Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757477AbbEEKK6 (ORCPT ); Tue, 5 May 2015 06:10:58 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:14055 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757430AbbEEKKu (ORCPT ); Tue, 5 May 2015 06:10:50 -0400 From: He Kuang To: , , , , , , CC: , , , Subject: [RFC PATCH 0/6] perf bpf: Probing with local variable Date: Tue, 5 May 2015 10:10:06 +0000 Message-ID: <1430820612-84443-1-git-send-email-hekuang@huawei.com> X-Mailer: git-send-email 1.8.3.4 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.197.210] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3528 Lines: 90 This patch set is based on https://lkml.org/lkml/2015/4/30/264 By using bpf 'config' section like this: char _config2[] SEC("config") = "generic_perform_write=generic_perform_write+122 file->f_mapping->a_ops bytes offset"; SEC("generic_perform_write") int NODE_generic_perform_write (struct pt_regs *ctx, void *a_ops, void *bytes, void* offset) { char fmt[] = "NODE_generic_perform_write, a_ops=%p, bytes=%p, offset=%p\n"; bpf_trace_printk(fmt, sizeof(fmt), a_ops, bytes, offset); return 1; } In this example, 'bytes' and 'offset' are local variables, a_ops is in the structure field of file parameter, and we probe in the body of the generic_perform_write() function. Perf can fetch and convert all the arguments and then we translate them into bpf bytecode as a prologue before calling bpf body functions. In the prologue, we fetch arguments from bpf context register and place them according to bpf calling conventions so the body function can access them as formal parameters. The perf command is as following: $ perf bpf -v bpf_bytecode.o ... bpf_prologue: insn num=26 (bf) r6 = r1 (79) r3 = *(u64 *)(r6 +112) (07) r3 += 248 (b7) r1 = 0 (7b) *(u64 *)(r10 -8) = r1 (bf) r1 = r10 (07) r1 += -8 (b7) r2 = 8 (85) call 4 (79) r3 = *(u64 *)(r10 -8) (07) r3 += 104 (b7) r1 = 0 (7b) *(u64 *)(r10 -8) = r1 (bf) r1 = r10 (07) r1 += -8 (b7) r2 = 8 (85) call 4 (79) r3 = *(u64 *)(r10 -8) (bf) r7 = r3 (79) r3 = *(u64 *)(r6 +24) (bf) r8 = r3 (79) r3 = *(u64 *)(r6 +88) (bf) r9 = r3 (bf) r2 = r7 (bf) r3 = r8 (bf) r4 = r9 ... Added new event: Writing event: p:perf_bpf_probe/generic_perform_write _stext+1257282 a_ops=+104(+248(%di)):u64 bytes=%r12:u64 offset=%cx:u64 perf_bpf_probe:generic_perform_write (on generic_perform_write+122 with a_ops=file->f_mapping->a_ops bytes offset) The trace output: sh-1260 [000] d... 112592.463169: : NODE_generic_perform_write, a_ops=ffffffff81a20160, bytes=0000000000000017, offset=000000000000031d sh-1260 [000] d... 112593.155105: : NODE_generic_perform_write, a_ops=ffffffff81a20160, bytes=000000000000000a, offset=0000000000000334 sh-1260 [000] d... 112599.015993: : NODE_generic_perform_write, a_ops=ffffffff81a20160, bytes=0000000000000017, offset=000000000000033e sh-1260 [000] d... 112600.790977: : NODE_generic_perform_write, a_ops=ffffffff81a20160, bytes=000000000000000a, offset=0000000000000355 He Kuang (6): perf bpf: Add headers for generate bpf bytecode perf bpf: Add pt_regs convert table for x86 perf bpf: Save pt_regs info from debuginfo perf bpf: Convert arglist to bpf prologue perf bpf: Process debuginfo for generating bpf prologue perf bpf: Generate bpf prologue for arguments tools/perf/arch/x86/util/dwarf-regs.c | 31 ++++++ tools/perf/util/bpf-loader.c | 66 ++++++++++++ tools/perf/util/bpf-loader.h | 188 ++++++++++++++++++++++++++++++++++ tools/perf/util/include/dwarf-regs.h | 2 + tools/perf/util/probe-event.c | 121 ++++++++++++++++++++++ tools/perf/util/probe-event.h | 12 +++ tools/perf/util/probe-finder.c | 101 ++++++++++++++++++ tools/perf/util/probe-finder.h | 4 + 8 files changed, 525 insertions(+) -- 1.8.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/