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Tue, 14 Apr 2026 14:29:31 +0000 (GMT) From: Maxim Khmelevskii To: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann Cc: bpf@vger.kernel.org, Ilya Leoshkevich , Heiko Carstens , Vasily Gorbik , Alexander Gordeev Subject: [PATCH bpf-next] s390/bpf: inline smp_processor_id and current_task Date: Tue, 14 Apr 2026 16:29:26 +0200 Message-ID: <20260414142930.528751-1-max@linux.ibm.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDE0MDEzNCBTYWx0ZWRfX0IN6RLOTCZ8y 2sBaWW50O+mbko41o95tba84mR1bcDQCHmGXm8M4tLNshiswRdKLw7s31lzQ5V5qjzrpkfOQWuR QhwZyJnAs2S5GpdyNec3LmXEJ/whWy8WYuYD/wyTfSrTmScqP9sCpUVXjZXNF6l1s4KC7pPabFA N9FDC5yZLyRy+l6+PPiLdj3rBPmSbcIZfTpkekPBUev49kF1FJStjMxBMb6RCSVHASs8Pyinyjz mQI6qa9/fu9FY/OnDt0SPun/VsJxhgcp4PZYxmlAL5JYBpNh/+opzWae4/IKZQnfD8oWdLHUM46 NBCg0bc12FaOAlEqIq78WDjpKIgCZhwZ1zNnOwNzRPfRybid/ONL+lVfuV5O5OexKgmEk4MYOzX w08InAvhvKBRrMaS0JIcQRL39Nx2JOKd8wwT35qe4CDcL4QCWuNmgDxGkRj7m1dIMOMqE21nDdl WvRXqeUwh0dbh+8FOIQ== X-Authority-Analysis: v=2.4 cv=eJ4jSnp1 c=1 sm=1 tr=0 ts=69de4f50 cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=NEAV23lmAAAA:8 a=VnNF1IyMAAAA:8 a=xk9cym82weemkfCegS0A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-GUID: Mnc2js8KdH3KEWTsikY5JMl_lK_7U-mV X-Proofpoint-ORIG-GUID: Mnc2js8KdH3KEWTsikY5JMl_lK_7U-mV X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-14_03,2026-04-13_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 lowpriorityscore=0 adultscore=0 priorityscore=1501 clxscore=1011 bulkscore=0 suspectscore=0 spamscore=0 impostorscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604070000 definitions=main-2604140134 Inline these calls in bpf jit: - bpf_get_smp_processor_id() - bpf_get_current_task() - bpf_get_current_task_btf() s390 has a 8 KiB per-CPU prefix area in the CPU's virtual address space, called the lowcore. It is a struct that contains the cpu number and a pointer to the current task. These are exactly the values returned by the BPF helpers. Emit a load from the lowcore instead of a helper function call. JIT output for `bpf_get_smp_processor_id`: Before: After: --------------- ---------------- brasl %r14,0x3ffe0385460 ly %r14,928 lgr %r14,%r2 JIT output for `bpf_get_current_task`: Before: After: --------------- ---------------- brasl %r14,0x3ffe0362a90 lg %r14,832 lgr %r14,%r2 Benchmark using [1] on KVM(virtme-ng). ./benchs/run_bench_trigger.sh glob-arr-inc arr-inc hash-inc +---------------+--------------------+--------------------+--------------+ | Name | Before | After | % change | |---------------+--------------------+--------------------+--------------| | glob-arr-inc | 244.954 ± 0.654M/s | 278.501 ± 0.834M/s | + 13.70% | | arr-inc | 311.597 ± 1.016M/s | 313.610 ± 0.331M/s | + 0.65% | | hash-inc | 47.421 ± 0.017M/s | 47.600 ± 0.004M/s | + 0.38% | +---------------+--------------------+--------------------+--------------+ [1] https://github.com/anakryiko/linux/commit/8dec900975ef Signed-off-by: Maxim Khmelevskii Reviewed-by: Ilya Leoshkevich --- arch/s390/net/bpf_jit_comp.c | 37 ++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index d08d159b6319..93ab2fb16b99 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include #include @@ -1777,6 +1778,30 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int j, ret; u64 func; + /* Implement helper call to bpf_get_smp_processor_id() inline */ + if (insn->src_reg == 0 && + insn->imm == BPF_FUNC_get_smp_processor_id) { + const u32 *cpu_nr = &get_lowcore()->cpu_nr; + + /* ly %b0, cpu_nr */ + EMIT6_DISP_LH(0xe3000000, 0x0058, BPF_REG_0, REG_0, REG_0, + (unsigned long)cpu_nr); + break; + } + + /* Implement helper call to bpf_get_current_task/_btf() inline */ + if (insn->src_reg == 0 && + (insn->imm == BPF_FUNC_get_current_task || + insn->imm == BPF_FUNC_get_current_task_btf)) { + const u64 *current_task = + &get_lowcore()->current_task; + + /* lg %b0, current_task */ + EMIT6_DISP_LH(0xe3000000, 0x0004, BPF_REG_0, REG_0, REG_0, + (unsigned long)current_task); + break; + } + ret = bpf_jit_get_func_addr(fp, insn, extra_pass, &func, &func_addr_fixed); if (ret < 0) @@ -3076,3 +3101,15 @@ bool bpf_jit_supports_timed_may_goto(void) { return true; } + +bool bpf_jit_inlines_helper_call(s32 imm) +{ + switch (imm) { + case BPF_FUNC_get_smp_processor_id: + case BPF_FUNC_get_current_task: + case BPF_FUNC_get_current_task_btf: + return true; + default: + return false; + } +} -- 2.53.0