Commit 6d64c497 authored by Andrew Donnellan's avatar Andrew Donnellan Committed by Michael Ellerman
Browse files

powerpc/secvar: Warn when PAGE_SIZE is smaller than max object size 



Due to sysfs constraints, when writing to a variable, we can only handle
writes of up to PAGE_SIZE.

It's possible that the maximum object size is larger than PAGE_SIZE, in
which case, print a warning on boot so that the user is aware.

Signed-off-by: default avatarAndrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: default avatarRussell Currey <ruscur@russell.cc>
Reviewed-by: default avatarStefan Berger <stefanb@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230210080401.345462-13-ajd@linux.ibm.com
parent 50a466bf

arch/powerpc/kernel/secvar-sysfs.c

+9 −0
Original line number Diff line number Diff line
@@ -225,6 +225,7 @@ static int secvar_sysfs_load_static(void) 


static int secvar_sysfs_init(void)

{

	u64 max_size;

	int rc;



	if (!secvar_ops) {
@@ -274,6 +275,14 @@ static int secvar_sysfs_init(void) 
		goto err;

	}



	// Due to sysfs limitations, we will only ever get a write buffer of

	// up to 1 page in size. Print a warning if this is potentially going

	// to cause problems, so that the user is aware.

	secvar_ops->max_size(&max_size);

	if (max_size > PAGE_SIZE)

		pr_warn_ratelimited("PAGE_SIZE (%lu) is smaller than maximum object size (%llu), writes are limited to PAGE_SIZE\n",

				    PAGE_SIZE, max_size);



	return 0;

err:

	kobject_put(secvar_kobj);