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Add a new BPF instruction for resolving absolute addresses of per-CPU
data from their per-CPU offsets. This instruction is internal-only and
users are not allowed to use them directly. They will only be used for
internal inlining optimizations for now between BPF verifier and BPF JITs.
We use a special BPF_MOV | BPF_ALU64 | BPF_X form with insn->off field
set to BPF_ADDR_PERCPU = -1. I used negative offset value to distinguish
them from positive ones used by user-exposed instructions.
Such instruction performs a resolution of a per-CPU offset stored in
a register to a valid kernel address which can be dereferenced. It is
useful in any use case where absolute address of a per-CPU data has to
be resolved (e.g., in inlining bpf_map_lookup_elem()).
BPF disassembler is also taught to recognize them to support dumping
final BPF assembly code (non-JIT'ed version).
Add arch-specific way for BPF JITs to mark support for this instructions.
This patch also adds support for these instructions in x86-64 BPF JIT.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20240402021307.1012571-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.
bpf sym names get looked up and compared/cleaned with various string
apis. This suggests they need to be NUL-terminated (strncpy() suggests
this but does not guarantee it).
| static int compare_symbol_name(const char *name, char *namebuf)
| {
| cleanup_symbol_name(namebuf);
| return strcmp(name, namebuf);
| }
| static void cleanup_symbol_name(char *s)
| {
| ...
| res = strstr(s, ".llvm.");
| ...
| }
Use strscpy() as this method guarantees NUL-termination on the
destination buffer.
This patch also replaces two uses of strncpy() used in log.c. These are
simple replacements as postfix has been zero-initialized on the stack
and has source arguments with a size less than the destination's size.
Note that this patch uses the new 2-argument version of strscpy
introduced in commit e6584c3964f2f ("string: Allow 2-argument strscpy()").
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Link: https://lore.kernel.org/bpf/20240402-strncpy-kernel-bpf-core-c-v1-1-7cb07a426e78@google.com
Introduce a test case to evaluate AF_XDP's robustness by pushing hardware
and software ring sizes to their limits. This test ensures AF_XDP's
reliability amidst potential producer/consumer throttling due to maximum
ring utilization. The testing strategy includes:
1. Configuring rings to their maximum allowable sizes.
2. Executing a series of tests across diverse batch sizes to assess
system's behavior under different configurations.
Signed-off-by: Tushar Vyavahare <tushar.vyavahare@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20240402114529.545475-8-tushar.vyavahare@intel.com
Add a new test case that stresses AF_XDP and the driver by configuring
small hardware and software ring sizes. This verifies that AF_XDP continues
to function properly even with insufficient ring space that could lead
to frequent producer/consumer throttling. The test procedure involves:
1. Set the minimum possible ring configuration(tx 64 and rx 128).
2. Run tests with various batch sizes(1 and 63) to validate the system's
behavior under different configurations.
Update Makefile to include network_helpers.o in the build process for
xskxceiver.
Signed-off-by: Tushar Vyavahare <tushar.vyavahare@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20240402114529.545475-7-tushar.vyavahare@intel.com
Introduce a new function, set_ring_size(), to manage asynchronous AF_XDP
socket closure. Retry set_hw_ring_size up to SOCK_RECONF_CTR times if it
fails due to an active AF_XDP socket. Return an error immediately for
non-EBUSY errors. This enhances robustness against asynchronous AF_XDP
socket closures during ring size changes.
Signed-off-by: Tushar Vyavahare <tushar.vyavahare@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20240402114529.545475-6-tushar.vyavahare@intel.com
Introduce a new function called set_hw_ring_size that allows for the
dynamic configuration of the ring size within the interface.
Signed-off-by: Tushar Vyavahare <tushar.vyavahare@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20240402114529.545475-5-tushar.vyavahare@intel.com
Introduce a new function called get_hw_size that retrieves both the
current and maximum size of the interface and stores this information
in the 'ethtool_ringparam' structure.
Remove ethtool_channels struct from xdp_hw_metadata.c due to redefinition
error. Remove unused linux/if.h include from flow_dissector BPF test to
address CI pipeline failure.
Signed-off-by: Tushar Vyavahare <tushar.vyavahare@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20240402114529.545475-4-tushar.vyavahare@intel.com
Convert the constant BATCH_SIZE into a variable named batch_size to allow
dynamic modification at runtime. This is required for the forthcoming
changes to support testing different hardware ring sizes.
