Description top the memcpy function copies n bytes from memory area src to memory area dest. The memcpy function copies n bytes from memory area src to memory area dest. In almost all conceivable cases a device driver should not be using this function. Translating addresses in kernel space from a message from linus torvalds to the linux kernel mailing list of 27 sep 1996, edited. This function does not handle bus mappings for dma transfers. Unfortunately, almost every device driver must use these functions, creating thousands. Description the memcpy function copies n bytes from memory area src to memory area dest.
Linux kernel module programming guide read and write a proc. The exact definition depends on the architecture, but it essentially looks like th. Things are actually worse than just physical and virtual addresses. The returned virtual address is a current cpu mapping for the memory address given. Ill take this opportunity to tell all device driver writers about the ugly secrets of portability. How to use memcpy in kernel driver kristof provost kristof at sigsegv. Another way around is to implement your driver as a kernel module, in which case you wont need to recompile the kernel to add another driver. How to use memcpy in kernel driver messages sorted by. Embedded linux conference europe 2015 supporting multi function devices in the linux kernel.
Supporting multifunction devices in the linux kernel. Contribute to linux4sam linux at91 development by creating an account on github. Browse other questions tagged c linux kernel device driver memcpy or ask your own question. Tried it on another machine, same version of compiler though. Linuxtopia books linux kernel module programming guide read and write a. It works the same way as read, a function is called when the proc file is written. Gcc uses builtin functions of which some may refer to libgcc which is not present in the kernel.
In our experiments, we discovered 11 userkernel pointer bugs in linux. Use the io memcpy functions when copying fromto io memory. For this reason, writing a device driver for linux requires performing a combined compilation with the kernel. For questions related to hardware requirements, refer to the documentation supplied with your intel adapter. Hi, there are three heapbased buffer overflows in marvell wifi chip driver in linux kernel, allow local users to cause a denial of servicesystem crash or possibly. Finding userkernel pointer bugs with type inference usenix. This driver supports 82599, x540, x550, and x552based virtual function devices that can only be activated on kernels that support sriov.
The wrapper functions used to access io memory are safe on all platforms and. It is only valid to use this function on addresses that have a kernel mapping. The kernel provides a few of the functions usually provided by the c library. Once equipped with ioremap and iounmap, a device driver can access any.