> In this case, have you tried reading and writing to the memory segment being > mmap'd from userland? > > Here's an example mmap'ing device driver if you need to see that: > https://github.com/claudioscordino/mmap_alloc That would not have worked, but your example code did give me an idea. I was using MAP_PRIVATE while I should've been using MAP_SHARED. It works now. Thanks! Jethro On 13-01-16 06:34, Kenneth Adam Miller wrote: > In this case, have you tried reading and writing to the memory segment being > mmap'd from userland? > > Here's an example mmap'ing device driver if you need to see that: > https://github.com/claudioscordino/mmap_alloc > > On Tue, Jan 12, 2016 at 6:10 PM, Jethro Beekman <kernel@xxxxxxxxxxx > <mailto:kernel@xxxxxxxxxxx>> wrote: > > I'm writing a device driver for a memory-mapped device on x86-64. I'm mapping > the device in the kernel using ioremap_cache(). My file_operations.mmap function > is as follows: > > static int dev_mmap(struct file *filep, struct vm_area_struct *vma) { > vma->vm_page_prot.pgprot|=_PAGE_BIT_RW; > return vm_iomap_memory(vma,START,LEN); > } > > The user process calls mmap(..,PROT_READ|PROT_WRITE|PROT_EXEC,..). The mapping > in /proc/[pid]/maps shows the write bit. However, when looking at the actual > page table entry does not have the RW bit set. For example: > > virtual address = 0000_0001_8000_0000 > cr3 = 0000_0000_700a_e000 > phys:0000_0000_700a_e000 = 0000_0000_7e05_5067 (P|RW|US|A|D) > phys:0000_0000_7e05_5030 = 0000_0001_66e2_9067 (P|RW|US|A|D) > phys:0000_0001_66e2_9000 = 0000_0001_69db_3067 (P|RW|US|A|D) > phys:0000_0001_69db_3000 = 0000_0000_8020_0225 (P|US|A|SOFTW1) > > Am I doing something wrong? > > Jethro > > _______________________________________________ > Kernelnewbies mailing list > Kernelnewbies@xxxxxxxxxxxxxxxxx <mailto:Kernelnewbies@xxxxxxxxxxxxxxxxx> > http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies > > _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
