From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E63ABFD45E4 for ; Wed, 25 Feb 2026 19:54:54 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4fLlg12wdwz3cQq; Thu, 26 Feb 2026 06:54:53 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=148.163.158.5 ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1772049293; cv=none; b=C6LaV+ypUXEQqGvanUIVZwJp1MU8dfeZWNFnWSg/x2tMNK1oW0iPqXWnyNRrZTdhCg+SpQxzCZQsb7fS7LFQECfsVGRvIKwson9KxEw71Zh+sHEvy1/DXb4Jj+kcTXrxTy1xGjqlAGc2Ie3BFXppQgAWghJSBCnFqlhfhRAXGsuBJe18ilzUcv1CIfioAdFtqmryrsc6UkMHYlLvkxFyzsUjqNPEuAnVrtkC9pNHcDzgrWPM+kuobsf04KqLZuT+6etwRaMp76coL2D8DACWn87ziitUtnRBe1aG8Rl80Kvln5bXD5YfpUhOT/YCbWTPrb4Bde4KO63mfO0aiQAEKA== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1772049293; c=relaxed/relaxed; bh=vQCdEPt9PM0lHc5oLaNfnQq+YNwDetByd5AI67ExUU8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=aZdsnUpA9pHEvcD865y/sDsD3UlXEvf34Y3bXAUaELKdHzzjM4W4Qe3PZP9SBaUWgX59sJeFBnDxMVak8sJq0XXKk3doSDMZU/va/IesCUS2UUrth+yCi8761dHO46Hzfd0riC36c21nbyPu8odb8hWbDDFn6AqilSOAfF3G/AIpNvhL2ljTyMlNbjoskcFzlkvNqONud78eYDzh+xkuIhYdPEQ6QJ8ZlAX9Wop5F+DR06wieBx0lQvKAEOe2S5ysvCDWKenIR27BoGEVFVZTAeWFUPtN/XRraxQGajwp96YRUJjQHgmd2S7U7h1yVLGgEMyVGwYwaSL473yaVDvYQ== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=DcNnnPZM; dkim-atps=neutral; spf=pass (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com; envelope-from=adubey@linux.ibm.com; receiver=lists.ozlabs.org) smtp.mailfrom=linux.ibm.com Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=DcNnnPZM; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com; envelope-from=adubey@linux.ibm.com; receiver=lists.ozlabs.org) Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4fLlg01GT4z3c9l for ; Thu, 26 Feb 2026 06:54:51 +1100 (AEDT) Received: from pps.filterd (m0353725.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 61PEe3vE2520093; Wed, 25 Feb 2026 19:54:34 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:message-id:mime-version :subject:to; s=pp1; bh=vQCdEPt9PM0lHc5oLaNfnQq+YNwDetByd5AI67ExU U8=; b=DcNnnPZMRJW4QFMJ3oek/2G31Xw2ZtbXcHE7VwiI4faIJpzqpnOWh/Rs7 QxYys6KXD71sgcxxelYb7epGLRFTCjT+Kmmk+7lxS8He8bHj0FLFNga1Vv5cHp53 cVuE0lysYIBxLY2kJsZS1qkMu/EkVn+EnmttDhR/T7FrnELJUNG/bPOoNs8cLPAH DGCOqrgYMWqDbicrkIFHrf8PQTNXjkK2cQj1WYH/Pd9YH8jOeRVhZu+NgUAQmjl1 8RnXy4Y0L0fwa6i0CAd7/uRCzyEC35k3Amyc9rnswhe0aPjNVXV4qF2w3mChC6sC FL1xxWmNz+WFmPk3W+z0dprTm4fcw== Received: from ppma23.wdc07v.mail.ibm.com (5d.69.3da9.ip4.static.sl-reverse.com [169.61.105.93]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4cf34c9gkr-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 25 Feb 2026 19:54:34 +0000 (GMT) Received: from pps.filterd (ppma23.wdc07v.mail.ibm.com [127.0.0.1]) by ppma23.wdc07v.mail.ibm.com (8.18.1.2/8.18.1.2) with ESMTP id 61PHAqka030267; Wed, 25 Feb 2026 19:54:33 GMT Received: from smtprelay01.fra02v.mail.ibm.com ([9.218.2.227]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4cfrhkf21j-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 25 Feb 2026 19:54:33 +0000 Received: from smtpav05.fra02v.mail.ibm.com (smtpav05.fra02v.mail.ibm.com [10.20.54.104]) by smtprelay01.