While running these tests, a bug was identified when the batch size is
roughly the same as the NIC ring size. This has now been addressed by
Maciej's fix in commit 913eda2b08cc ("i40e: xsk: remove count_mask").
Signed-off-by: Tushar Vyavahare <tushar.vyavahare@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20240402114529.545475-3-tushar.vyavahare@intel.com
This commit duplicates the ethtool.h file from the include/uapi/linux
directory in the kernel source to the tools/include/uapi/linux directory.
This action ensures that the ethtool.h file used in the tools directory
is in sync with the kernel's version, maintaining consistency across the
codebase.
There are some checkpatch warnings in this file that could be cleaned up,
but I preferred to move it over as-is for now to avoid disrupting the code.
Signed-off-by: Tushar Vyavahare <tushar.vyavahare@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20240402114529.545475-2-tushar.vyavahare@intel.com
LLVM generates bpf_addr_space_cast instruction while translating
pointers between native (zero) address space and
__attribute__((address_space(N))). The addr_space=0 is reserved as
bpf_arena address space.
rY = addr_space_cast(rX, 0, 1) is processed by the verifier and
converted to normal 32-bit move: wX = wY.
rY = addr_space_cast(rX, 1, 0) : used to convert a bpf arena pointer to
a pointer in the userspace vma. This has to be converted by the JIT.
Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Link: https://lore.kernel.org/r/20240325150716.4387-3-puranjay12@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add support for [LDX | STX | ST], PROBE_MEM32, [B | H | W | DW]
instructions. They are similar to PROBE_MEM instructions with the
following differences:
- PROBE_MEM32 supports store.
- PROBE_MEM32 relies on the verifier to clear upper 32-bit of the
src/dst register
- PROBE_MEM32 adds 64-bit kern_vm_start address (which is stored in R28
in the prologue). Due to bpf_arena constructions such R28 + reg +
off16 access is guaranteed to be within arena virtual range, so no
address check at run-time.
- PROBE_MEM32 allows STX and ST. If they fault the store is a nop. When
LDX faults the destination register is zeroed.
To support these on arm64, we do tmp2 = R28 + src/dst reg and then use
tmp2 as the new src/dst register. This allows us to reuse most of the
code for normal [LDX | STX | ST].
Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Link: https://lore.kernel.org/r/20240325150716.4387-2-puranjay12@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In order to prevent mptcpify prog from affecting the running results
of other BPF tests, a pid limit was added to restrict it from only
modifying its own program.
Suggested-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/8987e2938e15e8ec390b85b5dcbee704751359dc.1712054986.git.tanggeliang@kylinos.cn
Commit 20d59ee55172fdf6 ("libbpf: add bpf_core_cast() macro") added a
bpf_helpers include in bpf_core_read.h as a system include. Usually, the
includes are local, though, like in bpf_tracing.h. This commit adjusts
the include to be local as well.
Signed-off-by: Tobias Böhm <tobias@aibor.de>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/q5d5bgc6vty2fmaazd5e73efd6f5bhiru2le6fxn43vkw45bls@fhlw2s5ootdb
This patch improves the run-time calculation for program stats by
capturing the duration as soon as possible after the program returns.
Previously, the duration included u64_stats_t operations. While the
instrumentation overhead is part of the total time spent when stats are
enabled, distinguishing between the program's native execution time and
the time spent due to instrumentation is crucial for accurate
performance analysis.
By making this change, the patch facilitates more precise optimization
of BPF programs, enabling users to understand their performance in
environments without stats enabled.
I used a virtualized environment to measure the run-time over one minute
for a basic raw_tracepoint/sys_enter program, which just increments a
local counter. Although the virtualization introduced some performance
degradation that could affect the results, I observed approximately a
16% decrease in average run-time reported by stats with this change
(310 -> 260 nsec).
