Fix few issues found when building and running test_progs in
release mode.

First, potentially uninitialized idx variable in xskxceiver,
force-initialize to zero to satisfy compiler.

Few instances of defining uprobe trigger functions break in release mode
unless marked as noinline, due to being static. Add noinline to make
sure everything works.
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/20220816001929.369487-5-andrii@kernel.org

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

Make sure that entire libbpf code base is initializing bpf_attr and
perf_event_attr with memset(0). Also for bpf_attr make sure we
clear and pass to kernel only relevant parts of bpf_attr. bpf_attr is
a huge union of independent sub-command attributes, so there is no need
to clear and pass entire union bpf_attr, which over time grows quite
a lot and for most commands this growth is completely irrelevant.

Few cases where we were relying on compiler initialization of BPF UAPI
structs (like bpf_prog_info, bpf_map_info, etc) with `= {};` were
switched to memset(0) pattern for future-proofing.
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/20220816001929.369487-3-andrii@kernel.org

Fix if condition filtering empty ELF sections to prevent NULL
dereference.

Fixes: 47ea7417 ("libbpf: Skip empty sections in bpf_object__init_global_data_maps")
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/20220816001929.369487-2-andrii@kernel.org

Adds test for libbpf APIs that toggle bpf program auto-attaching.
Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220816234012.910255-2-haoluo@google.com

Adds libbpf APIs for disabling auto-attach for individual functions.
This is motivated by the use case of cgroup iter [1]. Some iter
types require their parameters to be non-zero, therefore applying
auto-attach on them will fail. With these two new APIs, users who
want to use auto-attach and these types of iters can disable
auto-attach on the program and perform manual attach.

[1] https://lore.kernel.org/bpf/CAEf4BzZ+a2uDo_t6kGBziqdz--m2gh2_EUwkGLDtMd65uwxUjA@mail.gmail.com/Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220816234012.910255-1-haoluo@google.com

Use SYS_PREFIX macro from bpf_misc.h instead of hard-coded '__x64_'
prefix for sys_setdomainname attach point in lsm test.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220816055231.717006-1-asavkov@redhat.com

Similar with commit 10b62d6a ("libbpf: Add names for auxiliary maps"),
let's make bpf_prog_load() also ignore name if kernel doesn't support
program name.

To achieve this, we need to call sys_bpf_prog_load() directly in
probe_kern_prog_name() to avoid circular dependency. sys_bpf_prog_load()
also need to be exported in the libbpf_internal.h file.
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20220813000936.6464-1-liuhangbin@gmail.com

The previous selftest changes require two kconfig changes in bpf-ci.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/2c27c6ebf7a03954915f83560653752450389564.1660254747.git.dxu@dxuuu.xyz

Test that the prog can read from the connection mark. This test is nice
because it ensures progs can interact with netfilter subsystem
correctly.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/d3bc620a491e4c626c20d80631063922cbe13e2b.1660254747.git.dxu@dxuuu.xyz

Add a test where we do a conntrack lookup on an existing connection.
This is nice because it's a more realistic test than artifically
creating a ct entry and looking it up afterwards.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/de5a617832f38f8b5631cc87e2a836da7c94d497.1660254747.git.dxu@dxuuu.xyz

When bpftool is linked against libcap, the library runs a "constructor"
function to compute the number of capabilities of the running kernel
[0], at the beginning of the execution of the program. As part of this,
it performs multiple calls to prctl(). Some of these may fail, and set
errno to a non-zero value:

    # strace -e prctl ./bpftool version
    prctl(PR_CAPBSET_READ, CAP_MAC_OVERRIDE) = 1
    prctl(PR_CAPBSET_READ, 0x30 /* CAP_??? */) = -1 EINVAL (Invalid argument)
    prctl(PR_CAPBSET_READ, CAP_CHECKPOINT_RESTORE) = 1
    prctl(PR_CAPBSET_READ, 0x2c /* CAP_??? */) = -1 EINVAL (Invalid argument)
    prctl(PR_CAPBSET_READ, 0x2a /* CAP_??? */) = -1 EINVAL (Invalid argument)
    prctl(PR_CAPBSET_READ, 0x29 /* CAP_??? */) = -1 EINVAL (Invalid argument)
    ** fprintf added at the top of main(): we have errno == 1
    ./bpftool v7.0.0
    using libbpf v1.0
    features: libbfd, libbpf_strict, skeletons
    +++ exited with 0 +++

This has been addressed in libcap 2.63 [1], but until this version is
available everywhere, we can fix it on bpftool side.

Let's clean errno at the beginning of the main() function, to make sure
that these checks do not interfere with the batch mode, where we error
out if errno is set after a bpftool command.

