selftests/bpf: Cope with 512 bytes limit with bpf_global_percpu_ma

In the previous patch, the maximum data size for bpf_global_percpu_ma
is 512 bytes. This breaks selftest test_bpf_ma. The test is adjusted
in two aspects:
- Since the maximum allowed data size for bpf_global_percpu_ma is
512, remove all tests beyond that, names sizes 1024, 2048 and 4096.
- Previously the percpu data size is bucket_size - 8 in order to
avoid percpu allocation into the next bucket. This patch removed
such data size adjustment thanks to Patch 1.

Also, a better way to generate BTF type is used than adding
a member to the value struct.

Acked-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231222031807.1292853-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

selftests/bpf: Attempt to build BPF programs with -Wsign-compare

GCC's -Wall includes -Wsign-compare while clang does not.
Since BPF programs are built with clang we need to add this flag explicitly
to catch problematic comparisons like:

int i = -1;
unsigned int j = 1;
if (i < j) // this is false.

long i = -1;
unsigned int j = 1;
if (i < j) // this is true.

C standard for reference:

- If either operand is unsigned long the other shall be converted to unsigned long.

- Otherwise, if one operand is a long int and the other unsigned int, then if a
long int can represent all the values of an unsigned int, the unsigned int
shall be converted to a long int; otherwise both operands shall be converted to
unsigned long int.

- Otherwise, if either operand is long, the other shall be converted to long.

- Otherwise, if either operand is unsigned, the other shall be converted to unsigned.

Unfortunately clang's -Wsign-compare is very noisy.
It complains about (s32)a == (u32)b which is safe and doen't have surprising behavior.

This patch fixes some of the issues. It needs a follow up to fix the rest.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20231226191148.48536-2-alexei.starovoitov@gmail.com

selftests/bpf: Remove tests for zeroed-array kptr

bpf_mem_alloc() doesn't support zero-sized allocation, so removing these
tests from test_bpf_ma test. After the removal, there will no definition
for bin_data_8, so remove 8 from data_sizes array and adjust the index
of data_btf_ids array in all test cases accordingly.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231216131052.27621-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

selftests/bpf: Add more test cases for bpf memory allocator

Add the following 3 test cases for bpf memory allocator:
1) Do allocation in bpf program and free through map free
2) Do batch per-cpu allocation and per-cpu free in bpf program
3) Do per-cpu allocation in bpf program and free through map free

For per-cpu allocation, because per-cpu allocation can not refill timely
sometimes, so test 2) and test 3) consider it is OK for
bpf_percpu_obj_new_impl() to return NULL.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231020133202.4043247-8-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

selftests/bpf: Test all valid alloc sizes for bpf mem allocator

Add a test to test all possible and valid allocation size for bpf
memory allocator. For each possible allocation size, the test uses
the following two steps to test the alloc and free path:

1) allocate N (N > high_watermark) objects to trigger the refill
executed in irq_work.
2) free N objects to trigger the freeing executed in irq_work.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230908133923.2675053-5-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>