linux.git/tools/testing/selftests/bpf/Makefile, branch v6.11

selftests/bpf: Filter out _GNU_SOURCE when compiling test_cpp

2024-07-29T20:43:31+00:00

Jakub reports build failures when merging linux/master with net tree:

CXX      test_cpp
In file included from :454:
:2:9: error: '_GNU_SOURCE' macro redefined [-Werror,-Wmacro-redefined]
    2 | #define _GNU_SOURCE
      |         ^
:445:9: note: previous definition is here
  445 | #define _GNU_SOURCE 1

The culprit is commit cc937dad85ae ("selftests: centralize -D_GNU_SOURCE= to
CFLAGS in lib.mk") which unconditionally added -D_GNU_SOUCE to CLFAGS.
Apparently clang++ also unconditionally adds it for the C++ targets [0]
which causes a conflict. Add small change in the selftests makefile
to filter it out for test_cpp.

Not sure which tree it should go via, targeting bpf for now, but net
might be better?

0: https://stackoverflow.com/questions/11670581/why-is-gnu-source-defined-by-default-and-how-to-turn-it-off

Signed-off-by: Stanislav Fomichev 
Signed-off-by: Andrii Nakryiko 
Acked-by: Jiri Olsa 
Link: https://lore.kernel.org/bpf/20240725214029.1760809-1-sdf@fomichev.me

selftests/bpf: Add more ring buffer test coverage

2024-06-24T11:43:55+00:00

Add test coverage for reservations beyond the ring buffer size in order
to validate that bpf_ringbuf_reserve() rejects the request with NULL, all
other ring buffer tests keep passing as well:

  # ./vmtest.sh -- ./test_progs -t ringbuf
  [...]
  ./test_progs -t ringbuf
  [    1.165434] bpf_testmod: loading out-of-tree module taints kernel.
  [    1.165825] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
  [    1.284001] tsc: Refined TSC clocksource calibration: 3407.982 MHz
  [    1.286871] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fc34e357, max_idle_ns: 440795379773 ns
  [    1.289555] clocksource: Switched to clocksource tsc
  #274/1   ringbuf/ringbuf:OK
  #274/2   ringbuf/ringbuf_n:OK
  #274/3   ringbuf/ringbuf_map_key:OK
  #274/4   ringbuf/ringbuf_write:OK
  #274     ringbuf:OK
  #275     ringbuf_multi:OK
  [...]

Signed-off-by: Daniel Borkmann 
Signed-off-by: Andrii Nakryiko 
[ Test fixups for getting BPF CI back to work ]
Signed-off-by: Daniel Borkmann 
Link: https://lore.kernel.org/bpf/20240621140828.18238-2-daniel@iogearbox.net

bpf: disable strict aliasing in test_global_func9.c

2024-05-13T00:30:15+00:00

The BPF selftest test_global_func9.c performs type punning and breaks
srict-aliasing rules.

In particular, given:

  int global_func9(struct __sk_buff *skb)
  {
	int result = 0;

	[...]
	{
		const struct C c = {.x = skb->len, .y = skb->family };

		result |= foo((const struct S *)&c);
	}
  }

When building with strict-aliasing enabled (the default) the
initialization of `c' gets optimized away in its entirely:

	[... no initialization of `c' ...]
	r1 = r10
	r1 += -40
	call	foo
	w0 |= w6

Since GCC knows that `foo' accesses s->x, we get a "maybe
uninitialized" warning.

On the other hand, when strict-aliasing is disabled GCC only optimizes
away the store to `.y':

	r1 = *(u32 *) (r6+0)
	*(u32 *) (r10+-40) = r1  ; This is .x = skb->len in `c'
	r1 = r10
	r1 += -40
	call	foo
	w0 |= w6

In this case the warning is not emitted, because s-> is initialized.

This patch disables strict aliasing in this test when building with
GCC.  clang seems to not optimize this particular code even when
strict aliasing is enabled.

Tested in bpf-next master.

