookie()) depending on whether uprobe
is multi or singular. So, multi-uprobes and singular uprobes cannot be
intermixed.
All the above implies that we have to make an early and conservative
call about the use of multi-uprobes. And so this patch modifies libbpf's
existing feature detector for multi-uprobe support to also check correct
PID filtering. If PID filtering is not yet fixed, we fall back to
singular uprobes for USDTs.
This extension to feature detection is simple thanks to kernel's -EINVAL
addition for pid < 0.
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240521163401.3005045-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Adjust `union bpf_attr` size passed to kernel in two feature-detecting
functions to take into account prog_token_fd field.
Libbpf is avoiding memset()'ing entire `union bpf_attr` by only using
minimal set of bpf_attr's fields. Two places have been missed when
wiring BPF token support in libbpf's feature detection logic.
Fix them trivially.
Fixes: f3dcee938f48 ("libbpf: Wire up token_fd into feature probing logic")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240513180804.403775-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Optional struct_ops maps are defined using question mark at the start
of the section name, e.g.:
SEC("?.struct_ops")
struct test_ops optional_map = { ... };
This commit teaches libbpf to detect if kernel allows '?' prefix
in datasec names, and if it doesn't then to rewrite such names
by replacing '?' with '_', e.g.:
DATASEC ?.struct_ops -> DATASEC _.struct_ops
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240306104529.6453-13-eddyz87@gmail.com
|
|
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>
|
|
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
|
