Commit Graph

22 Commits

Author SHA1 Message Date
Nathan Chancellor 2d5bcdcda8 bpf: Increase size of BTF_ID_LIST without CONFIG_DEBUG_INFO_BTF again
After commit 66e3a13e7c ("bpf: Add bpf_dynptr_slice and bpf_dynptr_slice_rdwr"),
clang builds without CONFIG_DEBUG_INFO_BTF warn:

  kernel/bpf/verifier.c:10298:24: warning: array index 16 is past the end of the array (that has type 'u32[16]' (aka 'unsigned int[16]')) [-Warray-bounds]
                                     meta.func_id == special_kfunc_list[KF_bpf_dynptr_slice_rdwr]) {
                                                     ^                  ~~~~~~~~~~~~~~~~~~~~~~~~
  kernel/bpf/verifier.c:9150:1: note: array 'special_kfunc_list' declared here
  BTF_ID_LIST(special_kfunc_list)
  ^
  include/linux/btf_ids.h:207:27: note: expanded from macro 'BTF_ID_LIST'
  #define BTF_ID_LIST(name) static u32 __maybe_unused name[16];
                            ^
  1 warning generated.

A warning of this nature was previously addressed by
commit beb3d47d1d ("bpf: Fix a BTF_ID_LIST bug with CONFIG_DEBUG_INFO_BTF not set")
but there have been new kfuncs added since then.

Quadruple the size of the CONFIG_DEBUG_INFO_BTF=n definition so that
this problem is unlikely to show up for some time.

Link: https://github.com/ClangBuiltLinux/linux/issues/1810
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20230307-bpf-kfuncs-warray-bounds-v1-1-00ad3191f3a6@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-03-07 07:49:28 -08:00
Yonghong Song 3144bfa507 bpf: Fix a compilation failure with clang lto build
When building the kernel with clang lto (CONFIG_LTO_CLANG_FULL=y), the
following compilation error will appear:

  $ make LLVM=1 LLVM_IAS=1 -j
  ...
  ld.lld: error: ld-temp.o <inline asm>:26889:1: symbol 'cgroup_storage_map_btf_ids' is already defined
  cgroup_storage_map_btf_ids:;
  ^
  make[1]: *** [/.../bpf-next/scripts/Makefile.vmlinux_o:61: vmlinux.o] Error 1

In local_storage.c, we have
  BTF_ID_LIST_SINGLE(cgroup_storage_map_btf_ids, struct, bpf_local_storage_map)
Commit c4bcfb38a9 ("bpf: Implement cgroup storage available to
non-cgroup-attached bpf progs") added the above identical BTF_ID_LIST_SINGLE
definition in bpf_cgrp_storage.c. With duplicated definitions, llvm linker
complains with lto build.

Also, extracting btf_id of 'struct bpf_local_storage_map' is defined four times
for sk, inode, task and cgrp local storages. Let us define a single global one
with a different name than cgroup_storage_map_btf_ids, which also fixed
the lto compilation error.

Fixes: c4bcfb38a9 ("bpf: Implement cgroup storage available to non-cgroup-attached bpf progs")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20221130052147.1591625-1-yhs@fb.com
2022-11-30 17:13:25 -08:00
Yonghong Song beb3d47d1d bpf: Fix a BTF_ID_LIST bug with CONFIG_DEBUG_INFO_BTF not set
With CONFIG_DEBUG_INFO_BTF not set, we hit the following compilation error,
  /.../kernel/bpf/verifier.c:8196:23: error: array index 6 is past the end of the array
  (that has type 'u32[5]' (aka 'unsigned int[5]')) [-Werror,-Warray-bounds]
        if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx])
                             ^                  ~~~~~~~~~~~~~~~~~~~~~~~
  /.../kernel/bpf/verifier.c:8174:1: note: array 'special_kfunc_list' declared here
  BTF_ID_LIST(special_kfunc_list)
  ^
  /.../include/linux/btf_ids.h:207:27: note: expanded from macro 'BTF_ID_LIST'
  #define BTF_ID_LIST(name) static u32 __maybe_unused name[5];
                            ^
  /.../kernel/bpf/verifier.c:8443:19: error: array index 5 is past the end of the array
  (that has type 'u32[5]' (aka 'unsigned int[5]')) [-Werror,-Warray-bounds]
                 btf_id == special_kfunc_list[KF_bpf_list_pop_back];
                           ^                  ~~~~~~~~~~~~~~~~~~~~
  /.../kernel/bpf/verifier.c:8174:1: note: array 'special_kfunc_list' declared here
  BTF_ID_LIST(special_kfunc_list)
  ^
  /.../include/linux/btf_ids.h:207:27: note: expanded from macro 'BTF_ID_LIST'
  #define BTF_ID_LIST(name) static u32 __maybe_unused name[5];
  ...

