stubhal.cpp revision 3d1c82a750046f055951242bf27909ad7d9cdf52 
1/*
2 * Copyright 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/* NOTE:
18 * This stub HAL is only used internally by the loader when a real HAL
19 * implementation is not present, in order to avoid needing "null HAL" checks
20 * throughout the loader. It does not enumerate any physical devices, and is
21 * only as conformant to the Vulkan and Android HAL interfaces as the loader
22 * needs it to be. Do not use it as an example of a correct implementation; the
23 * code in ../null_driver is better for that.
24 */
25
26#undef LOG_TAG
27#define LOG_TAG "vkstub"
28
29#include <array>
30#include <bitset>
31#include <mutex>
32#include <hardware/hwvulkan.h>
33#include <log/log.h>
34#include "stubhal.h"
35
36namespace vulkan {
37namespace stubhal {
38
39namespace {
40
41const size_t kMaxInstances = 32;
42static std::mutex g_instance_mutex;
43static std::bitset<kMaxInstances> g_instance_used(false);
44static std::array<hwvulkan_dispatch_t, kMaxInstances> g_instances;
45
46[[noreturn]] void NoOp() {
47    LOG_ALWAYS_FATAL("invalid stub function called");
48}
49
50VKAPI_ATTR VkResult
51EnumerateInstanceExtensionProperties(const char* /*layer_name*/,
52                                     uint32_t* count,
53                                     VkExtensionProperties* /*properties*/) {
54    *count = 0;
55    return VK_SUCCESS;
56}
57
58VKAPI_ATTR VkResult
59EnumerateInstanceLayerProperties(uint32_t* count,
60                                 VkLayerProperties* /*properties*/) {
61    *count = 0;
62    return VK_SUCCESS;
63}
64
65VKAPI_ATTR VkResult CreateInstance(const VkInstanceCreateInfo* /*create_info*/,
66                                   const VkAllocationCallbacks* /*allocator*/,
67                                   VkInstance* instance) {
68    std::lock_guard<std::mutex> lock(g_instance_mutex);
69    for (size_t i = 0; i < kMaxInstances; i++) {
70        if (!g_instance_used[i]) {
71            g_instance_used[i] = true;
72            g_instances[i].magic = HWVULKAN_DISPATCH_MAGIC;
73            *instance = reinterpret_cast<VkInstance>(&g_instances[i]);
74            return VK_SUCCESS;
75        }
76    }
77    ALOGE("no more instances available (max=%zu)", kMaxInstances);
78    return VK_ERROR_INITIALIZATION_FAILED;
79}
80
81VKAPI_ATTR void DestroyInstance(VkInstance instance,
82                                const VkAllocationCallbacks* /*allocator*/) {
83    std::lock_guard<std::mutex> lock(g_instance_mutex);
84    ssize_t idx =
85        reinterpret_cast<hwvulkan_dispatch_t*>(instance) - &g_instances[0];
86    ALOG_ASSERT(idx >= 0 && static_cast<size_t>(idx) < g_instance_used.size(),
87                "DestroyInstance: invalid instance handle");
88    g_instance_used[static_cast<size_t>(idx)] = false;
89}
90
91VKAPI_ATTR VkResult EnumeratePhysicalDevices(VkInstance /*instance*/,
92                                             uint32_t* count,
93                                             VkPhysicalDevice* /*gpus*/) {
94    *count = 0;
95    return VK_SUCCESS;
96}
97
98VKAPI_ATTR PFN_vkVoidFunction GetInstanceProcAddr(VkInstance /*instance*/,
99                                                  const char* name) {
100    if (strcmp(name, "vkCreateInstance") == 0)
101        return reinterpret_cast<PFN_vkVoidFunction>(CreateInstance);
102    if (strcmp(name, "vkDestroyInstance") == 0)
103        return reinterpret_cast<PFN_vkVoidFunction>(DestroyInstance);
104    if (strcmp(name, "vkEnumerateInstanceExtensionProperties") == 0)
105        return reinterpret_cast<PFN_vkVoidFunction>(
106            EnumerateInstanceExtensionProperties);
107    if (strcmp(name, "vkEnumeratePhysicalDevices") == 0)
108        return reinterpret_cast<PFN_vkVoidFunction>(EnumeratePhysicalDevices);
109    if (strcmp(name, "vkGetInstanceProcAddr") == 0)
110        return reinterpret_cast<PFN_vkVoidFunction>(GetInstanceProcAddr);
111
112    // None of the other Vulkan functions should ever be called, as they all
113    // take a VkPhysicalDevice or other object obtained from a physical device.
114    return reinterpret_cast<PFN_vkVoidFunction>(NoOp);
115}
116
117}  // anonymous namespace
118
119const hwvulkan_device_t kDevice = {
120    .common =
121        {
122            .tag = HARDWARE_DEVICE_TAG,
123            .version = HWVULKAN_DEVICE_API_VERSION_0_1,
124            .module = nullptr,
125            .close = nullptr,
126        },
127    .EnumerateInstanceExtensionProperties =
128        EnumerateInstanceExtensionProperties,
129    .CreateInstance = CreateInstance,
130    .GetInstanceProcAddr = GetInstanceProcAddr,
131};
132
133}  // namespace stubhal
134}  // namespace vulkan
135