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Hardware and software configuration
MacBook Air M2 2022 16GB,
MacOS Ventura 13.2.1
Full description
This is a DriverKit that controls PCIE FPGA devices for low-latency data exchange.
This driver has been implemented on Iokit, and now it needs to be launched on Driverkit to adapt to newer Macs.
Driverkit lacks the IOMemoryDescriptor::withAddressRange(Iokit) function to convert the app's memory of any size to a Descriptor.
Currently, we use args->structureOutputDescriptor->CreateMapping to map the Descriptor passed by the application to the kernel layer.
// App
size_t ***::xxRead(long long addr, size_t size, void * buff){
std::lock_guard<std::mutex> guard(usrLock);
kern_return_t kr;
uint64_t info[2] = {(uint64_t)addr, (uint64_t)size};
kr = IOConnectCallMethod(
connect,
kUserReadIO,
info,
2,
NULL, NULL, NULL, NULL,
buff,
&size);
return size;
}
// Driverkit
const IOUserClientMethodDispatch sMethods[kNumMethods] = {
[kUserReadIO] =
{
(IOUserClientMethodFunction) &SmiPcieUc::sUserReadIo,
.checkCompletionExists = false,
.checkScalarInputCount = 2, // Read Addr, size
.checkStructureInputSize = 0,
.checkScalarOutputCount = 0,
.checkStructureOutputSize = kIOUserClientVariableStructureSize} // Read Data
};
kern_return_t SmiPcieUc::sUserReadIo (OSObject * target, void* reference, IOUserClientMethodArguments* args){
IOMemoryMap * memMap = nullptr;
uint32_t * buffKptr = nullptr;
kern_return_t rt = 0;
if(target == nullptr){
Log("***Err***: sUserReadIo Target is Null!");
return kIOReturnError;
}
if(args->structureOutputDescriptor){
rt = args->structureOutputDescriptor->CreateMapping(0,0,0,0,0, &memMap);
if(rt == kIOReturnSuccess){
buffKptr = reinterpret_cast<uint32_t *>(memMap->GetAddress());
}
else {
Log("***Err***: sUserReadIo Mapping Failed!");
return kIOReturnNoMemory;
}
} else {
buffKptr = (uint32_t *) args->structureOutput;
}
rt = ((SmiPcieUc *)target)->UserReadIo((uint64_t *)&args->scalarInput[0], (size_t *)&args->scalarInput[1], buffKptr);
OSSafeReleaseNULL(memMap);
return rt;
}
phenomenon
When StructureOutputSize is greater than 4096, args>structureOutputDescriptor exists, and when it is less than or equal to 4096, args->structureOutputDescriptor and args->structureOutput are both equal to nullptr, (in IOkit, args->structureOutput is not empty)。
How to properly convert any size of application memory into the kernel space of Driverkit？
Posted
by
XuMoxiao.
Last updated
XuMoxiao.
.