This updates usage of the following API functions within
libbpf so their newly added error return is checked:
- bpf_program__set_expected_attach_type()
- bpf_program__set_type()
Signed-off-by: Grant Seltzer <grantseltzer@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220420161226.86803-2-grantseltzer@gmail.com
This adds an error return to the following API functions:
- bpf_program__set_expected_attach_type()
- bpf_program__set_type()
In both cases, the error occurs when the BPF object has
already been loaded when the function is called. In this
case -EBUSY is returned.
Signed-off-by: Grant Seltzer <grantseltzer@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220420161226.86803-1-grantseltzer@gmail.com
Add riscv-specific USDT argument specification parsing logic.
riscv USDT argument format is shown below:
- Memory dereference case:
"size@off(reg)", e.g. "-8@-88(s0)"
- Constant value case:
"size@val", e.g. "4@5"
- Register read case:
"size@reg", e.g. "-8@a1"
s8 will be marked as poison while it's a reg of riscv, we need
to alias it in advance. Both RV32 and RV64 have been tested.
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220419145238.482134-3-pulehui@huawei.com
The usdt_cookie is defined as __u64, which should not be
used as a long type because it will be cast to 32 bits
in 32-bit platforms.
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220419145238.482134-2-pulehui@huawei.com
Establish SEC("?abc") naming convention (i.e., adding question mark in
front of otherwise normal section name) that allows to set corresponding
program's autoload property to false. This is effectively just
a declarative way to do bpf_program__set_autoload(prog, false).
Having a way to do this declaratively in BPF code itself is useful and
convenient for various scenarios. E.g., for testing, when BPF object
consists of multiple independent BPF programs that each needs to be
tested separately. Opting out all of them by default and then setting
autoload to true for just one of them at a time simplifies testing code
(see next patch for few conversions in BPF selftests taking advantage of
this new feature).
Another real-world use case is in libbpf-tools for cases when different
BPF programs have to be picked depending on particulars of the host
kernel due to various incompatible changes (like kernel function renames
or signature change, or to pick kprobe vs fentry depending on
corresponding kernel support for the latter). Marking all the different
BPF program candidates as non-autoloaded declaratively makes this more
obvious in BPF source code and allows simpler code in user-space code.
When BPF program marked as SEC("?abc") it is otherwise treated just like
SEC("abc") and bpf_program__section_name() reported will be "abc".
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220419002452.632125-1-andrii@kernel.org
Parsing of USDT arguments is architecture-specific. On aarch64 it is
relatively easy since registers used are x[0-31] and sp. Format is
slightly different compared to x86_64. Possible forms are:
- "size@[reg[,offset]]" for dereferences, e.g. "-8@[sp,76]" and "-4@[sp]";
- "size@reg" for register values, e.g. "-4@x0";
- "size@value" for raw values, e.g. "-8@1".
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1649690496-1902-2-git-send-email-alan.maguire@oracle.com
Background:
Libbpf automatically replaces calls to BPF bpf_probe_read_{kernel,user}
[_str]() helpers with bpf_probe_read[_str](), if libbpf detects that
kernel doesn't support new APIs. Specifically, libbpf invokes the
probe_kern_probe_read_kernel function to load a small eBPF program into
the kernel in which bpf_probe_read_kernel API is invoked and lets the
kernel checks whether the new API is valid. If the loading fails, libbpf
considers the new API invalid and replaces it with the old API.
static int probe_kern_probe_read_kernel(void)
{
struct bpf_insn insns[] = {
BPF_MOV64_REG(BPF_REG_1, BPF_REG_10), /* r1 = r10 (fp) */
BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -8), /* r1 += -8 */
BPF_MOV64_IMM(BPF_REG_2, 8), /* r2 = 8 */
BPF_MOV64_IMM(BPF_REG_3, 0), /* r3 = 0 */
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_probe_read_kernel),
BPF_EXIT_INSN(),
};
int fd, insn_cnt = ARRAY_SIZE(insns);
fd = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL,
"GPL", insns, insn_cnt, NULL);
return probe_fd(fd);
}
Bug:
On older kernel versions [0], the kernel checks whether the version
number provided in the bpf syscall, matches the LINUX_VERSION_CODE.
If not matched, the bpf syscall fails. eBPF However, the
probe_kern_probe_read_kernel code does not set the kernel version
number provided to the bpf syscall, which causes the loading process
alwasys fails for old versions. It means that libbpf will replace the
new API with the old one even the kernel supports the new one.
