kernels: add linux-libre-aarch64

Some System On a Chip (SOC) have 64bit ARM CPUs that are also
capable of running arm 32bit applications.

Since:
- Parabola doesn't have an aarch64 package repository yet
- The devicetree of devices using such System On a Chip
  are not compiled when using the armv7 defconfig
- Drivers or other platform support code for such hardware
  might also not be compiled in with the armv7 defconfig
- This approach has already been tested with the linux-libre-x86_64
  kenrel

It's then a good idea to add support for such devices by adding
an arrch64 kernel as the maintenance and work is minimal.

The downside is that the external kernel modules that are either
compiled against the kernel or using DKMS will not work by default.

It's however still possible to compile them by hand by using
ARCH= and CROSS_COMPILE= as it is done for this kernel, so it
should be relatively easy to add support for the non-dkms modules.

As for DKMS, someone would need to look into it to understand how
to pass it the make flags (ARCH= and CROSS_COMPILE=) that are
required to automatically build modules.

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>

1 files changed, 272 insertions, 0 deletions

diff --git a/kernels/linux-libre-arm64/0005-PCI-pciehp-Prevent-deadlock-on-disconnect.patch b/kernels/linux-libre-arm64/0005-PCI-pciehp-Prevent-deadlock-on-disconnect.patch
new file mode 100644
index 000000000..7d05b2578
--- /dev/null
+++ b/kernels/linux-libre-arm64/0005-PCI-pciehp-Prevent-deadlock-on-disconnect.patch
@@ -0,0 +1,272 @@
+From b9bebf4cde0cf46438b2a7ab1652172e8e16c33e Mon Sep 17 00:00:00 2001
+From: Mika Westerberg <mika.westerberg@linux.intel.com>
+Date: Tue, 29 Oct 2019 20:00:22 +0300
+Subject: [PATCH 05/13] PCI: pciehp: Prevent deadlock on disconnect
+
+This addresses deadlocks in these common cases in hierarchies containing
+two switches:
+
+  - All involved ports are runtime suspended and they are unplugged. This
+    can happen easily if the drivers involved automatically enable runtime
+    PM (xHCI for example does that).
+
+  - System is suspended (e.g., closing the lid on a laptop) with a dock +
+    something else connected, and the dock is unplugged while suspended.
+
+These cases lead to the following deadlock:
+
+  INFO: task irq/126-pciehp:198 blocked for more than 120 seconds.
+  irq/126-pciehp  D    0   198      2 0x80000000
+  Call Trace:
+   schedule+0x2c/0x80
+   schedule_timeout+0x246/0x350
+   wait_for_completion+0xb7/0x140
+   kthread_stop+0x49/0x110
+   free_irq+0x32/0x70
+   pcie_shutdown_notification+0x2f/0x50
+   pciehp_remove+0x27/0x50
+   pcie_port_remove_service+0x36/0x50
+   device_release_driver+0x12/0x20
+   bus_remove_device+0xec/0x160
+   device_del+0x13b/0x350
+   device_unregister+0x1a/0x60
+   remove_iter+0x1e/0x30
+   device_for_each_child+0x56/0x90
+   pcie_port_device_remove+0x22/0x40
+   pcie_portdrv_remove+0x20/0x60
+   pci_device_remove+0x3e/0xc0
+   device_release_driver_internal+0x18c/0x250
+   device_release_driver+0x12/0x20
+   pci_stop_bus_device+0x6f/0x90
+   pci_stop_bus_device+0x31/0x90
+   pci_stop_and_remove_bus_device+0x12/0x20
+   pciehp_unconfigure_device+0x88/0x140
+   pciehp_disable_slot+0x6a/0x110
+   pciehp_handle_presence_or_link_change+0x263/0x400
+   pciehp_ist+0x1c9/0x1d0
+   irq_thread_fn+0x24/0x60
+   irq_thread+0xeb/0x190
+   kthread+0x120/0x140
+
+  INFO: task irq/190-pciehp:2288 blocked for more than 120 seconds.
+  irq/190-pciehp  D    0  2288      2 0x80000000
+  Call Trace:
+   __schedule+0x2a2/0x880
+   schedule+0x2c/0x80
+   schedule_preempt_disabled+0xe/0x10
+   mutex_lock+0x2c/0x30
+   pci_lock_rescan_remove+0x15/0x20
+   pciehp_unconfigure_device+0x4d/0x140
+   pciehp_disable_slot+0x6a/0x110
+   pciehp_handle_presence_or_link_change+0x263/0x400
+   pciehp_ist+0x1c9/0x1d0
+   irq_thread_fn+0x24/0x60
+   irq_thread+0xeb/0x190
+   kthread+0x120/0x140
+
+What happens here is that the whole hierarchy is runtime resumed and the
