diff options
| -rw-r--r-- | arch/powerpc/kernel/perf_counter.c | 6 | ||||
| -rw-r--r-- | include/linux/perf_counter.h | 15 | ||||
| -rw-r--r-- | kernel/perf_counter.c | 76 |
3 files changed, 97 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/perf_counter.c b/arch/powerpc/kernel/perf_counter.c index d05651584d4..e4349281b07 100644 --- a/arch/powerpc/kernel/perf_counter.c +++ b/arch/powerpc/kernel/perf_counter.c @@ -417,6 +417,8 @@ void hw_perf_restore(u64 disable) atomic64_set(&counter->hw.prev_count, val); counter->hw.idx = hwc_index[i] + 1; write_pmc(counter->hw.idx, val); + if (counter->user_page) + perf_counter_update_userpage(counter); } mb(); cpuhw->mmcr[0] |= MMCR0_PMXE | MMCR0_FCECE; @@ -572,6 +574,8 @@ static void power_perf_disable(struct perf_counter *counter) ppmu->disable_pmc(counter->hw.idx - 1, cpuhw->mmcr); write_pmc(counter->hw.idx, 0); counter->hw.idx = 0; + if (counter->user_page) + perf_counter_update_userpage(counter); break; } } @@ -698,6 +702,8 @@ static void record_and_restart(struct perf_counter *counter, long val, write_pmc(counter->hw.idx, val); atomic64_set(&counter->hw.prev_count, val); atomic64_set(&counter->hw.period_left, left); + if (counter->user_page) + perf_counter_update_userpage(counter); /* * Finally record data if requested. diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h index 18dc17d0a61..40b324e91bf 100644 --- a/include/linux/perf_counter.h +++ b/include/linux/perf_counter.h @@ -143,6 +143,17 @@ struct perf_counter_hw_event { #define PERF_COUNTER_IOC_ENABLE _IO('$', 0) #define PERF_COUNTER_IOC_DISABLE _IO('$', 1) +/* + * Structure of the page that can be mapped via mmap + */ +struct perf_counter_mmap_page { + __u32 version; /* version number of this structure */ + __u32 compat_version; /* lowest version this is compat with */ + __u32 lock; /* seqlock for synchronization */ + __u32 index; /* hardware counter identifier */ + __s64 offset; /* add to hardware counter value */ +}; + #ifdef __KERNEL__ /* * Kernel-internal data types and definitions: @@ -278,6 +289,9 @@ struct perf_counter { int oncpu; int cpu; + /* pointer to page shared with userspace via mmap */ + unsigned long user_page; + /* read() / irq related data */ wait_queue_head_t waitq; /* optional: for NMIs */ @@ -361,6 +375,7 @@ extern int perf_counter_task_enable(void); extern int hw_perf_group_sched_in(struct perf_counter *group_leader, struct perf_cpu_context *cpuctx, struct perf_counter_context *ctx, int cpu); +extern void perf_counter_update_userpage(struct perf_counter *counter); extern void perf_counter_output(struct perf_counter *counter, int nmi, struct pt_regs *regs); diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index ce34bff07bd..d9cfd902140 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -1177,6 +1177,7 @@ static int perf_release(struct inode *inode, struct file *file) mutex_unlock(&counter->mutex); mutex_unlock(&ctx->mutex); + free_page(counter->user_page); free_counter(counter); put_context(ctx); @@ -1346,12 +1347,87 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg) return err; } +void perf_counter_update_userpage(struct perf_counter *counter) +{ + struct perf_counter_mmap_page *userpg; + + if (!counter->user_page) + return; + userpg = (struct perf_counter_mmap_page *) counter->user_page; + + ++userpg->lock; + smp_wmb(); + userpg->index = counter->hw.idx; + userpg->offset = atomic64_read(&counter->count); + if (counter->state == PERF_COUNTER_STATE_ACTIVE) + userpg->offset -= atomic64_read(&counter->hw.prev_count); + smp_wmb(); + ++userpg->lock; +} + +static int perf_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) +{ + struct perf_counter *counter = vma->vm_file->private_data; + + if (!counter->user_page) + return VM_FAULT_SIGBUS; + + vmf->page = virt_to_page(counter->user_page); + get_page(vmf->page); + return 0; +} + +static struct vm_operations_struct perf_mmap_vmops = { + .fault = perf_mmap_fault, +}; + +static int perf_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct perf_counter *counter = file->private_data; + unsigned long userpg; + + if (!(vma->vm_flags & VM_SHARED) || (vma->vm_flags & VM_WRITE)) + return -EINVAL; + if (vma->vm_end - vma->vm_start != PAGE_SIZE) + return -EINVAL; + + /* + * For now, restrict to the case of a hardware counter + * on the current task. + */ + if (is_software_counter(counter) || counter->task != current) + return -EINVAL; + + userpg = counter->user_page; + if (!userpg) { + userpg = get_zeroed_page(GFP_KERNEL); + mutex_lock(&counter->mutex); + if (counter->user_page) { + free_page(userpg); + userpg = counter->user_page; + } else { + counter->user_page = userpg; + } + mutex_unlock(&counter->mutex); + if (!userpg) + return -ENOMEM; + } + + perf_counter_update_userpage(counter); + + vma->vm_flags &= ~VM_MAYWRITE; + vma->vm_flags |= VM_RESERVED; + vma->vm_ops = &perf_mmap_vmops; + return 0; +} + static const struct file_operations perf_fops = { .release = perf_release, .read = perf_read, .poll = perf_poll, .unlocked_ioctl = perf_ioctl, .compat_ioctl = perf_ioctl, + .mmap = perf_mmap, }; /* |