Solution:
After a discussion in [1], the solution is using BPF_PROG_TYPE_TRACEPOINT
program type instead of BPF_PROG_TYPE_KPROBE because kernel does not
enfoce version check for tracepoint programs. I test the patch in old
kernels (4.18 and 4.19) and it works well.
[0] https://elixir.bootlin.com/linux/v4.19/source/kernel/bpf/syscall.c#L1360
[1] Closes: https://github.com/libbpf/libbpf/issues/473
Signed-off-by: Runqing Yang <rainkin1993@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220409144928.27499-1-rainkin1993@gmail.com
Daniel Borkmann says:
====================
pull-request: bpf-next 2022-04-09
We've added 63 non-merge commits during the last 9 day(s) which contain
a total of 68 files changed, 4852 insertions(+), 619 deletions(-).
The main changes are:
1) Add libbpf support for USDT (User Statically-Defined Tracing) probes.
USDTs are an abstraction built on top of uprobes, critical for tracing
and BPF, and widely used in production applications, from Andrii Nakryiko.
2) While Andrii was adding support for x86{-64}-specific logic of parsing
USDT argument specification, Ilya followed-up with USDT support for s390
architecture, from Ilya Leoshkevich.
3) Support name-based attaching for uprobe BPF programs in libbpf. The format
supported is `u[ret]probe/binary_path:[raw_offset|function[+offset]]`, e.g.
attaching to libc malloc can be done in BPF via SEC("uprobe/libc.so.6:malloc")
now, from Alan Maguire.
4) Various load/store optimizations for the arm64 JIT to shrink the image
size by using arm64 str/ldr immediate instructions. Also enable pointer
authentication to verify return address for JITed code, from Xu Kuohai.
5) BPF verifier fixes for write access checks to helper functions, e.g.
rd-only memory from bpf_*_cpu_ptr() must not be passed to helpers that
write into passed buffers, from Kumar Kartikeya Dwivedi.
6) Fix overly excessive stack map allocation for its base map structure and
buckets which slipped-in from cleanups during the rlimit accounting removal
back then, from Yuntao Wang.
7) Extend the unstable CT lookup helpers for XDP and tc/BPF to report netfilter
connection tracking tuple direction, from Lorenzo Bianconi.
8) Improve bpftool dump to show BPF program/link type names, Milan Landaverde.
9) Minor cleanups all over the place from various others.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (63 commits)
bpf: Fix excessive memory allocation in stack_map_alloc()
selftests/bpf: Fix return value checks in perf_event_stackmap test
selftests/bpf: Add CO-RE relos into linked_funcs selftests
libbpf: Use weak hidden modifier for USDT BPF-side API functions
libbpf: Don't error out on CO-RE relos for overriden weak subprogs
samples, bpf: Move routes monitor in xdp_router_ipv4 in a dedicated thread
libbpf: Allow WEAK and GLOBAL bindings during BTF fixup
libbpf: Use strlcpy() in path resolution fallback logic
libbpf: Add s390-specific USDT arg spec parsing logic
libbpf: Make BPF-side of USDT support work on big-endian machines
libbpf: Minor style improvements in USDT code
libbpf: Fix use #ifdef instead of #if to avoid compiler warning
libbpf: Potential NULL dereference in usdt_manager_attach_usdt()
selftests/bpf: Uprobe tests should verify param/return values
libbpf: Improve string parsing for uprobe auto-attach
libbpf: Improve library identification for uprobe binary path resolution
selftests/bpf: Test for writes to map key from BPF helpers
selftests/bpf: Test passing rdonly mem to global func
bpf: Reject writes for PTR_TO_MAP_KEY in check_helper_mem_access
bpf: Check PTR_TO_MEM | MEM_RDONLY in check_helper_mem_access
...
====================
Link: https://lore.kernel.org/r/20220408231741.19116-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Use __weak __hidden for bpf_usdt_xxx() APIs instead of much more
confusing `static inline __noinline`. This was previously impossible due
to libbpf erroring out on CO-RE relocations pointing to eliminated weak
subprogs. Now that previous patch fixed this issue, switch back to
__weak __hidden as it's a more direct way of specifying the desired
behavior.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220408181425.2287230-3-andrii@kernel.org
During BPF static linking, all the ELF relocations and .BTF.ext
information (including CO-RE relocations) are preserved for __weak
subprograms that were logically overriden by either previous weak
subprogram instance or by corresponding "strong" (non-weak) subprogram.
This is just how native user-space linkers work, nothing new.
But libbpf is over-zealous when processing CO-RE relocation to error out
when CO-RE relocation belonging to such eliminated weak subprogram is
encountered. Instead of erroring out on this expected situation, log
debug-level message and skip the relocation.
