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Commit b7c4e3b7 authored by Jesse Hall's avatar Jesse Hall
Browse files

libvulkan: Use a stub HAL when no real Vulkan HAL is present 

This stub HAL enumerates zero VkPhysicalDevices. This allows a
VkInstane to be created and queried for physical devices successfully
even on devices without a Vulkan driver. Handling this with a stub HAL
avoids the need for NULL HAL and NULL driver function pointer checks
in many places throughout the loader, which would be more error-prone.

Fixes bug: 28100673
Change-Id: I76bea975929a85eda354730d6c815567b412b160
parent 2b97c063

vulkan/libvulkan/Android.mk

+1 −0
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ LOCAL_SRC_FILES := \ 
	driver.cpp \

	driver_gen.cpp \

	layers_extensions.cpp \

	stubhal.cpp \

	swapchain.cpp \

	vulkan_loader_data.cpp

LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk

vulkan/libvulkan/driver.cpp

+13 −9
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <sys/prctl.h>



#include "driver.h"

#include "stubhal.h"



// #define ENABLE_ALLOC_CALLSTACKS 1

#if ENABLE_ALLOC_CALLSTACKS
@@ -47,7 +48,7 @@ namespace { 


class CreateInfoWrapper {

   public:

    CreateInfoWrapper(hwvulkan_device_t* hw_dev,

    CreateInfoWrapper(const hwvulkan_device_t* hw_dev,

                      const VkInstanceCreateInfo& create_info,

                      const VkAllocationCallbacks& allocator);

    CreateInfoWrapper(VkPhysicalDevice physical_dev,
@@ -87,7 +88,7 @@ class CreateInfoWrapper { 
    const VkAllocationCallbacks& allocator_;



    union {

        hwvulkan_device_t* hw_dev_;

        const hwvulkan_device_t* hw_dev_;

        VkPhysicalDevice physical_dev_;

    };
@@ -102,7 +103,7 @@ class CreateInfoWrapper { 
    std::bitset<ProcHook::EXTENSION_COUNT> hal_extensions_;

};



CreateInfoWrapper::CreateInfoWrapper(hwvulkan_device_t* hw_dev,

CreateInfoWrapper::CreateInfoWrapper(const hwvulkan_device_t* hw_dev,

                                     const VkInstanceCreateInfo& create_info,

                                     const VkAllocationCallbacks& allocator)

    : is_instance_(true),
@@ -340,7 +341,7 @@ void CreateInfoWrapper::FilterExtension(const char* name) { 
    }

}



hwvulkan_device_t* g_hwdevice = nullptr;

const hwvulkan_device_t* g_hwdevice = nullptr;



VKAPI_ATTR void* DefaultAllocate(void*,

                                 size_t size,
@@ -428,15 +429,17 @@ bool Debuggable() { 
}



bool OpenHAL() {

    if (g_hwdevice)

        return true;

    ALOG_ASSERT(!g_hwdevice, "OpenHAL called more than once");



    // Use a stub device unless we successfully open a real HAL device.

    g_hwdevice = &stubhal::kDevice;



    const hwvulkan_module_t* module;

    int result =

        hw_get_module("vulkan", reinterpret_cast<const hw_module_t**>(&module));

    if (result != 0) {

        ALOGE("failed to load vulkan hal: %s (%d)", strerror(-result), result);

        return false;

        ALOGV("no Vulkan HAL present, using stub HAL");

        return true;

    }



    hwvulkan_device_t* device;
@@ -444,7 +447,8 @@ bool OpenHAL() { 
        module->common.methods->open(&module->common, HWVULKAN_DEVICE_0,

                                     reinterpret_cast<hw_device_t**>(&device));

    if (result != 0) {

        ALOGE("failed to open vulkan driver: %s (%d)", strerror(-result),

        // Any device with a Vulkan HAL should be able to open the device.

        ALOGE("failed to open Vulkan HAL device: %s (%d)", strerror(-result),

              result);

        return false;

    }

vulkan/libvulkan/stubhal.cpp

0 → 100644
+134 −0
Original line number Diff line number Diff line 
/*

 * Copyright 2016 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */



/* NOTE:

 * This stub HAL is only used internally by the loader when a real HAL

 * implementation is not present, in order to avoid needing "null HAL" checks

 * throughout the loader. It does not enumerate any physical devices, and is

 * only as conformant to the Vulkan and Android HAL interfaces as the loader

 * needs it to be. Do not use it as an example of a correct implementation; the

 * code in ../null_driver is better for that.

