From caf8a0d0499792ac1b3f5b0b84e5890df0039cb6 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Tue, 17 May 2016 11:56:24 -0300 Subject: [PATCH] perf trace: Warn when trying to resolve kernel addresses with kptr_restrict=1 Hook into the libtraceevent plugin kernel symbol resolver to warn the user that that can't happen with kptr_restrict=1. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Milian Wolff Cc: Namhyung Kim Cc: Wang Nan Link: http://lkml.kernel.org/n/tip-9gc412xx1gl0lvqj1d1xwlyb@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-trace.c | 20 +++++++++++++++++++- tools/perf/util/machine.c | 1 + tools/perf/util/machine.h | 1 + 3 files changed, 21 insertions(+), 1 deletion(-) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index 6e5c325..e488ac7 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -1160,6 +1160,24 @@ static int trace__tool_process(struct perf_tool *tool, return trace__process_event(trace, machine, event, sample); } +static char *trace__machine__resolve_kernel_addr(void *vmachine, unsigned long long *addrp, char **modp) +{ + struct machine *machine = vmachine; + + if (machine->kptr_restrict_warned) + return NULL; + + if (symbol_conf.kptr_restrict) { + pr_warning("Kernel address maps (/proc/{kallsyms,modules}) are restricted.\n\n" + "Check /proc/sys/kernel/kptr_restrict.\n\n" + "Kernel samples will not be resolved.\n"); + machine->kptr_restrict_warned = true; + return NULL; + } + + return machine__resolve_kernel_addr(vmachine, addrp, modp); +} + static int trace__symbols_init(struct trace *trace, struct perf_evlist *evlist) { int err = symbol__init(NULL); @@ -1171,7 +1189,7 @@ static int trace__symbols_init(struct trace *trace, struct perf_evlist *evlist) if (trace->host == NULL) return -ENOMEM; - if (trace_event__register_resolver(trace->host, machine__resolve_kernel_addr) < 0) + if (trace_event__register_resolver(trace->host, trace__machine__resolve_kernel_addr) < 0) return -errno; err = __machine__synthesize_threads(trace->host, &trace->tool, &trace->opts.target, diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c index b277984..bdc33ce 100644 --- a/tools/perf/util/machine.c +++ b/tools/perf/util/machine.c @@ -43,6 +43,7 @@ int machine__init(struct machine *machine, const char *root_dir, pid_t pid) machine->symbol_filter = NULL; machine->id_hdr_size = 0; + machine->kptr_restrict_warned = false; machine->comm_exec = false; machine->kernel_start = 0; diff --git a/tools/perf/util/machine.h b/tools/perf/util/machine.h index 83f4679..41ac9cf 100644 --- a/tools/perf/util/machine.h +++ b/tools/perf/util/machine.h @@ -28,6 +28,7 @@ struct machine { pid_t pid; u16 id_hdr_size; bool comm_exec; + bool kptr_restrict_warned; char *root_dir; struct rb_root threads; pthread_rwlock_t threads_lock; -- 2.7.4