Fixes: db2b8b0642 ("libbpf: Support CO-RE relocations for multi-prog sections")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220408181425.2287230-2-andrii@kernel.org
During BTF fix up for global variables, global variable can be global
weak and will have STB_WEAK binding in ELF. Support such global
variables in addition to non-weak ones.
This is not the problem when using BPF static linking, as BPF static
linker "fixes up" BTF during generation so that libbpf doesn't have to
do it anymore during bpf_object__open(), which led to this not being
noticed for a while, along with a pretty rare (currently) use of __weak
variables and maps.
Reported-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220407230446.3980075-2-andrii@kernel.org
Coverity static analyzer complains that strcpy() can cause buffer
overflow. Use libbpf_strlcpy() instead to be 100% sure this doesn't
happen.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220407230446.3980075-1-andrii@kernel.org
The logic is superficially similar to that of x86, but the small
differences (no need for register table and dynamic allocation of
register names, no $ sign before constants) make maintaining a common
implementation too burdensome. Therefore simply add a s390x-specific
version of parse_usdt_arg().
Note that while bcc supports index registers, this patch does not. This
should not be a problem in most cases, since s390 uses a default value
"nor" for STAP_SDT_ARG_CONSTRAINT.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220407214411.257260-4-iii@linux.ibm.com
BPF_USDT_ARG_REG_DEREF handling always reads 8 bytes, regardless of
the actual argument size. On little-endian the relevant argument bits
end up in the lower bits of val, and later on the code that handles
all the argument types expects them to be there.
On big-endian they end up in the upper bits of val, breaking that
expectation. Fix by right-shifting val on big-endian.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220407214411.257260-3-iii@linux.ibm.com
Fix several typos and references to non-existing headers.
Also use __BYTE_ORDER__ instead of __BYTE_ORDER for consistency with
the rest of the bpf code - see commit 45f2bebc80 ("libbpf: Fix
endianness detection in BPF_CORE_READ_BITFIELD_PROBED()") for
rationale).
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220407214411.257260-2-iii@linux.ibm.com
As reported by Naresh:
perf build errors on i386 [1] on Linux next-20220407 [2]
usdt.c:1181:5: error: "__x86_64__" is not defined, evaluates to 0
[-Werror=undef]
1181 | #if __x86_64__
| ^~~~~~~~~~
usdt.c:1196:5: error: "__x86_64__" is not defined, evaluates to 0
[-Werror=undef]
1196 | #if __x86_64__
| ^~~~~~~~~~
cc1: all warnings being treated as errors
Use #ifdef instead of #if to avoid this.
Fixes: 4c59e584d1 ("libbpf: Add x86-specific USDT arg spec parsing logic")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220407203842.3019904-1-andrii@kernel.org
For uprobe auto-attach, the parsing can be simplified for the SEC()
name to a single sscanf(); the return value of the sscanf can then
be used to distinguish between sections that simply specify
"u[ret]probe" (and thus cannot auto-attach), those that specify
"u[ret]probe/binary_path:function+offset" etc.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1649245431-29956-3-git-send-email-alan.maguire@oracle.com
In the process of doing path resolution for uprobe attach, libraries are
identified by matching a ".so" substring in the binary_path.
This matches a lot of patterns that do not conform to library.so[.version]
format, so instead match a ".so" _suffix_, and if that fails match a
".so." substring for the versioned library case.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1649245431-29956-2-git-send-email-alan.maguire@oracle.com
Add x86/x86_64-specific USDT argument specification parsing. Each
architecture will require their own logic, as all this is arch-specific
assembly-based notation. Architectures that libbpf doesn't support for
USDTs will pr_warn() with specific error and return -ENOTSUP.
We use sscanf() as a very powerful and easy to use string parser. Those
spaces in sscanf's format string mean "skip any whitespaces", which is
pretty nifty (and somewhat little known) feature.
All this was tested on little-endian architecture, so bit shifts are
probably off on big-endian, which our CI will hopefully prove.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Reviewed-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20220404234202.331384-6-andrii@kernel.org
Last part of architecture-agnostic user-space USDT handling logic is to
set up BPF spec and, optionally, IP-to-ID maps from user-space.