 */



#undef LOG_TAG

#define LOG_TAG "vkstub"



#include <array>

#include <bitset>

#include <mutex>

#include <hardware/hwvulkan.h>

#include <log/log.h>

#include "stubhal.h"



namespace vulkan {

namespace stubhal {



namespace {



const size_t kMaxInstances = 32;

static std::mutex g_instance_mutex;

static std::bitset<kMaxInstances> g_instance_used(false);

static std::array<hwvulkan_dispatch_t, kMaxInstances> g_instances;



[[noreturn]] void NoOp() {

    LOG_ALWAYS_FATAL("invalid stub function called");

}



VKAPI_ATTR VkResult

EnumerateInstanceExtensionProperties(const char* /*layer_name*/,

                                     uint32_t* count,

                                     VkExtensionProperties* /*properties*/) {

    *count = 0;

    return VK_SUCCESS;

}



VKAPI_ATTR VkResult

EnumerateInstanceLayerProperties(uint32_t* count,

                                 VkLayerProperties* /*properties*/) {

    *count = 0;

    return VK_SUCCESS;

}



VKAPI_ATTR VkResult CreateInstance(const VkInstanceCreateInfo* /*create_info*/,

                                   const VkAllocationCallbacks* /*allocator*/,

                                   VkInstance* instance) {

    std::lock_guard<std::mutex> lock(g_instance_mutex);

    for (size_t i = 0; i < kMaxInstances; i++) {

        if (!g_instance_used[i]) {

            g_instance_used[i] = true;

            g_instances[i].magic = HWVULKAN_DISPATCH_MAGIC;

            *instance = reinterpret_cast<VkInstance>(&g_instances[i]);

            return VK_SUCCESS;

        }

    }

    ALOGE("no more instances available (max=%zu)", kMaxInstances);

    return VK_ERROR_INITIALIZATION_FAILED;

}



VKAPI_ATTR void DestroyInstance(VkInstance instance,

                                const VkAllocationCallbacks* /*allocator*/) {

    std::lock_guard<std::mutex> lock(g_instance_mutex);

    ssize_t idx =

        reinterpret_cast<hwvulkan_dispatch_t*>(instance) - &g_instances[0];

    ALOG_ASSERT(idx >= 0 && idx < g_instance_used.size(),

                "DestroyInstance: invalid instance handle");

    g_instance_used[static_cast<size_t>(idx)] = false;

}



VKAPI_ATTR VkResult EnumeratePhysicalDevices(VkInstance /*instance*/,

                                             uint32_t* count,

                                             VkPhysicalDevice* /*gpus*/) {

    *count = 0;

    return VK_SUCCESS;

}



VKAPI_ATTR PFN_vkVoidFunction GetInstanceProcAddr(VkInstance /*instance*/,

                                                  const char* name) {

    if (strcmp(name, "vkCreateInstance") == 0)

        return reinterpret_cast<PFN_vkVoidFunction>(CreateInstance);

    if (strcmp(name, "vkDestroyInstance") == 0)

        return reinterpret_cast<PFN_vkVoidFunction>(DestroyInstance);

    if (strcmp(name, "vkEnumerateInstanceExtensionProperties") == 0)

        return reinterpret_cast<PFN_vkVoidFunction>(

            EnumerateInstanceExtensionProperties);

    if (strcmp(name, "vkEnumeratePhysicalDevices") == 0)

        return reinterpret_cast<PFN_vkVoidFunction>(EnumeratePhysicalDevices);

    if (strcmp(name, "vkGetInstanceProcAddr") == 0)

        return reinterpret_cast<PFN_vkVoidFunction>(GetInstanceProcAddr);



    // None of the other Vulkan functions should ever be called, as they all

    // take a VkPhysicalDevice or other object obtained from a physical device.

    return reinterpret_cast<PFN_vkVoidFunction>(NoOp);

}



}  // anonymous namespace



const hwvulkan_device_t kDevice = {

    .common =

        {

            .tag = HARDWARE_DEVICE_TAG,

            .version = HWVULKAN_DEVICE_API_VERSION_0_1,

            .module = nullptr,

            .close = nullptr,

        },

    .EnumerateInstanceExtensionProperties =

        EnumerateInstanceExtensionProperties,

    .CreateInstance = CreateInstance,

    .GetInstanceProcAddr = GetInstanceProcAddr,

};



}  // namespace stubhal

}  // namespace vulkan

vulkan/libvulkan/stubhal.h

0 → 100644
+30 −0
Original line number Diff line number Diff line 
/*

 * Copyright 2016 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */



#ifndef LIBVULKAN_STUBHAL_H

#define LIBVULKAN_STUBHAL_H 1



struct hwvulkan_device_t;



namespace vulkan {

namespace stubhal {



extern const hwvulkan_device_t kDevice;



}  // namespace stubhal

}  // namespace vulkan



#endif  // LIBVULKAN_STUBHAL_H