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 9BB05CC6B04 for ; Thu, 2 Apr 2026 05:43:37 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4fmW480mQ7z2ySk; Thu, 02 Apr 2026 16:43:36 +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=1775108616; cv=none; b=Yf9kXZ66fedXx/GMSm9dIjclQek8gNuo0dnfP67ryPE8ucuZ/W9AD67oFNOa+Vpbx6RQNUeIqRNx45EKR2bQVGfaL6jEmsOh6J1B1bdQUwcpXRjtuO8T9vnFIR+ON/xDIAmsZrtggu/TEpBi93MpXMOLO8O5Wl2hNFLPgXi5ThFScVbH7KOqHCLLv1gB8FWN9d14Q+KjuU6HunKmP0+6qWh/EoCd73zXBGVagrYs2UVhHy83khevvH6c6S+F49se7R6edIY9thc2Y5aEveZqnYkwUGeFdQle8BG869I8mDHkoW828a+SzKyMkAQ1Sc7LWuZy2Mr+LSrQDz8ceAat2A== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1775108616; c=relaxed/relaxed; bh=tn52H1i6z1CA9qnIiVNnl7FG0MDrNUpU8eclFwkV7ko=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=IFJWVm1pJHbY3PkY+cpcKkf4PAcu4VHsiTmNVS7IdKPIENJzviUeQrrFbWjpsKPFVUpwm5YysVKxSvngS2iY5QPLoMgl+FdRvds5stjpiA9ZRvkRrjZkVJEJ05Hm6fMQScpgH1yY2x/AF1Q9MKjkb6Yb7BxDI34UWL/zvR/MWEw/I9LnqytlNOGbDbrc4rPK1AWslwT1Guy6V6p+2eqPuz90FaiUo9crKwTXG/euezqPsKhxBdwqw/Xz6LjVlHV99DfS0EZuqghpDcdQqcMdt9R08KZ10jTysq75bg2xLqKpgdaKpXNPDStDAf/24zX8t8Vo5iqYETdNfA/ZbSzfjw== 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=B5ObazoV; dkim-atps=neutral; spf=pass (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com; envelope-from=skb99@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=B5ObazoV; 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=skb99@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 4fmW471jjWz2xm5 for ; Thu, 02 Apr 2026 16:43:35 +1100 (AEDT) Received: from pps.filterd (m0360072.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 631LOK20003273; Thu, 2 Apr 2026 05:43:03 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=tn52H1i6z1CA9qnIiVNnl7FG0MDrNUpU8eclFwkV7 ko=; b=B5ObazoVaC0JBwYCTQb0umZIISXvZ4en1tALvK5hKYrG4CDJDs/VTC56t VlQ9q8zrbjTSwrKcgyMJ9CJgXSh3HxHXUitz4esJ89FRgKnGo0vYq1S1UutFit56 dr1EGX6zmL5ilfBLIaq3mCZsBzgylJKg9pMMrPvX3fXpcBsL3LoSDHniOUtRe5za GkuEy+HnoPl+sVHUA0GH42vrUsmFrc+SUfqfMl7jvEU2nSpXppbVnc5aT168p4w2 4bGYGng4ZSADcfGuc72D1aufzq64WP4d6OuGl82+GHW/6F4Iir+OV+CXov3iuW1m M+4IGpDY8maCFViWrMTjzhmEUm1MQ== 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 4d66msahwf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 02 Apr 2026 05:43:02 +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 6320Lh5s013936; Thu, 2 Apr 2026 05:43:01 GMT Received: from smtprelay05.fra02v.mail.ibm.com ([9.218.2.225]) by ppma23.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4d6ttkrr6j-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 02 Apr 2026 05:43:01 +0000 Received: from smtpav01.fra02v.mail.ibm.com (smtpav01.fra02v.mail.ibm.com [10.20.54.100]) by smtprelay05.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 6325gv1i36962668 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 2 Apr 2026 05:42:57 GMT Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 786FD20043; Thu, 2 Apr 2026 05:42:57 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 8C56820040; Thu, 2 Apr 2026 05:42:50 +0000 (GMT) Received: from li-1cb9f04c-2ae1-11b2-a85c-a8a0a83790a8.bl1-in.ibm.com (unknown [9.123.13.162]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 2 Apr 2026 05:42:50 +0000 (GMT) From: Saket Kumar Bhaskar To: linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: hbathini@linux.ibm.com, sachinpb@linux.ibm.com, venkat88@linux.ibm.com, andrii@kernel.org, eddyz87@gmail.