usdt_manager performs a compact spec ID allocation to utilize
fixed-sized BPF maps as efficiently as possible. We also use hashmap to
deduplicate USDT arg spec strings and map identical strings to single
USDT spec, minimizing the necessary BPF map size. usdt_manager supports
arbitrary sequences of attachment and detachment, both of the same USDT
and multiple different USDTs and internally maintains a free list of
unused spec IDs. bpf_link_usdt's logic is extended with proper setup and
teardown of this spec ID free list and supporting BPF maps.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Reviewed-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20220404234202.331384-5-andrii@kernel.org
Implement architecture-agnostic parts of USDT parsing logic. The code is
the documentation in this case, it's futile to try to succinctly
describe how USDT parsing is done in any sort of concreteness. But
still, USDTs are recorded in special ELF notes section (.note.stapsdt),
where each USDT call site is described separately. Along with USDT
provider and USDT name, each such note contains USDT argument
specification, which uses assembly-like syntax to describe how to fetch
value of USDT argument. USDT arg spec could be just a constant, or
a register, or a register dereference (most common cases in x86_64), but
it technically can be much more complicated cases, like offset relative
to global symbol and stuff like that. One of the later patches will
implement most common subset of this for x86 and x86-64 architectures,
which seems to handle a lot of real-world production application.
USDT arg spec contains a compact encoding allowing usdt.bpf.h from
previous patch to handle the above 3 cases. Instead of recording which
register might be needed, we encode register's offset within struct
pt_regs to simplify BPF-side implementation. USDT argument can be of
different byte sizes (1, 2, 4, and 8) and signed or unsigned. To handle
this, libbpf pre-calculates necessary bit shifts to do proper casting
and sign-extension in a short sequences of left and right shifts.
The rest is in the code with sometimes extensive comments and references
to external "documentation" for USDTs.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Reviewed-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20220404234202.331384-4-andrii@kernel.org
Wire up libbpf USDT support APIs without yet implementing all the
nitty-gritty details of USDT discovery, spec parsing, and BPF map
initialization.
User-visible user-space API is simple and is conceptually very similar
to uprobe API.
bpf_program__attach_usdt() API allows to programmatically attach given
BPF program to a USDT, specified through binary path (executable or
shared lib), USDT provider and name. Also, just like in uprobe case, PID
filter is specified (0 - self, -1 - any process, or specific PID).
Optionally, USDT cookie value can be specified. Such single API
invocation will try to discover given USDT in specified binary and will
use (potentially many) BPF uprobes to attach this program in correct
locations.
Just like any bpf_program__attach_xxx() APIs, bpf_link is returned that
represents this attachment. It is a virtual BPF link that doesn't have
direct kernel object, as it can consist of multiple underlying BPF
uprobe links. As such, attachment is not atomic operation and there can
be brief moment when some USDT call sites are attached while others are
still in the process of attaching. This should be taken into
consideration by user. But bpf_program__attach_usdt() guarantees that
in the case of success all USDT call sites are successfully attached, or
all the successfuly attachments will be detached as soon as some USDT
call sites failed to be attached. So, in theory, there could be cases of
failed bpf_program__attach_usdt() call which did trigger few USDT
program invocations. This is unavoidable due to multi-uprobe nature of
USDT and has to be handled by user, if it's important to create an
illusion of atomicity.
USDT BPF programs themselves are marked in BPF source code as either
SEC("usdt"), in which case they won't be auto-attached through
skeleton's <skel>__attach() method, or it can have a full definition,
which follows the spirit of fully-specified uprobes:
SEC("usdt/<path>:<provider>:<name>"). In the latter case skeleton's
attach method will attempt auto-attachment. Similarly, generic
bpf_program__attach() will have enought information to go off of for
parameterless attachment.
USDT BPF programs are actually uprobes, and as such for kernel they are
marked as BPF_PROG_TYPE_KPROBE.
Another part of this patch is USDT-related feature probing:
- BPF cookie support detection from user-space;
- detection of kernel support for auto-refcounting of USDT semaphore.
The latter is optional. If kernel doesn't support such feature and USDT
doesn't rely on USDT semaphores, no error is returned. But if libbpf
detects that USDT requires setting semaphores and kernel doesn't support
this, libbpf errors out with explicit pr_warn() message. Libbpf doesn't
support poking process's memory directly to increment semaphore value,
like BCC does on legacy kernels, due to inherent raciness and danger of
such process memory manipulation. Libbpf let's kernel take care of this
properly or gives up.
Logistically, all the extra USDT-related infrastructure of libbpf is put
into a separate usdt.c file and abstracted behind struct usdt_manager.
Each bpf_object has lazily-initialized usdt_manager pointer, which is
only instantiated if USDT programs are attempted to be attached. Closing
BPF object frees up usdt_manager resources. usdt_manager keeps track of
USDT spec ID assignment and few other small things.
