Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 374 insertions, 0 deletions

diff --git a/drivers/video/aperture.c b/drivers/video/aperture.c
new file mode 100644
index 000000000..2b5a1e666
--- /dev/null
+++ b/drivers/video/aperture.c
@@ -0,0 +1,374 @@
+// SPDX-License-Identifier: MIT
+
+#include <linux/aperture.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/sysfb.h>
+#include <linux/types.h>
+#include <linux/vgaarb.h>
+
+#include <video/vga.h>
+
+/**
+ * DOC: overview
+ *
+ * A graphics device might be supported by different drivers, but only one
+ * driver can be active at any given time. Many systems load a generic
+ * graphics drivers, such as EFI-GOP or VESA, early during the boot process.
+ * During later boot stages, they replace the generic driver with a dedicated,
+ * hardware-specific driver. To take over the device, the dedicated driver
+ * first has to remove the generic driver. Aperture functions manage
+ * ownership of framebuffer memory and hand-over between drivers.
+ *
+ * Graphics drivers should call aperture_remove_conflicting_devices()
+ * at the top of their probe function. The function removes any generic
+ * driver that is currently associated with the given framebuffer memory.
+ * An example for a graphics device on the platform bus is shown below.
+ *
+ * .. code-block:: c
+ *
+ *	static int example_probe(struct platform_device *pdev)
+ *	{
+ *		struct resource *mem;
+ *		resource_size_t base, size;
+ *		int ret;
+ *
+ *		mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ *		if (!mem)
+ *			return -ENODEV;
+ *		base = mem->start;
+ *		size = resource_size(mem);
+ *
+ *		ret = aperture_remove_conflicting_devices(base, size, "example");
+ *		if (ret)
+ *			return ret;
+ *
+ *		// Initialize the hardware
+ *		...
+ *
+ *		return 0;
+ *	}
+ *
+ *	static const struct platform_driver example_driver = {
+ *		.probe = example_probe,
+ *		...
+ *	};
+ *
+ * The given example reads the platform device's I/O-memory range from the
+ * device instance. An active framebuffer will be located within this range.
+ * The call to aperture_remove_conflicting_devices() releases drivers that
+ * have previously claimed ownership of the range and are currently driving
+ * output on the framebuffer. If successful, the new driver can take over
+ * the device.
+ *
+ * While the given example uses a platform device, the aperture helpers work
+ * with every bus that has an addressable framebuffer. In the case of PCI,
+ * device drivers can also call aperture_remove_conflicting_pci_devices() and
+ * let the function detect the apertures automatically. Device drivers without
+ * knowledge of the framebuffer's location can call
+ * aperture_remove_all_conflicting_devices(), which removes all known devices.
+ *
+ * Drivers that are susceptible to being removed by other drivers, such as
+ * generic EFI or VESA drivers, have to register themselves as owners of their
+ * framebuffer apertures. Ownership of the framebuffer memory is achieved
+ * by calling devm_aperture_acquire_for_platform_device(). If successful, the
+ * driver is the owner of the framebuffer range. The function fails if the
+ * framebuffer is already owned by another driver. See below for an example.
+ *
+ * .. code-block:: c
+ *
+ *	static int generic_probe(struct platform_device *pdev)
+ *	{
+ *		struct resource *mem;
+ *		resource_size_t base, size;
+ *
+ *		mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ *		if (!mem)
+ *			return -ENODEV;
+ *		base = mem->start;
+ *		size = resource_size(mem);
+ *
+ *		ret = devm_aperture_acquire_for_platform_device(pdev, base, size);
+ *		if (ret)
+ *			return ret;
+ *
+ *		// Initialize the hardware
+ *		...
+ *
+ *		return 0;
+ *	}
+ *
+ *	static int generic_remove(struct platform_device *)
+ *	{
+ *		// Hot-unplug the device
+ *		...
+ *
+ *		return 0;
+ *	}
+ *
+ *	static const struct platform_driver generic_driver = {
+ *		.probe = generic_probe,
+ *		.remove = generic_remove,
+ *		...
+ *	};
+ *
+ * The similar to the previous example, the generic driver claims ownership
+ * of the framebuffer memory from its probe function. This will fail if the
+ * memory range, or parts of it, is already owned by another driver.
