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[PATCH 29/40] perf top: Support lookup of symbols in other mount namespaces.

From Arnaldo Carvalho de Melo <acme@kernel.org>
Newsgroups linux.kernel
Subject [PATCH 29/40] perf top: Support lookup of symbols in other mount namespaces.
Date 2017-07-26 16:30 +0200
Message-ID <u7vu3-1s1-47@gated-at.bofh.it> (permalink)
References <u7vkm-1ob-7@gated-at.bofh.it>
Organization linux.* mail to news gateway

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From: Krister Johansen <kjlx@templeofstupid.com>

The perf top command needs to unshare its fs from the helper threads in
order to successfully setns(2) during its symbol lookup.  It also needs
to impelement a force flag to ignore ownership of perf-<pid>.map files.

Signed-off-by: Krister Johansen <kjlx@templeofstupid.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas-Mich Richter <tmricht@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1499305693-1599-6-git-send-email-kjlx@templeofstupid.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/Documentation/perf-top.txt |  4 ++++
 tools/perf/builtin-top.c              | 15 +++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/tools/perf/Documentation/perf-top.txt b/tools/perf/Documentation/perf-top.txt
index e71d63843f45..d864ea6fd367 100644
--- a/tools/perf/Documentation/perf-top.txt
+++ b/tools/perf/Documentation/perf-top.txt
@@ -237,6 +237,10 @@ Default is to monitor all CPUS.
 --hierarchy::
 	Enable hierarchy output.
 
+--force::
+	Don't do ownership validation.
+
+
 INTERACTIVE PROMPTING KEYS
 --------------------------
 
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index e5a8f249077f..ee954bde7e3e 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -587,6 +587,13 @@ static void *display_thread_tui(void *arg)
 		.refresh	= top->delay_secs,
 	};
 
+	/* In order to read symbols from other namespaces perf to  needs to call
+	 * setns(2).  This isn't permitted if the struct_fs has multiple users.
+	 * unshare(2) the fs so that we may continue to setns into namespaces
+	 * that we're observing.
+	 */
+	unshare(CLONE_FS);
+
 	perf_top__sort_new_samples(top);
 
 	/*
@@ -628,6 +635,13 @@ static void *display_thread(void *arg)
 	struct perf_top *top = arg;
 	int delay_msecs, c;
 
+	/* In order to read symbols from other namespaces perf to  needs to call
+	 * setns(2).  This isn't permitted if the struct_fs has multiple users.
+	 * unshare(2) the fs so that we may continue to setns into namespaces
+	 * that we're observing.
+	 */
+	unshare(CLONE_FS);
+
 	display_setup_sig();
 	pthread__unblock_sigwinch();
 repeat:
@@ -1206,6 +1220,7 @@ int cmd_top(int argc, const char **argv)
 		    "Show raw trace event output (do not use print fmt or plugins)"),
 	OPT_BOOLEAN(0, "hierarchy", &symbol_conf.report_hierarchy,
 		    "Show entries in a hierarchy"),
+	OPT_BOOLEAN(0, "force", &symbol_conf.force, "don't complain, do it"),
 	OPT_END()
 	};
 	const char * const top_usage[] = {
-- 
2.9.4

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[GIT PULL 00/40] perf/core improvements and fixes Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:20 +0200
  [PATCH 15/40] tools include: Adopt strstarts() from the kernel Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:20 +0200
  [PATCH 30/40] perf script: Remove some bogus error handling Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 39/40] perf annotate stdio: Fix column header when using --show-total-period Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 33/40] perf script python: Add sample_read to dict Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 22/40] perf annotate stdio: Fix --show-total-period Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 40/40] perf tools: Add tools/include/uapi/asm-generic/fcntl.h to the MANIFEST Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 38/40] perf jevents: Make build fail on JSON parse error Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 36/40] perf report: Make --branch-history work without callgraphs(-g) option in perf record Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 26/40] perf annotate: Process tracing data in pipe mode Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 29/40] perf top: Support lookup of symbols in other mount namespaces. Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 32/40] perf script python: Refactor creation of perf sample dict Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 23/40] perf report: Fix kernel symbol adjustment for s390x Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 28/40] perf evsel: Add verbose output for sys_perf_event_open fallback Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 35/40] perf script python: Generate hooks with additional argument Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 21/40] perf annotate: Do not overwrite sample->period Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 27/40] perf jvmti: Fix linker error when libelf config is disabled Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 31/40] perf script python: Allocate memory only if handler exists Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 34/40] perf script python: Add perf_sample dict to tracepoint handlers Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 25/40] perf tools: Add EXCLUDE_EXTLIBS and EXTRA_PERFLIBS to makefile Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 24/40] perf cgroup: Fix refcount usage Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 37/40] perf report: Tag branch type/flag on "to" and tag cycles on "from" Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:30 +0200
  [PATCH 03/40] perf trace: Add missing ' = ' in the default formatting of syscall returns Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:40 +0200
  [PATCH 05/40] perf trace: Allow allocating sc->arg_fmt even without the syscall tracepoint Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:40 +0200
  [PATCH 01/40] perf intel-pt: Set no_aux_samples for the tracking event Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:40 +0200
  [PATCH 04/40] perf trace beauty mmap: Ignore 'fd' and 'offset' args for MAP_ANONYMOUS Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:40 +0200
  [PATCH 17/40] perf annotate: Introduce struct sym_hist_entry Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 16:40 +0200
  Re: [GIT PULL 00/40] perf/core improvements and fixes Ingo Molnar <mingo@kernel.org> - 2017-07-26 19:20 +0200

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