[PATCH] powerpc/powernv: Add mmap to opal export sysfs nodes
From: Jordan Niethe <hidden>
Date: 2019-03-15 00:56:26
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
The sysfs nodes created under /opal/exports/ do not currently support mmap. Skiboot trace buffers are not yet added to this location but this is a suitable for them to be exported to. Adding mmap support makes using these trace buffers more convenient. The state in the header of the trace buffer is needed to ensure the read position has not been overwritten. Thus the header of the buffer must be read, then the read position itself. Using lseek/read to do this introduces a delay that could result in incorrect reads if the read position is overwritten after the header is read. Signed-off-by: Jordan Niethe <redacted> --- arch/powerpc/platforms/powernv/opal.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 2b0eca104f86..3cfc683bb060 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c@@ -714,6 +714,15 @@ static ssize_t export_attr_read(struct file *fp, struct kobject *kobj, bin_attr->size); } +static int export_attr_mmap(struct file *fp, struct kobject *kobj, + struct bin_attribute *attr, + struct vm_area_struct *vma) +{ + return remap_pfn_range(vma, vma->vm_start, + __pa(attr->private) >> PAGE_SHIFT, + attr->size, PAGE_READONLY); +} + /* * opal_export_attrs: creates a sysfs node for each property listed in * the device-tree under /ibm,opal/firmware/exports/
@@ -759,6 +768,7 @@ static void opal_export_attrs(void) attr->attr.name = kstrdup(prop->name, GFP_KERNEL); attr->attr.mode = 0400; attr->read = export_attr_read; + attr->mmap = export_attr_mmap; attr->private = __va(vals[0]); attr->size = vals[1];
--
2.20.1