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 61PJsTjC61931992 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 25 Feb 2026 19:54:29 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C2C7020043; Wed, 25 Feb 2026 19:54:29 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 44A6820040; Wed, 25 Feb 2026 19:54:28 +0000 (GMT) Received: from ltcrain4-lp15.ltc.tadn.ibm.com (unknown [9.5.7.39]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 25 Feb 2026 19:54:28 +0000 (GMT) From: adubey@linux.ibm.com To: linuxppc-dev@lists.ozlabs.org Cc: bpf@vger.kernel.org, hbathini@linux.ibm.com, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, maddy@linux.ibm.com, Abhishek Dubey Subject: [PATCH v3 1/2] powerpc64/bpf: Implement JIT support for private stack Date: Wed, 25 Feb 2026 19:54:39 -0500 Message-ID: <20260226005440.9570-1-adubey@linux.ibm.com> X-Mailer: git-send-email 2.52.0 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMjI1MDE4OCBTYWx0ZWRfXys9uW3u7GfdB LHFwwheKLGiKdf1Myj//Z24w4+gyH5QO9jUjZzzTRSNfFxt3N0JbdO14QOD347wvDolgRc+YMIS K3exN6BVDIVZcnv8UKTMu6xaokkvTyg1rR2wbv6mcZgYjc3Omdy1VMHKFKpCFdODqXdPcd4abN7 5nSEv3ztvoPCyJnX2lFFIBOvC5MzDzCdCby9eOFMg0s4A4l7vrwFPdEKTQBt2AOwef3p3LL1669 C9kAjXJMNs1QCLMy3thPtmVEgAmsvm1VIl8Oda/nYSLFjdLnwk7eAJQFWFtD1IXfsXG8uaCNBJ6 0dZld2nQIln7PJm4cymNXSoboBszuXAaq0pC/SNno1cd5ZBvspQ9fA4sGhuxRJyhY4MOxq9C2Lj KzTP5pWsuxf4YRmREYEdBFrpEja5nTcsKj8J0a/Xn+wVDgC1RhrGKyKvBvJWUq2fEHa6tNh+kMV Pa8q4+x2MooxuKZQwGQ== X-Proofpoint-ORIG-GUID: wrO-PkZOBq3jQkdtQV0nO2VmKsOktGkT X-Authority-Analysis: v=2.4 cv=F9lat6hN c=1 sm=1 tr=0 ts=699f537a cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=HzLeVaNsDn8A:10 a=VkNPw1HP01LnGYTKEx00:22 a=Mpw57Om8IfrbqaoTuvik:22 a=GgsMoib0sEa3-_RKJdDe:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=F76KSA7jxJ0ultxYvGsA:9 X-Proofpoint-GUID: wrO-PkZOBq3jQkdtQV0nO2VmKsOktGkT X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-02-25_03,2026-02-25_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 phishscore=0 bulkscore=0 adultscore=0 spamscore=0 clxscore=1015 suspectscore=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2602250188 From: Abhishek Dubey Provision the private stack as a per-CPU allocation during bpf_int_jit_compile(). Align the stack to 16 bytes and place guard regions at both ends to detect runtime stack overflow and underflow. Round the private stack size up to the nearest 16-byte boundary. Make each guard region 16 bytes to preserve the required overall 16-byte alignment. When private stack is set, skip bpf stack size accounting in kernel stack. There is no stack pointer in powerpc. Stack referencing during JIT is done using frame pointer. Frame pointer calculation goes like: BPF frame pointer = Priv stack allocation start address + Overflow guard + Actual stack size defined by verifier Memory layout: High Addr +--------------------------------------------------+ | | | 16 bytes Underflow guard (0xEB9F12345678eb9fULL) | | | BPF FP -> +--------------------------------------------------+ | | | Private stack - determined by verifier | | 16-bytes aligned | | | +--------------------------------------------------+ | | Lower Addr | 16 byte Overflow guard (0xEB9F12345678eb9fULL) | | | Priv stack alloc ->+--------------------------------------------------+ start Update BPF_REG_FP to point to the calculated offset within the allocated private stack buffer. Now, BPF stack usage reference in the allocated private stack. The patch is rebase over fixes by Hari: https://lore.kernel.org/bpf/20260220063933.196141-1-hbathini@linux.ibm.com/ v1->v2: Fix ci-bot warning for percpu pointer casting Minor refactoring v2->v3: Fix ci-bot bug targeting clobbered NVRs on stack rollback [v2]: https://lore.kernel.org/bpf/20260225153950.15331-1-adubey@linux.ibm.com [v1]: https://lore.kernel.org/bpf/20260216152234.36632-1-adubey@linux.ibm.com Signed-off-by: Abhishek Dubey --- arch/powerpc/net/bpf_jit.h | 5 ++ arch/powerpc/net/bpf_jit_comp.c | 87 +++++++++++++++++++++++++++++-- arch/powerpc/net/bpf_jit_comp64.c | 29 +++++++++-- 3 files changed, 113 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h index 7354e1d72f79..eb0a400b5a98 100644 --- a/arch/powerpc/net/bpf_jit.h +++ b/arch/powerpc/net/bpf_jit.h @@ -178,8 +178,13 @@ struct codegen_context { bool is_subprog; bool exception_boundary; bool exception_cb; + void __percpu *priv_sp; }; +/* Memory size & magic-value to detect private stack overflow/underflow */ +#define PRIV_STACK_GUARD_SZ 16 +#define PRIV_STACK_GUARD_VAL 0xEB9F12345678eb9fULL + #define bpf_to_ppc(r) (ctx->b2p[r]) #ifdef CONFIG_PPC32 diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index 278e09b57560..adb2838bc653 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -129,25 +129,60 @@ bool bpf_jit_needs_zext(void) return true; } +static void priv_stack_init_guard(void __percpu *priv_stack_ptr, int alloc_size) +{ + int cpu, underflow_idx = (alloc_size - PRIV_STACK_GUARD_SZ) >> 3; + u64 *stack_ptr; + + for_each_possible_cpu(cpu) { + stack_ptr = per_cpu_ptr(priv_stack_ptr, cpu); + stack_ptr[0] = PRIV_STACK_GUARD_VAL; + stack_ptr[1] = PRIV_STACK_GUARD_VAL; + stack_ptr[underflow_idx] = PRIV_STACK_GUARD_VAL; + stack_ptr[underflow_idx + 1] = PRIV_STACK_GUARD_VAL; + } +} + +static void priv_stack_check_guard(void __percpu *priv_stack_ptr, int alloc_size, + struct bpf_prog *fp) +{ + int cpu, underflow_idx = (alloc_size - PRIV_STACK_GUARD_SZ) >> 3; + u64 *stack_ptr; + + for_each_possible_cpu(cpu) { + stack_ptr = per_cpu_ptr(priv_stack_ptr, cpu); + if (stack_ptr[0] != PRIV_STACK_GUARD_VAL || + stack_ptr[1] != PRIV_STACK_GUARD_VAL || + stack_ptr[underflow_idx] != PRIV_STACK_GUARD_VAL || + stack_ptr[underflow_idx + 1] != PRIV_STACK_GUARD_VAL) { + pr_err("BPF private stack overflow/underflow detected for prog %s\n", + bpf_jit_get_prog_name(fp)); + break; + } + } +} + struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) { u32 proglen; u32 alloclen; u8 *image = NULL; - u32 *code_base; - u32 *addrs; - struct powerpc_jit_data *jit_data; + u32 *code_base = NULL; + u32 *addrs = NULL; + struct powerpc_jit_data *jit_data = NULL; struct codegen_context cgctx; int pass; int flen; + int priv_stack_alloc_size; + void __percpu *priv_stack_ptr = NULL; struct bpf_binary_header *fhdr = NULL; struct bpf_binary_header *hdr = NULL; struct bpf_prog *org_fp = fp; - struct bpf_prog *tmp_fp; + struct bpf_prog *tmp_fp = NULL; bool bpf_blinded = false; bool extra_pass = false; u8 *fimage = NULL; - u32 *fcode_base; + u32 *fcode_base = NULL; u32 extable_len; u32 fixup_len; @@ -173,6 +208,26 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) fp->aux->jit_data = jit_data; } + priv_stack_ptr = fp->aux->priv_stack_ptr; + if (!priv_stack_ptr && fp->aux->jits_use_priv_stack) { + /* + * Allocate private stack of size equivalent to + * verifier-calculated stack size plus two memory + * guard regions to detect private stack overflow + * and underflow. + */ + priv_stack_alloc_size = round_up(fp->aux->stack_depth, 16) + + 2 * PRIV_STACK_GUARD_SZ; + priv_stack_ptr = __alloc_percpu_gfp(priv_stack_alloc_size, 16, GFP_KERNEL); + if (!priv_stack_ptr) { + fp = org_fp; + goto out_priv_stack; + } + + priv_stack_init_guard(priv_stack_ptr, priv_stack_alloc_size); + fp->aux->priv_stack_ptr = priv_stack_ptr; + } + flen = fp->len; addrs = jit_data->addrs; if (addrs) { @@ -209,6 +264,9 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) cgctx.is_subprog = bpf_is_subprog(fp); cgctx.exception_boundary = fp->aux->exception_boundary; cgctx.exception_cb = fp->aux->exception_cb; + cgctx.priv_sp = priv_stack_ptr; + if (priv_stack_ptr) + cgctx.stack_size = 0; /* Scouting faux-generate pass 0 */ if (bpf_jit_build_body(fp, NULL, NULL, &cgctx, addrs, 0, false)) { @@ -306,6 +364,11 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp) } bpf_prog_fill_jited_linfo(fp, addrs); out_addrs: + if (!image && priv_stack_ptr) { + fp->aux->priv_stack_ptr = NULL; + free_percpu(priv_stack_ptr); + } +out_priv_stack: kfree(addrs); kfree(jit_data); fp->aux->jit_data = NULL; @@ -419,6 +482,8 @@ void bpf_jit_free(struct bpf_prog *fp) if (fp->jited) { struct powerpc_jit_data *jit_data = fp->aux->jit_data; struct bpf_binary_header *hdr; + void __percpu *priv_stack_ptr; + int priv_stack_alloc_size; /* * If we fail the final pass of JIT (from jit_subprogs), @@ -432,6 +497,13 @@ void bpf_jit_free(struct bpf_prog *fp) } hdr = bpf_jit_binary_pack_hdr(fp); bpf_jit_binary_pack_free(hdr, NULL); + priv_stack_ptr = fp->aux->priv_stack_ptr; + if (priv_stack_ptr) { + priv_stack_alloc_size = round_up(fp->aux->stack_depth, 16) + + 2 * PRIV_STACK_GUARD_SZ; + priv_stack_check_guard(priv_stack_ptr, priv_stack_alloc_size, fp); + free_percpu(priv_stack_ptr); + } WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(fp)); } @@ -453,6 +525,11 @@ bool bpf_jit_supports_kfunc_call(void) return true; } +bool bpf_jit_supports_private_stack(void) +{ + return IS_ENABLED(CONFIG_PPC64); +} + bool bpf_jit_supports_arena(void) { return IS_ENABLED(CONFIG_PPC64); diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 640b84409687..65ab8b7a7f82 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -183,6 +183,22 @@ void bpf_jit_realloc_regs(struct codegen_context *ctx) { } +static void emit_fp_priv_stack(u32 *image, struct codegen_context *ctx) +{ + /* Load percpu data offset */ + EMIT(PPC_RAW_LD(bpf_to_ppc(TMP_REG_1), _R13, + offsetof(struct paca_struct, data_offset))); + PPC_LI64(bpf_to_ppc(BPF_REG_FP), (__force long)ctx->priv_sp); + /* + * Load base percpu pointer of private stack allocation. + * Runtime per-cpu address = (base + data_offset) + (guard + stack_size) + */ + EMIT(PPC_RAW_ADD(bpf_to_ppc(BPF_REG_FP), + bpf_to_ppc(TMP_REG_1), bpf_to_ppc(BPF_REG_FP))); + EMIT(PPC_RAW_ADDI(bpf_to_ppc(BPF_REG_FP), bpf_to_ppc(BPF_REG_FP), + PRIV_STACK_GUARD_SZ + round_up(ctx->stack_size, 16))); +} + /* * For exception boundary & exception_cb progs: * return increased size to accommodate additional NVRs. @@ -307,9 +323,16 @@ void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx) * Exception_cb not restricted from using stack area or arena. * Setup frame pointer to point to the bpf stack area */ - if (bpf_is_seen_register(ctx, bpf_to_ppc(BPF_REG_FP))) - EMIT(PPC_RAW_ADDI(bpf_to_ppc(BPF_REG_FP), _R1, - STACK_FRAME_MIN_SIZE + ctx->stack_size)); + if (bpf_is_seen_register(ctx, bpf_to_ppc(BPF_REG_FP))) { + if (ctx->priv_sp) { + /* Set up fp in private stack */ + emit_fp_priv_stack(image, ctx); + } else { + /* Setup frame pointer to point to the bpf stack area */ + EMIT(PPC_RAW_ADDI(bpf_to_ppc(BPF_REG_FP), _R1, + STACK_FRAME_MIN_SIZE + ctx->stack_size)); + } + } if (ctx->arena_vm_start) PPC_LI64(bpf_to_ppc(ARENA_VM_START), ctx->arena_vm_start); -- 2.52.0