+ *
+ * If successful, the generic driver is now subject to forced removal by
+ * another driver. This only works for platform drivers that support hot
+ * unplugging. When a driver calls aperture_remove_conflicting_devices()
+ * et al for the registered framebuffer range, the aperture helpers call
+ * platform_device_unregister() and the generic driver unloads itself. The
+ * generic driver also has to provide a remove function to make this work.
+ * Once hot unplugged from hardware, it may not access the device's
+ * registers, framebuffer memory, ROM, etc afterwards.
+ */
+
+struct aperture_range {
+	struct device *dev;
+	resource_size_t base;
+	resource_size_t size;
+	struct list_head lh;
+	void (*detach)(struct device *dev);
+};
+
+static LIST_HEAD(apertures);
+static DEFINE_MUTEX(apertures_lock);
+
+static bool overlap(resource_size_t base1, resource_size_t end1,
+		    resource_size_t base2, resource_size_t end2)
+{
+	return (base1 < end2) && (end1 > base2);
+}
+
+static void devm_aperture_acquire_release(void *data)
+{
+	struct aperture_range *ap = data;
+	bool detached = !ap->dev;
+
+	if (detached)
+		return;
+
+	mutex_lock(&apertures_lock);
+	list_del(&ap->lh);
+	mutex_unlock(&apertures_lock);
+}
+
+static int devm_aperture_acquire(struct device *dev,
+				 resource_size_t base, resource_size_t size,
+				 void (*detach)(struct device *))
+{
+	size_t end = base + size;
+	struct list_head *pos;
+	struct aperture_range *ap;
+
+	mutex_lock(&apertures_lock);
+
+	list_for_each(pos, &apertures) {
+		ap = container_of(pos, struct aperture_range, lh);
+		if (overlap(base, end, ap->base, ap->base + ap->size)) {
+			mutex_unlock(&apertures_lock);
+			return -EBUSY;
+		}
+	}
+
+	ap = devm_kzalloc(dev, sizeof(*ap), GFP_KERNEL);
+	if (!ap) {
+		mutex_unlock(&apertures_lock);
+		return -ENOMEM;
+	}
+
+	ap->dev = dev;
+	ap->base = base;
+	ap->size = size;
+	ap->detach = detach;
+	INIT_LIST_HEAD(&ap->lh);
+
+	list_add(&ap->lh, &apertures);
+
+	mutex_unlock(&apertures_lock);
+
+	return devm_add_action_or_reset(dev, devm_aperture_acquire_release, ap);
+}
+
+static void aperture_detach_platform_device(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+
+	/*
+	 * Remove the device from the device hierarchy. This is the right thing
+	 * to do for firmware-based fb drivers, such as EFI, VESA or VGA. After
+	 * the new driver takes over the hardware, the firmware device's state
+	 * will be lost.
+	 *
+	 * For non-platform devices, a new callback would be required.
+	 *
+	 * If the aperture helpers ever need to handle native drivers, this call
+	 * would only have to unplug the DRM device, so that the hardware device
+	 * stays around after detachment.
+	 */
+	platform_device_unregister(pdev);
+}
+
+/**
+ * devm_aperture_acquire_for_platform_device - Acquires ownership of an aperture
+ *                                             on behalf of a platform device.
+ * @pdev:	the platform device to own the aperture
+ * @base:	the aperture's byte offset in physical memory
+ * @size:	the aperture size in bytes
+ *
+ * Installs the given device as the new owner of the aperture. The function
+ * expects the aperture to be provided by a platform device. If another
+ * driver takes over ownership of the aperture, aperture helpers will then
+ * unregister the platform device automatically. All acquired apertures are
+ * released automatically when the underlying device goes away.
+ *
+ * The function fails if the aperture, or parts of it, is currently
+ * owned by another device. To evict current owners, callers should use
+ * remove_conflicting_devices() et al. before calling this function.
+ *
+ * Returns:
+ * 0 on success, or a negative errno value otherwise.
