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perf_counter: sysctl for system wide perf counters

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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: Peter 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: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-04-09 10:53:45 +02:00 committed by Ingo Molnar
parent 9ee318a782
commit 1ccd154978
3 changed files with 16 additions and 1 deletions
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2
include/linux/perf_counter.h
View file

@ -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) { }

4
kernel/perf_counter.c
View file

@ -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())

11
kernel/sysctl.c
View file

@ -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