diff options
| -rw-r--r-- | drivers/gpu/drm/i915/Makefile | 1 | ||||
| -rw-r--r-- | drivers/gpu/drm/i915/i915_user_extensions.c | 61 | ||||
| -rw-r--r-- | drivers/gpu/drm/i915/i915_user_extensions.h | 20 | ||||
| -rw-r--r-- | drivers/gpu/drm/i915/i915_utils.h | 31 | ||||
| -rw-r--r-- | include/uapi/drm/i915_drm.h | 22 |
5 files changed, 135 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile index 68fecf355471..60de05f3fa60 100644 --- a/drivers/gpu/drm/i915/Makefile +++ b/drivers/gpu/drm/i915/Makefile @@ -46,6 +46,7 @@ i915-y := i915_drv.o \ i915_sw_fence.o \ i915_syncmap.o \ i915_sysfs.o \ + i915_user_extensions.o \ intel_csr.o \ intel_device_info.o \ intel_pm.o \ diff --git a/drivers/gpu/drm/i915/i915_user_extensions.c b/drivers/gpu/drm/i915/i915_user_extensions.c new file mode 100644 index 000000000000..c822d0aafd2d --- /dev/null +++ b/drivers/gpu/drm/i915/i915_user_extensions.c @@ -0,0 +1,61 @@ +/* + * SPDX-License-Identifier: MIT + * + * Copyright © 2018 Intel Corporation + */ + +#include <linux/nospec.h> +#include <linux/sched/signal.h> +#include <linux/uaccess.h> + +#include <uapi/drm/i915_drm.h> + +#include "i915_user_extensions.h" +#include "i915_utils.h" + +int i915_user_extensions(struct i915_user_extension __user *ext, + const i915_user_extension_fn *tbl, + unsigned int count, + void *data) +{ + unsigned int stackdepth = 512; + + while (ext) { + int i, err; + u32 name; + u64 next; + + if (!stackdepth--) /* recursion vs useful flexibility */ + return -E2BIG; + + err = check_user_mbz(&ext->flags); + if (err) + return err; + + for (i = 0; i < ARRAY_SIZE(ext->rsvd); i++) { + err = check_user_mbz(&ext->rsvd[i]); + if (err) + return err; + } + + if (get_user(name, &ext->name)) + return -EFAULT; + + err = -EINVAL; + if (name < count) { + name = array_index_nospec(name, count); + if (tbl[name]) + err = tbl[name](ext, data); + } + if (err) + return err; + + if (get_user(next, &ext->next_extension) || + overflows_type(next, ext)) + return -EFAULT; + + ext = u64_to_user_ptr(next); + } + + return 0; +} diff --git a/drivers/gpu/drm/i915/i915_user_extensions.h b/drivers/gpu/drm/i915/i915_user_extensions.h new file mode 100644 index 000000000000..a14bf6bba9a1 --- /dev/null +++ b/drivers/gpu/drm/i915/i915_user_extensions.h @@ -0,0 +1,20 @@ +/* + * SPDX-License-Identifier: MIT + * + * Copyright © 2018 Intel Corporation + */ + +#ifndef I915_USER_EXTENSIONS_H +#define I915_USER_EXTENSIONS_H + +struct i915_user_extension; + +typedef int (*i915_user_extension_fn)(struct i915_user_extension __user *ext, + void *data); + +int i915_user_extensions(struct i915_user_extension __user *ext, + const i915_user_extension_fn *tbl, + unsigned int count, + void *data); + +#endif /* I915_USER_EXTENSIONS_H */ diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h index 9726df37c4c4..8baedcaddbba 100644 --- a/drivers/gpu/drm/i915/i915_utils.h +++ b/drivers/gpu/drm/i915/i915_utils.h @@ -105,6 +105,37 @@ __T; \ }) +/* + * container_of_user: Extract the superclass from a pointer to a member. + * + * Exactly like container_of() with the exception that it plays nicely + * with sparse for __user @ptr. + */ +#define container_of_user(ptr, type, member) ({ \ + void __user *__mptr = (void __user *)(ptr); \ + BUILD_BUG_ON_MSG(!__same_type(*(ptr), ((type *)0)->member) && \ + !__same_type(*(ptr), void), \ + "pointer type mismatch in container_of()"); \ + ((type __user *)(__mptr - offsetof(type, member))); }) + +/* + * check_user_mbz: Check that a user value exists and is zero + * + * Frequently in our uABI we reserve space for future extensions, and + * two ensure that userspace is prepared we enforce that space must + * be zero. (Then any future extension can safely assume a default value + * of 0.) + * + * check_user_mbz() combines checking that the user pointer is accessible + * and that the contained value is zero. + * + * Returns: -EFAULT if not accessible, -EINVAL if !zero, or 0 on success. + */ +#define check_user_mbz(U) ({ \ + typeof(*(U)) mbz__; \ + get_user(mbz__, (U)) ? -EFAULT : mbz__ ? -EINVAL : 0; \ +}) + static inline u64 ptr_to_u64(const void *ptr) { return (uintptr_t)ptr; diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h index aa2d4c73a97d..1c69ed16a923 100644 --- a/include/uapi/drm/i915_drm.h +++ b/include/uapi/drm/i915_drm.h @@ -63,6 +63,28 @@ extern "C" { #define I915_RESET_UEVENT "RESET" /* + * i915_user_extension: Base class for defining a chain of extensions + * + * Many interfaces need to grow over time. In most cases we can simply + * extend the struct and have userspace pass in more data. Another option, + * as demonstrated by Vulkan's approach to providing extensions for forward + * and backward compatibility, is to use a list of optional structs to + * provide those extra details. + * + * The key advantage to using an extension chain is that it allows us to + * redefine the interface more easily than an ever growing struct of + * increasing complexity, and for large parts of that interface to be + * entirely optional. The downside is more pointer chasing; chasing across + * the __user boundary with pointers encapsulated inside u64. + */ +struct i915_user_extension { + __u64 next_extension; + __u32 name; + __u32 flags; /* All undefined bits must be zero. */ + __u32 rsvd[4]; /* Reserved for future use; must be zero. */ +}; + +/* * MOCS indexes used for GPU surfaces, defining the cacheability of the * surface data and the coherency for this data wrt. CPU vs. GPU accesses. */ |