+ */
+int devm_aperture_acquire_for_platform_device(struct platform_device *pdev,
+					      resource_size_t base,
+					      resource_size_t size)
+{
+	return devm_aperture_acquire(&pdev->dev, base, size, aperture_detach_platform_device);
+}
+EXPORT_SYMBOL(devm_aperture_acquire_for_platform_device);
+
+static void aperture_detach_devices(resource_size_t base, resource_size_t size)
+{
+	resource_size_t end = base + size;
+	struct list_head *pos, *n;
+
+	mutex_lock(&apertures_lock);
+
+	list_for_each_safe(pos, n, &apertures) {
+		struct aperture_range *ap = container_of(pos, struct aperture_range, lh);
+		struct device *dev = ap->dev;
+
+		if (WARN_ON_ONCE(!dev))
+			continue;
+
+		if (!overlap(base, end, ap->base, ap->base + ap->size))
+			continue;
+
+		ap->dev = NULL; /* detach from device */
+		list_del(&ap->lh);
+
+		ap->detach(dev);
+	}
+
+	mutex_unlock(&apertures_lock);
+}
+
+/**
+ * aperture_remove_conflicting_devices - remove devices in the given range
+ * @base: the aperture's base address in physical memory
+ * @size: aperture size in bytes
+ * @name: a descriptive name of the requesting driver
+ *
+ * This function removes devices that own apertures within @base and @size.
+ *
+ * Returns:
+ * 0 on success, or a negative errno code otherwise
+ */
+int aperture_remove_conflicting_devices(resource_size_t base, resource_size_t size,
+					const char *name)
+{
+	/*
+	 * If a driver asked to unregister a platform device registered by
+	 * sysfb, then can be assumed that this is a driver for a display
+	 * that is set up by the system firmware and has a generic driver.
+	 *
+	 * Drivers for devices that don't have a generic driver will never
+	 * ask for this, so let's assume that a real driver for the display
+	 * was already probed and prevent sysfb to register devices later.
+	 */
+	sysfb_disable(NULL);
+
+	aperture_detach_devices(base, size);
+
+	return 0;
+}
+EXPORT_SYMBOL(aperture_remove_conflicting_devices);
+
+/**
+ * __aperture_remove_legacy_vga_devices - remove legacy VGA devices of a PCI devices
+ * @pdev: PCI device
+ *
+ * This function removes VGA devices provided by @pdev, such as a VGA
+ * framebuffer or a console. This is useful if you have a VGA-compatible
+ * PCI graphics device with framebuffers in non-BAR locations. Drivers
+ * should acquire ownership of those memory areas and afterwards call
+ * this helper to release remaining VGA devices.
+ *
+ * If your hardware has its framebuffers accessible via PCI BARS, use
+ * aperture_remove_conflicting_pci_devices() instead. The function will
+ * release any VGA devices automatically.
+ *
+ * WARNING: Apparently we must remove graphics drivers before calling
+ *          this helper. Otherwise the vga fbdev driver falls over if
+ *          we have vgacon configured.
+ *
+ * Returns:
+ * 0 on success, or a negative errno code otherwise
+ */
+int __aperture_remove_legacy_vga_devices(struct pci_dev *pdev)
+{
+	/* VGA framebuffer */
+	aperture_detach_devices(VGA_FB_PHYS_BASE, VGA_FB_PHYS_SIZE);
+
+	/* VGA textmode console */
+	return vga_remove_vgacon(pdev);
+}
+EXPORT_SYMBOL(__aperture_remove_legacy_vga_devices);
+
+/**
+ * aperture_remove_conflicting_pci_devices - remove existing framebuffers for PCI devices
+ * @pdev: PCI device
+ * @name: a descriptive name of the requesting driver
+ *
+ * This function removes devices that own apertures within any of @pdev's
+ * memory bars. The function assumes that PCI device with shadowed ROM
+ * drives a primary display and therefore kicks out vga16fb as well.
+ *
+ * Returns:
+ * 0 on success, or a negative errno code otherwise
+ */
+int aperture_remove_conflicting_pci_devices(struct pci_dev *pdev, const char *name)
+{
+	resource_size_t base, size;
+	int bar, ret = 0;
+
+	sysfb_disable(&pdev->dev);
+
+	for (bar = 0; bar < PCI_STD_NUM_BARS; ++bar) {
+		if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
+			continue;
+
+		base = pci_resource_start(pdev, bar);
+		size = pci_resource_len(pdev, bar);
+		aperture_detach_devices(base, size);
+	}
+
+	/*
+	 * If this is the primary adapter, there could be a VGA device
+	 * that consumes the VGA framebuffer I/O range. Remove this
+	 * device as well.
+	 */
+	if (pdev == vga_default_device())
+		ret = __aperture_remove_legacy_vga_devices(pdev);
+
+	return ret;
+
+}
+EXPORT_SYMBOL(aperture_remove_conflicting_pci_devices);