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Wed, 15 Feb 2023 23:59:39 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 5098620043; Wed, 15 Feb 2023 23:59:39 +0000 (GMT) Received: from heavy.boeblingen.de.ibm.com (unknown [9.179.4.133]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 15 Feb 2023 23:59:39 +0000 (GMT) From: Ilya Leoshkevich To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: bpf@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Jiri Olsa , Stanislav Fomichev , Ilya Leoshkevich Subject: [PATCH RFC bpf-next v2 4/4] bpf: Support 64-bit pointers to kfuncs Date: Thu, 16 Feb 2023 00:59:31 +0100 Message-Id: <20230215235931.380197-5-iii@linux.ibm.com> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230215235931.380197-1-iii@linux.ibm.com> References: <20230215235931.380197-1-iii@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: wjO52fAn_hpiVNaphz09jFzEBafAPmsU X-Proofpoint-ORIG-GUID: q6XqboKw0RQGimIICYCaoNDgsBzAutGz X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.930,Hydra:6.0.562,FMLib:17.11.170.22 definitions=2023-02-15_14,2023-02-15_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 mlxlogscore=999 clxscore=1015 phishscore=0 malwarescore=0 lowpriorityscore=0 impostorscore=0 adultscore=0 mlxscore=0 spamscore=0 bulkscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2302150197 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net X-Patchwork-State: RFC test_ksyms_module fails to emit a kfunc call targeting a module on s390x, because the verifier stores the difference between kfunc address and __bpf_call_base in bpf_insn.imm, which is s32, and modules are roughly (1 << 42) bytes away from the kernel on s390x. Fix by keeping BTF id in bpf_insn.imm for BPF_PSEUDO_KFUNC_CALLs, and storing the absolute address in bpf_kfunc_desc, which JITs retrieve as usual by calling bpf_jit_get_func_addr(). Introduce bpf_get_kfunc_addr() instead of exposing both find_kfunc_desc() and struct bpf_kfunc_desc. This also fixes the problem with XDP metadata functions outlined in the description of commit 63d7b53ab59f ("s390/bpf: Implement bpf_jit_supports_kfunc_call()") by replacing address lookups with BTF id lookups. This eliminates the inconsistency between "abstract" XDP metadata functions' BTF ids and their concrete addresses. Signed-off-by: Ilya Leoshkevich --- include/linux/bpf.h | 2 ++ kernel/bpf/core.c | 21 ++++++++++-- kernel/bpf/verifier.c | 79 +++++++++++++------------------------------ 3 files changed, 44 insertions(+), 58 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index be34f7deb6c3..83ce94d11484 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2227,6 +2227,8 @@ bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog); const struct btf_func_model * bpf_jit_find_kfunc_model(const struct bpf_prog *prog, const struct bpf_insn *insn); +int bpf_get_kfunc_addr(const struct bpf_prog *prog, u32 func_id, u16 offset, + u8 **func_addr); struct bpf_core_ctx { struct bpf_verifier_log *log; const struct btf *btf; diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 3390961c4e10..3644b90650b4 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1185,10 +1185,12 @@ int bpf_jit_get_func_addr(const struct bpf_prog *prog, { s16 off = insn->off; s32 imm = insn->imm; + bool fixed; u8 *addr; + int err; - *func_addr_fixed = insn->src_reg != BPF_PSEUDO_CALL; - if (!*func_addr_fixed) { + switch (insn->src_reg) { + case BPF_PSEUDO_CALL: /* Place-holder address till the last pass has collected * all addresses for JITed subprograms in which case we * can pick them up from prog->aux. @@ -1200,15 +1202,28 @@ int bpf_jit_get_func_addr(const struct bpf_prog *prog, addr = (u8 *)prog->aux->func[off]->bpf_func; else return -EINVAL; - } else { + fixed = false; + break; + case BPF_HELPER_CALL: /* Address of a BPF helper call. Since part of the core * kernel, it's always at a fixed location. __bpf_call_base * and the helper with imm relative to it are both in core * kernel. */ addr = (u8 *)__bpf_call_base + imm; + fixed = true; + break; + case BPF_PSEUDO_KFUNC_CALL: + err = bpf_get_kfunc_addr(prog, imm, off, &addr); + if (err) + return err; + fixed = true; + break; + default: + return -EINVAL; } + *func_addr_fixed = fixed; *func_addr = (unsigned long)addr; return 0; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 71158a6786a1..47d390923610 