Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752259AbdHNQj2 (ORCPT ); Mon, 14 Aug 2017 12:39:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:53322 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751042AbdHNQj0 (ORCPT ); Mon, 14 Aug 2017 12:39:26 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E5D812395F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=acme@kernel.org Date: Mon, 14 Aug 2017 13:39:15 -0300 From: Arnaldo Carvalho de Melo To: Thomas Richter Cc: wangnan0@huawei.com, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, brueckner@linux.vnet.ibm.com Subject: Re: [PATCHv2] perf bpf: Fix endianness problem when loading parameters in prologue Message-ID: <20170814163915.GB4114@kernel.org> References: <20170814114644.82526-1-tmricht@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170814114644.82526-1-tmricht@linux.vnet.ibm.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.8.3 (2017-05-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4650 Lines: 147 Em Mon, Aug 14, 2017 at 01:46:44PM +0200, Thomas Richter escreveu: > Perf BPF prologue generator unconditionally fetches 8 bytes for function > parameters, which causes problem on big endian machine. Thomas gives a > detail analysis for this problem: > > http://lkml.kernel.org/r/968ebda5-abe4-8830-8d69-49f62529d151@linux.vnet.ibm.com > > This patch parses the type of each argument and converts data from > memory to expected type. > > Now the test runs successfully on 4.13.0-rc5: > [root@s8360046 perf]# ./perf test bpf > 38: BPF filter : > 38.1: Basic BPF filtering : Ok > 38.2: BPF pinning : Ok > 38.3: BPF prologue generation : Ok > 38.4: BPF relocation checker : Ok > [root@s8360046 perf]# > > Signed-off-by: Thomas Richter > Signed-off-by: Wang Nan > Acked-by: Wang Nan > Tested-by: Wang Nan That is strange, who is the author of the patch? Also I think Tested-by is enough, being an even stronger form of Acked-by? But then you also have Signed-off-by: Wang in there... >From Documentation/process/submitting-patches.rst: --------- 12) When to use Acked-by: and Cc: --------------------------------- The Signed-off-by: tag indicates that the signer was involved in the development of the patch, or that he/she was in the patch's delivery path. If a person was not directly involved in the preparation or handling of a patch but wishes to signify and record their approval of it then they can ask to have an Acked-by: line added to the patch's changelog. Acked-by: is often used by the maintainer of the affected code when that maintainer neither contributed to nor forwarded the patch. ------------------ If Wang wrote the original patch and you made it better working together with him, probably having both of you in Signed-off-by lines should be enough? - Arnaldo > --- > tools/perf/tests/bpf-script-test-prologue.c | 4 ++- > tools/perf/util/bpf-prologue.c | 49 +++++++++++++++++++++++++++-- > 2 files changed, 50 insertions(+), 3 deletions(-) > > diff --git a/tools/perf/tests/bpf-script-test-prologue.c b/tools/perf/tests/bpf-script-test-prologue.c > index b4ebc75..43f1e16 100644 > --- a/tools/perf/tests/bpf-script-test-prologue.c > +++ b/tools/perf/tests/bpf-script-test-prologue.c > @@ -26,9 +26,11 @@ static void (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) = > (void *) 6; > > SEC("func=null_lseek file->f_mode offset orig") > -int bpf_func__null_lseek(void *ctx, int err, unsigned long f_mode, > +int bpf_func__null_lseek(void *ctx, int err, unsigned long _f_mode, > unsigned long offset, unsigned long orig) > { > + fmode_t f_mode = (fmode_t)_f_mode; > + > if (err) > return 0; > if (f_mode & FMODE_WRITE) > diff --git a/tools/perf/util/bpf-prologue.c b/tools/perf/util/bpf-prologue.c > index 1356220..827f914 100644 > --- a/tools/perf/util/bpf-prologue.c > +++ b/tools/perf/util/bpf-prologue.c > @@ -58,6 +58,46 @@ check_pos(struct bpf_insn_pos *pos) > return 0; > } > > +/* > + * Convert type string (u8/u16/u32/u64/s8/s16/s32/s64 ..., see > + * Documentation/trace/kprobetrace.txt) to size field of BPF_LDX_MEM > + * instruction (BPF_{B,H,W,DW}). > + */ > +static int > +argtype_to_ldx_size(const char *type) > +{ > + int arg_size = type ? atoi(&type[1]) : 64; > + > + switch (arg_size) { > + case 8: > + return BPF_B; > + case 16: > + return BPF_H; > + case 32: > + return BPF_W; > + case 64: > + default: > + return BPF_DW; > + } > +} > + > +static const char * > +insn_sz_to_str(int insn_sz) > +{ > + switch (insn_sz) { > + case BPF_B: > + return "BPF_B"; > + case BPF_H: > + return "BPF_H"; > + case BPF_W: > + return "BPF_W"; > + case BPF_DW: > + return "BPF_DW"; > + default: > + return "UNKNOWN"; > + } > +} > + > /* Give it a shorter name */ > #define ins(i, p) append_insn((i), (p)) > > @@ -258,9 +298,14 @@ gen_prologue_slowpath(struct bpf_insn_pos *pos, > } > > /* Final pass: read to registers */ > - for (i = 0; i < nargs; i++) > - ins(BPF_LDX_MEM(BPF_DW, BPF_PROLOGUE_START_ARG_REG + i, > + for (i = 0; i < nargs; i++) { > + int insn_sz = (args[i].ref) ? argtype_to_ldx_size(args[i].type) : BPF_DW; > + > + pr_debug("prologue: load arg %d, insn_sz is %s\n", > + i, insn_sz_to_str(insn_sz)); > + ins(BPF_LDX_MEM(insn_sz, BPF_PROLOGUE_START_ARG_REG + i, > BPF_REG_FP, -BPF_REG_SIZE * (i + 1)), pos); > + } > > ins(BPF_JMP_IMM(BPF_JA, BPF_REG_0, 0, JMP_TO_SUCCESS_CODE), pos); > > -- > 2.9.3