[PATCH 0/2 v2] Fix boot on Calxeda highbank

[PATCH 0/2 v2] Fix boot on Calxeda highbank

[Sjoerd Simons]

When upgrading our trusted Calxeda server to Debian Jessie recently the machine
wedged during booting the installer. Upon further investigation, this happens
due to the transition to the generic L2C infrastructure introduced in 3.16. The
generic l2x0 code unlocks the cache during setup, however the Caldexa SMC
interface doesn't seem to allow the kernel to enable enable non-secure access
to the lock registers.. Queue Imprecise aborts and a fairly unhappy machine.

First patch in this series adds detection to the l2x0 code to check if
unlocking is possible. Second patch adds a (empty) configure callback for the
highbank l2c, reflecting the fact that there seemingly isn't anything to
configured via an SMC on these maches.

Changes since v1:
 - Auto-detect when unlocking the cache is unsafe rather then requiring a
   explicit flag to be set in the machine-specific code

Sjoerd Simons (2):
  ARM: cache-l2c: Detect whether it's safe to unlock
  ARM: l2c: highbank: Add dummy configure function

 arch/arm/mach-highbank/highbank.c |  8 ++++++++
 arch/arm/mm/cache-l2x0.c          | 20 ++++++++++++++++++++
 2 files changed, 28 insertions(+)

-- 
2.1.4

[PATCH 1/2] ARM: cache-l2c: Detect whether it's safe to unlock

[Sjoerd Simons]

The L2C cache should only be unlocked when the cache is setup to allow
that. In the common case the l2x0 driver sets up the cache for that to
be the case (e.g. setting L310_AUX_CTRL_NS_LOCKDOWN on L2C-310), making
unlock safe. However when a secure firmware is in use, it may not be
possible for the L2c to be configured that way making unlocking unsafe.

To handle that, for caches where special configuration is needed to allow
unlocking, check whether this has been setup before unlocking.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
---
 arch/arm/mm/cache-l2x0.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
index e309c8f..2563458 100644
--- a/arch/arm/mm/cache-l2x0.c
+++ b/arch/arm/mm/cache-l2x0.c
@@ -42,6 +42,7 @@ struct l2c_init_data {
 	void (*fixup)(void __iomem *, u32, struct outer_cache_fns *);
 	void (*save)(void __iomem *);
 	void (*configure)(void __iomem *);
+	bool (*can_unlock)(void __iomem *);
 	struct outer_cache_fns outer_cache;
 };
 
@@ -100,6 +101,9 @@ static inline void l2c_unlock(void __iomem *base, unsigned num)
 {
 	unsigned i;
 
+	if (l2x0_data->can_unlock && !l2x0_data->can_unlock(base))
+		return;
+
 	for (i = 0; i < num; i++) {
 		writel_relaxed(0, base + L2X0_LOCKDOWN_WAY_D_BASE +
 			       i * L2X0_LOCKDOWN_STRIDE);
@@ -403,12 +407,18 @@ static void l2c220_enable(void __iomem *base, u32 aux, unsigned num_lock)
 	l2c_enable(base, aux, num_lock);
 }
 
+static bool l2c220_can_unlock(void __iomem *base)
+{
+	return readl_relaxed(base + L2X0_AUX_CTRL) & L220_AUX_CTRL_NS_LOCKDOWN;
+}
+
 static const struct l2c_init_data l2c220_data = {
 	.type = "L2C-220",
 	.way_size_0 = SZ_8K,
 	.num_lock = 1,
 	.enable = l2c220_enable,
 	.save = l2c_save,
+	.can_unlock = l2c220_can_unlock,
 	.outer_cache = {
 		.inv_range = l2c220_inv_range,
 		.clean_range = l2c220_clean_range,
@@ -681,6 +691,11 @@ static void __init l2c310_enable(void __iomem *base, u32 aux, unsigned num_lock)
 	}
 }
 