Signed-off-by: Jose Fernandez <josef@netflix.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240402034010.25060-1-josef@netflix.com
When testing send_signal and stacktrace_build_id_nmi using the riscv sbi
pmu driver without the sscofpmf extension or the riscv legacy pmu driver,
then failures as follows are encountered:
test_send_signal_common:FAIL:perf_event_open unexpected perf_event_open: actual -1 < expected 0
#272/3 send_signal/send_signal_nmi:FAIL
test_stacktrace_build_id_nmi:FAIL:perf_event_open err -1 errno 95
#304 stacktrace_build_id_nmi:FAIL
The reason is that the above pmu driver or hardware does not support
sampling events, that is, PERF_PMU_CAP_NO_INTERRUPT is set to pmu
capabilities, and then perf_event_open returns EOPNOTSUPP. Since
PERF_PMU_CAP_NO_INTERRUPT is not only set in the riscv-related pmu driver,
it is better to skip testing when this capability is set.
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240402073029.1299085-1-pulehui@huaweicloud.com
When generated BPF skeleton header is included in C++ code base, some
compiler setups will emit warning about using language extensions due to
typeof() usage, resulting in something like:
error: extension used [-Werror,-Wlanguage-extension-token]
obj->struct_ops.empty_tcp_ca = (typeof(obj->struct_ops.empty_tcp_ca))
^
It looks like __typeof__() is a preferred way to do typeof() with better
C++ compatibility behavior, so switch to that. With __typeof__() we get
no such warning.
Fixes: c2a0257c1edf ("bpftool: Cast pointers for shadow types explicitly.")
Fixes: 00389c58ffe9 ("bpftool: Add support for subskeletons")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kui-Feng Lee <thinker.li@gmail.com>
Acked-by: Quentin Monnet <qmo@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240401170713.2081368-1-andrii@kernel.org
Currently, cond_break macro uses bytes to encode the may_goto insn.
Patch [1] in llvm implemented may_goto insn in BPF backend.
Replace byte-level encoding with llvm inline asm for better usability.
Using llvm may_goto insn is controlled by macro __BPF_FEATURE_MAY_GOTO.
[1] 0e0bfacff7
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240402025446.3215182-1-yonghong.song@linux.dev
When more than 64 maps are used by a program and its subprograms the
verifier returns -E2BIG. Add a verbose message which highlights the
source of the error and also print the actual limit.
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240402073347.195920-1-aspsk@isovalent.com
In a few places in the bpf uapi headers, EOPNOTSUPP is missing a "P" in
the doc comments. This adds the missing "P".
Signed-off-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240329152900.398260-2-dlechner@baylibre.com
Improve the formatting of the attach flags for cgroup programs in the
relevant man page, and fix typos ("can be on of", "an userspace inet
socket") when introducing that list. Also fix a couple of other trivial
issues in docs.
[ Quentin: Fixed trival issues in bpftool-gen.rst and bpftool-iter.rst ]
Signed-off-by: Rameez Rehman <rameezrehman408@hotmail.com>
Signed-off-by: Quentin Monnet <qmo@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240331200346.29118-4-qmo@kernel.org
As it turns out, the terms in definition lists in the rST file are
already rendered with bold-ish formatting when generating the man pages;
all double-star sequences we have in the commands for the command
description are unnecessary, and can be removed to make the
documentation easier to read.
The rST files were automatically processed with:
sed -i '/DESCRIPTION/,/OPTIONS/ { /^\*/ s/\*\*//g }' b*.rst
Signed-off-by: Rameez Rehman <rameezrehman408@hotmail.com>
Signed-off-by: Quentin Monnet <qmo@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240331200346.29118-3-qmo@kernel.org
The rST manual pages for bpftool would use a mix of tabs and spaces for
indentation. While this is the norm in C code, this is rather unusual
for rST documents, and over time we've seen many contributors use a
wrong level of indentation for documentation update.
Let's fix bpftool's indentation in docs once and for all:
- Let's use spaces, that are more common in rST files.
- Remove one level of indentation for the synopsis, the command
description, and the "see also" section. As a result, all sections
start with the same indentation level in the generated man page.
- Rewrap the paragraphs after the changes.
There is no content change in this patch, only indentation and
rewrapping changes. The wrapping in the generated source files for the
manual pages is changed, but the pages displayed with "man" remain the
same, apart from the adjusted indentation level on relevant sections.
[ Quentin: rebased on bpf-next, removed indent level for command
description and options, updated synopsis, command summary, and "see
also" sections. ]
Signed-off-by: Rameez Rehman <rameezrehman408@hotmail.com>
Signed-off-by: Quentin Monnet <qmo@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240331200346.29118-2-qmo@kernel.org
When BPF selftests are built in RELEASE=1 mode with -O2 optimization
level, uprobe_multi binary, called from multi-uprobe tests is optimized
to the point that all the thousands of target uprobe_multi_func_XXX
functions are eliminated, breaking tests.