Subsequent patches will fill out remaining missing pieces of USDT
initialization and setup logic.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/20220404234202.331384-3-andrii@kernel.org
Add BPF-side implementation of libbpf-provided USDT support. This
consists of single header library, usdt.bpf.h, which is meant to be used
from user's BPF-side source code. This header is added to the list of
installed libbpf header, along bpf_helpers.h and others.
BPF-side implementation consists of two BPF maps:
- spec map, which contains "a USDT spec" which encodes information
necessary to be able to fetch USDT arguments and other information
(argument count, user-provided cookie value, etc) at runtime;
- IP-to-spec-ID map, which is only used on kernels that don't support
BPF cookie feature. It allows to lookup spec ID based on the place
in user application that triggers USDT program.
These maps have default sizes, 256 and 1024, which are chosen
conservatively to not waste a lot of space, but handling a lot of common
cases. But there could be cases when user application needs to either
trace a lot of different USDTs, or USDTs are heavily inlined and their
arguments are located in a lot of differing locations. For such cases it
might be necessary to size those maps up, which libbpf allows to do by
overriding BPF_USDT_MAX_SPEC_CNT and BPF_USDT_MAX_IP_CNT macros.
It is an important aspect to keep in mind. Single USDT (user-space
equivalent of kernel tracepoint) can have multiple USDT "call sites".
That is, single logical USDT is triggered from multiple places in user
application. This can happen due to function inlining. Each such inlined
instance of USDT invocation can have its own unique USDT argument
specification (instructions about the location of the value of each of
USDT arguments). So while USDT looks very similar to usual uprobe or
kernel tracepoint, under the hood it's actually a collection of uprobes,
each potentially needing different spec to know how to fetch arguments.
User-visible API consists of three helper functions:
- bpf_usdt_arg_cnt(), which returns number of arguments of current USDT;
- bpf_usdt_arg(), which reads value of specified USDT argument (by
it's zero-indexed position) and returns it as 64-bit value;
- bpf_usdt_cookie(), which functions like BPF cookie for USDT
programs; this is necessary as libbpf doesn't allow specifying actual
BPF cookie and utilizes it internally for USDT support implementation.
Each bpf_usdt_xxx() APIs expect struct pt_regs * context, passed into
BPF program. On kernels that don't support BPF cookie it is used to
fetch absolute IP address of the underlying uprobe.
usdt.bpf.h also provides BPF_USDT() macro, which functions like
BPF_PROG() and BPF_KPROBE() and allows much more user-friendly way to
get access to USDT arguments, if USDT definition is static and known to
the user. It is expected that majority of use cases won't have to use
bpf_usdt_arg_cnt() and bpf_usdt_arg() directly and BPF_USDT() will cover
all their needs.
Last, usdt.bpf.h is utilizing BPF CO-RE for one single purpose: to
detect kernel support for BPF cookie. If BPF CO-RE dependency is
undesirable, user application can redefine BPF_USDT_HAS_BPF_COOKIE to
either a boolean constant (or equivalently zero and non-zero), or even
point it to its own .rodata variable that can be specified from user's
application user-space code. It is important that
BPF_USDT_HAS_BPF_COOKIE is known to BPF verifier as static value (thus
.rodata and not just .data), as otherwise BPF code will still contain
bpf_get_attach_cookie() BPF helper call and will fail validation at
runtime, if not dead-code eliminated.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/20220404234202.331384-2-andrii@kernel.org
attach_probe selftest fails on Debian-based distros with `failed to
resolve full path for 'libc.so.6'`. The reason is that these distros
embraced multiarch to the point where even for the "main" architecture
they store libc in /lib/<triple>.
This is configured in /etc/ld.so.conf and in theory it's possible to
replicate the loader's parsing and processing logic in libbpf, however
a much simpler solution is to just enumerate the known library paths.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220404225020.51029-1-iii@linux.ibm.com
Since core relos is an optional part of the .BTF.ext ELF section, we should
skip parsing it instead of returning -EINVAL if header size is less than
offsetofend(struct btf_ext_header, core_relo_len).
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220404005320.1723055-1-ytcoode@gmail.com
Now that u[ret]probes can use name-based specification, it makes
sense to add support for auto-attach based on SEC() definition.
