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perf top: Support lookup of symbols in other mount namespaces.

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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 <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Brendan Gregg <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas-Mich Richter <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
This commit is contained in:
Krister Johansen 2017-07-05 18:48:12 -07:00 • committed by Arnaldo Carvalho de Melo
commit 868a832918
2 changed files with 19 additions and 0 deletions
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4
tools/perf/Documentation/perf-top.txt
View file

@ -237,6 +237,10 @@ Default is to monitor all CPUS.
--hierarchy::
Enable hierarchy output.
--force::
Don't do ownership validation.
INTERACTIVE PROMPTING KEYS
--------------------------

15
tools/perf/builtin-top.c
View file

@ -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[] = {