There exists many build errors when make M=samples/bpf on the Loongson
platform. This issue is MIPS related, x86 compiles just fine.
Here are some errors:
CLANG-bpf samples/bpf/sockex2_kern.o
In file included from samples/bpf/sockex2_kern.c:2:
In file included from ./include/uapi/linux/in.h:24:
In file included from ./include/linux/socket.h:8:
In file included from ./include/linux/uio.h:8:
In file included from ./include/linux/kernel.h:11:
In file included from ./include/linux/bitops.h:32:
In file included from ./arch/mips/include/asm/bitops.h:19:
In file included from ./arch/mips/include/asm/barrier.h:11:
./arch/mips/include/asm/addrspace.h:13:10: fatal error: 'spaces.h' file not found
^~~~~~~~~~
1 error generated.
CLANG-bpf samples/bpf/sockex2_kern.o
In file included from samples/bpf/sockex2_kern.c:2:
In file included from ./include/uapi/linux/in.h:24:
In file included from ./include/linux/socket.h:8:
In file included from ./include/linux/uio.h:8:
In file included from ./include/linux/kernel.h:11:
In file included from ./include/linux/bitops.h:32:
In file included from ./arch/mips/include/asm/bitops.h:22:
In file included from ./arch/mips/include/asm/cpu-features.h:13:
In file included from ./arch/mips/include/asm/cpu-info.h:15:
In file included from ./include/linux/cache.h:6:
./arch/mips/include/asm/cache.h:12:10: fatal error: 'kmalloc.h' file not found
^~~~~~~~~~~
1 error generated.
CLANG-bpf samples/bpf/sockex2_kern.o
In file included from samples/bpf/sockex2_kern.c:2:
In file included from ./include/uapi/linux/in.h:24:
In file included from ./include/linux/socket.h:8:
In file included from ./include/linux/uio.h:8:
In file included from ./include/linux/kernel.h:11:
In file included from ./include/linux/bitops.h:32:
In file included from ./arch/mips/include/asm/bitops.h:22:
./arch/mips/include/asm/cpu-features.h:15:10: fatal error: 'cpu-feature-overrides.h' file not found
^~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
$ find arch/mips/include/asm -name spaces.h | sort
arch/mips/include/asm/mach-ar7/spaces.h
...
arch/mips/include/asm/mach-generic/spaces.h
...
arch/mips/include/asm/mach-loongson64/spaces.h
...
arch/mips/include/asm/mach-tx49xx/spaces.h
$ find arch/mips/include/asm -name kmalloc.h | sort
arch/mips/include/asm/mach-generic/kmalloc.h
arch/mips/include/asm/mach-ip32/kmalloc.h
arch/mips/include/asm/mach-tx49xx/kmalloc.h
$ find arch/mips/include/asm -name cpu-feature-overrides.h | sort
arch/mips/include/asm/mach-ath25/cpu-feature-overrides.h
...
arch/mips/include/asm/mach-generic/cpu-feature-overrides.h
...
arch/mips/include/asm/mach-loongson64/cpu-feature-overrides.h
...
arch/mips/include/asm/mach-tx49xx/cpu-feature-overrides.h
In the arch/mips/Makefile, there exists the following board-dependent
options:
include arch/mips/Kbuild.platforms
cflags-y += -I$(srctree)/arch/mips/include/asm/mach-generic
So we can do the similar things in samples/bpf/Makefile, just add
platform specific and generic include dir for MIPS Loongson64 to
fix the build errors.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/1611669925-25315-1-git-send-email-yangtiezhu@loongson.cn
!perfmon_capable() is checked before the last switch(func_id) in
bpf_base_func_proto. Thus, the cases BPF_FUNC_trace_printk and
BPF_FUNC_snprintf_btf can be moved to that last switch(func_id) to omit
the inline !perfmon_capable() checks.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210127174615.3038-1-tklauser@distanz.ch
Those hooks run as BPF_CGROUP_RUN_SA_PROG_LOCK and operate on a locked socket.
Note that we could remove the switch for prog->expected_attach_type altogether
since all current sock_addr attach types are covered. However, it makes sense
to keep it as a safe-guard in case new sock_addr attach types are added that
might not operate on a locked socket. Therefore, avoid to let this slip through.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210127232853.3753823-5-sdf@google.com
Can be used to query/modify socket state for unconnected UDP sendmsg.
Those hooks run as BPF_CGROUP_RUN_SA_PROG_LOCK and operate on
a locked socket.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210127232853.3753823-2-sdf@google.com
When dealing with BPF/BTF/pahole and DWARF v5 I wanted to build bpftool.
