From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from canpmsgout06.his.huawei.com (canpmsgout06.his.huawei.com [113.46.200.221]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8692019F121; Wed, 19 Aug 2026 03:41:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=113.46.200.221 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787110901; cv=none; b=pmWlIBEhz47vOKto0yLRIsGkCSCABeIMrmMakMzQQjaeZW808q8aWx/1YxP1qI+FIKo+huSHV8Y2TxuENDshTQ2UVJ3Do48lTStVgH4pnEndHdDRhHvJuB7Dgl2y0dtgnhqyAhy5ViTNulKICBGwMAx/Chy5XvJi1R+Tj5jHveQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787110901; c=relaxed/simple; bh=VVdxYlVk3Z4rA00QLnrFa4FgdNSWCSlJ8XwxuC1/sPg=; h=Message-ID:Date:MIME-Version:Subject:From:To:CC:References: In-Reply-To:Content-Type; b=BEL4pk3+Y2OndYLfRUhVVpMVnQb4k7D1rU+KryrVtVrTjG88gZvrUpNPogOMYClTtiJCyjd1dKQl2+a+armsSK/pz/X6XPGxR0s92JAYI4+G/T99b+DL7kqu9xvaToFJQ8/ILMymNfLWHo6MO6ecNqfpiYL2/LVkWp6kpL6LRXY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b=rmBsn313; arc=none smtp.client-ip=113.46.200.221 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=huawei.com header.i=@huawei.com header.b="rmBsn313" dkim-signature: v=1; a=rsa-sha256; d=huawei.com; s=dkim; c=relaxed/relaxed; q=dns/txt; h=From; bh=ZrPuPOBmVfVWOOXrIVWVaTVmfGyieHoTBzLjPjrT0sc=; b=rmBsn313FBwyQbzJfZoLYwOjhXeAfYylrm+hMl83g2lrxxHyLZKLaqyY0wCt9DYW3w9lz/iJ9 zJM/KGr9aQaPu4JzxbnTDbQ2pqP7eh2oXCNQo9wYJzyfhb+Dh4SAwhm5UeiEhcXH3RMciaW76X4 2BvS6zSvYOAQG8hMoJAXZfM= Received: from mail.maildlp.com (unknown [172.19.163.104]) by canpmsgout06.his.huawei.com (SkyGuard) with ESMTPS id 4hPsXn0RfHzRhVN; Wed, 19 Aug 2026 11:30:49 +0800 (CST) Received: from kwepemf100007.china.huawei.com (unknown [7.202.181.221]) by mail.maildlp.com (Postfix) with ESMTPS id 6248F4057F; Wed, 19 Aug 2026 11:41:28 +0800 (CST) Received: from [10.67.110.68] (10.67.110.68) by kwepemf100007.china.huawei.com (7.202.181.221) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.36; Wed, 19 Aug 2026 11:41:27 +0800 Message-ID: <4ba94268-cd39-438c-a788-a5b75cfd8813@huawei.com> Date: Wed, 19 Aug 2026 11:41:21 +0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf-next 1/2] bpf, riscv: Add support for signed arena loads Content-Language: en-US From: Pu Lehui To: Chen Pei CC: , , , , , , , , , , , , , , , , , , , References: <3445fb0231f9c72496ae840e9dca675b15899433.1786708960.git.cp0613@linux.alibaba.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems200001.china.huawei.com (7.221.188.67) To kwepemf100007.china.huawei.com (7.202.181.221) oops need to revert this reviewed-by On 2026/8/18 22:27, Pu Lehui wrote: > > > On 2026/8/17 15:24, Chen Pei wrote: >> Signed loads from arena memory are currently rejected on riscv64, as >> bpf_jit_supports_insn() refuses BPF_MEMSX loads when in_arena is set, >> while x86 and arm64 gained support for them in v6.18. Compilers such >> as GCC-14 are free to generate signed loads into arena memory, which >> breaks loading of otherwise valid BPF programs on riscv64. >> >> Implement BPF_PROBE_MEM32SX support in the RV64 JIT by reusing the >> existing arena handling: the arena base (RV_REG_ARENA) is added to >> the source register and the load is emitted with sign extension >> (lb/lh/lw). Add BPF_PROBE_MEM32SX to the add_exception_handler() >> mode gate so that faulting loads get an exception table entry which >> clears the destination register and resumes execution. >> >> Verified by running the arena LDSX selftests (arena_ldsx_disasm, >> arena_ldsx_exception, arena_ldsx_s8/s16/s32) on