Fix the problem by increase the size of BTF_ID_LIST to 16 to avoid compilation error
and also prevent potentially unintended issue due to out-of-bound access.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221123155759.2669749-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-11-23 13:20:33 -08:00
Yonghong Song 5e67b8ef12 bpf: Make struct cgroup btf id global
Make struct cgroup btf id global so later patch can reuse
the same btf id.

Acked-by: David Vernet <void@manifault.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221026042840.672602-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-10-25 23:19:19 -07:00
Kumar Kartikeya Dwivedi e423414375 bpf: Fix build error in case of !CONFIG_DEBUG_INFO_BTF
BTF_ID_FLAGS macro needs to be able to take 0 or 1 args, so make it a
variable argument. BTF_SET8_END is incorrect, it should just be empty.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: ab21d6063c ("bpf: Introduce 8-byte BTF set")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20220722113605.6513-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-07-22 09:07:07 -07:00
Kumar Kartikeya Dwivedi ab21d6063c bpf: Introduce 8-byte BTF set
Introduce support for defining flags for kfuncs using a new set of
macros, BTF_SET8_START/BTF_SET8_END, which define a set which contains
8 byte elements (each of which consists of a pair of BTF ID and flags),
using a new BTF_ID_FLAGS macro.

This will be used to tag kfuncs registered for a certain program type
as acquire, release, sleepable, ret_null, etc. without having to create
more and more sets which was proving to be an unscalable solution.

Now, when looking up whether a kfunc is allowed for a certain program,
we can also obtain its kfunc flags in the same call and avoid further
lookups.

The resolve_btfids change is split into a separate patch.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220721134245.2450-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-07-21 20:59:42 -07:00
Stanislav Fomichev 69fd337a97 bpf: per-cgroup lsm flavor
Allow attaching to lsm hooks in the cgroup context.

Attaching to per-cgroup LSM works exactly like attaching
to other per-cgroup hooks. New BPF_LSM_CGROUP is added
to trigger new mode; the actual lsm hook we attach to is
signaled via existing attach_btf_id.

For the hooks that have 'struct socket' or 'struct sock' as its first
argument, we use the cgroup associated with that socket. For the rest,
we use 'current' cgroup (this is all on default hierarchy == v2 only).
Note that for some hooks that work on 'struct sock' we still
take the cgroup from 'current' because some of them work on the socket
that hasn't been properly initialized yet.

Behind the scenes, we allocate a shim program that is attached
to the trampoline and runs cgroup effective BPF programs array.
This shim has some rudimentary ref counting and can be shared
between several programs attaching to the same lsm hook from
different cgroups.

Note that this patch bloats cgroup size because we add 211
cgroup_bpf_attach_type(s) for simplicity sake. This will be
addressed in the subsequent patch.

Also note that we only add non-sleepable flavor for now. To enable
sleepable use-cases, bpf_prog_run_array_cg has to grab trace rcu,
shim programs have to be freed via trace rcu, cgroup_bpf.effective
should be also trace-rcu-managed + maybe some other changes that
I'm not aware of.

Reviewed-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220628174314.1216643-4-sdf@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-06-29 13:21:51 -07:00
Geliang Tang 3bc253c2e6 bpf: Add bpf_skc_to_mptcp_sock_proto
This patch implements a new struct bpf_func_proto, named
bpf_skc_to_mptcp_sock_proto. Define a new bpf_id BTF_SOCK_TYPE_MPTCP,
and a new helper bpf_skc_to_mptcp_sock(), which invokes another new
helper bpf_mptcp_sock_from_subflow() in net/mptcp/bpf.c to get struct
mptcp_sock from a given subflow socket.

v2: Emit BTF type, add func_id checks in verifier.c and bpf_trace.c,
remove build check for CONFIG_BPF_JIT
v5: Drop EXPORT_SYMBOL (Martin)

Co-developed-by: Nicolas Rybowski <nicolas.rybowski@tessares.net>
Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Nicolas Rybowski <nicolas.rybowski@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220519233016.105670-2-mathew.j.martineau@linux.intel.com
2022-05-20 15:29:00 -07:00
Kumar Kartikeya Dwivedi dee872e124 bpf: Populate kfunc BTF ID sets in struct btf
This patch prepares the kernel to support putting all kinds of kfunc BTF
ID sets in the struct btf itself. The various kernel subsystems will
make register_btf_kfunc_id_set call in the initcalls (for built-in code
and modules).