The format proposed is
SEC("u[ret]probe/binary:[raw_offset|[function_name[+offset]]")
For example, to trace malloc() in libc:
SEC("uprobe/libc.so.6:malloc")
...or to trace function foo2 in /usr/bin/foo:
SEC("uprobe//usr/bin/foo:foo2")
Auto-attach is done for all tasks (pid -1). prog can be an absolute
path or simply a program/library name; in the latter case, we use
PATH/LD_LIBRARY_PATH to resolve the full path, falling back to
standard locations (/usr/bin:/usr/sbin or /usr/lib64:/usr/lib) if
the file is not found via environment-variable specified locations.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1648654000-21758-4-git-send-email-alan.maguire@oracle.com
kprobe attach is name-based, using lookups of kallsyms to translate
a function name to an address. Currently uprobe attach is done
via an offset value as described in [1]. Extend uprobe opts
for attach to include a function name which can then be converted
into a uprobe-friendly offset. The calcualation is done in
several steps:
1. First, determine the symbol address using libelf; this gives us
the offset as reported by objdump
2. If the function is a shared library function - and the binary
provided is a shared library - no further work is required;
the address found is the required address
3. Finally, if the function is local, subtract the base address
associated with the object, retrieved from ELF program headers.
The resultant value is then added to the func_offset value passed
in to specify the uprobe attach address. So specifying a func_offset
of 0 along with a function name "printf" will attach to printf entry.
The modes of operation supported are then
1. to attach to a local function in a binary; function "foo1" in
"/usr/bin/foo"
2. to attach to a shared library function in a shared library -
function "malloc" in libc.
[1] https://www.kernel.org/doc/html/latest/trace/uprobetracer.html
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1648654000-21758-3-git-send-email-alan.maguire@oracle.com
bpf_program__attach_uprobe_opts() requires a binary_path argument
specifying binary to instrument. Supporting simply specifying
"libc.so.6" or "foo" should be possible too.
Library search checks LD_LIBRARY_PATH, then /usr/lib64, /usr/lib.
This allows users to run BPF programs prefixed with
LD_LIBRARY_PATH=/path2/lib while still searching standard locations.
Similarly for non .so files, we check PATH and /usr/bin, /usr/sbin.
Path determination will be useful for auto-attach of BPF uprobe programs
using SEC() definition.
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1648654000-21758-2-git-send-email-alan.maguire@oracle.com
- Add new environment variables, USERCFLAGS and USERLDFLAGS to allow
additional flags to be passed to user-space programs.
- Fix missing fflush() bugs in Kconfig and fixdep
- Fix a minor bug in the comment format of the .config file
- Make kallsyms ignore llvm's local labels, .L*
- Fix UAPI compile-test for cross-compiling with Clang
- Extend the LLVM= syntax to support LLVM=<suffix> form for using a
particular version of LLVm, and LLVM=<prefix> form for using custom
LLVM in a particular directory path.
- Clean up Makefiles
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Merge tag 'kbuild-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- Add new environment variables, USERCFLAGS and USERLDFLAGS to allow
additional flags to be passed to user-space programs.
- Fix missing fflush() bugs in Kconfig and fixdep
- Fix a minor bug in the comment format of the .config file
- Make kallsyms ignore llvm's local labels, .L*
- Fix UAPI compile-test for cross-compiling with Clang
- Extend the LLVM= syntax to support LLVM=<suffix> form for using a
particular version of LLVm, and LLVM=<prefix> form for using custom
LLVM in a particular directory path.
- Clean up Makefiles
* tag 'kbuild-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild: Make $(LLVM) more flexible
kbuild: add --target to correctly cross-compile UAPI headers with Clang
fixdep: use fflush() and ferror() to ensure successful write to files
arch: syscalls: simplify uapi/kapi directory creation
usr/include: replace extra-y with always-y
certs: simplify empty certs creation in certs/Makefile
certs: include certs/signing_key.x509 unconditionally
kallsyms: ignore all local labels prefixed by '.L'
kconfig: fix missing '# end of' for empty menu
kconfig: add fflush() before ferror() check
kbuild: replace $(if A,A,B) with $(or A,B)
kbuild: Add environment variables for userprogs flags
kbuild: unify cmd_copy and cmd_shipped
If BPF object doesn't have an BTF info, don't attempt to search for BTF
types describing BPF map key or value layout.
Fixes: 262cfb74ff ("libbpf: Init btf_{key,value}_type_id on internal map open")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220320001911.3640917-1-andrii@kernel.org
Currently, libbpf considers a single routine in .text to be a program. This
is particularly confusing when it comes to library objects - a single routine
meant to be used as an extern will instead be considered a bpf_program.
This patch hides this compatibility behavior behind the pre-existing
SEC_NAME strict mode flag.
Signed-off-by: Delyan Kratunov <delyank@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/018de8d0d67c04bf436055270d35d394ba393505.1647473511.git.delyank@fb.com
Adding bpf_program__attach_kprobe_multi_opts function for attaching
kprobe program to multiple functions.
struct bpf_link *
bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
const char *pattern,
const struct bpf_kprobe_multi_opts *opts);
User can specify functions to attach with 'pattern' argument that
allows wildcards (*?' supported) or provide symbols or addresses
directly through opts argument. These 3 options are mutually
exclusive.
