selftests/bpf: Add get_preempt_count() support for RISC-V

Currently, there is no RISC-V support for get_preempt_count() and
its fallback path always returns 0.

Add it so that bpf_in_interrupt(), bpf_in_nmi(), bpf_in_hardirq(),
bpf_in_serving_softirq(), and bpf_in_task() work for RISC-V as well.

Given that RISC-V has supported CONFIG_THREAD_INFO_IN_TASK since its
initial commit fbe934d69eb7 ("RISC-V: Build Infrastructure") in 2017,
directly retrieve preempt_count from the thread_info embedded within
task_struct via bpf_get_current_task_btf().

This aligns the implementation with arm64, powerpc, and loongarch.

Tested on a RISC-V virtual machine.

Before:
  $ sudo ./test_progs -t exe_ctx
  ...
  #114     exe_ctx:FAIL
  Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED

After:
  $ sudo ./test_progs -t exe_ctx
  #114     exe_ctx:OK
  Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Tested-by: Pu Lehui <pulehui@huawei.com>
Reviewed-by: Pu Lehui <pulehui@huawei.com>
Link: https://lore.kernel.org/bpf/20260722022906.8778-1-yangtiezhu@loongson.cn
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

0 files changed, 0 insertions, 0 deletions