Signed-off-by: Jose E. Marchesi 
Cc: david.faust@oracle.com
Cc: cupertino.miranda@oracle.com
Cc: Yonghong Song 
Cc: Eduard Zingerman 
Link: https://lore.kernel.org/r/20240511212213.23418-1-jose.marchesi@oracle.com
Signed-off-by: Alexei Starovoitov

selftests/bpf: Retire test_sock_addr.(c|sh)

2024-05-13T00:10:42+00:00

Fully remove test_sock_addr.c and test_sock_addr.sh, as test coverage
has been fully moved to prog_tests/sock_addr.c.

Signed-off-by: Jordan Rife 
Link: https://lore.kernel.org/r/20240510190246.3247730-14-jrife@google.com
Signed-off-by: Alexei Starovoitov

selftests/bpf: Use start_server_addr in test_tcp_check_syncookie

2024-05-09T20:40:38+00:00

Include network_helpers.h in test_tcp_check_syncookie_user.c, use
public helper start_server_addr() in it instead of the local defined
function start_server(). This can avoid duplicate code.

Add two helpers v6only_true() and v6only_false() to set IPV6_V6ONLY
sockopt to true or false, set them to post_socket_cb pointer of struct
network_helper_opts, and pass it to start_server_setsockopt().

In order to use functions defined in network_helpers.c, Makefile needs
to be updated too.

Signed-off-by: Geliang Tang 
Link: https://lore.kernel.org/r/e0c5324f5da84f453f47543536e70f126eaa8678.1714907662.git.tanggeliang@kylinos.cn
Signed-off-by: Martin KaFai Lau

bpf: avoid UB in usages of the __imm_insn macro

2024-05-08T16:56:30+00:00

[Changes from V2:
 - no-strict-aliasing is only applied when building with GCC.
 - cpumask_failure.c is excluded, as it doesn't use __imm_insn.]

The __imm_insn macro is defined in bpf_misc.h as:

  #define __imm_insn(name, expr) [name]"i"(*(long *)&(expr))

This may lead to type-punning and strict aliasing rules violations in
it's typical usage where the address of a struct bpf_insn is passed as
expr, like in:

  __imm_insn(st_mem,
             BPF_ST_MEM(BPF_W, BPF_REG_1, offsetof(struct __sk_buff, mark), 42))

Where:

  #define BPF_ST_MEM(SIZE, DST, OFF, IMM)				\
	((struct bpf_insn) {					\
		.code  = BPF_ST | BPF_SIZE(SIZE) | BPF_MEM,	\
		.dst_reg = DST,					\
		.src_reg = 0,					\
		.off   = OFF,					\
		.imm   = IMM })

In all the actual instances of this in the BPF selftests the value is
fed to a volatile asm statement as soon as it gets read from memory,
and thus it is unlikely anti-aliasing rules breakage may lead to
misguided optimizations.

However, GCC detects the potential problem (indirectly) by issuing a
warning stating that a temporary  is used uninitialized,
where the temporary corresponds to the memory read by *(long *).

This patch adds -fno-strict-aliasing to the compilation flags of the
particular selftests that do type punning via __imm_insn, only for
GCC.

Tested in master bpf-next.
No regressions.

Signed-off-by: Jose E. Marchesi 
Cc: david.faust@oracle.com
Cc: cupertino.miranda@oracle.com
Cc: Yonghong Song 
Cc: Eduard Zingerman 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/r/20240508103551.14955-1-jose.marchesi@oracle.com
Signed-off-by: Alexei Starovoitov

selftests/bpf: Add CFLAGS per source file and runner

2024-05-07T21:41:00+00:00

This patch adds support to specify CFLAGS per source file and per test
runner.

Signed-off-by: Cupertino Miranda 
Signed-off-by: Andrii Nakryiko 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20240507122220.207820-2-cupertino.miranda@oracle.com

bpf: Temporarily define BPF_NO_PRESEVE_ACCESS_INDEX for GCC

2024-05-07T21:40:00+00:00

The vmlinux.h file generated by bpftool makes use of compiler pragmas
in order to install the CO-RE preserve_access_index in all the struct
types derived from the BTF info:

  #ifndef __VMLINUX_H__
  #define __VMLINUX_H__

  #ifndef BPF_NO_PRESERVE_ACCESS_INDEX
  #pragma clang attribute push (__attribute__((preserve_access_index)), apply_t = record
  #endif

  [... type definitions generated from kernel BTF ... ]

  #ifndef BPF_NO_PRESERVE_ACCESS_INDEX
  #pragma clang attribute pop
  #endif

The `clang attribute push/pop' pragmas are specific to clang/llvm and
are not supported by GCC.

