On 03.08.2014 00:09, Russell King - ARM Linux wrote:

On Thu, Jul 17, 2014 at 06:38:56PM +0200, Tomasz Figa wrote:

quoted

Certain implementations of secure hypervisors (namely the one found on
Samsung Exynos-based boards) do not provide access to individual L2C
registers. This makes the .write_sec()-based interface insufficient and
provoking ugly hacks.

This patch is first step to make the driver not rely on availability of
writes to individual registers. This is achieved by refactoring the
driver to use a commit-like operation scheme: all register values are
prepared first and stored in an instance of l2x0_regs struct and then a
single callback is responsible to flush those values to the hardware.

This isn't going to work very well...

quoted

+static const struct l2c_init_data *l2x0_data;

So you keep a pointer to the init data...

quoted

+static void l2c_resume(void)
+{
+	l2x0_data->enable(l2x0_base, l2x0_saved_regs.aux_ctrl,
+				l2x0_data->num_lock);

which you dereference at resume time...

quoted

 static const struct l2c_init_data l2c210_data __initconst = {

but the structures which get assigned to the pointer are marked __initconst.

Good catch. The code was tested on Exynos which requires the cache to be
resumed from early assembly code and so I did not hit issues caused by this.

Proposed solution: kmemdup() in init, so that only used data remain in
memory and the structures can be kept __initconst.

Best regards,
Tomasz