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2115,8 +2115,8 @@ static int add_subprog(struct bpf_verifier_env *env, int off) struct bpf_kfunc_desc { struct btf_func_model func_model; u32 func_id; - s32 imm; u16 offset; + unsigned long addr; }; struct bpf_kfunc_btf { @@ -2166,6 +2166,19 @@ find_kfunc_desc(const struct bpf_prog *prog, u32 func_id, u16 offset) sizeof(tab->descs[0]), kfunc_desc_cmp_by_id_off); } +int bpf_get_kfunc_addr(const struct bpf_prog *prog, u32 func_id, u16 offset, + u8 **func_addr) +{ + const struct bpf_kfunc_desc *desc; + + desc = find_kfunc_desc(prog, func_id, offset); + if (!desc) + return -EFAULT; + + *func_addr = (u8 *)desc->addr; + return 0; +} + static struct btf *__find_kfunc_desc_btf(struct bpf_verifier_env *env, s16 offset) { @@ -2261,8 +2274,8 @@ static int add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, s16 offset) struct bpf_kfunc_desc *desc; const char *func_name; struct btf *desc_btf; - unsigned long call_imm; unsigned long addr; + void *xdp_kfunc; int err; prog_aux = env->prog->aux; @@ -2346,24 +2359,21 @@ static int add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, s16 offset) return -EINVAL; } - call_imm = BPF_CALL_IMM(addr); - /* Check whether or not the relative offset overflows desc->imm */ - if ((unsigned long)(s32)call_imm != call_imm) { - verbose(env, "address of kernel function %s is out of range\n", - func_name); - return -EINVAL; - } - if (bpf_dev_bound_kfunc_id(func_id)) { err = bpf_dev_bound_kfunc_check(&env->log, prog_aux); if (err) return err; + + xdp_kfunc = bpf_dev_bound_resolve_kfunc(env->prog, func_id); + if (xdp_kfunc) + addr = (unsigned long)xdp_kfunc; + /* fallback to default kfunc when not supported by netdev */ } desc = &tab->descs[tab->nr_descs++]; desc->func_id = func_id; - desc->imm = call_imm; desc->offset = offset; + desc->addr = addr; err = btf_distill_func_proto(&env->log, desc_btf, func_proto, func_name, &desc->func_model); @@ -2373,30 +2383,6 @@ static int add_kfunc_call(struct bpf_verifier_env *env, u32 func_id, s16 offset) return err; } -static int kfunc_desc_cmp_by_imm(const void *a, const void *b) -{ - const struct bpf_kfunc_desc *d0 = a; - const struct bpf_kfunc_desc *d1 = b; - - if (d0->imm > d1->imm) - return 1; - else if (d0->imm < d1->imm) - return -1; - return 0; -} - -static void sort_kfunc_descs_by_imm(struct bpf_prog *prog) -{ - struct bpf_kfunc_desc_tab *tab; - - tab = prog->aux->kfunc_tab; - if (!tab) - return; - - sort(tab->descs, tab->nr_descs, sizeof(tab->descs[0]), - kfunc_desc_cmp_by_imm, NULL); -} - bool bpf_prog_has_kfunc_call(const struct bpf_prog *prog) { return !!prog->aux->kfunc_tab; @@ -2407,14 +2393,15 @@ bpf_jit_find_kfunc_model(const struct bpf_prog *prog, const struct bpf_insn *insn) { const struct bpf_kfunc_desc desc = { - .imm = insn->imm, + .func_id = insn->imm, + .offset = insn->off, }; const struct bpf_kfunc_desc *res; struct bpf_kfunc_desc_tab *tab; tab = prog->aux->kfunc_tab; res = bsearch(&desc, tab->descs, tab->nr_descs, - sizeof(tab->descs[0]), kfunc_desc_cmp_by_imm); + sizeof(tab->descs[0]), kfunc_desc_cmp_by_id_off); return res ? &res->func_model : NULL; } @@ -16269,7 +16256,6 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, struct bpf_insn *insn_buf, int insn_idx, int *cnt) { const struct bpf_kfunc_desc *desc; - void *xdp_kfunc; if (!insn->imm) { verbose(env, "invalid kernel function call not eliminated in verifier pass\n"); @@ -16277,20 +16263,6 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, } *cnt = 0; - - if (bpf_dev_bound_kfunc_id(insn->imm)) { - xdp_kfunc = bpf_dev_bound_resolve_kfunc(env->prog, insn->imm); - if (xdp_kfunc) { - insn->imm = BPF_CALL_IMM(xdp_kfunc); - return 0; - } - - /* fallback to default kfunc when not supported by netdev */ - } - - /* insn->imm has the btf func_id. Replace it with - * an address (relative to __bpf_call_base). - */ desc = find_kfunc_desc(env->prog, insn->imm, insn->off); if (!desc) { verbose(env, "verifier internal error: kernel function descriptor not found for func_id %u\n", @@ -16298,7 +16270,6 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, return -EFAULT; } - insn->imm = desc->imm; if (insn->off) return 0; if (desc->func_id == special_kfunc_list[KF_bpf_obj_new_impl]) { @@ -16852,8 +16823,6 @@ static int do_misc_fixups(struct bpf_verifier_env *env) } } - sort_kfunc_descs_by_imm(env->prog); - return 0; }