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Commit caf8a0d0 authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

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 <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-9gc412xx1gl0lvqj1d1xwlyb@git.kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 45e90056

tools/perf/builtin-trace.c

+19 −1
Original line number Diff line number Diff line
@@ -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,

tools/perf/util/machine.c

+1 −0
Original line number Diff line number Diff line
@@ -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;

tools/perf/util/machine.h

+1 −0
Original line number Diff line number Diff line
@@ -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;