/* * This module provides an interface to trigger and test firmware loading. * * It is designed to be used for basic evaluation of the firmware loading * subsystem (for example when validating firmware verification). It lacks * any extra dependencies, and will not normally be loaded by the system * unless explicitly requested by name. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include #include #include #include #include #include #include #include #include #include static DEFINE_MUTEX(test_fw_mutex); static const struct firmware *test_firmware; static ssize_t test_fw_misc_read(struct file *f, char __user *buf, size_t size, loff_t *offset) { ssize_t rc = 0; mutex_lock(&test_fw_mutex); if (test_firmware) rc = simple_read_from_buffer(buf, size, offset, test_firmware->data, test_firmware->size); mutex_unlock(&test_fw_mutex); return rc; } static const struct file_operations test_fw_fops = { .owner = THIS_MODULE, .read = test_fw_misc_read, }; static struct miscdevice test_fw_misc_device = { .minor = MISC_DYNAMIC_MINOR, .name = "test_firmware", .fops = &test_fw_fops, }; static ssize_t trigger_request_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { int rc; char *name; name = kstrndup(buf, count, GFP_KERNEL); if (!name) return -ENOSPC; pr_info("loading '%s'\n", name); mutex_lock(&test_fw_mutex); release_firmware(test_firmware); test_firmware = NULL; rc = request_firmware(&test_firmware, name, dev); if (rc) { pr_info("load of '%s' failed: %d\n", name, rc); goto out; } pr_info("loaded: %zu\n", test_firmware->size); rc = count; out: mutex_unlock(&test_fw_mutex); kfree(name); return rc; } static DEVICE_ATTR_WO(trigger_request); static DECLARE_COMPLETION(async_fw_done); static void trigger_async_request_cb(const struct firmware *fw, void *context) { test_firmware = fw; complete(&async_fw_done); } static ssize_t trigger_async_request_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { int rc; char *name; name = kstrndup(buf, count, GFP_KERNEL); if (!name) return -ENOSPC; pr_info("loading '%s'\n", name); mutex_lock(&test_fw_mutex); release_firmware(test_firmware); test_firmware = NULL; rc = request_firmware_nowait(THIS_MODULE, 1, name, dev, GFP_KERNEL, NULL, trigger_async_request_cb); if (rc) { pr_info("async load of '%s' failed: %d\n", name, rc); kfree(name); goto out; } /* Free 'name' ASAP, to test for race conditions */ kfree(name); wait_for_completion(&async_fw_done); if (test_firmware) { pr_info("loaded: %zu\n", test_firmware->size); rc = count; } else { pr_err("failed to async load firmware\n"); rc = -ENODEV; } out: mutex_unlock(&test_fw_mutex); return rc; } static DEVICE_ATTR_WO(trigger_async_request); static int __init test_firmware_init(void) { int rc; rc = misc_register(&test_fw_misc_device); if (rc) { pr_err("could not register misc device: %d\n", rc); return rc; } rc = device_create_file(test_fw_misc_device.this_device, &dev_attr_trigger_request); if (rc) { pr_err("could not create sysfs interface: %d\n", rc); goto dereg; } rc = device_create_file(test_fw_misc_device.this_device, &dev_attr_trigger_async_request); if (rc) { pr_err("could not create async sysfs interface: %d\n", rc); goto remove_file; } pr_warn("interface ready\n"); return 0; remove_file: device_remove_file(test_fw_misc_device.this_device, &dev_attr_trigger_async_request); dereg: misc_deregister(&test_fw_misc_device); return rc; } module_init(test_firmware_init); static void __exit test_firmware_exit(void) { release_firmware(test_firmware); device_remove_file(test_fw_misc_device.this_device, &dev_attr_trigger_async_request); device_remove_file(test_fw_misc_device.this_device, &dev_attr_trigger_request); misc_deregister(&test_fw_misc_device); pr_warn("removed interface\n"); } module_exit(test_firmware_exit); MODULE_AUTHOR("Kees Cook "); MODULE_LICENSE("GPL"); ion>space:mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-01-29 13:50:06 -0800
commit39cb2c9a316e77f6dfba96c543e55b6672d5a37e (patch)
tree98fe974ee4e20121253de7f61fc8d01bdb3821c1 /tools/testing/selftests/ftrace/test.d/00basic
parent2c5d9555d6d937966d79d4c6529a5f7b9206e405 (diff)
drm/i915: Check for NULL i915_vma in intel_unpin_fb_obj()
I've seen this trigger twice now, where the i915_gem_object_to_ggtt() call in intel_unpin_fb_obj() returns NULL, resulting in an oops immediately afterwards as the (inlined) call to i915_vma_unpin_fence() tries to dereference it. It seems to be some race condition where the object is going away at shutdown time, since both times happened when shutting down the X server. The call chains were different: - VT ioctl(KDSETMODE, KD_TEXT): intel_cleanup_plane_fb+0x5b/0xa0 [i915] drm_atomic_helper_cleanup_planes+0x6f/0x90 [drm_kms_helper] intel_atomic_commit_tail+0x749/0xfe0 [i915] intel_atomic_commit+0x3cb/0x4f0 [i915] drm_atomic_commit+0x4b/0x50 [drm] restore_fbdev_mode+0x14c/0x2a0 [drm_kms_helper] drm_fb_helper_restore_fbdev_mode_unlocked+0x34/0x80 [drm_kms_helper] drm_fb_helper_set_par+0x2d/0x60 [drm_kms_helper] intel_fbdev_set_par+0x18/0x70 [i915] fb_set_var+0x236/0x460 fbcon_blank+0x30f/0x350 do_unblank_screen+0xd2/0x1a0 vt_ioctl+0x507/0x12a0 tty_ioctl+0x355/0xc30 do_vfs_ioctl+0xa3/0x5e0 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x13/0x94 - i915 unpin_work workqueue: intel_unpin_work_fn+0x58/0x140 [i915] process_one_work+0x1f1/0x480 worker_thread+0x48/0x4d0 kthread+0x101/0x140 and this patch purely papers over the issue by adding a NULL pointer check and a WARN_ON_ONCE() to avoid the oops that would then generally make the machine unresponsive. Other callers of i915_gem_object_to_ggtt() seem to also check for the returned pointer being NULL and warn about it, so this clearly has happened before in other places. [ Reported it originally to the i915 developers on Jan 8, applying the ugly workaround on my own now after triggering the problem for the second time with no feedback. This is likely to be the same bug reported as https://bugs.freedesktop.org/show_bug.cgi?id=98829 https://bugs.freedesktop.org/show_bug.cgi?id=99134 which has a patch for the underlying problem, but it hasn't gotten to me, so I'm applying the workaround. ] Cc: Daniel Vetter <daniel.vetter@intel.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Imre Deak <imre.deak@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'tools/testing/selftests/ftrace/test.d/00basic')