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perfcounters: provide expansion room in the ABI

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Impact: ABI change

This expands several fields in the perf_counter_hw_event struct and adds
a "flags" argument to the perf_counter_open system call, in order that
features can be added in future without ABI changes.

In particular the record_type field is expanded to 64 bits, and the
space for flag bits has been expanded from 32 to 64 bits.

This also adds some new fields:

* read_format (64 bits) is intended to provide a way to specify what
  userspace wants to get back when it does a read() on a simple
  (non-interrupting) counter;

* exclude_idle (1 bit) provides a way for userspace to ask that events
  that occur when the cpu is idle be excluded;

* extra_config_len will provide a way for userspace to supply an
  arbitrary amount of extra machine-specific PMU configuration data
  immediately following the perf_counter_hw_event struct, to allow
  sophisticated users to program things such as instruction matching
  CAMs and address range registers;

* __reserved_3 and __reserved_4 provide space for future expansion.

Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Paul Mackerras 2009-03-04 20:36:51 +11:00
parent a1ef58f442
commit 2743a5b0fa
3 changed files with 17 additions and 7 deletions
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12
include/linux/perf_counter.h
View File

@ -69,9 +69,10 @@ struct perf_counter_hw_event {
__s64 type; __s64 type;
__u64 irq_period; __u64 irq_period;
__u32 record_type; __u64 record_type;
__u64 read_format;
__u32 disabled : 1, /* off by default */ __u64 disabled : 1, /* off by default */
nmi : 1, /* NMI sampling */ nmi : 1, /* NMI sampling */
raw : 1, /* raw event type */ raw : 1, /* raw event type */
inherit : 1, /* children inherit it */ inherit : 1, /* children inherit it */
@ -80,10 +81,15 @@ struct perf_counter_hw_event {
exclude_user : 1, /* don't count user */ exclude_user : 1, /* don't count user */
exclude_kernel : 1, /* ditto kernel */ exclude_kernel : 1, /* ditto kernel */
exclude_hv : 1, /* ditto hypervisor */ exclude_hv : 1, /* ditto hypervisor */
exclude_idle : 1, /* don't count when idle */
__reserved_1 : 23; __reserved_1 : 55;
__u32 extra_config_len;
__u32 __reserved_4;
__u64 __reserved_2; __u64 __reserved_2;
__u64 __reserved_3;
}; };
/* /*

2
include/linux/syscalls.h
View File

@ -698,5 +698,5 @@ int kernel_execve(const char *filename, char *const argv[], char *const envp[]);
asmlinkage long sys_perf_counter_open( asmlinkage long sys_perf_counter_open(
const struct perf_counter_hw_event __user *hw_event_uptr, const struct perf_counter_hw_event __user *hw_event_uptr,
pid_t pid, int cpu, int group_fd); pid_t pid, int cpu, int group_fd, unsigned long flags);
#endif #endif

10
kernel/perf_counter.c
View File

@ -1683,16 +1683,16 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event,
} }
/** /**
* sys_perf_task_open - open a performance counter, associate it to a task/cpu * sys_perf_counter_open - open a performance counter, associate it to a task/cpu
* *
* @hw_event_uptr: event type attributes for monitoring/sampling * @hw_event_uptr: event type attributes for monitoring/sampling
* @pid: target pid * @pid: target pid
* @cpu: target cpu * @cpu: target cpu
* @group_fd: group leader counter fd * @group_fd: group leader counter fd
*/ */
SYSCALL_DEFINE4(perf_counter_open, SYSCALL_DEFINE5(perf_counter_open,
const struct perf_counter_hw_event __user *, hw_event_uptr, const struct perf_counter_hw_event __user *, hw_event_uptr,
pid_t, pid, int, cpu, int, group_fd) pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
{ {
struct perf_counter *counter, *group_leader; struct perf_counter *counter, *group_leader;
struct perf_counter_hw_event hw_event; struct perf_counter_hw_event hw_event;
@ -1703,6 +1703,10 @@ SYSCALL_DEFINE4(perf_counter_open,
int fput_needed2 = 0; int fput_needed2 = 0;
int ret; int ret;
/* for future expandability... */
if (flags)
return -EINVAL;
if (copy_from_user(&hw_event, hw_event_uptr, sizeof(hw_event)) != 0) if (copy_from_user(&hw_event, hw_event_uptr, sizeof(hw_event)) != 0)
return -EFAULT; return -EFAULT;