At the moment the BTF dumping services in libbpf do not support
dicriminating between types dumped because they are directly referred
and types dumped because they are dependencies.  A suitable API is
being worked now. See [1] and [2].

In the interim, this patch changes the selftests/bpf Makefile so it
passes -DBPF_NO_PRESERVE_ACCESS_INDEX to GCC when it builds the
selftests.  This workaround is temporary, and may have an impact on
the results of the GCC-built tests.

[1] https://lore.kernel.org/bpf/20240503111836.25275-1-jose.marchesi@oracle.com/T/#u
[2] https://lore.kernel.org/bpf/20240504205510.24785-1-jose.marchesi@oracle.com/T/#u

Tested in bpf-next master.
No regressions.

Signed-off-by: Jose E. Marchesi 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20240507095011.15867-1-jose.marchesi@oracle.com

bpf: Disable some `attribute ignored' warnings in GCC

2024-05-07T21:31:20+00:00

This patch modifies selftests/bpf/Makefile to pass -Wno-attributes to
GCC.  This is because of the following attributes which are ignored:

- btf_decl_tag
- btf_type_tag

  There are many of these.  At the moment none of these are
  recognized/handled by gcc-bpf.

  We are aware that btf_decl_tag is necessary for some of the
  selftest harness to communicate test failure/success.  Support for
  it is in progress in GCC upstream:

  https://gcc.gnu.org/pipermail/gcc-patches/2024-May/650482.html

  However, the GCC master branch is not yet open, so the series
  above (currently under review upstream) wont be able to make it
  there until 14.1 gets released, probably mid next week.

  As for btf_type_tag, more extensive work will be needed in GCC
  upstream to support it in both BTF and DWARF.  We have a WIP big
  patch for that, but that is not needed to compile/build the
  selftests.

- used

  There are SEC macros defined in the selftests as:

  #define SEC(N) __attribute__((section(N),used))

  The SEC macro is used for both functions and global variables.
  According to the GCC documentation `used' attribute is really only
  meaningful for functions, and it warns when the attribute is used
  for other global objects, like for example ctl_array in
  test_xdp_noinline.c.

  Ignoring this is benign.

- align_value

  In progs/test_cls_redirect.c:127 there is:

  typedef uint8_t *net_ptr __attribute__((align_value(8)));

  GCC warns that it is ignoring this attribute, because it is not
  implemented by GCC.

  I think ignoring this attribute in GCC is benign, because according
  to the clang documentation [1] its purpose seems to be merely
  declarative and doesn't seem to translate into extra checks at
  run-time, only to perhaps better optimized code ("runtime behavior
  is undefined if the pointed memory object is not aligned to the
  specified alignment").

  [1] https://clang.llvm.org/docs/AttributeReference.html#align-value

Tested in bpf-next master.

Signed-off-by: Jose E. Marchesi 
Signed-off-by: Andrii Nakryiko 
Acked-by: Yonghong Song 
Link: https://lore.kernel.org/bpf/20240507074227.4523-3-jose.marchesi@oracle.com

bpf: Missing trailing slash in tools/testing/selftests/bpf/Makefile

2024-05-02T16:22:01+00:00

tools/lib/bpf/Makefile assumes that the patch in OUTPUT is a directory
and that it includes a trailing slash.  This seems to be a common
expectation for OUTPUT among all the Makefiles.

In the rule for runqslower in tools/testing/selftests/bpf/Makefile the
variable BPFTOOL_OUTPUT is set to a directory name that lacks a
trailing slash.  This results in a malformed BPF_HELPER_DEFS being
defined in lib/bpf/Makefile.

This problem becomes evident when a file like
tools/lib/bpf/bpf_tracing.h gets updated.

This patch fixes the problem by adding the missing slash in the value
for BPFTOOL_OUTPUT in the $(OUTPUT)/runqslower rule.

Regtested by running selftests in bpf-next master and building
samples/bpf programs.

Signed-off-by: Jose E. Marchesi 
Signed-off-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/20240502140831.23915-1-jose.marchesi@oracle.com