selftests/bpf: More open-coded gettid syscall cleanup

Commit 0e2fb011a0ba ("selftests/bpf: Clean up open-coded gettid syscall
invocations") addressed the issue that older libc may not have a gettid(

selftests/bpf: More open-coded gettid syscall cleanup

Commit 0e2fb011a0ba ("selftests/bpf: Clean up open-coded gettid syscall
invocations") addressed the issue that older libc may not have a gettid()
function call wrapper for the associated syscall.

A few more instances have crept into tests, use sys_gettid() instead, and
poison raw gettid() usage to avoid future issues.

Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20250911163056.543071-1-alan.maguire@oracle.com

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selftests/bpf: Test concurrent task local data key creation

Test thread-safety of tld_create_key(). Since tld_create_key() does
not rely on locks but memory barriers and atomic operations to protect

selftests/bpf: Test concurrent task local data key creation

Test thread-safety of tld_create_key(). Since tld_create_key() does
not rely on locks but memory barriers and atomic operations to protect
the shared metadata, the thread-safety of the function is non-trivial.
Make sure concurrent tld_key_create(), both valid and invalid, can not
race and corrupt metatada, which may leads to TLDs not being thread-
specific or duplicate TLDs with the same name.

Signed-off-by: Amery Hung <ameryhung@gmail.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20250730185903.3574598-5-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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selftests/bpf: Test basic task local data operations

Test basic operations of task local data with valid and invalid
tld_create_key().

For invalid calls, make sure they return the right error code

selftests/bpf: Test basic task local data operations

Test basic operations of task local data with valid and invalid
tld_create_key().

For invalid calls, make sure they return the right error code and check
that the TLDs are not inserted by running tld_get_data("
value_not_exists") on the bpf side. The call should a null pointer.

For valid calls, first make sure the TLDs are created by calling
tld_get_data() on the bpf side. The call should return a valid pointer.

Finally, verify that the TLDs are indeed task-specific (i.e., their
addresses do not overlap) with multiple user threads. This done by
writing values unique to each thread, reading them from both user space
and bpf, and checking if the value read back matches the value written.

Signed-off-by: Amery Hung <ameryhung@gmail.com>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20250730185903.3574598-4-ameryhung@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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