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, chleroy@kernel.org, maddy@linux.ibm.com, mpe@ellerman.id.au, adubey@linux.ibm.com Subject: [PATCH] powerpc64/bpf: Add powerpc64 JIT support for timed may_goto Date: Thu, 2 Apr 2026 11:12:49 +0530 Message-ID: <20260402054249.28801-1-skb99@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-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=J6enLQnS c=1 sm=1 tr=0 ts=69ce01e7 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=7RCMQfSFa8QzyXN4T_sA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDAyMDA0NCBTYWx0ZWRfX5YrZn1txn5V5 BSkm+dBi8xzeyggIr1Gcv/pjMrwjTo3n8kGM6Xr545nehMctNCfu58mdqKvvpjiJZwl/dOrkCLg mrNcgxV+DzhORJRsa2e6kQ8h7cJdXAku0Ni9NZn/iSeu8wfRo9nMoBC7thyZPJg9h+ArpaAASre MQRcQEHK4rHJ1vVQlLVxx4EcLw/4Vwe73nthAmJxX7RTAU1kEY/ZfnOIxZrggPKEQ7IuUqMNXDW ACCP7xp4skFEx3our4sKm1E5K0qbUyvGNXaDL0dsOKP1Ar85hkNSlbb/tQF29HtrGlIoD7lgx05 LyOS/XyTcfGacjtV9LFnO+4aOEOOaTIbhI4IEkpo1BlQIRprhmirSHq3tNFGD0pBww44oq+5ghi JaeApm7YeIykz5OgH8hjSgrQAU89Y+SWrCDYLXDOS77d0hRseThd5Twyd+ZVny7zEt5EeXZgUCX Aeoq86g3A18Oo63vzQw== X-Proofpoint-GUID: vs3isL1flFXw2oYtIyLClA-AVni--OYZ X-Proofpoint-ORIG-GUID: E1PDOn4jGweE507C_YSJg1ufIXh5XJ8u 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=2026-04-02_01,2026-04-01_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 clxscore=1011 adultscore=0 priorityscore=1501 bulkscore=0 phishscore=0 malwarescore=0 lowpriorityscore=0 spamscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2604020044 When verifier sees a timed may_goto instruction, it emits a call to arch_bpf_timed_may_goto() with a stack offset in BPF_REG_AX (powerpc64 R12) and expects the refreshed count value to be returned in the same register. The verifier doesn't save or restore any registers before emitting this call. arch_bpf_timed_may_goto() should act as a trampoline to call bpf_check_timed_may_goto() with powerpc64 ELF ABI calling convention. To support this custom calling convention, implement arch_bpf_timed_may_goto() in assembly and make sure BPF caller saved registers are preserved, then call bpf_check_timed_may_goto with the powerpc64 ABI calling convention where first argument and return value both are in R3. Finally, move the result back into BPF_REG_AX(R12) before returning. Also, introduce bpf_jit_emit_func_call() that computes the offset from kernel_toc_addr(), validates that the target and emits the ADDIS/ADDI sequence to load the function address before performing the indirect branch via MTCTR/BCTRL. The existing code in bpf_jit_emit_func_call_rel() is refactored to use this function. Signed-off-by: Saket Kumar Bhaskar --- arch/powerpc/net/Makefile | 2 +- arch/powerpc/net/bpf_jit_comp.c | 5 +++ arch/powerpc/net/bpf_jit_comp64.c | 59 ++++++++++++++++++++++----- arch/powerpc/net/bpf_timed_may_goto.S | 57 ++++++++++++++++++++++++++ 4 files changed, 111 insertions(+), 12 deletions(-) create mode 100644 arch/powerpc/net/bpf_timed_may_goto.S diff --git a/arch/powerpc/net/Makefile b/arch/powerpc/net/Makefile index 8e60af32e51e..204fc57ac56e 100644 --- a/arch/powerpc/net/Makefile +++ b/arch/powerpc/net/Makefile @@ -2,4 +2,4 @@ # # Arch-specific network modules # -obj-$(CONFIG_BPF_JIT) += bpf_jit_comp.o bpf_jit_comp$(BITS).o +obj-$(CONFIG_BPF_JIT) += bpf_jit_comp.o bpf_jit_comp$(BITS).o bpf_timed_may_goto.o diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index 50103b3794fb..9b2b456b0765 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -537,6 +537,11 @@ bool bpf_jit_supports_subprog_tailcalls(void) return IS_ENABLED(CONFIG_PPC64); } +bool bpf_jit_supports_timed_may_goto(void) +{ + return IS_ENABLED(CONFIG_PPC64); +} + bool bpf_jit_supports_kfunc_call(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 db364d9083e7..d39241444cd9 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -451,10 +451,28 @@ void arch_bpf_stack_walk(bool (*consume_fn)(void *, u64, u64, u64), void *cookie } } +static int bpf_jit_emit_func_call(u32 *image, struct codegen_context *ctx, u64 func_addr, int reg) +{ + long reladdr; + + reladdr = func_addr - kernel_toc_addr(); + if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { + pr_err("eBPF: address of %ps out of range of kernel_toc.