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Commit 1ccd1549 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: sysctl for system wide perf counters 



Impact: add sysctl for paranoid/relaxed perfcounters policy

Allow the use of system wide perf counters to everybody, but provide
a sysctl to disable it for the paranoid security minded.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090409085524.514046352@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 9ee318a7

include/linux/perf_counter.h

+2 −0
Original line number Diff line number Diff line
@@ -568,6 +568,8 @@ struct perf_callchain_entry { 


extern struct perf_callchain_entry *perf_callchain(struct pt_regs *regs);



extern int sysctl_perf_counter_priv;



#else

static inline void

perf_counter_task_sched_in(struct task_struct *task, int cpu)		{ }

kernel/perf_counter.c

+3 −1
Original line number Diff line number Diff line
@@ -42,6 +42,8 @@ static atomic_t nr_mmap_tracking __read_mostly; 
static atomic_t nr_munmap_tracking __read_mostly;

static atomic_t nr_comm_tracking __read_mostly;



int sysctl_perf_counter_priv __read_mostly; /* do we need to be privileged */



/*

 * Mutex for (sysadmin-configurable) counter reservations:

 */
@@ -1132,7 +1134,7 @@ static struct perf_counter_context *find_get_context(pid_t pid, int cpu) 
	 */

	if (cpu != -1) {

		/* Must be root to operate on a CPU counter: */

		if (!capable(CAP_SYS_ADMIN))

		if (sysctl_perf_counter_priv && !capable(CAP_SYS_ADMIN))

			return ERR_PTR(-EACCES);



		if (cpu < 0 || cpu > num_possible_cpus())

kernel/sysctl.c

+11 −0
Original line number Diff line number Diff line
@@ -49,6 +49,7 @@ 
#include <linux/reboot.h>

#include <linux/ftrace.h>

#include <linux/slow-work.h>

#include <linux/perf_counter.h>



#include <asm/uaccess.h>

#include <asm/processor.h>
@@ -920,6 +921,16 @@ static struct ctl_table kern_table[] = { 
		.child		= slow_work_sysctls,

	},

#endif

#ifdef CONFIG_PERF_COUNTERS

	{

		.ctl_name	= CTL_UNNUMBERED,

		.procname	= "perf_counter_privileged",

		.data		= &sysctl_perf_counter_priv,

		.maxlen		= sizeof(sysctl_perf_counter_priv),

		.mode		= 0644,

		.proc_handler	= &proc_dointvec,

	},

#endif

/*

 * NOTE: do not add new entries to this table unless you have read

 * Documentation/sysctl/ctl_unnumbered.txt