[PATCH bpf-next 2/2] bpf, riscv: inline bpf_get_current_task() and bpf_get_current_task_btf()

[Björn Töpel]

On Tue, 2 Jun 2026 at 22:59, Varun R Mallya <varunrmallya at gmail.com> wrote:
>
> On RISC-V, the current task pointer is stored in the thread pointer
> register (tp). Emit a single `mv a5, tp` instead of a full helper
> call for BPF_FUNC_get_current_task and BPF_FUNC_get_current_task_btf.
>
> Register bpf_jit_inlines_helper_call() entries for both helpers so the
> verifier treats them as inlined, and add the expected `mv a5, tp`
> annotation to the riscv64 selftests.
>
> The following show changes before and after this patch.
>
> Before patch:
>
>       auipc  t1,0x817a    # load upper PC-relative address
>       jalr   -2004(t1)    # call bpf_get_current_task helper
>       mv     a5,a0        # move return value to BPF_REG_0
>
> After patch:
>
>       mv     a5,tp        # directly: a5 = current (tp = thread pointer)
>
> Benchmark (bpf_prog_test_run wrapping bpf_get_current_task in loop,
> batch=100, 10s, QEMU RISC-V):
>
>               | runs/sec  | helper-calls/sec | ns/call
>  -------------+-----------+------------------+---------
>  Before patch |   173,490 |       17,349,090 |      57
>  After patch  |   320,497 |       32,049,780 |      31
>  -------------+-----------+------------------+---------
>  Improvement  |   +84.7%  |          +84.7%  |  -45.6%
>
> Signed-off-by: Varun R Mallya <varunrmallya at gmail.com>

Acked-by: Björn Töpel <bjorn at kernel.org>