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Tue, 5 Aug 2025 06:28:39 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 1BC2020043; Tue, 5 Aug 2025 06:28:39 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6329920040; Tue, 5 Aug 2025 06:28:32 +0000 (GMT) Received: from li-621bac4c-27c7-11b2-a85c-c2bf7c4b3c07.ibm.com.com (unknown [9.43.39.141]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 5 Aug 2025 06:28:32 +0000 (GMT) From: Saket Kumar Bhaskar To: bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Cc: hbathini@linux.ibm.com, sachinpb@linux.ibm.com, venkat88@linux.ibm.com, andrii@kernel.org, eddyz87@gmail.com, mykolal@fb.com, ast@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, christophe.leroy@csgroup.eu, naveen@kernel.org, maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, memxor@gmail.com, iii@linux.ibm.com, shuah@kernel.org Subject: [bpf-next 5/6] bpf,powerpc: Implement PROBE_ATOMIC instructions Date: Tue, 5 Aug 2025 11:57:46 +0530 Message-ID: <20250805062747.3479221-6-skb99@linux.ibm.com> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20250805062747.3479221-1-skb99@linux.ibm.com> References: <20250805062747.3479221-1-skb99@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-GUID: cMapiujoCaDYWPc6M9nlonA3aMn4IR7W X-Authority-Analysis: v=2.4 cv=M65NKzws c=1 sm=1 tr=0 ts=6891a49c cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=2OwXVqhp2XgA:10 a=VnNF1IyMAAAA:8 a=I9DJoMOgBESJXZyRRMQA:9 X-Proofpoint-ORIG-GUID: DOHj20Ewu0d5mY2NQXm-zlLvBjAbqg4q X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODA1MDA0NSBTYWx0ZWRfX2QrxuUck/E// pm7s8+xq1uWVnBtf9t2bH3Kneh1Bb63rmsIOD95BH3gxQM+Pc985+bb4HndNDkwTmGoqgOrPYxG d8qMdGKj9ZW8g5LayUOuDwk+aH+9CgBlhMnGAoQJdC3APy0CEx9TDnCZUMX892mP0ttHd2Anw/Y q8pRZZNbXMXxGCpvx5L4f49ZitFtvg8O68weQmLnQG35tXVqRC5i+Ee8mgKpwtvPKm/ynXAP1yD k1k9m8Qzzof2ScW/OKUK5b3jse/IA1yan1hMezltVPHRfnfJu0YAHjxw2J/fdiLacrS8k3B3tq7 voPGUfbsFyf753FSWqkC+282qbFYnRDi5p8lMhbnXd0PHmNEl9nrix1kuA2UYVtLVs7psBpSXIz eKn5+1b8ZzjWGndjbnWLt3xTLqo341TKynpYzdomYdeFDVSkF6OlFdODY8qpy6MY2HKcte0y X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-05_01,2025-08-04_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 malwarescore=0 spamscore=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 clxscore=1015 mlxscore=0 phishscore=0 priorityscore=1501 mlxlogscore=896 adultscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2508050045 Content-Type: text/plain; charset="utf-8" powerpc supports BPF atomic operations using a loop around Load-And-Reserve(LDARX/LWARX) and Store-Conditional(STDCX/STWCX) instructions gated by sync instructions to enforce full ordering. To implement arena_atomics, arena vm start address is added to the dst_reg to be used for both the LDARX/LWARX and STDCX/STWCX instructions. Further, an exception table entry is added for LDARX/LWARX instruction to land after the loop on fault. At the end of sequence, dst_reg is restored by subtracting arena vm start address. bpf_jit_supports_insn() is introduced to selectively enable instruction support as in other architectures like x86 and arm64. Signed-off-by: Saket Kumar Bhaskar --- arch/powerpc/net/bpf_jit_comp.c | 16 ++++++++++++++++ arch/powerpc/net/bpf_jit_comp64.c | 26 ++++++++++++++++++++++++++ 2 files changed, 42 insertions(+) diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_com= p.c index 2b3f90930c27..69232ee56c6a 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -452,6 +452,22 @@ bool bpf_jit_supports_far_kfunc_call(void) return IS_ENABLED(CONFIG_PPC64); } =20 +bool bpf_jit_supports_insn(struct bpf_insn *insn, bool in_arena) +{ + if (!in_arena) + return true; + switch (insn->code) { + case BPF_STX | BPF_ATOMIC | BPF_H: + case BPF_STX | BPF_ATOMIC | BPF_B: + case BPF_STX | BPF_ATOMIC | BPF_W: + case BPF_STX | BPF_ATOMIC | BPF_DW: + if (bpf_atomic_is_load_store(insn)) + return false; + return IS_ENABLED(CONFIG_PPC64); + } + return true; +} + void *arch_alloc_bpf_trampoline(unsigned int size) { return bpf_prog_pack_alloc(size, bpf_jit_fill_ill_insns); diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_c= omp64.c index 6a85cd847075..8931bded97f4 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -1164,6 +1164,32 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *ima= ge, u32 *fimage, struct code =20 break; =20 + /* + * BPF_STX PROBE_ATOMIC (arena atomic ops) + */ + case BPF_STX | BPF_PROBE_ATOMIC | BPF_W: + case BPF_STX | BPF_PROBE_ATOMIC | BPF_DW: + EMIT(PPC_RAW_ADD(dst_reg, dst_reg, bpf_to_ppc(ARENA_VM_START))); + ret =3D bpf_jit_emit_atomic_ops(image, ctx, &insn[i], + &jmp_off, &tmp_idx, &addrs[i + 1]); + if (ret) { + if (ret =3D=3D -EOPNOTSUPP) { + pr_err_ratelimited( + "eBPF filter atomic op code %02x (@%d) unsupported\n", + code, i); + } + return ret; + } + /* LDARX/LWARX should land here on exception. */ + ret =3D bpf_add_extable_entry(fp, image, fimage, pass, ctx, + tmp_idx, jmp_off, dst_reg, code); + if (ret) + return ret; + + /* Retrieve the dst_reg */ + EMIT(PPC_RAW_SUB(dst_reg, dst_reg, bpf_to_ppc(ARENA_VM_START))); + break; + /* * BPF_STX ATOMIC (atomic ops) */ --=20 2.43.5