The 'hook' is one of the many program types, e.g. XDP and TC/SCHED_CLS,
STRUCT_OPS, and 'types' are check (allowed or not), acquire, release,
and ret_null (with PTR_TO_BTF_ID_OR_NULL return type).

A maximum of BTF_KFUNC_SET_MAX_CNT (32) kfunc BTF IDs are permitted in a
set of certain hook and type for vmlinux sets, since they are allocated
on demand, and otherwise set as NULL. Module sets can only be registered
once per hook and type, hence they are directly assigned.

A new btf_kfunc_id_set_contains function is exposed for use in verifier,
this new method is faster than the existing list searching method, and
is also automatic. It also lets other code not care whether the set is
unallocated or not.

Note that module code can only do single register_btf_kfunc_id_set call
per hook. This is why sorting is only done for in-kernel vmlinux sets,
because there might be multiple sets for the same hook and type that
must be concatenated, hence sorting them is required to ensure bsearch
in btf_id_set_contains continues to work correctly.

Next commit will update the kernel users to make use of this
infrastructure.

Finally, add __maybe_unused annotation for BTF ID macros for the
!CONFIG_DEBUG_INFO_BTF case, so that they don't produce warnings during
build time.

The previous patch is also needed to provide synchronization against
initialization for module BTF's kfunc_set_tab introduced here, as
described below:

  The kfunc_set_tab pointer in struct btf is write-once (if we consider
  the registration phase (comprised of multiple register_btf_kfunc_id_set
  calls) as a single operation). In this sense, once it has been fully
  prepared, it isn't modified, only used for lookup (from the verifier
  context).

  For btf_vmlinux, it is initialized fully during the do_initcalls phase,
  which happens fairly early in the boot process, before any processes are
  present. This also eliminates the possibility of bpf_check being called
  at that point, thus relieving us of ensuring any synchronization between
  the registration and lookup function (btf_kfunc_id_set_contains).

  However, the case for module BTF is a bit tricky. The BTF is parsed,
  prepared, and published from the MODULE_STATE_COMING notifier callback.
  After this, the module initcalls are invoked, where our registration
  function will be called to populate the kfunc_set_tab for module BTF.

  At this point, BTF may be available to userspace while its corresponding
  module is still intializing. A BTF fd can then be passed to verifier
  using bpf syscall (e.g. for kfunc call insn).

  Hence, there is a race window where verifier may concurrently try to
  lookup the kfunc_set_tab. To prevent this race, we must ensure the
  operations are serialized, or waiting for the __init functions to
  complete.

  In the earlier registration API, this race was alleviated as verifier
  bpf_check_mod_kfunc_call didn't find the kfunc BTF ID until it was added
  by the registration function (called usually at the end of module __init
  function after all module resources have been initialized). If the
  verifier made the check_kfunc_call before kfunc BTF ID was added to the
  list, it would fail verification (saying call isn't allowed). The
  access to list was protected using a mutex.

  Now, it would still fail verification, but for a different reason
  (returning ENXIO due to the failed btf_try_get_module call in
  add_kfunc_call), because if the __init call is in progress the module
  will be in the middle of MODULE_STATE_COMING -> MODULE_STATE_LIVE
  transition, and the BTF_MODULE_LIVE flag for btf_module instance will
  not be set, so the btf_try_get_module call will fail.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220114163953.1455836-3-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2022-01-18 14:26:41 -08:00
Song Liu d19ddb476a bpf: Introduce btf_tracing_ids
Similar to btf_sock_ids, btf_tracing_ids provides btf ID for task_struct,
file, and vm_area_struct via easy to understand format like
btf_tracing_ids[BTF_TRACING_TYPE_[TASK|file|VMA]].