+parent PCIe downstream port, which got the hot-remove event, starts
+removing devices below it, taking pci_lock_rescan_remove() lock. When the
+child PCIe port is runtime resumed it calls pciehp_check_presence() which
+ends up calling pciehp_card_present() and pciehp_check_link_active().  Both
+of these use pcie_capability_read_word(), which notices that the underlying
+device is already gone and returns PCIBIOS_DEVICE_NOT_FOUND with the
+capability value set to 0. When pciehp gets this value it thinks that its
+child device is also hot-removed and schedules its IRQ thread to handle the
+event.
+
+The deadlock happens when the child's IRQ thread runs and tries to acquire
+pci_lock_rescan_remove() which is already taken by the parent and the
+parent waits for the child's IRQ thread to finish.
+
+Prevent this from happening by checking the return value of
+pcie_capability_read_word() and if it is PCIBIOS_DEVICE_NOT_FOUND stop
+performing any hot-removal activities.
+
+[bhelgaas: add common scenarios to commit log]
+Link: https://lore.kernel.org/r/20191029170022.57528-2-mika.westerberg@linux.intel.com
+Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
+Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
+Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
+---
+ drivers/pci/hotplug/pciehp.h      |  6 ++--
+ drivers/pci/hotplug/pciehp_core.c | 11 ++++--
+ drivers/pci/hotplug/pciehp_ctrl.c |  4 +--
+ drivers/pci/hotplug/pciehp_hpc.c  | 59 +++++++++++++++++++++++++------
+ 4 files changed, 61 insertions(+), 19 deletions(-)
+
+diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
+index 882ce82c4699..aa61d4c219d7 100644
+--- a/drivers/pci/hotplug/pciehp.h
++++ b/drivers/pci/hotplug/pciehp.h
+@@ -174,10 +174,10 @@ void pciehp_set_indicators(struct controller *ctrl, int pwr, int attn);
+ 
+ void pciehp_get_latch_status(struct controller *ctrl, u8 *status);
+ int pciehp_query_power_fault(struct controller *ctrl);
+-bool pciehp_card_present(struct controller *ctrl);
+-bool pciehp_card_present_or_link_active(struct controller *ctrl);
++int pciehp_card_present(struct controller *ctrl);
++int pciehp_card_present_or_link_active(struct controller *ctrl);
+ int pciehp_check_link_status(struct controller *ctrl);
+-bool pciehp_check_link_active(struct controller *ctrl);
++int pciehp_check_link_active(struct controller *ctrl);
+ void pciehp_release_ctrl(struct controller *ctrl);
+ 
+ int pciehp_sysfs_enable_slot(struct hotplug_slot *hotplug_slot);
+diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
+index 56daad828c9e..312cc45c44c7 100644
+--- a/drivers/pci/hotplug/pciehp_core.c
++++ b/drivers/pci/hotplug/pciehp_core.c
+@@ -139,10 +139,15 @@ static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
+ {
+ 	struct controller *ctrl = to_ctrl(hotplug_slot);
+ 	struct pci_dev *pdev = ctrl->pcie->port;
++	int ret;
+ 
+ 	pci_config_pm_runtime_get(pdev);
+-	*value = pciehp_card_present_or_link_active(ctrl);
++	ret = pciehp_card_present_or_link_active(ctrl);
+ 	pci_config_pm_runtime_put(pdev);
++	if (ret < 0)
++		return ret;
++
++	*value = ret;
+ 	return 0;
+ }
+ 
+@@ -158,13 +163,13 @@ static int get_adapter_status(struct hotplug_slot *hotplug_slot, u8 *value)
+  */
+ static void pciehp_check_presence(struct controller *ctrl)
+ {
+-	bool occupied;
++	int occupied;
+ 
+ 	down_read(&ctrl->reset_lock);
+ 	mutex_lock(&ctrl->state_lock);
+ 
+ 	occupied = pciehp_card_present_or_link_active(ctrl);
+-	if ((occupied && (ctrl->state == OFF_STATE ||
++	if ((occupied > 0 && (ctrl->state == OFF_STATE ||
+ 			  ctrl->state == BLINKINGON_STATE)) ||
+ 	    (!occupied && (ctrl->state == ON_STATE ||
+ 			   ctrl->state == BLINKINGOFF_STATE)))
+diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
+index dd8e4a5fb282..6503d15effbb 100644
+--- a/drivers/pci/hotplug/pciehp_ctrl.c
++++ b/drivers/pci/hotplug/pciehp_ctrl.c
+@@ -226,7 +226,7 @@ void pciehp_handle_disable_request(struct controller *ctrl)
