Commit 0c8a4e41 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf/core: Further simplify perf_mmap() 



Perform CSE and such.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarRavi Bangoria <ravi.bangoria@amd.com>
Link: https://lore.kernel.org/r/20241104135519.354909594@infradead.org
parent 95487837

kernel/events/core.c

+10 −11
Original line number Diff line number Diff line
@@ -6698,9 +6698,18 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) 
		return ret;



	vma_size = vma->vm_end - vma->vm_start;

	nr_pages = vma_size / PAGE_SIZE;



	if (nr_pages > INT_MAX)

		return -ENOMEM;



	if (vma_size != PAGE_SIZE * nr_pages)

		return -EINVAL;



	user_extra = nr_pages;



	if (vma->vm_pgoff == 0) {

		nr_pages = (vma_size / PAGE_SIZE) - 1;

		nr_pages -= 1;



		/*

		 * If we have rb pages ensure they're a power-of-two number, so we
@@ -6709,9 +6718,6 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) 
		if (nr_pages != 0 && !is_power_of_2(nr_pages))

			return -EINVAL;



		if (vma_size != PAGE_SIZE * (1 + nr_pages))

			return -EINVAL;



		WARN_ON_ONCE(event->ctx->parent_ctx);

again:

		mutex_lock(&event->mmap_mutex);
@@ -6735,8 +6741,6 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) 
			rb = event->rb;

			goto unlock;

		}



		user_extra = nr_pages + 1;

	} else {

		/*

		 * AUX area mapping: if rb->aux_nr_pages != 0, it's already
@@ -6748,10 +6752,6 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) 
		if (!event->rb)

			return -EINVAL;



		nr_pages = vma_size / PAGE_SIZE;

		if (nr_pages > INT_MAX)

			return -ENOMEM;



		mutex_lock(&event->mmap_mutex);

		ret = -EINVAL;
@@ -6795,7 +6795,6 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) 
		}



		atomic_set(&rb->aux_mmap_count, 1);

		user_extra = nr_pages;

	}



	user_lock_limit = sysctl_perf_event_mlock >> (PAGE_SHIFT - 10);