While looking into the source code I found duplicate assignments in misc tools
for the LLVM eco system, e.g. clang and llvm-objcopy.
Move the Clang, LLC and/or LLVM utils definitions to tools/scripts/Makefile.include
file and add missing includes where needed. Honestly, I was inspired by the commit
c8a950d0d3 ("tools: Factor HOSTCC, HOSTLD, HOSTAR definitions").
I tested with bpftool and perf on Debian/testing AMD64 and LLVM/Clang v11.1.0-rc1.
Build instructions:
[ make and make-options ]
MAKE="make V=1"
MAKE_OPTS="HOSTCC=clang HOSTCXX=clang++ HOSTLD=ld.lld CC=clang LD=ld.lld LLVM=1 LLVM_IAS=1"
MAKE_OPTS="$MAKE_OPTS PAHOLE=/opt/pahole/bin/pahole"
[ clean-up ]
$MAKE $MAKE_OPTS -C tools/ clean
[ bpftool ]
$MAKE $MAKE_OPTS -C tools/bpf/bpftool/
[ perf ]
PYTHON=python3 $MAKE $MAKE_OPTS -C tools/perf/
I was careful with respecting the user's wish to override custom compiler, linker,
GNU/binutils and/or LLVM utils settings.
Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com> # tools/build and tools/perf
Link: https://lore.kernel.org/bpf/20210128015117.20515-1-sedat.dilek@gmail.com
Return 3 to indicate that permission check for port 111
should be skipped.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210127193140.3170382-2-sdf@google.com
At the moment, BPF_CGROUP_INET{4,6}_BIND hooks can rewrite user_port
to the privileged ones (< ip_unprivileged_port_start), but it will
be rejected later on in the __inet_bind or __inet6_bind.
Let's add another return value to indicate that CAP_NET_BIND_SERVICE
check should be ignored. Use the same idea as we currently use
in cgroup/egress where bit #1 indicates CN. Instead, for
cgroup/bind{4,6}, bit #1 indicates that CAP_NET_BIND_SERVICE should
be bypassed.
v5:
- rename flags to be less confusing (Andrey Ignatov)
- rework BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY to work on flags
and accept BPF_RET_SET_CN (no behavioral changes)
v4:
- Add missing IPv6 support (Martin KaFai Lau)
v3:
- Update description (Martin KaFai Lau)
- Fix capability restore in selftest (Martin KaFai Lau)
v2:
- Switch to explicit return code (Martin KaFai Lau)
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrey Ignatov <rdna@fb.com>
Link: https://lore.kernel.org/bpf/20210127193140.3170382-1-sdf@google.com
sk_psock_destroy() is a RCU callback, I can't see any reason why
it could be used outside.
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Lorenz Bauer <lmb@cloudflare.com>
Link: https://lore.kernel.org/bpf/20210127221501.46866-1-xiyou.wangcong@gmail.com
This 'BPF_ADD' is duplicated, and I belive it should be 'BPF_AND'.
Fixes: 981f94c3e9 ("bpf: Add bitwise atomic instructions")
Signed-off-by: Menglong Dong <dong.menglong@zte.com.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/bpf/20210127022507.23674-1-dong.menglong@zte.com.cn
Fix bug in handling bpf_testmod unloading that will cause test_progs exiting
prematurely if bpf_testmod unloading failed. This is especially problematic
when running a subset of test_progs that doesn't require root permissions and
doesn't rely on bpf_testmod, yet will fail immediately due to exit(1) in
unload_bpf_testmod().
Fixes: 9f7fa22589 ("selftests/bpf: Add bpf_testmod kernel module for testing")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210126065019.1268027-1-andrii@kernel.org
There exists many build warnings when make M=samples/bpf on the Loongson
platform, this issue is MIPS related, x86 compiles just fine.