So ensure they are preserved by using weak attribute.
But, actually, compiling uprobe_multi binary with -O2 takes a really
long time, and is quite useless (it's not a benchmark). So in addition
to ensuring that uprobe_multi_func_XXX functions are preserved, opt-out
of -O2 explicitly in Makefile and stick to -O0. This saves a lot of
compilation time.
With -O2, just recompiling uprobe_multi:
$ touch uprobe_multi.c
$ time make RELEASE=1 -j90
make RELEASE=1 -j90 291.66s user 2.54s system 99% cpu 4:55.52 total
With -O0:
$ touch uprobe_multi.c
$ time make RELEASE=1 -j90
make RELEASE=1 -j90 22.40s user 1.91s system 99% cpu 24.355 total
5 minutes vs (still slow, but...) 24 seconds.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240329190410.4191353-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
syzbot reported the following lock sequence:
cpu 2:
grabs timer_base lock
spins on bpf_lpm lock
cpu 1:
grab rcu krcp lock
spins on timer_base lock
cpu 0:
grab bpf_lpm lock
spins on rcu krcp lock
bpf_lpm lock can be the same.
timer_base lock can also be the same due to timer migration.
but rcu krcp lock is always per-cpu, so it cannot be the same lock.
Hence it's a false positive.
To avoid lockdep complaining move kfree_rcu() after spin_unlock.
Reported-by: syzbot+1fa663a2100308ab6eab@syzkaller.appspotmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240329171439.37813-1-alexei.starovoitov@gmail.com
Geliang Tang says:
====================
Simplify bpf_tcp_ca test by using connect_fd_to_fd and start_server
helpers.
v4:
- Matt reminded me that I shouldn't send a square-to patch to BPF (thanks),
so I update them into two patches in v4.
v3:
- split v2 as two patches as Daniel suggested.
- The patch "selftests/bpf: Use start_server in bpf_tcp_ca" is merged
by Daniel (thanks), but I forgot to drop 'settimeo(lfd, 0)' in it, so
I send a squash-to patch to fix this.
====================
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
To simplify the code, use BPF selftests helper connect_fd_to_fd() in
bpf_tcp_ca.c instead of open-coding it. This helper is defined in
network_helpers.c, and exported in network_helpers.h, which is already
included in bpf_tcp_ca.c.
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Link: https://lore.kernel.org/r/e105d1f225c643bee838409378dd90fd9aabb6dc.1711447102.git.tanggeliang@kylinos.cn
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Yonghong Song says:
====================
bpf: Fix a couple of test failures with LTO kernel
With a LTO kernel built with clang, with one of earlier version of kernel,
I encountered two test failures, ksyms and kprobe_multi_bench_attach/kernel.
Now with latest bpf-next, only kprobe_multi_bench_attach/kernel failed.
But it is possible in the future ksyms selftest may fail again.
Both test failures are due to static variable/function renaming
due to cross-file inlining. For Ksyms failure, the solution is
to strip .llvm.<hash> suffixes for symbols in /proc/kallsyms before
comparing against the ksym in bpf program.
For kprobe_multi_bench_attach/kernel failure, the solution is
to either provide names in /proc/kallsyms to the kernel or
ignore those names who have .llvm.<hash> suffix since the kernel
sym name comparison is against /proc/kallsyms.
Please see each individual patches for details.
Changelogs:
v2 -> v3:
- no need to check config file, directly so strstr with '.llvm.'.
- for kprobe_multi_bench with syms, instead of skipping the syms,
consult /proc/kallyms to find corresponding names.
- add a test with populating addrs to the kernel for kprobe
multi attach.
v1 -> v2:
- Let libbpf handle .llvm.<hash suffixes since it may impact
bpf program ksym.
