From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750972AbcFVFTC (ORCPT ); Wed, 22 Jun 2016 01:19:02 -0400 Received: from ozlabs.org ([103.22.144.67]:34753 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751005AbcFVFTA (ORCPT ); Wed, 22 Jun 2016 01:19:00 -0400 Message-ID: <1466572690.19785.4.camel@ellerman.id.au> Subject: Re: [PATCH] ppc: Fix BPF JIT for ABIv2 From: Michael Ellerman To: Thadeu Lima de Souza Cascardo Cc: "Naveen N. Rao" , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, Matt Evans , Daniel Borkmann , Alexei Starovoitov , Denis Kirjanov , Paul Mackerras , "David S. Miller" , Ananth N Mavinakayanahalli Date: Wed, 22 Jun 2016 15:18:10 +1000 In-Reply-To: <20160617130042.GO3516@indiana.gru.redhat.com> References: <908d3552b5eb240b28f70aee7c4c86e2b600aa02.1465304785.git.naveen.n.rao@linux.vnet.ibm.com> <3rWKtT2tSrz9t2G@ozlabs.org> <20160617130042.GO3516@indiana.gru.redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.5-1ubuntu3.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2016-06-17 at 10:00 -0300, Thadeu Lima de Souza Cascardo wrote: > From a984dc02b6317a1d3a3c2302385adba5227be5bd Mon Sep 17 00:00:00 2001 > From: Thadeu Lima de Souza Cascardo > Date: Wed, 15 Jun 2016 13:22:12 -0300 > Subject: [PATCH] ppc: Fix BPF JIT for ABIv2 > > ABIv2 used for ppc64le does not use function descriptors. Without this patch, > whenever BPF JIT is enabled, we get a crash as below. > ... > diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h > index 889fd19..28b89ed 100644 > --- a/arch/powerpc/net/bpf_jit.h > +++ b/arch/powerpc/net/bpf_jit.h > @@ -70,7 +70,7 @@ DECLARE_LOAD_FUNC(sk_load_half); > DECLARE_LOAD_FUNC(sk_load_byte); > DECLARE_LOAD_FUNC(sk_load_byte_msh); > > -#ifdef CONFIG_PPC64 > +#if defined(CONFIG_PPC64) && (!defined(_CALL_ELF) || _CALL_ELF != 2) > #define FUNCTION_DESCR_SIZE 24 > #else > #define FUNCTION_DESCR_SIZE 0 > diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c > index 2d66a84..035b887 100644 > --- a/arch/powerpc/net/bpf_jit_comp.c > +++ b/arch/powerpc/net/bpf_jit_comp.c > @@ -664,7 +664,7 @@ void bpf_jit_compile(struct bpf_prog *fp) > > if (image) { > bpf_flush_icache(code_base, code_base + (proglen/4)); > -#ifdef CONFIG_PPC64 > +#if defined(CONFIG_PPC64) && (!defined(_CALL_ELF) || _CALL_ELF != 2) > /* Function descriptor nastiness: Address + TOC */ > ((u64 *)image)[0] = (u64)code_base; > ((u64 *)image)[1] = local_paca->kernel_toc; Confirmed that even with this patch we still crash: # echo 1 > /proc/sys/net/core/bpf_jit_enable # modprobe test_bpf BPF filter opcode 0020 (@3) unsupported BPF filter opcode 0020 (@2) unsupported BPF filter opcode 0020 (@0) unsupported Unable to handle kernel paging request for data at address 0xd0000000054f65e8 Faulting instruction address: 0xc0000000008765f8 cpu 0x0: Vector: 300 (Data Access) at [c0000000034f3480] pc: c0000000008765f8: skb_copy_bits+0x158/0x330 lr: c00000000008fb7c: bpf_slow_path_byte+0x28/0x54 sp: c0000000034f3700 msr: 800000010280b033 dar: d0000000054f65e8 dsisr: 40000000 current = 0xc0000001f857d8d0 paca = 0xc000000007b80000 softe: 0 irq_happened: 0x01 pid = 2993, comm = modprobe Linux version 4.7.0-rc3-00055-g9497a1c1c5b4-dirty (michael@ka3.ozlabs.ibm.com) () #30 SMP Wed Jun 22 15:06:58 AEST 2016 enter ? for help [c0000000034f3770] c00000000008fb7c bpf_slow_path_byte+0x28/0x54 [c0000000034f37e0] d000000007bb004c [c0000000034f3900] d000000005331668 test_bpf_init+0x5fc/0x7f8 [test_bpf] [c0000000034f3a30] c00000000000b628 do_one_initcall+0x68/0x1d0 [c0000000034f3af0] c0000000009beb24 do_init_module+0x90/0x240 [c0000000034f3b80] c0000000001642bc load_module+0x206c/0x22f0 [c0000000034f3d30] c0000000001648b0 SyS_finit_module+0x120/0x180 [c0000000034f3e30] c000000000009260 system_call+0x38/0x108 --- Exception: c01 (System Call) at 00003fff7ffa2db4 cheers