Re: [PATCH bpf-next 1/3] bpf,s390: introduce emit_store_stack_imm64() for trampoline

Ilya Leoshkevich
2026-02-23T11:45:19Z

On 2/23/26 09:40, Menglong Dong wrote:
> Introduce a helper to store 64-bit immediate on the trampoline stack with
> a help of a register.
>
> Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
> ---
> arch/s390/net/bpf_jit_comp.c | 27 +++++++++++----------------
> 1 file changed, 11 insertions(+), 16 deletions(-)

[...]

> @@ -2743,18 +2747,9 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
> * arg_cnt = m->nr_args;
> */
>
> - if (flags & BPF_TRAMP_F_IP_ARG) {
> - /* %r0 = func_addr */
> - load_imm64(jit, REG_0, (u64)func_addr);
> - /* stg %r0,ip_off(%r15) */
> - EMIT6_DISP_LH(0xe3000000, 0x0024, REG_0, REG_0, REG_15,
> - tjit->ip_off);
> - }
> - /* lghi %r0,nr_bpf_args */
> - EMIT4_IMM(0xa7090000, REG_0, nr_bpf_args);

LGHI is more space-efficient than load_imm64(), can we keep it open-coded?

With this changed:

Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>