Here are some warnings:
CC samples/bpf/ibumad_user.o
samples/bpf/ibumad_user.c: In function ‘dump_counts’:
samples/bpf/ibumad_user.c:46:24: warning: format ‘%llu’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘__u64’ {aka ‘long unsigned int’} [-Wformat=]
printf("0x%02x : %llu\n", key, value);
~~~^ ~~~~~
%lu
CC samples/bpf/offwaketime_user.o
samples/bpf/offwaketime_user.c: In function ‘print_ksym’:
samples/bpf/offwaketime_user.c:34:17: warning: format ‘%llx’ expects argument of type ‘long long unsigned int’, but argument 3 has type ‘__u64’ {aka ‘long unsigned int’} [-Wformat=]
printf("%s/%llx;", sym->name, addr);
~~~^ ~~~~
%lx
samples/bpf/offwaketime_user.c: In function ‘print_stack’:
samples/bpf/offwaketime_user.c:68:17: warning: format ‘%lld’ expects argument of type ‘long long int’, but argument 3 has type ‘__u64’ {aka ‘long unsigned int’} [-Wformat=]
printf(";%s %lld\n", key->waker, count);
~~~^ ~~~~~
%ld
MIPS needs __SANE_USERSPACE_TYPES__ before <linux/types.h> to select
'int-ll64.h' in arch/mips/include/uapi/asm/types.h, then it can avoid
build warnings when printing __u64 with %llu, %llx or %lld.
The header tools/include/linux/types.h defines __SANE_USERSPACE_TYPES__,
it seems that we can include <linux/types.h> in the source files which
have build warnings, but it has no effect due to actually it includes
usr/include/linux/types.h instead of tools/include/linux/types.h, the
problem is that "usr/include" is preferred first than "tools/include"
in samples/bpf/Makefile, that sounds like a ugly hack to -Itools/include
before -Iusr/include.
So define __SANE_USERSPACE_TYPES__ for MIPS in samples/bpf/Makefile
is proper, if add "TPROGS_CFLAGS += -D__SANE_USERSPACE_TYPES__" in
samples/bpf/Makefile, it appears the following error:
Auto-detecting system features:
... libelf: [ on ]
... zlib: [ on ]
... bpf: [ OFF ]
BPF API too old
make[3]: *** [Makefile:293: bpfdep] Error 1
make[2]: *** [Makefile:156: all] Error 2
With #ifndef __SANE_USERSPACE_TYPES__ in tools/include/linux/types.h,
the above error has gone and this ifndef change does not hurt other
compilations.
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/1611551146-14052-1-git-send-email-yangtiezhu@loongson.cn
Update struct bpf_perf_event_data with the addr field to match the
tools headers with the kernel headers.
Signed-off-by: Florian Lehner <dev@der-flo.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210123185221.23946-1-dev@der-flo.net
Let us use a local variable in nsswitchthread(), so we can remove a
lot of casting for better readability.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210122154725.22140-7-bjorn.topel@gmail.com
Instead of passing void * all over the place, let us pass the actual
type (ifobject) and remove the void-ptr-to-type-ptr casting.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210122154725.22140-2-bjorn.topel@gmail.com
Add detection for kernel version, and adapt the BPF program based on
kernel support. This way, users will get the best possible performance
from the BPF program.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Marek Majtyka <alardam@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/bpf/20210122105351.11751-4-bjorn.topel@gmail.com
Fold xp_assign_dev and __xp_assign_dev. The former directly calls the
latter.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/bpf/20210122105351.11751-3-bjorn.topel@gmail.com
The explicit_free parameter of the __xsk_rcv() function was used to
mark whether the call was via the generic XDP or the native XDP
path. Instead of clutter the code with if-statements and "true/false"
parameters which are hard to understand, simply move the explicit free
to the __xsk_map_redirect() which is always called from the native XDP
path.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/bpf/20210122105351.11751-2-bjorn.topel@gmail.com
This patch add a xdp program on egress to show that we can modify
the packet on egress. In this sample we will set the pkt's src
mac to egress's mac address. The xdp_prog will be attached when
-X option supplied.
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20210122025007.2968381-1-liuhangbin@gmail.com
The current LLVM and Clang build procedure in samples/bpf/README.rst is
out of date. See below that the links are not accessible any more.
$ git clone http://llvm.org/git/llvm.git
Cloning into 'llvm'...
fatal: unable to access 'http://llvm.org/git/llvm.git/': Maximum (20) redirects followed
$ git clone --depth 1 http://llvm.org/git/clang.git
Cloning into 'clang'...
fatal: unable to access 'http://llvm.org/git/clang.git/': Maximum (20) redirects followed
The LLVM community has adopted new ways to build the compiler. There are
different ways to build LLVM and Clang, the Clang Getting Started page [1]
has one way. As Yonghong said, it is better to copy the build procedure
in Documentation/bpf/bpf_devel_QA.rst to keep consistent.
I verified the procedure and it is proved to be feasible, so we should
update README.rst to reflect the reality. At the same time, update the
related comment in Makefile.
Additionally, as Fangrui said, the dir llvm-project/llvm/build/install is
not used, BUILD_SHARED_LIBS=OFF is the default option [2], so also change
Documentation/bpf/bpf_devel_QA.rst together.