riscv64 QEMU, all >> passing. >> >> Signed-off-by: Chen Pei >> --- >>   arch/riscv/net/bpf_jit_comp64.c | 15 +++++++++------ >>   1 file changed, 9 insertions(+), 6 deletions(-) >> >> diff --git a/arch/riscv/net/bpf_jit_comp64.c >> b/arch/riscv/net/bpf_jit_comp64.c >> index f9d5347ba966..5786f7dfc8a7 100644 >> --- a/arch/riscv/net/bpf_jit_comp64.c >> +++ b/arch/riscv/net/bpf_jit_comp64.c >> @@ -777,6 +777,7 @@ static int add_exception_handler(const struct >> bpf_insn *insn, int dst_reg, >>       if (BPF_MODE(insn->code) != BPF_PROBE_MEM && >>           BPF_MODE(insn->code) != BPF_PROBE_MEMSX && >>           BPF_MODE(insn->code) != BPF_PROBE_MEM32 && >> +        BPF_MODE(insn->code) != BPF_PROBE_MEM32SX && >>           BPF_MODE(insn->code) != BPF_PROBE_ATOMIC) >>           return 0; >> @@ -1902,13 +1903,19 @@ int bpf_jit_emit_insn(const struct bpf_insn >> *insn, struct rv_jit_context *ctx, >>       case BPF_LDX | BPF_PROBE_MEM32 | BPF_H: >>       case BPF_LDX | BPF_PROBE_MEM32 | BPF_W: >>       case BPF_LDX | BPF_PROBE_MEM32 | BPF_DW: >> +    /* LDX | PROBE_MEM32SX: dst = *(signed size *)(src + RV_REG_ARENA >> + off) */ >> +    case BPF_LDX | BPF_PROBE_MEM32SX | BPF_B: >> +    case BPF_LDX | BPF_PROBE_MEM32SX | BPF_H: >> +    case BPF_LDX | BPF_PROBE_MEM32SX | BPF_W: >>       { >>           bool sign_ext; >>           sign_ext = BPF_MODE(insn->code) == BPF_MEMSX || >> -               BPF_MODE(insn->code) == BPF_PROBE_MEMSX; >> +               BPF_MODE(insn->code) == BPF_PROBE_MEMSX || >> +               BPF_MODE(insn->code) == BPF_PROBE_MEM32SX; >> -        if (BPF_MODE(insn->code) == BPF_PROBE_MEM32) { >> +        if (BPF_MODE(insn->code) == BPF_PROBE_MEM32 || >> +            BPF_MODE(insn->code) == BPF_PROBE_MEM32SX) { >>               emit_add(RV_REG_T2, rs, RV_REG_ARENA, ctx); >>               rs = RV_REG_T2; >>           } >> @@ -2126,10 +2133,6 @@ bool bpf_jit_supports_insn(struct bpf_insn >> *insn, bool in_arena) >>               if (insn->imm == BPF_CMPXCHG) >>                   return rv_ext_enabled(ZACAS); >>               break; >> -        case BPF_LDX | BPF_MEMSX | BPF_B: >> -        case BPF_LDX | BPF_MEMSX | BPF_H: >> -        case BPF_LDX | BPF_MEMSX | BPF_W: >> -            return false; >>           } >>       } > > Reviewed-by: Pu Lehui > Hi Chen Pei, It's happy for the verifier_ldsx, but it not happy for the other test, pls take a look. [2026-08-19 11:33:11] root@(none):/mnt/bpf# ./test_progs -a arena_atomics [2026-08-19 11:33:18] [2026-08-19 11:33:20] [ 34.529770] bpf_testmod: loading out-of-tree module taints kernel. [2026-08-19 11:33:20] [ 34.530186] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel [2026-08-19 11:33:21] [ 35.541256] ------------[ cut here ]------------ [2026-08-19 11:33:21] [ 35.541573] WARNING: arch/riscv/net/bpf_jit_comp64.c:915 at add_exception_handler+0xce/0xf0, CPU#0: test_progs/122 [2026-08-19 11:33:21] [ 35.544546] Modules linked in: bpf_testmod(OE) [2026-08-19 11:33:21] [ 35.545885] CPU: 0 UID: 0 PID: 122 Comm: test_progs Tainted: G OE 7.2.0-next-20260818-00007-gc29447b2149d #8 PREEMPTLAZY [2026-08-19 11:33:21] [ 35.546625] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE [2026-08-19 11:33:21] [ 35.546892] Hardware name: riscv-virtio,qemu (DT) [2026-08-19 11:33:21] [ 35.547240] epc : add_exception_handler+0xce/0xf0 [2026-08-19 11:33:21] [ 35.547538] ra : bpf_jit_emit_insn+0x5a8/0x2d18 [2026-08-19 11:33:21] [ 35.547799] epc : ffffffff8002571e ra : ffffffff8002b3c8 sp : ff20000000eeb700 [2026-08-19 