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Call user space function from Linux kernel module

I am programming a simple Linux character device driver to output data to a piece of equipment through I / O ports. I have a function that performs floating point operations to calculate the correct output for hardware; unfortunately, this means that I need to store this function in user space, since the Linux kernel does not handle floating point operations very well.

Here's the pseudo-view of the installation (note that this code does nothing concrete, it just shows the relative layout of my code):

User Space Function :

char calculate_output(char x){
    double y = 2.5*x;
    double z = sqrt(y);

    char output = 0xA3;

    if(z > 35.67){
        output = 0xC0;
    }

    return output;
}

Kernelspace Code :

unsigned i;
for(i = 0; i < 300; i++){
    if(inb(INPUT_PORT) & NEED_DATA){
        char seed = inb(SEED_PORT);
        char output = calculate_output(seed);
        outb(output, OUTPUT_PORT);
    }

    /* do some random stuff here */
}

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  • userpace
    • kernelspace ,
    • userpace , (ioctl?),
    • kernelspace
  • kernelspace
  • userpace

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:

while (1) {
    read(fd, buf, sizeof buf);
    calculate_output(buf, output);
    write(fd, output, sizeof output);
}

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