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211112150243.1270987-3-songliubraving@fb.com
2021-11-12 10:19:09 -08:00
Song Liu 9e2ad638ae bpf: Extend BTF_ID_LIST_GLOBAL with parameter for number of IDs
syzbot reported the following BUG w/o CONFIG_DEBUG_INFO_BTF

BUG: KASAN: global-out-of-bounds in task_iter_init+0x212/0x2e7 kernel/bpf/task_iter.c:661
Read of size 4 at addr ffffffff90297404 by task swapper/0/1

CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.15.0-syzkaller #0
Hardware name: ... Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0xf/0x309 mm/kasan/report.c:256
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
task_iter_init+0x212/0x2e7 kernel/bpf/task_iter.c:661
do_one_initcall+0x103/0x650 init/main.c:1295
do_initcall_level init/main.c:1368 [inline]
do_initcalls init/main.c:1384 [inline]
do_basic_setup init/main.c:1403 [inline]
kernel_init_freeable+0x6b1/0x73a init/main.c:1606
kernel_init+0x1a/0x1d0 init/main.c:1497
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>

This is caused by hard-coded name[1] in BTF_ID_LIST_GLOBAL (w/o
CONFIG_DEBUG_INFO_BTF). Fix this by adding a parameter n to
BTF_ID_LIST_GLOBAL. This avoids ifdef CONFIG_DEBUG_INFO_BTF in btf.c and
filter.c.

Fixes: 7c7e3d31e7 ("bpf: Introduce helper bpf_find_vma")
Reported-by: syzbot+e0d81ec552a21d9071aa@syzkaller.appspotmail.com
Reported-by: Eric Dumazet <edumazet@google.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211112150243.1270987-2-songliubraving@fb.com
2021-11-12 10:19:09 -08:00
Daniel Xu eb529c5b10 bpf: Fix bpf-next builds without CONFIG_BPF_EVENTS
This commit fixes linker errors along the lines of:

    s390-linux-ld: task_iter.c:(.init.text+0xa4): undefined reference to `btf_task_struct_ids'`

Fix by defining btf_task_struct_ids unconditionally in kernel/bpf/btf.c
since there exists code that unconditionally uses btf_task_struct_ids.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/05d94748d9f4b3eecedc4fddd6875418a396e23c.1629942444.git.dxu@dxuuu.xyz
2021-08-25 19:41:39 -07:00
Daniel Xu 33c5cb3601 bpf: Consolidate task_struct BTF_ID declarations
No need to have it defined 5 times. Once is enough.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/6dcefa5bed26fe1226f26683f36819bb53ec19a2.1629772842.git.dxu@dxuuu.xyz
2021-08-25 10:37:05 -07:00
Daniel Xu 1b07d00a15 bpf: Add BTF_ID_LIST_GLOBAL_SINGLE macro
Same as BTF_ID_LIST_SINGLE macro except defines a global ID.

Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/a867a97517df42fd3953eeb5454402b57e74538f.1629772842.git.dxu@dxuuu.xyz
2021-08-25 10:37:05 -07:00
Kuniyuki Iwashima 2c860a43dd bpf: af_unix: Implement BPF iterator for UNIX domain socket.
This patch implements the BPF iterator for the UNIX domain socket.

Currently, the batch optimisation introduced for the TCP iterator in the
commit 04c7820b77 ("bpf: tcp: Bpf iter batching and lock_sock") is not
used for the UNIX domain socket.  It will require replacing the big lock
for the hash table with small locks for each hash list not to block other
processes.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210814015718.42704-2-kuniyu@amazon.co.jp
2021-08-15 00:13:32 -07:00
Lorenz Bauer 27774b7073 btf: Add BTF_ID_LIST_SINGLE macro
Add a convenience macro that allows defining a BTF ID list with
a single item. This lets us cut down on repetitive macros.

Suggested-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200921121227.255763-4-lmb@cloudflare.com
2020-09-21 15:00:40 -07:00
Jiri Olsa eae2e83e62 bpf: Add BTF_SET_START/END macros
Adding support to define sorted set of BTF ID values.

Following defines sorted set of BTF ID values:

  BTF_SET_START(btf_allowlist_d_path)
  BTF_ID(func, vfs_truncate)
  BTF_ID(func, vfs_fallocate)
  BTF_ID(func, dentry_open)
  BTF_ID(func, vfs_getattr)
  BTF_ID(func, filp_close)
  BTF_SET_END(btf_allowlist_d_path)

It defines following 'struct btf_id_set' variable to access
values and count:

  struct btf_id_set btf_allowlist_d_path;

Adding 'allowed' callback to struct bpf_func_proto, to allow
verifier the check on allowed callers.

Adding btf_id_set_contains function, which will be used by
allowed callbacks to verify the caller's BTF ID value is
within allowed set.