+static bool l2c310_can_unlock(void __iomem *base)
+{
+	return readl_relaxed(base + L2X0_AUX_CTRL) & L310_AUX_CTRL_NS_LOCKDOWN;
+}
+
 static void __init l2c310_fixup(void __iomem *base, u32 cache_id,
 	struct outer_cache_fns *fns)
 {
@@ -763,6 +778,7 @@ static const struct l2c_init_data l2c310_init_fns __initconst = {
 	.fixup = l2c310_fixup,
 	.save = l2c310_save,
 	.configure = l2c310_configure,
+	.can_unlock = l2c310_can_unlock,
 	.outer_cache = {
 		.inv_range = l2c210_inv_range,
 		.clean_range = l2c210_clean_range,
@@ -1084,6 +1100,7 @@ static const struct l2c_init_data of_l2c220_data __initconst = {
 	.of_parse = l2x0_of_parse,
 	.enable = l2c220_enable,
 	.save = l2c_save,
+	.can_unlock = l2c220_can_unlock,
 	.outer_cache = {
 		.inv_range   = l2c220_inv_range,
 		.clean_range = l2c220_clean_range,
@@ -1211,6 +1228,7 @@ static const struct l2c_init_data of_l2c310_data __initconst = {
 	.fixup = l2c310_fixup,
 	.save  = l2c310_save,
 	.configure = l2c310_configure,
+	.can_unlock = l2c310_can_unlock,
 	.outer_cache = {
 		.inv_range   = l2c210_inv_range,
 		.clean_range = l2c210_clean_range,
@@ -1240,6 +1258,7 @@ static const struct l2c_init_data of_l2c310_coherent_data __initconst = {
 	.fixup = l2c310_fixup,
 	.save  = l2c310_save,
 	.configure = l2c310_configure,
+	.can_unlock = l2c310_can_unlock,
 	.outer_cache = {
 		.inv_range   = l2c210_inv_range,
 		.clean_range = l2c210_clean_range,
@@ -1585,6 +1604,7 @@ static const struct l2c_init_data of_bcm_l2x0_data __initconst = {
 	.enable = l2c310_enable,
 	.save  = l2c310_save,
 	.configure = l2c310_configure,
+	.can_unlock = l2c310_can_unlock,
 	.outer_cache = {
 		.inv_range   = bcm_inv_range,
 		.clean_range = bcm_clean_range,
-- 
2.1.4

Re: [PATCH 1/2] ARM: cache-l2c: Detect whether it's safe to unlock

[Russell King - ARM Linux]

On Tue, May 12, 2015 at 09:39:14AM +0200, Sjoerd Simons wrote:
> The L2C cache should only be unlocked when the cache is setup to allow
> that. In the common case the l2x0 driver sets up the cache for that to
> be the case (e.g. setting L310_AUX_CTRL_NS_LOCKDOWN on L2C-310), making
> unlock safe. However when a secure firmware is in use, it may not be
> possible for the L2c to be configured that way making unlocking unsafe.
> 
> To handle that, for caches where special configuration is needed to allow
> unlocking, check whether this has been setup before unlocking.

I've come up with a different solution to this, which of course I prefer.
I'll post the patches later today, thanks.

-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.

Re: [PATCH 1/2] ARM: cache-l2c: Detect whether it's safe to unlock

[Sjoerd Simons]

Hey Russell,

On Fri, 2015-05-15 at 12:34 +0100, Russell King - ARM Linux wrote:
> On Tue, May 12, 2015 at 09:39:14AM +0200, Sjoerd Simons wrote:
> > To handle that, for caches where special configuration is needed to allow
> > unlocking, check whether this has been setup before unlocking.
> 
> I've come up with a different solution to this, which of course I prefer.
> I'll post the patches later today, thanks.

Did you get round to create/posting those patches? If not, i'm happy to
do a set with your suggested solution as well if you can point me in the
right direction :)

-- 
Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Collabora Ltd.

Re: [PATCH 1/2] ARM: cache-l2c: Detect whether it's safe to unlock

[Russell King - ARM Linux]

On Wed, May 27, 2015 at 03:00:13PM +0200, Sjoerd Simons wrote:
> Hey Russell,
> 
> On Fri, 2015-05-15 at 12:34 +0100, Russell King - ARM Linux wrote:
> > On Tue, May 12, 2015 at 09:39:14AM +0200, Sjoerd Simons wrote:
> > > To handle that, for caches where special configuration is needed to allow
> > > unlocking, check whether this has been setup before unlocking.
> > 
> > I've come up with a different solution to this, which of course I prefer.
> > I'll post the patches later today, thanks.
> 
> Did you get round to create/posting those patches? If not, i'm happy to
> do a set with your suggested solution as well if you can point me in the
> right direction :)

Expect some to fall into your mailbox imminently.  Sorry, once an email
gets buried, it gets forgotten about. :p

-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.

[PATCH 2/2] ARM: l2c: highbank: Add dummy configure function

[Sjoerd Simons]

Add empty configure function for the highbank l2c to reflect that the
cache can't be confured through a SMC. This prevent a useless
WARN_ONCE during early boot.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
---
 arch/arm/mach-highbank/highbank.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm/mach-highbank/highbank.c b/arch/arm/mach-highbank/highbank.c
index 231fba0..623eb5e8 100644
--- a/arch/arm/mach-highbank/highbank.c
+++ b/arch/arm/mach-highbank/highbank.c
@@ -60,12 +60,20 @@ static void highbank_l2c310_write_sec(unsigned long val, unsigned reg)
 			  reg);
 }
 
+static void highbank_l2c310_configure(const struct l2x0_regs *regs)
+{
+}
+
 static void __init highbank_init_irq(void)
 {
 	irqchip_init();
 
 	if (of_find_compatible_node(NULL, NULL, "arm,cortex-a9"))
 		highbank_scu_map_io();
+
+	if (IS_ENABLED(CONFIG_CACHE_L2X0)) {
+		outer_cache.configure = highbank_l2c310_configure;
+	}
 }
 
 static void highbank_power_off(void)
-- 
2.1.4