From 2743a5b0fa6f309da904f2190a9cc25deee34dbd Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Wed, 4 Mar 2009 20:36:51 +1100 Subject: perfcounters: provide expansion room in the ABI 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 --- kernel/perf_counter.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'kernel/perf_counter.c') diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 16b14ba99d34..b2e838959f3e 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -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 * @pid: target pid * @cpu: target cpu * @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, - 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_hw_event hw_event; @@ -1703,6 +1703,10 @@ SYSCALL_DEFINE4(perf_counter_open, int fput_needed2 = 0; int ret; + /* for future expandability... */ + if (flags) + return -EINVAL; + if (copy_from_user(&hw_event, hw_event_uptr, sizeof(hw_event)) != 0) return -EFAULT; -- cgit v1.2.2