====================
Link: https://lore.kernel.org/r/20240326041443.1197498-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Get addrs directly from available_filter_functions_addrs and
send to the kernel during kprobe_multi_attach. This avoids
consultation of /proc/kallsyms. But available_filter_functions_addrs
is introduced in 6.5, i.e., it is introduced recently,
so I skip the test if the kernel does not support it.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240326041523.1200301-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In my locally build clang LTO kernel (enabling CONFIG_LTO and
CONFIG_LTO_CLANG_THIN), kprobe_multi_bench_attach/kernel subtest
failed like:
test_kprobe_multi_bench_attach:PASS:get_syms 0 nsec
test_kprobe_multi_bench_attach:PASS:kprobe_multi_empty__open_and_load 0 nsec
libbpf: prog 'test_kprobe_empty': failed to attach: No such process
test_kprobe_multi_bench_attach:FAIL:bpf_program__attach_kprobe_multi_opts unexpected error: -3
#117/1 kprobe_multi_bench_attach/kernel:FAIL
There are multiple symbols in /sys/kernel/debug/tracing/available_filter_functions
are renamed in /proc/kallsyms due to cross file inlining. One example is for
static function __access_remote_vm in mm/memory.c.
In a non-LTO kernel, we have the following call stack:
ptrace_access_vm (global, kernel/ptrace.c)
access_remote_vm (global, mm/memory.c)
__access_remote_vm (static, mm/memory.c)
With LTO kernel, it is possible that access_remote_vm() is inlined by
ptrace_access_vm(). So we end up with the following call stack:
ptrace_access_vm (global, kernel/ptrace.c)
__access_remote_vm (static, mm/memory.c)
The compiler renames __access_remote_vm to __access_remote_vm.llvm.<hash>
to prevent potential name collision.
The kernel bpf_kprobe_multi_link_attach() and ftrace_lookup_symbols() try
to find addresses based on /proc/kallsyms, hence the current test failed
with LTO kenrel.
This patch consulted /proc/kallsyms to find the corresponding entries
for the ksym and this solved the issue.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240326041518.1199758-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
These two functions allow selftests to do loading/searching
kallsyms based on their specific compare functions.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240326041513.1199440-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Refactor trace helper function load_kallsyms_local() such that
it invokes a common function with a compare function as input.
The common function will be used later for other local functions.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240326041508.1199239-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Refactor some functions in kprobe_multi_test.c to extract
some helper functions who will be used in later patches
to avoid code duplication.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240326041503.1198982-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
With CONFIG_LTO_CLANG_THIN enabled, with some of previous
version of kernel code base ([1]), I hit the following
error:
test_ksyms:PASS:kallsyms_fopen 0 nsec
test_ksyms:FAIL:ksym_find symbol 'bpf_link_fops' not found
#118 ksyms:FAIL
The reason is that 'bpf_link_fops' is renamed to
bpf_link_fops.llvm.8325593422554671469
Due to cross-file inlining, the static variable 'bpf_link_fops'
in syscall.c is used by a function in another file. To avoid
potential duplicated names, the llvm added suffix
'.llvm.<hash>' ([2]) to 'bpf_link_fops' variable.
Such renaming caused a problem in libbpf if 'bpf_link_fops'
is used in bpf prog as a ksym but 'bpf_link_fops' does not
match any symbol in /proc/kallsyms.
To fix this issue, libbpf needs to understand that suffix '.llvm.<hash>'
is caused by clang lto kernel and to process such symbols properly.
With latest bpf-next code base built with CONFIG_LTO_CLANG_THIN,
I cannot reproduce the above failure any more. But such an issue
could happen with other symbols or in the future for bpf_link_fops symbol.
For example, with my current kernel, I got the following from
/proc/kallsyms:
ffffffff84782154 d __func__.net_ratelimit.llvm.6135436931166841955
ffffffff85f0a500 d tk_core.llvm.726630847145216431
ffffffff85fdb960 d __fs_reclaim_map.llvm.10487989720912350772
ffffffff864c7300 d fake_dst_ops.llvm.54750082607048300
I could not easily create a selftest to test newly-added
libbpf functionality with a static C test since I do not know
which symbol is cross-file inlined. But based on my particular kernel,
the following test change can run successfully.
> diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms.c b/tools/testing/selftests/bpf/prog_tests/ksyms.c
> index 6a86d1f07800..904a103f7b1d 100644
> --- a/tools/testing/selftests/bpf/prog_tests/ksyms.c
> +++ b/tools/testing/selftests/bpf/prog_tests/ksyms.c
> @@ -42,6 +42,7 @@ void test_ksyms(void)
> ASSERT_EQ(data->out__bpf_link_fops, link_fops_addr, "bpf_link_fops");
> ASSERT_EQ(data->out__bpf_link_fops1, 0, "bpf_link_fops1");
> ASSERT_EQ(data->out__btf_size, btf_size, "btf_size");
> + ASSERT_NEQ(data->out__fake_dst_ops, 0, "fake_dst_ops");
> ASSERT_EQ(data->out__per_cpu_start, per_cpu_start_addr, "__per_cpu_start");
>
> cleanup:
> diff --git a/tools/testing/selftests/bpf/progs/test_ksyms.c b/tools/testing/selftests/bpf/progs/test_ksyms.c
> index 6c9cbb5a3bdf..fe91eef54b66 100644
> --- a/tools/testing/selftests/bpf/progs/test_ksyms.c
> +++ b/tools/testing/selftests/bpf/progs/test_ksyms.c
> @@ -9,11 +9,13 @@ __u64 out__bpf_link_fops = -1;
> __u64 out__bpf_link_fops1 = -1;
> __u64 out__btf_size = -1;
> __u64 out__per_cpu_start = -1;
> +__u64 out__fake_dst_ops = -1;
>
> extern const void bpf_link_fops __ksym;
> extern const void __start_BTF __ksym;
> extern const void __stop_BTF __ksym;
> extern const void __per_cpu_start __ksym;
> +extern const void fake_dst_ops __ksym;
> /* non-existing symbol, weak, default to zero */
> extern const void bpf_link_fops1 __ksym __weak;
>
> @@ -23,6 +25,7 @@ int handler(const void *ctx)
> out__bpf_link_fops = (__u64)&bpf_link_fops;
> out__btf_size = (__u64)(&__stop_BTF - &__start_BTF);
> out__per_cpu_start = (__u64)&__per_cpu_start;
> + out__fake_dst_ops = (__u64)&fake_dst_ops;
>
> out__bpf_link_fops1 = (__u64)&bpf_link_fops1;
This patch fixed the issue in libbpf such that
the suffix '.llvm.<hash>' will be ignored during comparison of
bpf prog ksym vs. symbols in /proc/kallsyms, this resolved the issue.
Currently, only static variables in /proc/kallsyms are checked
with '.llvm.<hash>' suffix since in bpf programs function ksyms
with '.llvm.<hash>' suffix are most likely kfunc's and unlikely
to be cross-file inlined.
Note that currently kernel does not support gcc build with lto.
[1] https://lore.kernel.org/bpf/20240302165017.1627295-1-yonghong.song@linux.dev/
[2] https://github.com/llvm/llvm-project/blob/release/18.x/llvm/include/llvm/IR/ModuleSummaryIndex.h#L1714-L1719
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240326041458.1198161-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently libbpf_kallsyms_parse() function is declared as a global
function but actually it is not a API and there is no external
users in bpftool/bpf-selftests. So let us mark the function as
static.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240326041453.1197949-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Replace CHECK with ASSERT macros for ksyms tests.
This test failed earlier with clang lto kernel, but the
issue is gone with latest code base. But replacing
CHECK with ASSERT still improves code as ASSERT is
preferred in selftests.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240326041448.1197812-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch adds a test to ensure all static tcp-cc kfuncs is visible to
the struct_ops bpf programs. It is checked by successfully loading
the struct_ops programs calling these tcp-cc kfuncs.
This patch needs to enable the CONFIG_TCP_CONG_DCTCP and
the CONFIG_TCP_CONG_BBR.
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240322191433.4133280-2-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The commit 7aae231ac93b ("bpf: tcp: Limit calling some tcp cc functions to CONFIG_DYNAMIC_FTRACE")
added CONFIG_DYNAMIC_FTRACE guard because pahole was only generating
btf for ftrace-able functions. The ftrace filter had already been
removed from pahole, so the CONFIG_DYNAMIC_FTRACE guard can be
removed.
The commit 569c484f9995 ("bpf: Limit static tcp-cc functions in the .BTF_ids list to x86")
has added CONFIG_X86 guard because it failed the powerpc arch which
prepended a "." to the local static function, so "cubictcp_init" becomes
".cubictcp_init". "__bpf_kfunc" has been added to kfunc
since then and it uses the __unused compiler attribute.