At last, we recommend that developers who want the fastest incremental
builds use the Ninja build system [1], you can find it in your system's
package manager, usually the package is ninja or ninja-build [3], so add
ninja to build dependencies suggested by Nathan.
[1] https://clang.llvm.org/get_started.html
[2] https://www.llvm.org/docs/CMake.html
[3] https://github.com/ninja-build/ninja/wiki/Pre-built-Ninja-packages
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Cc: Fangrui Song <maskray@google.com>
Link: https://lore.kernel.org/bpf/1611279584-26047-1-git-send-email-yangtiezhu@loongson.cn
For very large ELF objects (with many sections), we could
get special value SHN_XINDEX (65535) for elf object's string
table index - e_shstrndx.
Call elf_getshdrstrndx to get the proper string table index,
instead of reading it directly from ELF header.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210121202203.9346-4-jolsa@kernel.org
This fixes up the markup to fix a warning, be more consistent with
use of monospace, and use the correct .rst syntax for <em> (* instead
of _).
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/bpf/20210120133946.2107897-2-jackmanb@google.com
Stanislav Fomichev says:
====================
First patch adds custom getsockopt for TCP_ZEROCOPY_RECEIVE
to remove kmalloc and lock_sock overhead from the dat path.
Second patch removes kzalloc/kfree from getsockopt for the common cases.
Third patch switches cgroup_bpf_enabled to be per-attach to
to add only overhead for the cgroup attach types used on the system.
No visible user-side changes.
v9:
- include linux/tcp.h instead of netinet/tcp.h in sockopt_sk.c
- note that v9 depends on the commit 4be34f3d07 ("bpf: Don't leak
memory in bpf getsockopt when optlen == 0") from bpf tree
v8:
- add bpi.h to tools/include/uapi in the same patch (Martin KaFai Lau)
- kmalloc instead of kzalloc when exporting buffer (Martin KaFai Lau)
- note that v8 depends on the commit 4be34f3d07 ("bpf: Don't leak
memory in bpf getsockopt when optlen == 0") from bpf tree
v7:
- add comment about buffer contents for retval != 0 (Martin KaFai Lau)
- export tcp.h into tools/include/uapi (Martin KaFai Lau)
- note that v7 depends on the commit 4be34f3d07 ("bpf: Don't leak
memory in bpf getsockopt when optlen == 0") from bpf tree
v6:
- avoid indirect cost for new bpf_bypass_getsockopt (Eric Dumazet)
v5:
- reorder patches to reduce the churn (Martin KaFai Lau)
v4:
- update performance numbers
- bypass_bpf_getsockopt (Martin KaFai Lau)
v3:
- remove extra newline, add comment about sizeof tcp_zerocopy_receive
(Martin KaFai Lau)
- add another patch to remove lock_sock overhead from
TCP_ZEROCOPY_RECEIVE; technically, this makes patch #1 obsolete,
but I'd still prefer to keep it to help with other socket
options
v2:
- perf numbers for getsockopt kmalloc reduction (Song Liu)
- (sk) in BPF_CGROUP_PRE_CONNECT_ENABLED (Song Liu)
- 128 -> 64 buffer size, BUILD_BUG_ON (Martin KaFai Lau)
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When we attach any cgroup hook, the rest (even if unused/unattached) start
to contribute small overhead. In particular, the one we want to avoid is
__cgroup_bpf_run_filter_skb which does two redirections to get to
the cgroup and pushes/pulls skb.
Let's split cgroup_bpf_enabled to be per-attach to make sure
only used attach types trigger.
I've dropped some existing high-level cgroup_bpf_enabled in some
places because BPF_PROG_CGROUP_XXX_RUN macros usually have another
cgroup_bpf_enabled check.
I also had to copy-paste BPF_CGROUP_RUN_SA_PROG_LOCK for
GETPEERNAME/GETSOCKNAME because type for cgroup_bpf_enabled[type]
has to be constant and known at compile time.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210115163501.805133-4-sdf@google.com
When we attach a bpf program to cgroup/getsockopt any other getsockopt()
syscall starts incurring kzalloc/kfree cost.
Let add a small buffer on the stack and use it for small (majority)
{s,g}etsockopt values. The buffer is small enough to fit into
the cache line and cover the majority of simple options (most
of them are 4 byte ints).
It seems natural to do the same for setsockopt, but it's a bit more
involved when the BPF program modifies the data (where we have to
kmalloc). The assumption is that for the majority of setsockopt
calls (which are doing pure BPF options or apply policy) this
will bring some benefit as well.