  [0] https://git.kernel.org/pub/scm/libs/libcap/libcap.git/tree/libcap/cap_alloc.c?h=libcap-2.65#n20
  [1] https://git.kernel.org/pub/scm/libs/libcap/libcap.git/commit/?id=f25a1b7e69f7b33e6afb58b3e38f3450b7d2d9a0Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220815162205.45043-1-quentin@isovalent.com

Adding or removing room space _below_ layers 2 or 3, as the description
mentions, is ambiguous. This was written with a mental image of the
packet with layer 2 at the top, layer 3 under it, and so on. But it has
led users to believe that it was on lower layers (before the beginning
of the L2 and L3 headers respectively).

Let's make it more explicit, and specify between which layers the room
space is adjusted.
Reported-by: Rumen Telbizov <rumen.telbizov@menlosecurity.com>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220812153727.224500-3-quentin@isovalent.com

This is the wrong library name: libcap, not libpcap.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220812153727.224500-1-quentin@isovalent.com

The bpftool self-created maps can appear in final map show output due to
deferred removal in kernel. These maps don't have a name, which would make
users confused about where it comes from.

With a libbpf_ prefix name, users could know who created these maps.
It also could make some tests (like test_offload.py, which skip base maps
without names as a workaround) filter them out.

Kernel adds bpf prog/map name support in the same merge
commit fadad670 ("Merge branch 'bpf-extend-info'"). So we can also use
kernel_supports(NULL, FEAT_PROG_NAME) to check if kernel supports map name.

As discussed [1], Let's make bpf_map_create accept non-null
name string, and silently ignore the name if kernel doesn't support.

  [1] https://lore.kernel.org/bpf/CAEf4BzYL1TQwo1231s83pjTdFPk9XWWhfZC5=KzkU-VO0k=0Ug@mail.gmail.com/Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220811034020.529685-1-liuhangbin@gmail.com

Let's use the generic helper bpf_map_area_alloc() instead of the
open-coded kzalloc helpers in bpf maps creation path.
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20220810151840.16394-5-laoar.shao@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Some of the bpf maps are created with __GFP_NOWARN, i.e. arraymap,
bloom_filter, bpf_local_storage, bpf_struct_ops, lpm_trie,
queue_stack_maps, reuseport_array, stackmap and xskmap, while others are
created without __GFP_NOWARN, i.e. cpumap, devmap, hashtab,
local_storage, offload, ringbuf and sock_map. But there are not key
differences between the creation of these maps. So let make this
allocation flag consistent in all bpf maps creation. Then we can use a
generic helper to alloc all bpf maps.
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20220810151840.16394-4-laoar.shao@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

bpf_map_area_alloc() should be paired with bpf_map_area_free().
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20220810151840.16394-3-laoar.shao@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

__GFP_ZERO will clear the memory, so we don't need to memset it.
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20220810151840.16394-2-laoar.shao@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

As suggested in [0], make sure that libbpf_print saves and restored
errno and as such guaranteed that no matter what actual print callback
user installs, macros like pr_warn/pr_info/pr_debug are completely
transparent as far as errno goes.

While libbpf code is pretty careful about not clobbering important errno
values accidentally with pr_warn(), it's a trivial change to make sure
that pr_warn can be used anywhere without a risk of clobbering errno.

No functional changes, just future proofing.

  [0] https://github.com/libbpf/libbpf/pull/536Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Daniel Müller <deso@posteo.net>
Link: https://lore.kernel.org/r/20220810183425.1998735-1-andrii@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Artem Savkov says:

====================

eBPF is often used for kernel debugging, and one of the widely used and
powerful debugging techniques is post-mortem debugging with a full memory dump.
Triggering a panic at exactly the right moment allows the user to get such a
dump and thus a better view at the system's state. Right now the only way to
do this in BPF is to signal userspace to trigger kexec/panic. This is
suboptimal as going through userspace requires context changes and adds
significant delays taking system further away from "the right moment". On a
single-cpu system the situation is even worse because BPF program won't even be
able to block the thread of interest.

This patchset tries to solve this problem by allowing properly marked tracing
bpf programs to call crash_kexec() kernel function. The only requirement for
now to run programs calling crash_kexec() or other destructive kfuncs is
CAP_SYS_BOOT capability. When signature checking for bpf programs is available
it is possible that stricter rules will be applied to programs utilizing
destructive kfuncs.

