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Mon, 1 Jul 2024 13:34:41 GMT Received: from smtprelay07.fra02v.mail.ibm.com ([9.218.2.229]) by ppma12.dal12v.mail.ibm.com (PPS) with ESMTPS id 402vktypwj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 01 Jul 2024 13:34:41 +0000 Received: from smtpav01.fra02v.mail.ibm.com (smtpav01.fra02v.mail.ibm.com [10.20.54.100]) by smtprelay07.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 461DYZZR52625802 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 1 Jul 2024 13:34:37 GMT Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BB1762004E; Mon, 1 Jul 2024 13:34:35 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 428BE20040; Mon, 1 Jul 2024 13:34:35 +0000 (GMT) Received: from heavy.ibm.com (unknown [9.179.5.21]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 1 Jul 2024 13:34:35 +0000 (GMT) From: Ilya Leoshkevich To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: bpf@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Ilya Leoshkevich Subject: [PATCH bpf-next v2 02/11] s390/bpf: Factor out emitting probe nops Date: Mon, 1 Jul 2024 15:24:40 +0200 Message-ID: <20240701133432.3883-3-iii@linux.ibm.com> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240701133432.3883-1-iii@linux.ibm.com> References: <20240701133432.3883-1-iii@linux.ibm.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: N8I2qQW25-6P7OT0FwZp_GvR8oB79LRt X-Proofpoint-ORIG-GUID: N8I2qQW25-6P7OT0FwZp_GvR8oB79LRt X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.28.16 definitions=2024-07-01_12,2024-06-28_01,2024-05-17_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 suspectscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 mlxlogscore=999 adultscore=0 phishscore=0 bulkscore=0 malwarescore=0 spamscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2406140001 definitions=main-2407010103 X-Patchwork-Delegate: bpf@iogearbox.net The upcoming arena support for the loop-based BPF_XCHG implementation requires emitting nop and extable entries separately. Move nop handling into a separate function, and keep track of the nop offset. Signed-off-by: Ilya Leoshkevich --- arch/s390/net/bpf_jit_comp.c | 62 +++++++++++++++++++++++------------- 1 file changed, 40 insertions(+), 22 deletions(-) diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c index 4be8f5cadd02..260e7009784b 100644 --- a/arch/s390/net/bpf_jit_comp.c +++ b/arch/s390/net/bpf_jit_comp.c @@ -693,24 +693,52 @@ bool ex_handler_bpf(const struct exception_table_entry *x, struct pt_regs *regs) return true; } +/* + * A single BPF probe instruction + */ +struct bpf_jit_probe { + int prg; /* JITed instruction offset */ + int nop_prg; /* JITed nop offset */ +}; + +static void bpf_jit_probe_init(struct bpf_jit_probe *probe) +{ + probe->prg = -1; + probe->nop_prg = -1; +} + +/* + * Handlers of certain exceptions leave psw.addr pointing to the instruction + * directly after the failing one. Therefore, create two exception table + * entries and also add a nop in case two probing instructions come directly + * after each other. + */ +static void bpf_jit_probe_emit_nop(struct bpf_jit *jit, + struct bpf_jit_probe *probe) +{ + probe->nop_prg = jit->prg; + /* bcr 0,%0 */ + _EMIT2(0x0700); +} + static int bpf_jit_probe_mem(struct bpf_jit *jit, struct bpf_prog *fp, - int probe_prg, int nop_prg) + struct bpf_jit_probe *probe) { struct exception_table_entry *ex; - int reg, prg; + int i, prg, reg; s64 delta; u8 *insn; - int i; + bpf_jit_probe_emit_nop(jit, probe); if (!fp->aux->extable) /* Do nothing during early JIT passes. */ return 0; - insn = jit->prg_buf + probe_prg; + insn = jit->prg_buf + probe->prg; reg = get_probe_mem_regno(insn); if (WARN_ON_ONCE(reg < 0)) /* JIT bug - unexpected probe instruction. */ return -1; - if (WARN_ON_ONCE(probe_prg + insn_length(*insn) != nop_prg)) + if (WARN_ON_ONCE(probe->prg + insn_length(*insn) != probe->nop_prg)) /* JIT bug - gap between probe and nop instructions. */ return -1; for (i = 0; i < 2; i++) { @@ -719,7 +747,7 @@ static int bpf_jit_probe_mem(struct bpf_jit *jit, struct bpf_prog *fp, return -1; ex = &fp->aux->extable[jit->excnt]; /* Add extable entries for probe and nop instructions. */ - prg = i == 0 ? probe_prg : nop_prg; + prg = i == 0 ? probe->prg : probe->nop_prg; delta = jit->prg_buf + prg - (u8 *)&ex->insn; if (WARN_ON_ONCE(delta < INT_MIN || delta > INT_MAX)) /* JIT bug - code and extable must be close. */ @@ -729,7 +757,7 @@ static int bpf_jit_probe_mem(struct bpf_jit *jit, struct bpf_prog *fp, * Always land on the nop. Note that extable infrastructure * ignores fixup field, it is handled by ex_handler_bpf(). */ - delta = jit->prg_buf + nop_prg - (u8 *)&ex->fixup; + delta = jit->prg_buf + probe->nop_prg - (u8 *)&ex->fixup; if (WARN_ON_ONCE(delta < INT_MIN || delta > INT_MAX)) /* JIT bug - landing pad and extable must be close. */ return -1; @@ -782,19 +810,19 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, s32 branch_oc_off = insn->off; u32 dst_reg = insn->dst_reg; u32 src_reg = insn->src_reg; + struct bpf_jit_probe probe; int last, insn_count = 1; u32 *addrs = jit->addrs; s32 imm = insn->imm; s16 off = insn->off; - int probe_prg = -1; unsigned int mask; - int nop_prg; int err; + bpf_jit_probe_init(&probe); if (BPF_CLASS(insn->code) == BPF_LDX && (BPF_MODE(insn->code) == BPF_PROBE_MEM || BPF_MODE(insn->code) == BPF_PROBE_MEMSX)) - probe_prg = jit->prg; + probe.prg = jit->prg; switch (insn->code) { /* @@ -1897,18 +1925,8 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, return -1; } - if (probe_prg != -1) { - /* - * Handlers of certain exceptions leave psw.addr pointing to - * the instruction directly after the failing one. Therefore, - * create two exception table entries and also add a nop in - * case two probing instructions come directly after each - * other. - */ - nop_prg = jit->prg; - /* bcr 0,%0 */ - _EMIT2(0x0700); - err = bpf_jit_probe_mem(jit, fp, probe_prg, nop_prg); + if (probe.prg != -1) { + err = bpf_jit_probe_mem(jit, fp, &probe); if (err < 0) return err; }