When using symbols or addresses, user can also provide cookie value
for each symbol/address that can be retrieved later in bpf program
with bpf_get_attach_cookie helper.
struct bpf_kprobe_multi_opts {
size_t sz;
const char **syms;
const unsigned long *addrs;
const __u64 *cookies;
size_t cnt;
bool retprobe;
size_t :0;
};
Symbols, addresses and cookies are provided through opts object
(syms/addrs/cookies) as array pointers with specified count (cnt).
Each cookie value is paired with provided function address or symbol
with the same array index.
The program can be also attached as return probe if 'retprobe' is set.
For quick usage with NULL opts argument, like:
bpf_program__attach_kprobe_multi_opts(prog, "ksys_*", NULL)
the 'prog' will be attached as kprobe to 'ksys_*' functions.
Also adding new program sections for automatic attachment:
kprobe.multi/<symbol_pattern>
kretprobe.multi/<symbol_pattern>
The symbol_pattern is used as 'pattern' argument in
bpf_program__attach_kprobe_multi_opts function.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220316122419.933957-10-jolsa@kernel.org
Adding new kprobe_multi struct to bpf_link_create_opts object
to pass multiple kprobe data to link_create attr uapi.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220316122419.933957-9-jolsa@kernel.org
Move the kallsyms parsing in internal libbpf_kallsyms_parse
function, so it can be used from other places.
It will be used in following changes.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220316122419.933957-8-jolsa@kernel.org
Add support for setting the new batch_size parameter to BPF_PROG_TEST_RUN
to libbpf; just add it as an option and pass it through to the kernel.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20220309105346.100053-4-toke@redhat.com
Fix the following coccicheck warning:
tools/lib/bpf/bpf.c:114:31-32: WARNING: Use ARRAY_SIZE
tools/lib/bpf/xsk.c:484:34-35: WARNING: Use ARRAY_SIZE
tools/lib/bpf/xsk.c:485:35-36: WARNING: Use ARRAY_SIZE
It has been tested with gcc (Debian 8.3.0-6) 8.3.0 on x86_64.
Signed-off-by: Guo Zhengkui <guozhengkui@vivo.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220306023426.19324-1-guozhengkui@vivo.com
xsk_umem__create() does mmap for fill/comp rings, but xsk_umem__delete()
doesn't do the unmap. This works fine for regular cases, because
xsk_socket__delete() does unmap for the rings. But for the case that
xsk_socket__create_shared() fails, umem rings are not unmapped.
fill_save/comp_save are checked to determine if rings have already be
unmapped by xsk. If fill_save and comp_save are NULL, it means that the
rings have already been used by xsk. Then they are supposed to be
unmapped by xsk_socket__delete(). Otherwise, xsk_umem__delete() does the
unmap.
Fixes: 2f6324a393 ("libbpf: Support shared umems between queues and devices")
Signed-off-by: Cheng Li <lic121@chinatelecom.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220301132623.GA19995@vscode.7~
Allow registering and unregistering custom handlers for BPF program.
This allows user applications and libraries to plug into libbpf's
declarative SEC() definition handling logic. This allows to offload
complex and intricate custom logic into external libraries, but still
provide a great user experience.
One such example is USDT handling library, which has a lot of code and
complexity which doesn't make sense to put into libbpf directly, but it
would be really great for users to be able to specify BPF programs with
something like SEC("usdt/<path-to-binary>:<usdt_provider>:<usdt_name>")
and have correct BPF program type set (BPF_PROGRAM_TYPE_KPROBE, as it is
uprobe) and even support BPF skeleton's auto-attach logic.
In some cases, it might be even good idea to override libbpf's default
handling, like for SEC("perf_event") programs. With custom library, it's
possible to extend logic to support specifying perf event specification
right there in SEC() definition without burdening libbpf with lots of
custom logic or extra library dependecies (e.g., libpfm4). With current
patch it's possible to override libbpf's SEC("perf_event") handling and
specify a completely custom ones.
Further, it's possible to specify a generic fallback handling for any
SEC() that doesn't match any other custom or standard libbpf handlers.
This allows to accommodate whatever legacy use cases there might be, if
necessary.
See doc comments for libbpf_register_prog_handler() and
libbpf_unregister_prog_handler() for detailed semantics.