Without this patch (we remove about 1% __kmalloc):
3.38% 0.07% tcp_mmap [kernel.kallsyms] [k] __cgroup_bpf_run_filter_getsockopt
|
--3.30%--__cgroup_bpf_run_filter_getsockopt
|
--0.81%--__kmalloc
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210115163501.805133-3-sdf@google.com
Add custom implementation of getsockopt hook for TCP_ZEROCOPY_RECEIVE.
We skip generic hooks for TCP_ZEROCOPY_RECEIVE and have a custom
call in do_tcp_getsockopt using the on-stack data. This removes
3% overhead for locking/unlocking the socket.
Without this patch:
3.38% 0.07% tcp_mmap [kernel.kallsyms] [k] __cgroup_bpf_run_filter_getsockopt
|
--3.30%--__cgroup_bpf_run_filter_getsockopt
|
--0.81%--__kmalloc
With the patch applied:
0.52% 0.12% tcp_mmap [kernel.kallsyms] [k] __cgroup_bpf_run_filter_getsockopt_kern
Note, exporting uapi/tcp.h requires removing netinet/tcp.h
from test_progs.h because those headers have confliciting
definitions.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210115163501.805133-2-sdf@google.com
llvm patch https://reviews.llvm.org/D84002 permitted
to emit empty rodata datasec if the elf .rodata section
contains read-only data from local variables. These
local variables will be not emitted as BTF_KIND_VARs
since llvm converted these local variables as
static variables with private linkage without debuginfo
types. Such an empty rodata datasec will make
skeleton code generation easy since for skeleton
a rodata struct will be generated if there is a
.rodata elf section. The existence of a rodata
btf datasec is also consistent with the existence
of a rodata map created by libbpf.
The btf with such an empty rodata datasec will fail
in the kernel though as kernel will reject a datasec
with zero vlen and zero size. For example, for the below code,
int sys_enter(void *ctx)
{
int fmt[6] = {1, 2, 3, 4, 5, 6};
int dst[6];
bpf_probe_read(dst, sizeof(dst), fmt);
return 0;
}
We got the below btf (bpftool btf dump ./test.o):
[1] PTR '(anon)' type_id=0
[2] FUNC_PROTO '(anon)' ret_type_id=3 vlen=1
'ctx' type_id=1
[3] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED
[4] FUNC 'sys_enter' type_id=2 linkage=global
[5] INT 'char' size=1 bits_offset=0 nr_bits=8 encoding=SIGNED
[6] ARRAY '(anon)' type_id=5 index_type_id=7 nr_elems=4
[7] INT '__ARRAY_SIZE_TYPE__' size=4 bits_offset=0 nr_bits=32 encoding=(none)
[8] VAR '_license' type_id=6, linkage=global-alloc
[9] DATASEC '.rodata' size=0 vlen=0
[10] DATASEC 'license' size=0 vlen=1
type_id=8 offset=0 size=4
When loading the ./test.o to the kernel with bpftool,
we see the following error:
libbpf: Error loading BTF: Invalid argument(22)
libbpf: magic: 0xeb9f
...
[6] ARRAY (anon) type_id=5 index_type_id=7 nr_elems=4
[7] INT __ARRAY_SIZE_TYPE__ size=4 bits_offset=0 nr_bits=32 encoding=(none)
[8] VAR _license type_id=6 linkage=1
[9] DATASEC .rodata size=24 vlen=0 vlen == 0
libbpf: Error loading .BTF into kernel: -22. BTF is optional, ignoring.
Basically, libbpf changed .rodata datasec size to 24 since elf .rodata
section size is 24. The kernel then rejected the BTF since vlen = 0.
Note that the above kernel verifier failure can be worked around with
changing local variable "fmt" to a static or global, optionally const, variable.
This patch permits a datasec with vlen = 0 in kernel.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210119153519.3901963-1-yhs@fb.com
Qais Yousef says:
====================
Changes in v3:
* Fix not returning error value correctly in
trigger_module_test_write() (Yonghong)
* Add Yonghong acked-by to patch 1.
Changes in v2:
* Fix compilation error. (Andrii)
* Make the new test use write() instead of read() (Andrii)
Add some missing glue logic to teach bpf about bare tracepoints - tracepoints
without any trace event associated with them.
Bare tracepoints are declare with DECLARE_TRACE(). Full tracepoints are declare
with TRACE_EVENT().