Changes in v5:
 - documentation numbering fixed
 - no more warning on failed kfunc registration

Changes in v4:
 - added description for KF_DESTRUCTIVE flag to documentation

Changes in v3:
 - moved kfunc set registration to kernel/bpf/helpers.c

Changes in v2:
 - BPF_PROG_LOAD flag dropped as it doesn't fully achieve it's aim of
   preventing accidental execution of destructive bpf programs
 - selftest moved to the end of patchset
 - switched to kfunc destructive flag instead of a separate set

Changes from RFC:
 - sysctl knob dropped
 - using crash_kexec() instead of panic()
 - using kfuncs instead of adding a new helper
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Add a test checking that programs calling destructive kfuncs can only do
so if they have CAP_SYS_BOOT capabilities.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Link: https://lore.kernel.org/r/20220810065905.475418-4-asavkov@redhat.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Allow properly marked bpf programs to call crash_kexec().
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Link: https://lore.kernel.org/r/20220810065905.475418-3-asavkov@redhat.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Add KF_DESTRUCTIVE flag for destructive functions. Functions with this
flag set will require CAP_SYS_BOOT capabilities.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Link: https://lore.kernel.org/r/20220810065905.475418-2-asavkov@redhat.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Poll test case was not testing all the functionality of the poll feature
in the test suite. This patch updates the poll test case which contains 2
test cases to test the RX and the TX poll functionality and additional 2
more test cases to check the timeout feature of the poll event.

Poll test suite has 4 test cases:

1. TEST_TYPE_RX_POLL: Check if RX path POLLIN function works as expect.
   TX path can use any method to send the traffic.

2. TEST_TYPE_TX_POLL: Check if TX path POLLOUT function works as expect.
   RX path can use any method to receive the traffic.

3. TEST_TYPE_POLL_RXQ_EMPTY: Call poll function with parameter POLLIN on
   empty RX queue will cause timeout. If timeout then test case passes.

4. TEST_TYPE_POLL_TXQ_FULL: When TX queue is filled and packets are not
   cleaned by the kernel then if we invoke the poll function with POLLOUT
   it should trigger timeout.
Signed-off-by: Shibin Koikkara Reeny <shibin.koikkara.reeny@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/bpf/20220803144354.98122-1-shibin.koikkara.reeny@intel.com

Add an additional test, "data_slice_use_after_release2", for ensuring
that data slices are correctly invalidated by the verifier after the
dynptr whose ref obj id they track is released. In particular, this
tests data slice invalidation for dynptrs located at a non-zero offset
from the frame pointer.
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220809214055.4050604-2-joannelkoong@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

When a data slice is obtained from a dynptr (through the bpf_dynptr_data API),
the ref obj id of the dynptr must be found and then associated with the data
slice.

The ref obj id of the dynptr must be found *before* the caller saved regs are
reset. Without this fix, the ref obj id tracking is not correct for
dynptrs that are at an offset from the frame pointer.

Please also note that the data slice's ref obj id must be assigned after the
ret types are parsed, since RET_PTR_TO_ALLOC_MEM-type return regs get
zero-marked.

Fixes: 34d4ef57 ("bpf: Add dynptr data slices")
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20220809214055.4050604-1-joannelkoong@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Before, you could see the following errors:

  $ ./vmtest.sh -j
  ./vmtest.sh: option requires an argument -- j
  ./vmtest.sh: line 357: OPTARG: unbound variable

  $ ./vmtest.sh -z
  ./vmtest.sh: illegal option -- z
  ./vmtest.sh: line 357: OPTARG: unbound variable

Fix by adding ':' as first character of optstring. Reason is that getopts
requires ':' as the first character for OPTARG to be set in the `?` and `:`
error cases.

Note that the ':' as the first character of the optstring switches getopts
to silent mode. The desire to run in this mode seems to have been there all
along, as the script takes care of reporting errors.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Müller <deso@posteo.net>
Link: https://lore.kernel.org/bpf/0f93b56198328b6b4da7b4cf4662d05c3edb5fd2.1660064925.git.dxu@dxuuu.xyz

Set the exit trap only after argument parsing is done. This way argument
parse failure or `-h` will not require sudo.

Reasoning is that it's confusing that a help message would require root
access.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Müller <deso@posteo.net>
Link: https://lore.kernel.org/bpf/6a802aa37758e5a7e6aa5de294634f5518005e2b.1660064925.git.dxu@dxuuu.xyz

Currently in funciton __get_type_size(), the corresponding
btf_type is returned only in invalid cases. Let us always
return btf_type regardless of valid or invalid cases.
Such a new functionality will be used in subsequent patches.
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220807175116.4179242-1-yhs@fb.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Kurt Kanzenbach says:

====================

Hi,

add a BPF-helper for accessing CLOCK_TAI. Use cases for such a BPF helper
include functionalities such as Tx launch time (e.g. ETF and TAPRIO Qdiscs),
timestamping and policing.