+ 
+ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events)
+ {
+-	bool present, link_active;
++	int present, link_active;
+ 
+ 	/*
+ 	 * If the slot is on and presence or link has changed, turn it off.
+@@ -257,7 +257,7 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events)
+ 	mutex_lock(&ctrl->state_lock);
+ 	present = pciehp_card_present(ctrl);
+ 	link_active = pciehp_check_link_active(ctrl);
+-	if (!present && !link_active) {
++	if (present <= 0 && link_active <= 0) {
+ 		mutex_unlock(&ctrl->state_lock);
+ 		return;
+ 	}
+diff --git a/drivers/pci/hotplug/pciehp_hpc.c b/drivers/pci/hotplug/pciehp_hpc.c
+index 86d97f3112f0..a2a263764ef8 100644
+--- a/drivers/pci/hotplug/pciehp_hpc.c
++++ b/drivers/pci/hotplug/pciehp_hpc.c
+@@ -201,17 +201,29 @@ static void pcie_write_cmd_nowait(struct controller *ctrl, u16 cmd, u16 mask)
+ 	pcie_do_write_cmd(ctrl, cmd, mask, false);
+ }
+ 
+-bool pciehp_check_link_active(struct controller *ctrl)
++/**
++ * pciehp_check_link_active() - Is the link active
++ * @ctrl: PCIe hotplug controller
++ *
++ * Check whether the downstream link is currently active. Note it is
++ * possible that the card is removed immediately after this so the
++ * caller may need to take it into account.
++ *
++ * If the hotplug controller itself is not available anymore returns
++ * %-ENODEV.
++ */
++int pciehp_check_link_active(struct controller *ctrl)
+ {
+ 	struct pci_dev *pdev = ctrl_dev(ctrl);
+ 	u16 lnk_status;
+-	bool ret;
++	int ret;
+ 
+-	pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
+-	ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
++	ret = pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
++	if (ret == PCIBIOS_DEVICE_NOT_FOUND || lnk_status == (u16)~0)
++		return -ENODEV;
+ 
+-	if (ret)
+-		ctrl_dbg(ctrl, "%s: lnk_status = %x\n", __func__, lnk_status);
++	ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
++	ctrl_dbg(ctrl, "%s: lnk_status = %x\n", __func__, lnk_status);
+ 
+ 	return ret;
+ }
+@@ -373,13 +385,29 @@ void pciehp_get_latch_status(struct controller *ctrl, u8 *status)
+ 	*status = !!(slot_status & PCI_EXP_SLTSTA_MRLSS);
+ }
+ 
+-bool pciehp_card_present(struct controller *ctrl)
++/**
++ * pciehp_card_present() - Is the card present
++ * @ctrl: PCIe hotplug controller
++ *
++ * Function checks whether the card is currently present in the slot and
++ * in that case returns true. Note it is possible that the card is
++ * removed immediately after the check so the caller may need to take
++ * this into account.
++ *
++ * It the hotplug controller itself is not available anymore returns
++ * %-ENODEV.
++ */
++int pciehp_card_present(struct controller *ctrl)
+ {
+ 	struct pci_dev *pdev = ctrl_dev(ctrl);
+ 	u16 slot_status;
++	int ret;
+ 
+-	pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
+-	return slot_status & PCI_EXP_SLTSTA_PDS;
++	ret = pcie_capability_read_word(pdev, PCI_EXP_SLTSTA, &slot_status);
++	if (ret == PCIBIOS_DEVICE_NOT_FOUND || slot_status == (u16)~0)
++		return -ENODEV;
++
++	return !!(slot_status & PCI_EXP_SLTSTA_PDS);
+ }
+ 
+ /**
+@@ -390,10 +418,19 @@ bool pciehp_card_present(struct controller *ctrl)
+  * Presence Detect State bit, this helper also returns true if the Link Active
+  * bit is set.  This is a concession to broken hotplug ports which hardwire
+  * Presence Detect State to zero, such as Wilocity's [1ae9:0200].
++ *
++ * Returns: %1 if the slot is occupied and %0 if it is not. If the hotplug
++ *	    port is not present anymore returns %-ENODEV.
+  */
+-bool pciehp_card_present_or_link_active(struct controller *ctrl)
++int pciehp_card_present_or_link_active(struct controller *ctrl)
+ {
+-	return pciehp_card_present(ctrl) || pciehp_check_link_active(ctrl);
++	int ret;
++
++	ret = pciehp_card_present(ctrl);
++	if (ret)
++		return ret;
++
++	return pciehp_check_link_active(ctrl);
+ }
+ 
+ int pciehp_query_power_fault(struct controller *ctrl)
+-- 
+2.24.1
+