BPF can attach to these tracepoints as RAW_TRACEPOINT() only as there're no
events in tracefs created with them.
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reuse module_attach infrastructure to add a new bare tracepoint to check
we can attach to it as a raw tracepoint.
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210119122237.2426878-3-qais.yousef@arm.com
Gary Lin says:
====================
This patch series implements jump padding to x64 jit to cover some
corner cases that used to consume more than 20 jit passes and caused
failure.
v4:
- Add the detailed comments about the possible padding bytes
- Add the second test case which triggers jmp_cond padding and imm32 nop
jmp padding.
- Add the new test case as another subprog
v3:
- Copy the instructions of prologue separately or the size calculation
of the first BPF instruction would include the prologue.
- Replace WARN_ONCE() with pr_err() and EFAULT
- Use MAX_PASSES in the for loop condition check
- Remove the "padded" flag from x64_jit_data. For the extra pass of
subprogs, padding is always enabled since it won't hurt the images
that converge without padding.
v2:
- Simplify the sample code in the commit description and provide the
jit code
- Check the expected padding bytes with WARN_ONCE
- Move the 'padded' flag to 'struct x64_jit_data'
- Remove the EXPECTED_FAIL flag from bpf_fill_maxinsns11() in test_bpf
- Add 2 verifier tests
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Some subsystems only have bare tracepoints (a tracepoint with no
associated trace event) to avoid the problem of trace events being an
ABI that can't be changed.
>From bpf presepective, bare tracepoints are what it calls
RAW_TRACEPOINT().
Since bpf assumed there's 1:1 mapping, it relied on hooking to
DEFINE_EVENT() macro to create bpf mapping of the tracepoints. Since
bare tracepoints use DECLARE_TRACE() to create the tracepoint, bpf had
no knowledge about their existence.
By teaching bpf_probe.h to parse DECLARE_TRACE() in a similar fashion to
DEFINE_EVENT(), bpf can find and attach to the new raw tracepoints.
Enabling that comes with the contract that changes to raw tracepoints
don't constitute a regression if they break existing bpf programs.
We need the ability to continue to morph and modify these raw
tracepoints without worrying about any ABI.
Update Documentation/bpf/bpf_design_QA.rst to document this contract.
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210119122237.2426878-2-qais.yousef@arm.com
There are 3 tests added into verifier's jit tests to trigger x64
jit jump padding.
The first test can be represented as the following assembly code:
1: bpf_call bpf_get_prandom_u32
2: if r0 == 1 goto pc+128
3: if r0 == 2 goto pc+128
...
129: if r0 == 128 goto pc+128
130: goto pc+128
131: goto pc+127
...
256: goto pc+2
257: goto pc+1
258: r0 = 1
259: ret
We first store a random number to r0 and add the corresponding
conditional jumps (2~129) to make verifier believe that those jump
instructions from 130 to 257 are reachable. When the program is sent to
x64 jit, it starts to optimize out the NOP jumps backwards from 257.
Since there are 128 such jumps, the program easily reaches 15 passes and
triggers jump padding.
Here is the x64 jit code of the first test:
0: 0f 1f 44 00 00 nop DWORD PTR [rax+rax*1+0x0]
5: 66 90 xchg ax,ax
7: 55 push rbp
8: 48 89 e5 mov rbp,rsp
b: e8 4c 90 75 e3 call 0xffffffffe375905c
10: 48 83 f8 01 cmp rax,0x1
14: 0f 84 fe 04 00 00 je 0x518
1a: 48 83 f8 02 cmp rax,0x2
1e: 0f 84 f9 04 00 00 je 0x51d
...
f6: 48 83 f8 18 cmp rax,0x18
fa: 0f 84 8b 04 00 00 je 0x58b
100: 48 83 f8 19 cmp rax,0x19
104: 0f 84 86 04 00 00 je 0x590
10a: 48 83 f8 1a cmp rax,0x1a
10e: 0f 84 81 04 00 00 je 0x595
...
500: 0f 84 83 01 00 00 je 0x689
506: 48 81 f8 80 00 00 00 cmp rax,0x80
50d: 0f 84 76 01 00 00 je 0x689
513: e9 71 01 00 00 jmp 0x689
518: e9 6c 01 00 00 jmp 0x689
...
5fe: e9 86 00 00 00 jmp 0x689
603: e9 81 00 00 00 jmp 0x689
608: 0f 1f 00 nop DWORD PTR [rax]
60b: eb 7c jmp 0x689
60d: eb 7a jmp 0x689
...
