drm/msm: Add fault-injection support

Intended as a way to trigger error paths in mesa.

Signed-off-by: Rob Clark <[e-mail]>
Reviewed-by: Dmitry Baryshkov <[e-mail]>
Patchwork: https://patchwork.freedesktop.org/patch/496710/
Link: https://lore.kernel.org/r/[e-mail]

drivers/gpu/drm/msm/msm_debugfs.c

···
 #ifdef CONFIG_DEBUG_FS
 
 #include <linux/debugfs.h>
+#include <linux/fault-inject.h>
 
 #include <drm/drm_debugfs.h>
 #include <drm/drm_file.h>
···
 
 	if (priv->kms && priv->kms->funcs->debugfs_init)
 		priv->kms->funcs->debugfs_init(priv->kms, minor);
+
+#ifdef CONFIG_FAULT_INJECTION
+	fault_create_debugfs_attr("fail_gem_alloc", minor->debugfs_root,
+				  &fail_gem_alloc);
+	fault_create_debugfs_attr("fail_gem_iova", minor->debugfs_root,
+				  &fail_gem_iova);
+#endif
 }
 #endif
 

drivers/gpu/drm/msm/msm_drv.c

···
  */
 
 #include <linux/dma-mapping.h>
+#include <linux/fault-inject.h>
 #include <linux/kthread.h>
 #include <linux/sched/mm.h>
 #include <linux/uaccess.h>
···
 static bool modeset = true;
 MODULE_PARM_DESC(modeset, "Use kernel modesetting [KMS] (1=on (default), 0=disable)");
 module_param(modeset, bool, 0600);
+
+#ifdef CONFIG_FAULT_INJECTION
+DECLARE_FAULT_ATTR(fail_gem_alloc);
+DECLARE_FAULT_ATTR(fail_gem_iova);
+#endif
 
 static irqreturn_t msm_irq(int irq, void *arg)
 {
···
 		flags |= MSM_BO_WC;
 	}
 
+	if (should_fail(&fail_gem_alloc, args->size))
+		return -ENOMEM;
+
 	return msm_gem_new_handle(dev, file, args->size,
 			args->flags, &args->handle, NULL);
 }
···
 	if (!priv->gpu)
 		return -EINVAL;
 
+	if (should_fail(&fail_gem_iova, obj->size))
+		return -ENOMEM;
+
 	/*
 	 * Don't pin the memory here - just get an address so that userspace can
 	 * be productive
···
 	/* Only supported if per-process address space is supported: */
 	if (priv->gpu->aspace == ctx->aspace)
 		return -EOPNOTSUPP;
+
+	if (should_fail(&fail_gem_iova, obj->size))
+		return -ENOMEM;
 
 	return msm_gem_set_iova(obj, ctx->aspace, iova);
 }

drivers/gpu/drm/msm/msm_drv.h

···
 #include <drm/msm_drm.h>
 #include <drm/drm_gem.h>
 
+#ifdef CONFIG_FAULT_INJECTION
+extern struct fault_attr fail_gem_alloc;
+extern struct fault_attr fail_gem_iova;
+#else
+#  define should_fail(attr, size) 0
+#endif
+
 struct msm_kms;
 struct msm_gpu;
 struct msm_mmu;