There is an existing
"__bpf_kfunc static u32 bpf_kfunc_call_test_static_unused_arg(u32 arg, u32 unused)"
test in bpf_testmod.c to cover the static kfunc case.
cross compile on ppc64 with CONFIG_DYNAMIC_FTRACE disabled:
> readelf -s vmlinux | grep cubictcp_
56938: c00000000144fd00 184 FUNC LOCAL DEFAULT 2 cubictcp_cwnd_event [<localentry>: 8]
56939: c00000000144fdb8 200 FUNC LOCAL DEFAULT 2 cubictcp_recalc_[...] [<localentry>: 8]
56940: c00000000144fe80 296 FUNC LOCAL DEFAULT 2 cubictcp_init [<localentry>: 8]
56941: c00000000144ffa8 228 FUNC LOCAL DEFAULT 2 cubictcp_state [<localentry>: 8]
56942: c00000000145008c 1908 FUNC LOCAL DEFAULT 2 cubictcp_cong_avoid [<localentry>: 8]
56943: c000000001450800 1644 FUNC LOCAL DEFAULT 2 cubictcp_acked [<localentry>: 8]
> bpftool btf dump file vmlinux | grep cubictcp_
[51540] FUNC 'cubictcp_acked' type_id=38137 linkage=static
[51541] FUNC 'cubictcp_cong_avoid' type_id=38122 linkage=static
[51543] FUNC 'cubictcp_cwnd_event' type_id=51542 linkage=static
[51544] FUNC 'cubictcp_init' type_id=9186 linkage=static
[51545] FUNC 'cubictcp_recalc_ssthresh' type_id=35021 linkage=static
[51547] FUNC 'cubictcp_state' type_id=38141 linkage=static
The patch removed both config guards.
Cc: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240322191433.4133280-1-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Following the recent upgrade of one of our BPF programs, we encountered
significant latency spikes affecting other applications running on the same
host. After thorough investigation, we identified that these spikes were
primarily caused by the prolonged duration required to free a
non-preallocated htab with approximately 2 million keys.
Notably, our kernel configuration lacks the presence of CONFIG_PREEMPT. In
scenarios where kernel execution extends excessively, other threads might
be starved of CPU time, resulting in latency issues across the system. To
mitigate this, we've adopted a proactive approach by incorporating
cond_resched() calls within the kernel code. This ensures that during
lengthy kernel operations, the scheduler is invoked periodically to provide
opportunities for other threads to execute.
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240327032022.78391-1-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Andrii Nakryiko says:
====================
bench: fast in-kernel triggering benchmarks
Remove "legacy" triggering benchmarks which rely on syscalls (and thus syscall
overhead is a noticeable part of benchmark, unfortunately). Replace them with
faster versions that rely on triggering BPF programs in-kernel through another
simple "driver" BPF program. See patch #2 with comparison results.
raw_tp/tp/fmodret benchmarks required adding a simple kfunc in kernel to be
able to trigger a simple tracepoint from BPF program (plus it is also allowed
to be replaced by fmod_ret programs). This limits raw_tp/tp/fmodret benchmarks
to new kernels only, but it keeps bench tool itself very portable and most of
other benchmarks will still work on wide variety of kernels without the need
to worry about building and deploying custom kernel module. See patches #5
and #6 for details.
v1->v2:
- move new TP closer to BPF test run code;
- rename/move kfunc and register it for fmod_rets (Alexei);
- limit --trig-batch-iters param to [1, 1000] (Alexei).
====================
Link: https://lore.kernel.org/r/20240326162151.3981687-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Utilize bpf_modify_return_test_tp() kfunc to have a fast way to trigger
tp/raw_tp/fmodret programs from another BPF program, which gives us
comparable batched benchmarks to (batched) kprobe/fentry benchmarks.
We don't switch kprobe/fentry batched benchmarks to this kfunc to make
bench tool usable on older kernels as well.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240326162151.3981687-7-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add a simple bpf_modify_return_test_tp() kfunc, available to all program
types, that is useful for various testing and benchmarking scenarios, as
it allows to trigger most tracing BPF program types from BPF side,
allowing to do complex testing and benchmarking scenarios.
It is also attachable to for fmod_ret programs, making it a good and
simple way to trigger fmod_ret program under test/benchmark.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240326162151.3981687-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Instead of front-loading all possible benchmarking BPF programs for
trigger benchmarks, explicitly specify which BPF programs are used by
specific benchmark and load only it.
This allows to be more flexible in supporting older kernels, where some
program types might not be possible to load (e.g., those that rely on
newly added kfunc).
