Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755788AbbHYN1z (ORCPT ); Tue, 25 Aug 2015 09:27:55 -0400 Received: from szxga01-in.huawei.com ([58.251.152.64]:28231 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755067AbbHYN1w (ORCPT ); Tue, 25 Aug 2015 09:27:52 -0400 From: Wang Nan To: CC: , , , , Subject: [PATCH 2/2] perf probe: Support probing at absolute address Date: Tue, 25 Aug 2015 13:27:36 +0000 Message-ID: <1440509256-193590-2-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.3.4 In-Reply-To: <1440509256-193590-1-git-send-email-wangnan0@huawei.com> References: <1440509256-193590-1-git-send-email-wangnan0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.107.193.248] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8451 Lines: 295 It should be useful to allow 'perf probe' probe at absolute offset of a target. For example, when (u)probing at a instruction of a shared object in a embedded system where debuginfo is not avaliable but we know the offset of that instruction by manually digging. This patch enables following perf probe command syntax: # perf probe +0xffffffff811e6615 And # perf probe /lib/x86_64-linux-gnu/libc-2.19.so +0xeb860 In the above example, we don't need a anchor symbol, so it is possible to compute absolute addresses using other methods and then use 'perf probe' to create the probing points. Signed-off-by: Wang Nan Cc: Arnaldo Carvalho de Melo Cc: Ingo Molnar Cc: Masami Hiramatsu Cc: Namhyung Kim --- tools/perf/util/probe-event.c | 144 +++++++++++++++++++++++++++++++++++++---- tools/perf/util/probe-event.h | 3 + tools/perf/util/probe-finder.c | 21 +----- 3 files changed, 138 insertions(+), 30 deletions(-) diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 6c7e538..59de69a4 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -1194,9 +1194,13 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev) *ptr++ = '\0'; } - tmp = strdup(arg); - if (tmp == NULL) - return -ENOMEM; + if (arg[0] == '\0') + tmp = NULL; + else { + tmp = strdup(arg); + if (tmp == NULL) + return -ENOMEM; + } if (file_spec) pp->file = tmp; @@ -1283,11 +1287,6 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev) return -EINVAL; } - if (pp->offset && !pp->function) { - semantic_error("Offset requires an entry function.\n"); - return -EINVAL; - } - if (pp->retprobe && !pp->function) { semantic_error("Return probe requires an entry function.\n"); return -EINVAL; @@ -1299,6 +1298,11 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev) return -EINVAL; } + if (!pp->function && !pp->offset && !pp->file) { + semantic_error("Absolute address should not be zero.\n"); + return -EINVAL; + } + pr_debug("symbol:%s file:%s line:%d offset:%lu return:%d lazy:%s\n", pp->function, pp->file, pp->line, pp->offset, pp->retprobe, pp->lazy_line); @@ -1609,7 +1613,7 @@ error: static char *synthesize_perf_probe_point(struct perf_probe_point *pp) { char *buf, *tmp; - char offs[32] = "", line[32] = "", file[32] = ""; + char offs[32] = "", line[32] = "", file[32] = "", addr[32] = ""; int ret, len; buf = zalloc(MAX_CMDLEN); @@ -1622,6 +1626,11 @@ static char *synthesize_perf_probe_point(struct perf_probe_point *pp) if (ret <= 0) goto error; } + if (!pp->function) { + ret = e_snprintf(addr, 32, "0x%lx", pp->offset); + if (ret <= 0) + goto error; + } if (pp->line) { ret = e_snprintf(line, 32, ":%d", pp->line); if (ret <= 0) @@ -1639,9 +1648,11 @@ static char *synthesize_perf_probe_point(struct perf_probe_point *pp) goto error; } - if (pp->function) - ret = e_snprintf(buf, MAX_CMDLEN, "%s%s%s%s%s", pp->function, - offs, pp->retprobe ? "%return" : "", line, + if (pp->function || pp->offset) + ret = e_snprintf(buf, MAX_CMDLEN, "%s%s%s%s%s", + pp->function ? : addr, + pp->function ? offs : "", + pp->retprobe ? "%return" : "", line, file); else ret = e_snprintf(buf, MAX_CMDLEN, "%s%s", file, line); @@ -1786,6 +1797,11 @@ char *synthesize_probe_trace_command(struct probe_trace_event *tev) if (tev->uprobes) ret = e_snprintf(buf + len, MAX_CMDLEN - len, "%s:0x%lx", tp->module, tp->address); + else if (tp->symbol[0] == '0' && tp->symbol[1] == 'x') + /* Absolute address. See try_to_find_absolute_address() */ + ret = e_snprintf(buf + len, MAX_CMDLEN - len, "%s%s0x%lx", + tp->module ?: "", tp->module ? ":" : "", + tp->address); else ret = e_snprintf(buf + len, MAX_CMDLEN - len, "%s%s%s+%lu", tp->module ?: "", tp->module ? ":" : "", @@ -2572,6 +2588,87 @@ err_out: goto out; } +static int try_to_find_absolute_address(struct perf_probe_event *pev, + struct probe_trace_event **tevs) +{ + struct perf_probe_point *pp = &pev->point; + struct probe_trace_event *tev; + struct probe_trace_point *tp; + int i, err; + + if (perf_probe_event_need_dwarf(pev) || pev->point.function) + return -EINVAL; + + /* + * This is 'perf probe /lib/libc.so +0xabcd'. Try to probe at + * absolute address. + * + * Only one tev can be generated by this. + */ + *tevs = zalloc(sizeof(*tev)); + if (!*tevs) + return -ENOMEM; + + tev = *tevs; + tp = &tev->point; + + /* + * Don't use tp->offset, use address directly, because + * in synthesize_probe_trace_command() address cannot be + * zero. + */ + tp->address = pev->point.offset; + tp->retprobe = pp->retprobe; + tev->uprobes = pev->uprobes; + + err = -ENOMEM; + /* Give it a '0x' leading symbol name */ + if (asprintf(&tp->symbol, "0x%lx", tp->address) < 0) + goto errout; + + /* For kprobe, check range */ + if ((!tev->uprobes) && + (kprobe_warn_out_range(tev->point.symbol, + tev->point.address))) { + err = -EACCES; + goto errout; + } + + if (asprintf(&tp->realname, "abs_%lx", tp->address) < 0) + goto errout; + + if (pev->target) { + tp->module = strdup(pev->target); + if (!tp->module) + goto errout; + } + + if (tev->group) { + tev->group = strdup(pev->group); + if (!tev->group) + goto errout; + } + + if (pev->event) { + tev->event = strdup(pev->event); + if (!tev->event) + goto errout; + } + + tev->nargs = pev->nargs; + for (i = 0; i < tev->nargs; i++) + copy_to_probe_trace_arg(&tev->args[i], &pev->args[i]); + + return 1; + +errout: + if (*tevs) { + clear_probe_trace_events(*tevs, 1); + *tevs = NULL; + } + return err; +} + bool __weak arch__prefers_symtab(void) { return false; } static int convert_to_probe_trace_events(struct perf_probe_event *pev, @@ -2588,6 +2685,10 @@ static int convert_to_probe_trace_events(struct perf_probe_event *pev, } } + ret = try_to_find_absolute_address(pev, tevs); + if (ret > 0) + return ret; + if (arch__prefers_symtab() && !perf_probe_event_need_dwarf(pev)) { ret = find_probe_trace_events_from_map(pev, tevs); if (ret > 0) @@ -2758,3 +2859,22 @@ end: return ret; } +int copy_to_probe_trace_arg(struct probe_trace_arg *tvar, + struct perf_probe_arg *pvar) +{ + tvar->value = strdup(pvar->var); + if (tvar->value == NULL) + return -ENOMEM; + if (pvar->type) { + tvar->type = strdup(pvar->type); + if (tvar->type == NULL) + return -ENOMEM; + } + if (pvar->name) { + tvar->name = strdup(pvar->name); + if (tvar->name == NULL) + return -ENOMEM; + } else + tvar->name = NULL; + return 0; +} diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h index 83ee95e..174a3cf 100644 --- a/tools/perf/util/probe-event.h +++ b/tools/perf/util/probe-event.h @@ -156,4 +156,7 @@ int e_snprintf(char *str, size_t size, const char *format, ...) /* Maximum index number of event-name postfix */ #define MAX_EVENT_INDEX 1024 +int copy_to_probe_trace_arg(struct probe_trace_arg *tvar, + struct perf_probe_arg *pvar); + #endif /*_PROBE_EVENT_H */ diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index 7b80f8c..29c43c068 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -553,24 +553,9 @@ static int find_variable(Dwarf_Die *sc_die, struct probe_finder *pf) char buf[32], *ptr; int ret = 0; - if (!is_c_varname(pf->pvar->var)) { - /* Copy raw parameters */ - pf->tvar->value = strdup(pf->pvar->var); - if (pf->tvar->value == NULL) - return -ENOMEM; - if (pf->pvar->type) { - pf->tvar->type = strdup(pf->pvar->type); - if (pf->tvar->type == NULL) - return -ENOMEM; - } - if (pf->pvar->name) { - pf->tvar->name = strdup(pf->pvar->name); - if (pf->tvar->name == NULL) - return -ENOMEM; - } else - pf->tvar->name = NULL; - return 0; - } + /* Copy raw parameters */ + if (!is_c_varname(pf->pvar->var)) + return copy_to_probe_trace_arg(pf->tvar, pf->pvar); if (pf->pvar->name) pf->tvar->name = strdup(pf->pvar->name); -- 1.8.3.4 -- 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/