From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753921AbbDBMgs (ORCPT ); Thu, 2 Apr 2015 08:36:48 -0400 Received: from terminus.zytor.com ([198.137.202.10]:60951 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753440AbbDBMgn (ORCPT ); Thu, 2 Apr 2015 08:36:43 -0400 Date: Thu, 2 Apr 2015 05:35:42 -0700 From: tip-bot for Alexei Starovoitov Message-ID: Cc: acme@redhat.com, linux-kernel@vger.kernel.org, rostedt@goodmis.org, daniel@iogearbox.net, akpm@linux-foundation.org, davem@davemloft.net, acme@infradead.org, peterz@infradead.org, ast@plumgrid.com, masami.hiramatsu.pt@hitachi.com, namhyung@kernel.org, torvalds@linux-foundation.org, hpa@zytor.com, a.p.zijlstra@chello.nl, tglx@linutronix.de, jolsa@redhat.com, mingo@kernel.org Reply-To: davem@davemloft.net, acme@infradead.org, akpm@linux-foundation.org, daniel@iogearbox.net, acme@redhat.com, linux-kernel@vger.kernel.org, rostedt@goodmis.org, a.p.zijlstra@chello.nl, tglx@linutronix.de, mingo@kernel.org, jolsa@redhat.com, torvalds@linux-foundation.org, hpa@zytor.com, namhyung@kernel.org, peterz@infradead.org, ast@plumgrid.com, masami.hiramatsu.pt@hitachi.com In-Reply-To: <1427312966-8434-6-git-send-email-ast@plumgrid.com> References: <1427312966-8434-6-git-send-email-ast@plumgrid.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:perf/core] tracing: Allow BPF programs to call bpf_trace_printk() Git-Commit-ID: 9c959c863f8217a2ff3d7c296e8223654d240569 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 9c959c863f8217a2ff3d7c296e8223654d240569 Gitweb: http://git.kernel.org/tip/9c959c863f8217a2ff3d7c296e8223654d240569 Author: Alexei Starovoitov AuthorDate: Wed, 25 Mar 2015 12:49:22 -0700 Committer: Ingo Molnar CommitDate: Thu, 2 Apr 2015 13:25:50 +0200 tracing: Allow BPF programs to call bpf_trace_printk() Debugging of BPF programs needs some form of printk from the program, so let programs call limited trace_printk() with %d %u %x %p modifiers only. Similar to kernel modules, during program load verifier checks whether program is calling bpf_trace_printk() and if so, kernel allocates trace_printk buffers and emits big 'this is debug only' banner. Signed-off-by: Alexei Starovoitov Reviewed-by: Steven Rostedt Cc: Andrew Morton Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Daniel Borkmann Cc: David S. Miller Cc: Jiri Olsa Cc: Linus Torvalds Cc: Masami Hiramatsu Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1427312966-8434-6-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar --- include/uapi/linux/bpf.h | 1 + kernel/trace/bpf_trace.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 79 insertions(+) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 238c688..cc47ef4 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -166,6 +166,7 @@ enum bpf_func_id { BPF_FUNC_map_delete_elem, /* int map_delete_elem(&map, &key) */ BPF_FUNC_probe_read, /* int bpf_probe_read(void *dst, int size, void *src) */ BPF_FUNC_ktime_get_ns, /* u64 bpf_ktime_get_ns(void) */ + BPF_FUNC_trace_printk, /* int bpf_trace_printk(const char *fmt, int fmt_size, ...) */ __BPF_FUNC_MAX_ID, }; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 8f57872..2d56ce5 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -10,6 +10,7 @@ #include #include #include +#include #include "trace.h" static DEFINE_PER_CPU(int, bpf_prog_active); @@ -90,6 +91,74 @@ static const struct bpf_func_proto bpf_ktime_get_ns_proto = { .ret_type = RET_INTEGER, }; +/* + * limited trace_printk() + * only %d %u %x %ld %lu %lx %lld %llu %llx %p conversion specifiers allowed + */ +static u64 bpf_trace_printk(u64 r1, u64 fmt_size, u64 r3, u64 r4, u64 r5) +{ + char *fmt = (char *) (long) r1; + int mod[3] = {}; + int fmt_cnt = 0; + int i; + + /* + * bpf_check()->check_func_arg()->check_stack_boundary() + * guarantees that fmt points to bpf program stack, + * fmt_size bytes of it were initialized and fmt_size > 0 + */ + if (fmt[--fmt_size] != 0) + return -EINVAL; + + /* check format string for allowed specifiers */ + for (i = 0; i < fmt_size; i++) { + if ((!isprint(fmt[i]) && !isspace(fmt[i])) || !isascii(fmt[i])) + return -EINVAL; + + if (fmt[i] != '%') + continue; + + if (fmt_cnt >= 3) + return -EINVAL; + + /* fmt[i] != 0 && fmt[last] == 0, so we can access fmt[i + 1] */ + i++; + if (fmt[i] == 'l') { + mod[fmt_cnt]++; + i++; + } else if (fmt[i] == 'p') { + mod[fmt_cnt]++; + i++; + if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0) + return -EINVAL; + fmt_cnt++; + continue; + } + + if (fmt[i] == 'l') { + mod[fmt_cnt]++; + i++; + } + + if (fmt[i] != 'd' && fmt[i] != 'u' && fmt[i] != 'x') + return -EINVAL; + fmt_cnt++; + } + + return __trace_printk(1/* fake ip will not be printed */, fmt, + mod[0] == 2 ? r3 : mod[0] == 1 ? (long) r3 : (u32) r3, + mod[1] == 2 ? r4 : mod[1] == 1 ? (long) r4 : (u32) r4, + mod[2] == 2 ? r5 : mod[2] == 1 ? (long) r5 : (u32) r5); +} + +static const struct bpf_func_proto bpf_trace_printk_proto = { + .func = bpf_trace_printk, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_STACK, + .arg2_type = ARG_CONST_STACK_SIZE, +}; + static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func_id) { switch (func_id) { @@ -103,6 +172,15 @@ static const struct bpf_func_proto *kprobe_prog_func_proto(enum bpf_func_id func return &bpf_probe_read_proto; case BPF_FUNC_ktime_get_ns: return &bpf_ktime_get_ns_proto; + + case BPF_FUNC_trace_printk: + /* + * this program might be calling bpf_trace_printk, + * so allocate per-cpu printk buffers + */ + trace_printk_init_buffers(); + + return &bpf_trace_printk_proto; default: return NULL; }