This patch also bumps libbpf development version to v0.8 and adds new
APIs there.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/20220305010129.1549719-3-andrii@kernel.org
Allow some BPF program types to support auto-attach only in subste of
cases. Currently, if some BPF program type specifies attach callback, it
is assumed that during skeleton attach operation all such programs
either successfully attach or entire skeleton attachment fails. If some
program doesn't support auto-attachment from skeleton, such BPF program
types shouldn't have attach callback specified.
This is limiting for cases when, depending on how full the SEC("")
definition is, there could either be enough details to support
auto-attach or there might not be and user has to use some specific API
to provide more details at runtime.
One specific example of such desired behavior might be SEC("uprobe"). If
it's specified as just uprobe auto-attach isn't possible. But if it's
SEC("uprobe/<some_binary>:<some_func>") then there are enough details to
support auto-attach. Note that there is a somewhat subtle difference
between auto-attach behavior of BPF skeleton and using "generic"
bpf_program__attach(prog) (which uses the same attach handlers under the
cover). Skeleton allow some programs within bpf_object to not have
auto-attach implemented and doesn't treat that as an error. Instead such
BPF programs are just skipped during skeleton's (optional) attach step.
bpf_program__attach(), on the other hand, is called when user *expects*
auto-attach to work, so if specified program doesn't implement or
doesn't support auto-attach functionality, that will be treated as an
error.
Another improvement to the way libbpf is handling SEC()s would be to not
require providing dummy kernel function name for kprobe. Currently,
SEC("kprobe/whatever") is necessary even if actual kernel function is
determined by user at runtime and bpf_program__attach_kprobe() is used
to specify it. With changes in this patch, it's possible to support both
SEC("kprobe") and SEC("kprobe/<actual_kernel_function"), while only in
the latter case auto-attach will be performed. In the former one, such
kprobe will be skipped during skeleton attach operation.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/20220305010129.1549719-2-andrii@kernel.org
The page_cnt parameter is used to specify the number of memory pages
allocated for each per-CPU buffer, it must be non-zero and a power of 2.
Currently, the __perf_buffer__new() function attempts to validate that
the page_cnt is a power of 2 but forgets checking for the case where
page_cnt is zero, we can fix it by replacing 'page_cnt & (page_cnt - 1)'
with 'page_cnt == 0 || (page_cnt & (page_cnt - 1))'.
If so, we also don't need to add a check in perf_buffer__new_v0_6_0() to
make sure that page_cnt is non-zero and the check for zero in
perf_buffer__new_raw_v0_6_0() can also be removed.
The code will be cleaner and more readable.
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220303005921.53436-1-ytcoode@gmail.com
Currently if a declaration appears in the BTF before the definition, the
definition is dumped as a conflicting name, e.g.:
$ bpftool btf dump file vmlinux format raw | grep "'unix_sock'"
[81287] FWD 'unix_sock' fwd_kind=struct
[89336] STRUCT 'unix_sock' size=1024 vlen=14
$ bpftool btf dump file vmlinux format c | grep "struct unix_sock"
struct unix_sock;
struct unix_sock___2 { <--- conflict, the "___2" is unexpected
struct unix_sock___2 *unix_sk;
This causes a compilation error if the dump output is used as a header file.
Fix it by skipping declaration when counting duplicated type names.
Fixes: 351131b51c ("libbpf: add btf_dump API for BTF-to-C conversion")
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220301053250.1464204-2-xukuohai@huawei.com
When a BPF map of type BPF_MAP_TYPE_PERF_EVENT_ARRAY doesn't have the
max_entries parameter set, the map will be created with max_entries set
to the number of available CPUs. When we try to reuse such a pinned map,
map_is_reuse_compat will return false, as max_entries in the map
definition differs from max_entries of the existing map, causing the
following error:
libbpf: couldn't reuse pinned map at '/sys/fs/bpf/m_logging': parameter mismatch
Fix this by overwriting max_entries in the map definition. For this to
work, we need to do this in bpf_object__create_maps, before calling
bpf_object__reuse_map.
Fixes: 57a00f4164 ("libbpf: Add auto-pinning of maps when loading BPF objects")
Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220225152355.315204-1-stijn@linux-ipv6.be
The check in the last return statement is unnecessary, we can just return
the ret variable.
But we can simplify the function further by returning 0 immediately if we
find the section size and -ENOENT otherwise.
Thus we can also remove the ret variable.
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220223085244.3058118-1-ytcoode@gmail.com
The check 't->size && t->size != size' is redundant because if t->size
compares unequal to 0, we will just skip straight to sorting variables.
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220220072750.209215-1-ytcoode@gmail.com