Also removing extra '\' in __BTF_ID_LIST macro.

Added BTF_SET_START_GLOBAL macro for global sets.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-10-jolsa@kernel.org
2020-08-25 15:37:41 -07:00
Yonghong Song fce557bcef bpf: Make btf_sock_ids global
tcp and udp bpf_iter can reuse some socket ids in
btf_sock_ids, so make it global.

I put the extern definition in btf_ids.h as a central
place so it can be easily discovered by developers.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200720163402.1393427-1-yhs@fb.com
2020-07-21 13:26:26 -07:00
Yonghong Song 0f12e584b2 bpf: Add BTF_ID_LIST_GLOBAL in btf_ids.h
Existing BTF_ID_LIST used a local static variable
to store btf_ids. This patch provided a new macro
BTF_ID_LIST_GLOBAL to store btf_ids in a global
variable which can be shared among multiple files.

The existing BTF_ID_LIST is still retained.
Two reasons. First, BTF_ID_LIST is also used to build
btf_ids for helper arguments which typically
is an array of 5. Since typically different
helpers have different signature, it makes
little sense to share them. Second, some
current computed btf_ids are indeed local.
If later those btf_ids are shared between
different files, they can use BTF_ID_LIST_GLOBAL then.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/bpf/20200720163401.1393159-1-yhs@fb.com
2020-07-21 13:26:26 -07:00
Jiri Olsa 11bb2f7a45 bpf: Fix cross build for CONFIG_DEBUG_INFO_BTF option
Stephen and 0-DAY CI Kernel Test Service reported broken cross build
for arm (arm-linux-gnueabi-gcc (GCC) 9.3.0), with following output:

   /tmp/ccMS5uth.s: Assembler messages:
   /tmp/ccMS5uth.s:69: Error: unrecognized symbol type ""
   /tmp/ccMS5uth.s:82: Error: unrecognized symbol type ""

Having '@object' for .type  diretive is  wrong because '@' is comment
character for some architectures. Using STT_OBJECT instead that should
work everywhere.

Also using HOST* variables to build resolve_btfids so it's properly
build in crossbuilds (stolen from objtool's Makefile).

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/bpf/20200714102534.299280-2-jolsa@kernel.org
2020-07-14 10:20:31 -07:00
Jiri Olsa 079ef53673 bpf: Fix build for disabled CONFIG_DEBUG_INFO_BTF option
Stephen reported following linker warnings on powerpc build:

  ld: warning: orphan section `.BTF_ids' from `kernel/trace/bpf_trace.o' being placed in section `.BTF_ids'
  ld: warning: orphan section `.BTF_ids' from `kernel/bpf/btf.o' being placed in section `.BTF_ids'
  ld: warning: orphan section `.BTF_ids' from `kernel/bpf/stackmap.o' being placed in section `.BTF_ids'
  ld: warning: orphan section `.BTF_ids' from `net/core/filter.o' being placed in section `.BTF_ids'
  ld: warning: orphan section `.BTF_ids' from `kernel/trace/bpf_trace.o' being placed in section `.BTF_ids'

It's because we generated .BTF_ids section even when
CONFIG_DEBUG_INFO_BTF is not enabled. Fixing this by
generating empty btf_id arrays for this case.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/bpf/20200714102534.299280-1-jolsa@kernel.org
2020-07-14 10:20:31 -07:00
Jiri Olsa 5a2798ab32 bpf: Add BTF_ID_LIST/BTF_ID/BTF_ID_UNUSED macros
Adding support to generate .BTF_ids section that will hold BTF
ID lists for verifier.

Adding macros that will help to define lists of BTF ID values
placed in .BTF_ids section. They are initially filled with zeros
(during compilation) and resolved later during the linking phase
by resolve_btfids tool.

Following defines list of one BTF ID value:

  BTF_ID_LIST(bpf_skb_output_btf_ids)
  BTF_ID(struct, sk_buff)

It also defines following variable to access the list:

  extern u32 bpf_skb_output_btf_ids[];

The BTF_ID_UNUSED macro defines 4 zero bytes. It's used when we
want to define 'unused' entry in BTF_ID_LIST, like:

  BTF_ID_LIST(bpf_skb_output_btf_ids)
  BTF_ID(struct, sk_buff)
  BTF_ID_UNUSED
  BTF_ID(struct, task_struct)

Suggested-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200711215329.41165-4-jolsa@kernel.org
2020-07-13 10:42:02 -07:00