Change memory protection

andparker · 06-06-2011, 04:57 AM

Hello,
How can I change the memory protection inside a driver?

I want to execute 32-bits code inside a rom in the ISA space. I can read this area, but when I try to do a call to the rom code I receive always and exception.

I find some docs over internet, but always refere to remap an user area. I want to execute this code from the driver.

Any idea?
Andrew

nini09 · 06-06-2011, 03:15 PM

Most code can't execute in ROM space. You have to copy to RAM space.

andparker · 06-07-2011, 03:33 AM

Hello nini09,

Really the code is already copied in an area of ram.

I can execute this code from userspace, but not from the driver.
In userspace, I do a mmap with the PROT_EXEC flag and I can call the rom code without problems.

But under kernelspace, inside the driver, I don’t know how to change the memory protetcion.
Surely is with ‘remap_pfn_range’ or similar, but I don’t know how to obtain or build the VMA strcut.

Thanks,
Andrew

nini09 · 06-07-2011, 03:46 PM

You can read insmod code and maybe you can get some idea.

andparker · 06-08-2011, 12:18 PM

No very useful for me, but thanks.
Really I can't understand how is as easy to do under userspace and dificult under the kernelspace!