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240326162151.3981687-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Remove "legacy" benchmarks triggered by syscalls in favor of newly added
in-kernel/batched benchmarks. Drop -batched suffix now as well.
Next patch will restore "feature parity" by adding back
tp/raw_tp/fmodret benchmarks based on in-kernel kfunc approach.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240326162151.3981687-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Existing kprobe/fentry triggering benchmarks have 1-to-1 mapping between
one syscall execution and BPF program run. While we use a fast
get_pgid() syscall, syscall overhead can still be non-trivial.
This patch adds kprobe/fentry set of benchmarks significantly amortizing
the cost of syscall vs actual BPF triggering overhead. We do this by
employing BPF_PROG_TEST_RUN command to trigger "driver" raw_tp program
which does a tight parameterized loop calling cheap BPF helper
(bpf_get_numa_node_id()), to which kprobe/fentry programs are
attached for benchmarking.
This way 1 bpf() syscall causes N executions of BPF program being
benchmarked. N defaults to 100, but can be adjusted with
--trig-batch-iters CLI argument.
For comparison we also implement a new baseline program that instead of
triggering another BPF program just does N atomic per-CPU counter
increments, establishing the limit for all other types of program within
this batched benchmarking setup.
Taking the final set of benchmarks added in this patch set (including
tp/raw_tp/fmodret, added in later patch), and keeping for now "legacy"
syscall-driven benchmarks, we can capture all triggering benchmarks in
one place for comparison, before we remove the legacy ones (and rename
xxx-batched into just xxx).
$ benchs/run_bench_trigger.sh
usermode-count : 79.500 ± 0.024M/s
kernel-count : 49.949 ± 0.081M/s
syscall-count : 9.009 ± 0.007M/s
fentry-batch : 31.002 ± 0.015M/s
fexit-batch : 20.372 ± 0.028M/s
fmodret-batch : 21.651 ± 0.659M/s
rawtp-batch : 36.775 ± 0.264M/s
tp-batch : 19.411 ± 0.248M/s
kprobe-batch : 12.949 ± 0.220M/s
kprobe-multi-batch : 15.400 ± 0.007M/s
kretprobe-batch : 5.559 ± 0.011M/s
kretprobe-multi-batch: 5.861 ± 0.003M/s
fentry-legacy : 8.329 ± 0.004M/s
fexit-legacy : 6.239 ± 0.003M/s
fmodret-legacy : 6.595 ± 0.001M/s
rawtp-legacy : 8.305 ± 0.004M/s
tp-legacy : 6.382 ± 0.001M/s
kprobe-legacy : 5.528 ± 0.003M/s
kprobe-multi-legacy : 5.864 ± 0.022M/s
kretprobe-legacy : 3.081 ± 0.001M/s
kretprobe-multi-legacy: 3.193 ± 0.001M/s
Note how xxx-batch variants are measured with significantly higher
throughput, even though it's exactly the same in-kernel overhead. As
such, results can be compared only between benchmarks of the same kind
(syscall vs batched):
fentry-legacy : 8.329 ± 0.004M/s
fentry-batch : 31.002 ± 0.015M/s
kprobe-multi-legacy : 5.864 ± 0.022M/s
kprobe-multi-batch : 15.400 ± 0.007M/s
Note also that syscall-count is setting a theoretical limit for
syscall-triggered benchmarks, while kernel-count is setting similar
limits for batch variants. usermode-count is a happy and unachievable
case of user space counting without doing any syscalls, and is mostly
the measure of CPU speed for such a trivial benchmark.
As was mentioned, tp/raw_tp/fmodret require kernel-side kfunc to produce
similar benchmark, which we address in a separate patch.
Note that run_bench_trigger.sh allows to override a list of benchmarks
to run, which is very useful for performance work.
Cc: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240326162151.3981687-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Rename uprobe-base to more precise usermode-count (it will match other
baseline-like benchmarks, kernel-count and syscall-count). Also use
BENCH_TRIG_USERMODE() macro to define all usermode-based triggering
benchmarks, which include usermode-count and uprobe/uretprobe benchmarks.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240326162151.3981687-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Use the well defined helper sizeof_field() to calculate the size of a
struct member, instead of doing custom calculations.
Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
Link: https://lore.kernel.org/r/20240327065334.8140-1-haiyue.wang@intel.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