683: eb 04 jmp 0x689
685: eb 02 jmp 0x689
687: 66 90 xchg ax,ax
689: b8 01 00 00 00 mov eax,0x1
68e: c9 leave
68f: c3 ret
As expected, a 3 bytes NOPs is inserted at 608 due to the transition
from imm32 jmp to imm8 jmp. A 2 bytes NOPs is also inserted at 687 to
replace a NOP jump.
The second test case is tricky. Here is the assembly code:
1: bpf_call bpf_get_prandom_u32
2: if r0 == 1 goto pc+2048
3: if r0 == 2 goto pc+2048
...
2049: if r0 == 2048 goto pc+2048
2050: goto pc+2048
2051: goto pc+16
2052: goto pc+15
...
2064: goto pc+3
2065: goto pc+2
2066: goto pc+1
...
[repeat "goto pc+16".."goto pc+1" 127 times]
...
4099: r0 = 2
4100: ret
There are 4 major parts of the program.
1) 1~2049: Those are instructions to make 2050~4098 reachable. Some of
them also could generate the padding for jmp_cond.
2) 2050: This is the target instruction for the imm32 nop jmp padding.
3) 2051~4098: The repeated "goto 1~16" instructions are designed to be
consumed by the nop jmp optimization. In the end, those
instrucitons become 128 continuous 0 offset jmp and are
optimized out in 1 pass, and this make insn 2050 an imm32
nop jmp in the next pass, so that we can trigger the
5 bytes padding.
4) 4099~4100: Those are the instructions to end the program.
The x64 jit code is like this:
0: 0f 1f 44 00 00 nop DWORD PTR [rax+rax*1+0x0]
5: 66 90 xchg ax,ax
7: 55 push rbp
8: 48 89 e5 mov rbp,rsp
b: e8 bc 7b d5 d3 call 0xffffffffd3d57bcc
10: 48 83 f8 01 cmp rax,0x1
14: 0f 84 7e 66 00 00 je 0x6698
1a: 48 83 f8 02 cmp rax,0x2
1e: 0f 84 74 66 00 00 je 0x6698
24: 48 83 f8 03 cmp rax,0x3
28: 0f 84 6a 66 00 00 je 0x6698
2e: 48 83 f8 04 cmp rax,0x4
32: 0f 84 60 66 00 00 je 0x6698
38: 48 83 f8 05 cmp rax,0x5
3c: 0f 84 56 66 00 00 je 0x6698
42: 48 83 f8 06 cmp rax,0x6
46: 0f 84 4c 66 00 00 je 0x6698
...
666c: 48 81 f8 fe 07 00 00 cmp rax,0x7fe
6673: 0f 1f 40 00 nop DWORD PTR [rax+0x0]
6677: 74 1f je 0x6698
6679: 48 81 f8 ff 07 00 00 cmp rax,0x7ff
6680: 0f 1f 40 00 nop DWORD PTR [rax+0x0]
6684: 74 12 je 0x6698
6686: 48 81 f8 00 08 00 00 cmp rax,0x800
668d: 0f 1f 40 00 nop DWORD PTR [rax+0x0]
6691: 74 05 je 0x6698
6693: 0f 1f 44 00 00 nop DWORD PTR [rax+rax*1+0x0]
6698: b8 02 00 00 00 mov eax,0x2
669d: c9 leave
669e: c3 ret
Since insn 2051~4098 are optimized out right before the padding pass,
there are several conditional jumps from the first part are replaced with
imm8 jmp_cond, and this triggers the 4 bytes padding, for example at
6673, 6680, and 668d. On the other hand, Insn 2050 is replaced with the
5 bytes nops at 6693.
The third test is to invoke the first and second tests as subprogs to test
bpf2bpf. Per the system log, there was one more jit happened with only
one pass and the same jit code was produced.
v4:
- Add the second test case which triggers jmp_cond padding and imm32 nop
jmp padding.
- Add the new test case as another subprog
Signed-off-by: Gary Lin <glin@suse.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210119102501.511-4-glin@suse.com
The x64 bpf jit expects bpf images converge within the given passes, but
it could fail to do so with some corner cases. For example:
l0: ja 40
l1: ja 40
[... repeated ja 40 ]
l39: ja 40
l40: ret #0
This bpf program contains 40 "ja 40" instructions which are effectively
NOPs and designed to be replaced with valid code dynamically. Ideally,
bpf jit should optimize those "ja 40" instructions out when translating
the bpf instructions into x64 machine code. However, do_jit() can only
remove one "ja 40" for offset==0 on each pass, so it requires at least
40 runs to eliminate those JMPs and exceeds the current limit of
passes(20). In the end, the program got rejected when BPF_JIT_ALWAYS_ON
is set even though it's legit as a classic socket filter.
