From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DE3B1C04AA7 for ; Wed, 15 May 2019 05:39:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9AA072168B for ; Wed, 15 May 2019 05:39:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557898755; bh=RQbZdEywXTKImIQgtR0Ab98Z5+mb/iASPOUkCd/efAY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=J4MGgRjZS2jTPN8DJP2Vd4XtWc8dpvtvnjHbhu2D2V7Vji7qHN/YSvVoldQE0SaN1 gNAWmbDBDuxWNciscyo7qvt3BKyTEJjqzFMqWnW0bo7x4ylUM2Nv/WydP21gtNmjEH xoWeRa2hLU5bQTLcTJRVeeYV1ZlpDAUAOV3LRJ5g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726598AbfEOFjO (ORCPT ); Wed, 15 May 2019 01:39:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:53216 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725781AbfEOFjO (ORCPT ); Wed, 15 May 2019 01:39:14 -0400 Received: from localhost.localdomain (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 51AA52166E; Wed, 15 May 2019 05:39:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557898752; bh=RQbZdEywXTKImIQgtR0Ab98Z5+mb/iASPOUkCd/efAY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZOhIAVfAd9m4jWGQvrRabdqEUCl3BNIzW+QB0ASst+V7nx3nqHG2P/kLrmQSWWjA4 TbGgbzJWNXtphr/r4g7+2pDuVmcyQWQRdVUC3gjfUfn5lWGP5iGRuSxqQiaGjK4iK8 tZ3qJoonlsnGe9n7Rj2WFUyRo4VNdTg67B5X00VM= From: Masami Hiramatsu To: Steven Rostedt , Linus Torvalds , Shuah Khan , Arnaldo Carvalho de Melo , Peter Zijlstra Cc: mhiramat@kernel.org, linux-kernel@vger.kernel.org, Andy Lutomirski , Ingo Molnar , Andrew Morton , Changbin Du , Jann Horn , Kees Cook , Andy Lutomirski , Alexei Starovoitov , Nadav Amit , Joel Fernandes , yhs@fb.com Subject: [PATCH -tip v9 6/6] perf-probe: Add user memory access attribute support Date: Wed, 15 May 2019 14:39:05 +0900 Message-Id: <155789874562.26965.10836126971405890891.stgit@devnote2> X-Mailer: git-send-email 2.17.1 In-Reply-To: <155789866428.26965.8344923934342528416.stgit@devnote2> References: <155789866428.26965.8344923934342528416.stgit@devnote2> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add user memory access attribute for kprobe event arguments. If a given 'local variable' is in user-space, User can specify memory access method by '@user' suffix. This is not only for string but also for data structure. If we access a field of data structure in user memory from kernel on some arch, it will fail. e.g. perf probe -a "sched_setscheduler param->sched_priority" This will fail to access the "param->sched_priority" because the param is __user pointer. Instead, we can now specify @user suffix for such argument. perf probe -a "sched_setscheduler param->sched_priority@user" Note that kernel memory access with "@user" must always fail on any arch. Signed-off-by: Masami Hiramatsu Acked-by: Steven Rostedt (VMware) --- Changes in v8 - Fix a typo and rename user field to user_access field. (Thanks Ingo!) --- tools/perf/Documentation/perf-probe.txt | 3 ++- tools/perf/util/probe-event.c | 11 +++++++++++ tools/perf/util/probe-event.h | 2 ++ tools/perf/util/probe-file.c | 7 +++++++ tools/perf/util/probe-file.h | 1 + tools/perf/util/probe-finder.c | 19 ++++++++++++------- 6 files changed, 35 insertions(+), 8 deletions(-) diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt index b6866a05edd2..ed3ecfa422e1 100644 --- a/tools/perf/Documentation/perf-probe.txt +++ b/tools/perf/Documentation/perf-probe.txt @@ -194,12 +194,13 @@ PROBE ARGUMENT -------------- Each probe argument follows below syntax. - [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE] + [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE][@user] 'NAME' specifies the name of this argument (optional). You can use the name of local variable, local data structure member (e.g. var->field, var.field2), local array with fixed index (e.g. array[1], var->array[0], var->pointer[2]), or kprobe-tracer argument format (e.g. $retval, %ax, etc). Note that the name of this argument will be set as the last member name if you specify a local data structure member (e.g. field2 for 'var->field1.field2'.) '$vars' and '$params' special arguments are also available for NAME, '$vars' is expanded to the local variables (including function parameters) which can access at given probe point. '$params' is expanded to only the function parameters. 'TYPE' casts the type of this argument (optional). If omitted, perf probe automatically set the type based on debuginfo (*). Currently, basic types (u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal integers (x/x8/x16/x32/x64), signedness casting (u/s), "string" and bitfield are supported. (see TYPES for detail) On x86 systems %REG is always the short form of the register: for example %AX. %RAX or %EAX is not valid. +"@user" is a special attribute which means the LOCALVAR will be treated as a user-space memory. This is only valid for kprobe event. TYPES ----- diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 198e09ff611e..a7ca17be5fc5 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -1577,6 +1577,17 @@ static int parse_perf_probe_arg(char *str, struct perf_probe_arg *arg) str = tmp + 1; } + tmp = strchr(str, '@'); + if (tmp && tmp != str && strcmp(tmp + 1, "user")) { /* user attr */ + if (!user_access_is_supported()) { + semantic_error("ftrace does not support user access\n"); + return -EINVAL; + } + *tmp = '\0'; + arg->user_access = true; + pr_debug("user_access "); + } + tmp = strchr(str, ':'); if (tmp) { /* Type setting */ *tmp = '\0'; diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h index 05c8d571a901..96a319cd2378 100644 --- a/tools/perf/util/probe-event.h +++ b/tools/perf/util/probe-event.h @@ -37,6 +37,7 @@ struct probe_trace_point { struct probe_trace_arg_ref { struct probe_trace_arg_ref *next; /* Next reference */ long offset; /* Offset value */ + bool user_access; /* User-memory access */ }; /* kprobe-tracer and uprobe-tracer tracing argument */ @@ -82,6 +83,7 @@ struct perf_probe_arg { char *var; /* Variable name */ char *type; /* Type name */ struct perf_probe_arg_field *field; /* Structure fields */ + bool user_access; /* User-memory access */ }; /* Perf probe probing event (point + arg) */ diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c index 4062bc4412a9..89ce1a9c3798 100644 --- a/tools/perf/util/probe-file.c +++ b/tools/perf/util/probe-file.c @@ -1015,6 +1015,7 @@ enum ftrace_readme { FTRACE_README_PROBE_TYPE_X = 0, FTRACE_README_KRETPROBE_OFFSET, FTRACE_README_UPROBE_REF_CTR, + FTRACE_README_USER_ACCESS, FTRACE_README_END, }; @@ -1027,6 +1028,7 @@ static struct { DEFINE_TYPE(FTRACE_README_PROBE_TYPE_X, "*type: * x8/16/32/64,*"), DEFINE_TYPE(FTRACE_README_KRETPROBE_OFFSET, "*place (kretprobe): *"), DEFINE_TYPE(FTRACE_README_UPROBE_REF_CTR, "*ref_ctr_offset*"), + DEFINE_TYPE(FTRACE_README_USER_ACCESS, "*[u]*"), }; static bool scan_ftrace_readme(enum ftrace_readme type) @@ -1087,3 +1089,8 @@ bool uprobe_ref_ctr_is_supported(void) { return scan_ftrace_readme(FTRACE_README_UPROBE_REF_CTR); } + +bool user_access_is_supported(void) +{ + return scan_ftrace_readme(FTRACE_README_USER_ACCESS); +} diff --git a/tools/perf/util/probe-file.h b/tools/perf/util/probe-file.h index 2a249182f2a6..986c1c94f64f 100644 --- a/tools/perf/util/probe-file.h +++ b/tools/perf/util/probe-file.h @@ -70,6 +70,7 @@ int probe_cache__show_all_caches(struct strfilter *filter); bool probe_type_is_available(enum probe_type type); bool kretprobe_offset_is_supported(void); bool uprobe_ref_ctr_is_supported(void); +bool user_access_is_supported(void); #else /* ! HAVE_LIBELF_SUPPORT */ static inline struct probe_cache *probe_cache__new(const char *tgt __maybe_unused, struct nsinfo *nsi __maybe_unused) { diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index c37fbef1711d..c202027716d0 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -294,7 +294,7 @@ static int convert_variable_location(Dwarf_Die *vr_die, Dwarf_Addr addr, static int convert_variable_type(Dwarf_Die *vr_die, struct probe_trace_arg *tvar, - const char *cast) + const char *cast, bool user_access) { struct probe_trace_arg_ref **ref_ptr = &tvar->ref; Dwarf_Die type; @@ -334,7 +334,8 @@ static int convert_variable_type(Dwarf_Die *vr_die, pr_debug("%s type is %s.\n", dwarf_diename(vr_die), dwarf_diename(&type)); - if (cast && strcmp(cast, "string") == 0) { /* String type */ + if (cast && (!strcmp(cast, "string") || !strcmp(cast, "ustring"))) { + /* String type */ ret = dwarf_tag(&type); if (ret != DW_TAG_pointer_type && ret != DW_TAG_array_type) { @@ -357,6 +358,7 @@ static int convert_variable_type(Dwarf_Die *vr_die, pr_warning("Out of memory error\n"); return -ENOMEM; } + (*ref_ptr)->user_access = user_access; } if (!die_compare_name(&type, "char") && !die_compare_name(&type, "unsigned char")) { @@ -411,7 +413,7 @@ static int convert_variable_type(Dwarf_Die *vr_die, static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname, struct perf_probe_arg_field *field, struct probe_trace_arg_ref **ref_ptr, - Dwarf_Die *die_mem) + Dwarf_Die *die_mem, bool user_access) { struct probe_trace_arg_ref *ref = *ref_ptr; Dwarf_Die type; @@ -448,6 +450,7 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname, *ref_ptr = ref; } ref->offset += dwarf_bytesize(&type) * field->index; + ref->user_access = user_access; goto next; } else if (tag == DW_TAG_pointer_type) { /* Check the pointer and dereference */ @@ -519,17 +522,18 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname, } } ref->offset += (long)offs; + ref->user_access = user_access; /* If this member is unnamed, we need to reuse this field */ if (!dwarf_diename(die_mem)) return convert_variable_fields(die_mem, varname, field, - &ref, die_mem); + &ref, die_mem, user_access); next: /* Converting next field */ if (field->next) return convert_variable_fields(die_mem, field->name, - field->next, &ref, die_mem); + field->next, &ref, die_mem, user_access); else return 0; } @@ -555,11 +559,12 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf) else if (ret == 0 && pf->pvar->field) { ret = convert_variable_fields(vr_die, pf->pvar->var, pf->pvar->field, &pf->tvar->ref, - &die_mem); + &die_mem, pf->pvar->user_access); vr_die = &die_mem; } if (ret == 0) - ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type); + ret = convert_variable_type(vr_die, pf->tvar, pf->pvar->type, + pf->pvar->user_access); /* *expr will be cached in libdw. Don't free it. */ return ret; }