Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752813AbdHKKp7 (ORCPT ); Fri, 11 Aug 2017 06:45:59 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:3067 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751995AbdHKKp5 (ORCPT ); Fri, 11 Aug 2017 06:45:57 -0400 From: Wang Nan To: , CC: , , "Wang Nan" , Alexei Starovoitov , Hendrik Brueckner , Li Zefan Subject: [PATCH] perf bpf: Fix endianness problem when loading parameters in prologue Date: Sat, 12 Aug 2017 18:49:59 +0000 Message-ID: <20170812184959.32694-1-wangnan0@huawei.com> X-Mailer: git-send-email 2.10.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.110.60.55] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020201.598D8AD7.0139,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 6ea0736f91c041566e1fcd1adccb2b67 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3071 Lines: 107 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. Signed-off-by: Wang Nan Cc: Arnaldo Carvalho de Melo Cc: Thomas Richter Cc: Alexei Starovoitov Cc: Hendrik Brueckner Cc: Li Zefan --- 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 6cdbee1..ce28993 100644 --- a/tools/perf/util/bpf-prologue.c +++ b/tools/perf/util/bpf-prologue.c @@ -57,6 +57,46 @@ 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)) @@ -257,9 +297,14 @@ 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 = argtype_to_ldx_size(args[i].type); + + 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); -- 2.10.1