Commit 08a022ad authored by Jordan Niethe's avatar Jordan Niethe Committed by Michael Ellerman
Browse files

powerpc/powernv/memtrace: Allow mmaping trace buffers 



Let the memory removed from the linear mapping to be used for the trace
buffers be mmaped. This is a useful way of providing cache-inhibited
memory for the alignment_handler selftest.

Signed-off-by: default avatarJordan Niethe <jniethe5@gmail.com>
[mpe: make memtrace_mmap() static as noticed by lkp@intel.com]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210225032108.1458352-1-jniethe5@gmail.com
parent acd4dfeb

arch/powerpc/platforms/powernv/memtrace.c

+17 −1
Original line number Diff line number Diff line
@@ -46,10 +46,26 @@ static ssize_t memtrace_read(struct file *filp, char __user *ubuf, 
	return simple_read_from_buffer(ubuf, count, ppos, ent->mem, ent->size);

}



static int memtrace_mmap(struct file *filp, struct vm_area_struct *vma)

{

	struct memtrace_entry *ent = filp->private_data;



	if (ent->size < vma->vm_end - vma->vm_start)

		return -EINVAL;



	if (vma->vm_pgoff << PAGE_SHIFT >= ent->size)

		return -EINVAL;



	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

	return remap_pfn_range(vma, vma->vm_start, PHYS_PFN(ent->start) + vma->vm_pgoff,

			       vma->vm_end - vma->vm_start, vma->vm_page_prot);

}



static const struct file_operations memtrace_fops = {

	.llseek = default_llseek,

	.read	= memtrace_read,

	.open	= simple_open,

	.mmap   = memtrace_mmap,

};



#define FLUSH_CHUNK_SIZE SZ_1G
@@ -187,7 +203,7 @@ static int memtrace_init_debugfs(void) 
		dir = debugfs_create_dir(ent->name, memtrace_debugfs_dir);



		ent->dir = dir;

		debugfs_create_file("trace", 0400, dir, ent, &memtrace_fops);

		debugfs_create_file_unsafe("trace", 0600, dir, ent, &memtrace_fops);

		debugfs_create_x64("start", 0400, dir, &ent->start);

		debugfs_create_x64("size", 0400, dir, &ent->size);

	}