11:33:21] [ 35.548128] gp : ffffffff81db8ed0 tp : ff60000083130d40 t0 : ffffffff8001e650 [2026-08-19 11:33:21] [ 35.548454] t1 : 0000000000000007 t2 : 0000000000000040 s0 : ff20000000eeb710 [2026-08-19 11:33:21] [ 35.548785] s1 : 00000000000000fb a0 : 0000000000000007 a1 : 000000000000000a [2026-08-19 11:33:21] [ 35.549114] a2 : ff600000809549a0 a3 : ffffffff78000790 a4 : ff60000080a8bc24 [2026-08-19 11:33:21] [ 35.549439] a5 : 0000000000000087 a6 : ffffffff78000664 a7 : 0000000000000089 [2026-08-19 11:33:21] [ 35.549765] s2 : ff600000809549a0 s3 : ff2000000017d1e8 s4 : 0000000000000000 [2026-08-19 11:33:21] [ 35.550094] s5 : 0000000000000001 s6 : 0000000000000001 s7 : 0000000000000031 [2026-08-19 11:33:21] [ 35.550419] s8 : ff60000084994800 s9 : 0000000000000000 s10: 0000000000000000 [2026-08-19 11:33:21] [ 35.550737] s11: 000000084290e9f4 t3 : 0000000000000000 t4 : 000000000000000b [2026-08-19 11:33:21] [ 35.551079] t5 : 0000000000000008 t6 : ff600000808fc3a0 ssp : 0000000000000000 [2026-08-19 11:33:21] [ 35.551409] status: 0000000200000120 badaddr: ffffffff8002571e cause: 0000000000000003 [2026-08-19 11:33:21] [ 35.551882] [] add_exception_handler+0xce/0xf0 [2026-08-19 11:33:21] [ 35.552318] [] bpf_jit_emit_insn+0x5a8/0x2d18 [2026-08-19 11:33:21] [ 35.552602] [] bpf_int_jit_compile+0x9a/0x480 [2026-08-19 11:33:21] [ 35.552888] [] __bpf_prog_select_runtime+0x10c/0x1d8 [2026-08-19 11:33:21] [ 35.553197] [] bpf_check+0xaca/0x31b8 [2026-08-19 11:33:21] [ 35.553459] [] bpf_prog_load+0x546/0xad0 [2026-08-19 11:33:21] [ 35.553720] [] __sys_bpf+0x1948/0x2c38 [2026-08-19 11:33:21] [ 35.553974] [] __riscv_sys_bpf+0x2a/0x40 [2026-08-19 11:33:21] [ 35.554238] [] do_trap_ecall_u+0x1ea/0x398 [2026-08-19 11:33:21] [ 35.554528] [] handle_exception+0x16c/0x178 [2026-08-19 11:33:21] [ 35.555320] ---[ end trace 0000000000000000 ]--- [2026-08-19 11:33:21] serial_test_arena_atomics:PASS:arena atomics skeleton open 0 nsec [2026-08-19 11:33:21] libbpf: prog 'add': BPF program load failed: -ENOTSUPP [2026-08-19 11:33:21] libbpf: prog 'add': -- BEGIN PROG LOAD LOG -- [2026-08-19 11:33:21] processed 37 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 0 [2026-08-19 11:33:21] -- END PROG LOAD LOG -- [2026-08-19 11:33:21] libbpf: prog 'add': failed to load: -ENOTSUPP [2026-08-19 11:33:21] libbpf: failed to load object 'arena_atomics' [2026-08-19 11:33:21] libbpf: failed to load BPF skeleton 'arena_atomics': -ENOTSUPP [2026-08-19 11:33:21] serial_test_arena_atomics:FAIL:arena atomics skeleton load unexpected error: -524 (errno 524) [2026-08-19 11:33:21] #1 arena_atomics:FAIL [2026-08-19 11:33:21] [2026-08-19 11:33:21] All error logs: [2026-08-19 11:33:21] serial_test_arena_atomics:PASS:arena atomics skeleton open 0 nsec [2026-08-19 11:33:21] libbpf: prog 'add': BPF program load failed: -ENOTSUPP [2026-08-19 11:33:21] libbpf: prog 'add': -- BEGIN PROG LOAD LOG -- [2026-08-19 11:33:21] processed 37 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 0 [2026-08-19 11:33:21] -- END PROG LOAD LOG -- [2026-08-19 11:33:21] libbpf: prog 'add': failed to load: -ENOTSUPP [2026-08-19 11:33:21] libbpf: failed to load object 'arena_atomics' [2026-08-19 11:33:21] libbpf: failed to load BPF skeleton 'arena_atomics': -ENOTSUPP [2026-08-19 11:33:21] serial_test_arena_atomics:FAIL:arena atomics skeleton load unexpected error: -524 (errno 524) [2026-08-19 11:33:21] #1 arena_atomics:FAIL [2026-08-19 11:33:21] Summary: 0/0 PASSED, 0 SKIPPED, 1/0 FAILED [2026-08-19 11:33:21] root@(none):/mnt/bpf#