Patch #1 - Introduce BPF helper
Patch #2 - Add test case (skb based)

Changes since v1:

 * Update changelog (Alexei Starovoitov)
 * Add test case (Alexei Starovoitov, Andrii Nakryiko)
 * Add missing function prototype (netdev ci)

Previous versions:

 * v1: https://lore.kernel.org/r/20220606103734.92423-1-kurt@linutronix.de/

Jesper Dangaard Brouer (1):
  bpf: Add BPF-helper for accessing CLOCK_TAI
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Add BPF-helper test case for CLOCK_TAI access. The added test verifies that:

 * Timestamps are generated
 * Timestamps are moving forward
 * Timestamps are reasonable
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/20220809060803.5773-3-kurt@linutronix.deSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Commit 3dc6ffae ("timekeeping: Introduce fast accessor to clock tai")
introduced a fast and NMI-safe accessor for CLOCK_TAI. Especially in time
sensitive networks (TSN), where all nodes are synchronized by Precision Time
Protocol (PTP), it's helpful to have the possibility to generate timestamps
based on CLOCK_TAI instead of CLOCK_MONOTONIC. With a BPF helper for TAI in
place, it becomes very convenient to correlate activity across different
machines in the network.

Use cases for such a BPF helper include functionalities such as Tx launch
time (e.g. ETF and TAPRIO Qdiscs) and timestamping.

Note: CLOCK_TAI is nothing new per se, only the NMI-safe variant of it is.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
[Kurt: Wrote changelog and renamed helper]
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/20220809060803.5773-2-kurt@linutronix.deSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Discussion around a recently-submitted patch provided historical
context for check_refcount_ok [0]. Specifically, the function and its
helpers - may_be_acquire_function and arg_type_may_be_refcounted -
predate the OBJ_RELEASE type flag and the addition of many more helpers
with acquire/release semantics.

The purpose of check_refcount_ok is to ensure:
  1) Helper doesn't have multiple uses of return reg's ref_obj_id
  2) Helper with release semantics only has one arg needing to be
  released, since that's tracked using meta->ref_obj_id

With current verifier, it's safe to remove check_refcount_ok and its
helpers. Since addition of OBJ_RELEASE type flag, case 2) has been
handled by the arg_type_is_release check in check_func_arg. To ensure
case 1) won't result in verifier silently prioritizing one use of
ref_obj_id, this patch adds a helper_multiple_ref_obj_use check which
fails loudly if a helper passes > 1 test for use of ref_obj_id.

  [0]: lore.kernel.org/bpf/20220713234529.4154673-1-davemarchevsky@fb.com
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Joanne Koong <joannelkoong@gmail.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220808171559.3251090-1-davemarchevsky@fb.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

The current ifdefry for code shared by the BPF and ctnetlink side looks
ugly. As per Pablo's request, simplify this by unconditionally compiling
in the code. This can be revisited when the shared code between the two
grows further.
Suggested-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220725085130.11553-1-memxor@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

In bpf_seq_read, seq->op->next() could return an ERR and jump to
the label stop. However, the existing code in stop does not handle
the case when p (returned from next()) is an ERR. Adds the handling
of ERR of p by converting p into an error and jumping to done.

Because all the current implementations do not have a case that
returns ERR from next(), so this patch doesn't have behavior changes
right now.
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/r/20220805214821.1058337-4-haoluo@google.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

cgroup_get_from_file() currently fails with -EBADF if called on cgroup
v1. However, the current implementation works on cgroup v1 as well, so
the restriction is unnecessary.

This enabled cgroup_get_from_fd() to work on cgroup v1, which would be
the only thing stopping bpf cgroup_iter from supporting cgroup v1.
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/r/20220805214821.1058337-3-haoluo@google.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

This allows to declare a kfunc as sleepable and prevents its use in
a non sleepable program.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Co-developed-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/r/20220805214821.1058337-2-haoluo@google.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Most tools which use bpf_get_stack or bpf_get_stackid symbolicate the
stack - meaning the stack of addresses in the target process' address
space is transformed into meaningful symbol names. The
BPF_F_USER_BUILD_ID flag eases this process by finding the build_id of
the file-backed vma which the address falls in and translating the
address to an offset within the backing file.

To be more specific, the offset is a "file offset" from the beginning of
the backing file. The symbols in ET_DYN ELF objects have a st_value
which is also described as an "offset" - but an offset in the process
address space, relative to the base address of the object.

It's necessary to translate between the "file offset" and "virtual
address offset" during symbolication before they can be directly
compared. Failure to do so can lead to confusing bugs, so this patch
clarifies language in the documentation in an attempt to keep this from
happening.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220808164723.3107500-1-davemarchevsky@fb.com

Currently, resolve_full_path() requires executable permission for both
programs and shared libraries. This causes failures on distos like Debian
since the shared libraries are not installed executable and Linux is not
requiring shared libraries to have executable permissions. Let's remove
executable permission check for shared libraries.
Reported-by: Goro Fuji <goro@fastly.com>
Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220806102021.3867130-1-hengqi.chen@gmail.com