To make bpf images more likely converge within 20 passes, this commit
pads some instructions with NOPs in the last 5 passes:
1. conditional jumps
A possible size variance comes from the adoption of imm8 JMP. If the
offset is imm8, we calculate the size difference of this BPF instruction
between the previous and the current pass and fill the gap with NOPs.
To avoid the recalculation of jump offset, those NOPs are inserted before
the JMP code, so we have to subtract the 2 bytes of imm8 JMP when
calculating the NOP number.
2. BPF_JA
There are two conditions for BPF_JA.
a.) nop jumps
If this instruction is not optimized out in the previous pass,
instead of removing it, we insert the equivalent size of NOPs.
b.) label jumps
Similar to condition jumps, we prepend NOPs right before the JMP
code.
To make the code concise, emit_nops() is modified to use the signed len and
return the number of inserted NOPs.
For bpf-to-bpf, we always enable padding for the extra pass since there
is only one extra run and the jump padding doesn't affected the images
that converge without padding.
After applying this patch, the corner case was loaded with the following
jit code:
flen=45 proglen=77 pass=17 image=ffffffffc03367d4 from=jump pid=10097
JIT code: 00000000: 0f 1f 44 00 00 55 48 89 e5 53 41 55 31 c0 45 31
JIT code: 00000010: ed 48 89 fb eb 30 eb 2e eb 2c eb 2a eb 28 eb 26
JIT code: 00000020: eb 24 eb 22 eb 20 eb 1e eb 1c eb 1a eb 18 eb 16
JIT code: 00000030: eb 14 eb 12 eb 10 eb 0e eb 0c eb 0a eb 08 eb 06
JIT code: 00000040: eb 04 eb 02 66 90 31 c0 41 5d 5b c9 c3
0: 0f 1f 44 00 00 nop DWORD PTR [rax+rax*1+0x0]
5: 55 push rbp
6: 48 89 e5 mov rbp,rsp
9: 53 push rbx
a: 41 55 push r13
c: 31 c0 xor eax,eax
e: 45 31 ed xor r13d,r13d
11: 48 89 fb mov rbx,rdi
14: eb 30 jmp 0x46
16: eb 2e jmp 0x46
...
3e: eb 06 jmp 0x46
40: eb 04 jmp 0x46
42: eb 02 jmp 0x46
44: 66 90 xchg ax,ax
46: 31 c0 xor eax,eax
48: 41 5d pop r13
4a: 5b pop rbx
4b: c9 leave
4c: c3 ret
At the 16th pass, 15 jumps were already optimized out, and one jump was
replaced with NOPs at 44 and the image converged at the 17th pass.
v4:
- Add the detailed comments about the possible padding bytes
v3:
- Copy the instructions of prologue separately or the size calculation
of the first BPF instruction would include the prologue.
- Replace WARN_ONCE() with pr_err() and EFAULT
- Use MAX_PASSES in the for loop condition check
- Remove the "padded" flag from x64_jit_data. For the extra pass of
subprogs, padding is always enabled since it won't hurt the images
that converge without padding.
v2:
- Simplify the sample code in the description and provide the jit code
- Check the expected padding bytes with WARN_ONCE
- Move the 'padded' flag to 'struct x64_jit_data'
Signed-off-by: Gary Lin <glin@suse.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210119102501.511-2-glin@suse.com
Commit 91c960b005 ("bpf: Rename BPF_XADD and prepare to encode other
atomics in .imm") modified the BPF documentation, but missed some ReST
markup.
Hence, make htmldocs warns on Documentation/networking/filter.rst:1053:
WARNING: Inline emphasis start-string without end-string.
Add some minimal markup to address this warning.
Fixes: 91c960b005 ("bpf: Rename BPF_XADD and prepare to encode other atomics in .imm")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/bpf/20210118080004.6367-1-lukas.bulwahn@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Brendan Jackman added extend atomic operations to the BPF instruction
set in commit 7064a7341a ("Merge branch 'Atomics for eBPF'"), which
introduces the BPF_ATOMIC_OP macro. However, that macro was missing
for the BPF samples. Fix that by adding it into bpf_insn.h.
Fixes: 91c960b005 ("bpf: Rename BPF_XADD and prepare to encode other atomics in .imm")
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/bpf/20210118091753.107572-1-bjorn.topel@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