\n", (void *)func_addr); + return -ERANGE; + } + + EMIT(PPC_RAW_ADDIS(reg, _R2, PPC_HA(reladdr))); + EMIT(PPC_RAW_ADDI(reg, reg, PPC_LO(reladdr))); + EMIT(PPC_RAW_MTCTR(reg)); + EMIT(PPC_RAW_BCTRL()); + + return 0; +} + int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context *ctx, u64 func) { unsigned long func_addr = func ? ppc_function_entry((void *)func) : 0; - long reladdr; + int ret; /* bpf to bpf call, func is not known in the initial pass. Emit 5 nops as a placeholder */ if (!func) { @@ -469,6 +487,7 @@ int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context * } #ifdef CONFIG_PPC_KERNEL_PCREL + long reladdr; reladdr = func_addr - local_paca->kernelbase; /* @@ -507,16 +526,9 @@ int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context * EMIT(PPC_RAW_BCTRL()); #else if (core_kernel_text(func_addr)) { - reladdr = func_addr - kernel_toc_addr(); - if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) { - pr_err("eBPF: address of %ps out of range of kernel_toc.\n", (void *)func); - return -ERANGE; - } - - EMIT(PPC_RAW_ADDIS(_R12, _R2, PPC_HA(reladdr))); - EMIT(PPC_RAW_ADDI(_R12, _R12, PPC_LO(reladdr))); - EMIT(PPC_RAW_MTCTR(_R12)); - EMIT(PPC_RAW_BCTRL()); + ret = bpf_jit_emit_func_call(image, ctx, func_addr, _R12); + if (ret) + return ret; } else { if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V1)) { /* func points to the function descriptor */ @@ -1755,6 +1767,31 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code if (ret < 0) return ret; + /* + * Call to arch_bpf_timed_may_goto() is emitted by the + * verifier and called with custom calling convention with + * first argument and return value in BPF_REG_AX (_R12). + * + * The generic helper or bpf function call emission path + * may use the same scratch register as BPF_REG_AX to + * materialize the target address. This would clobber AX + * and break timed may_goto semantics. + * + * Emit a minimal indirect call sequence here using a temp + * register and skip the normal post-call return-value move. + */ + + if (func_addr == (u64)arch_bpf_timed_may_goto) { +#ifdef CONFIG_PPC_KERNEL_PCREL + PPC_LI_ADDR(tmp1_reg, func_addr); + EMIT(PPC_RAW_MTCTR(tmp1_reg)); + EMIT(PPC_RAW_BCTRL()); +#else + bpf_jit_emit_func_call(image, ctx, func_addr, tmp1_reg); +#endif + break; + } + /* Take care of powerpc ABI requirements before kfunc call */ if (insn[i].src_reg == BPF_PSEUDO_KFUNC_CALL) { if (prepare_for_kfunc_call(fp, image, ctx, &insn[i])) diff --git a/arch/powerpc/net/bpf_timed_may_goto.S b/arch/powerpc/net/bpf_timed_may_goto.S new file mode 100644 index 000000000000..0b9afe3cfa1f --- /dev/null +++ b/arch/powerpc/net/bpf_timed_may_goto.S @@ -0,0 +1,57 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (c) 2025 IBM Corporation, Saket Kumar Bhaskar */ + +#include +#include + +/* + * arch_bpf_timed_may_goto() trampoline for powerpc64 + * + * Custom BPF convention (verifier/JIT): + * - input: stack offset in BPF_REG_AX (r12) + * - output: updated count in BPF_REG_AX (r12) + * + * Call bpf_check_timed_may_goto(ptr) with normal powerpc64 ABI: + * - r3 = ptr, return in r3 + * + * Preserve BPF regs R0-R5 (mapping: r8, r3-r7). + */ + +SYM_FUNC_START(arch_bpf_timed_may_goto) + /* Prologue: save LR, allocate frame */ + mflr r0 + std r0, 16(r1) + stdu r1, -112(r1) + + /* Save BPF registers R0 - R5 (r8, r3-r7) */ + std r3, 24(r1) + std r4, 32(r1) + std r5, 40(r1) + std r6, 48(r1) + std r7, 56(r1) + std r8, 64(r1) + + /* + * r3 = BPF_REG_FP + BPF_REG_AX + * BPF_REG_FP is r31; BPF_REG_AX is r12 (stack offset in bytes). + */ + add r3, r31, r12 + bl bpf_check_timed_may_goto + + /* Put return value back into AX */ + mr r12, r3 + + /* Restore BPF registers R0 - R5 (r8, r3-r7) */ + ld r3, 24(r1) + ld r4, 32(r1) + ld r5, 40(r1) + ld r6, 48(r1) + ld r7, 56(r1) + ld r8, 64(r1) + + /* Epilogue: pop frame, restore LR, return */ + addi r1, r1, 112 + ld r0, 16(r1) + mtlr r0 + blr +SYM_FUNC_END(arch_bpf_timed_may_goto) -- 2.52.0