Module working? Writer done
This commit is contained in:
parent
ede1b4ff6a
commit
200739c892
2 changed files with 59 additions and 50 deletions
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@ -6,8 +6,10 @@ CC += ${MY_CFLAGS}
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KDIR := /lib/modules/$(shell uname -r)/build
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KDIR_CROSS := ${HOME}/Git/linux
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KDIR_UOE := /disk/scratch/s2018374/linux
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KDIR_SSHFS := /tmp/inf-sshfs/linux
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PWD := $(shell pwd)
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GITDIR := $(shell git rev-parse --show-toplevel)
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all:
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$(MAKE) -C $(KDIR) M=$(PWD) modules
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@ -21,6 +23,10 @@ all-uoe:
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$(MAKE) -C $(KDIR_UOE) M=$(PWD) modules
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EXTRA_CFLAGS="$(MY_CFLAGS)"
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all-sshfs:
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$(MAKE) -C $(KDIR_SSHFS) M=$(PWD) modules
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EXTRA_CFLAGS="$(MY_CFLAGS)"
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clean:
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$(MAKE) -C $(KDIR) M=$(PWD) clean
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@ -29,3 +35,11 @@ clean-cross:
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clean-uoe:
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$(MAKE) -C $(KDIR_UOE) M=$(PWD) clean
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clean-sshfs:
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$(MAKE) -C $(KDIR_SSHFS) M=$(PWD) clean
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# Extra
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install:
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cp my_shmem.ko $(GITDIR)/test/shared
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@ -1,5 +1,7 @@
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// [TODO] Clean up headers...
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#include <linux/device.h>
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#include "asm-generic/memory_model.h"
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#include "asm/page-def.h"
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#include "linux/gfp.h"
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#include "linux/mutex.h"
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#include "linux/pfn_t.h"
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@ -45,22 +47,20 @@ const char* DEV_NAME = "my_shmem";
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*/
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static void my_shmem_vmops_close(struct vm_area_struct *vma)
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{
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// [TODO] Flush only pages we need to flush, via `walk_page_vma`, etc.
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// However this works -- and it's proof-of-concept anyways
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struct my_shmem_page *curr;
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mutex_lock(&my_shmem_pages_mtx);
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list_for_each_entry(curr, &my_shmem_pages, list) {
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struct page *pg = curr->page;
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// Ref: `arch_dma_prep_coherent`
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ulong vaddr_start = (ulong) page_address(pg);
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ulong vaddr_bgn = (ulong) page_address(pg);
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ulong vaddr_end = vaddr_bgn + PAGE_SIZE;
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BUG_ON(!virt_addr_valid((void *) vaddr_bgn));
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pr_info("[%s] Before flush: 0x%px has 0x%lx [+%ld].\n",
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__func__, page_address(pg), *(ulong *)(page_address(pg)),
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__func__, (void *) vaddr_bgn, *(ulong *) vaddr_bgn,
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sizeof(ulong));
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// [!!] `dcache_clean_poc` seems not exported.
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__dcache_clean_poc(vaddr_start, vaddr_start + PAGE_SIZE);
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__dcache_clean_poc(vaddr_bgn, vaddr_end);
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pr_info("[%s] After flush: 0x%px has 0x%lx [+%ld].\n",
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__func__, page_address(pg), *(ulong *)(page_address(pg)),
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__func__, (void *) vaddr_bgn, *(ulong *) vaddr_bgn,
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sizeof(ulong));
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}
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mutex_unlock(&my_shmem_pages_mtx);
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@ -69,31 +69,39 @@ static void my_shmem_vmops_close(struct vm_area_struct *vma)
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static vm_fault_t my_shmem_vmops_fault(struct vm_fault *vmf)
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{
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pr_info("[%s] vm_fault @ 0x%lx (real address 0x%lx).\n",
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__func__, vmf->address, vmf->real_address);
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struct vm_area_struct *vma_of_vmf = vmf->vma;
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ulong nr_pages_from_vm_start =
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(vmf->address - vmf->vma->vm_start) >> PAGE_SHIFT;
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const pgoff_t _dbg_offset_from_page = vmf->pgoff;
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phys_addr_t _dbg_phys;
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(vmf->address - vma_of_vmf->vm_start) >> PAGE_SHIFT;
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const pgoff_t _dbg_offset_from_vma = vmf->pgoff;
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phys_addr_t _dbg_phys_of_page;
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BUG_ON(!vma_of_vmf->vm_mm);
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mutex_lock(&my_shmem_pages_mtx);
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if (nr_pages_from_vm_start < my_shmem_page_count) {
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/* Offset in range, return existing page */
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pr_info("[%s] Found remappable page nr: %lu, offset: %lu. "
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"Total pages allocated: %ld.\n",
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__func__, nr_pages_from_vm_start, _dbg_offset_from_page,
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my_shmem_page_count);
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"Total pages allocated: %ld (list size: %ld).\n",
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__func__, nr_pages_from_vm_start, _dbg_offset_from_vma,
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my_shmem_page_count, list_count_nodes(&my_shmem_pages));
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// We won't delete elements from list here!
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// Find correct entry
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struct my_shmem_page *page_entry;
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list_for_each_entry(page_entry, &my_shmem_pages, list) {
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if (!nr_pages_from_vm_start)
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break;
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if (!nr_pages_from_vm_start) break;
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nr_pages_from_vm_start--;
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}
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// Found correct page entry, remap
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// No get_page here, get_page at alloc time only keeps memory
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// valid for module code.
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// Found correct entry, remap to userspace
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pr_info("[%s] Remapped pfn: %ld, kernel vaddr: %px.\n",
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__func__, page_to_pfn(page_entry->page),
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page_to_virt(page_entry->page));
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// get_page(page_entry->page);
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vmf->page = page_entry->page;
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_dbg_phys = page_to_phys(page_entry->page);
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_dbg_phys_of_page = page_to_phys(page_entry->page);
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mutex_unlock(&my_shmem_pages_mtx);
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goto ok_ret_remapped;
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@ -104,6 +112,7 @@ static vm_fault_t my_shmem_vmops_fault(struct vm_fault *vmf)
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nr_pages_from_vm_start - my_shmem_page_count + 1;
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pr_info("[%s] Not enough remappable pages, allocating %ld more...\n",
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__func__, nr_pages_to_alloc);
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struct page *last_pg;
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for (; nr_pages_to_alloc > 0; nr_pages_to_alloc--)
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{
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// Allocate page handle in kernel
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@ -114,26 +123,29 @@ static vm_fault_t my_shmem_vmops_fault(struct vm_fault *vmf)
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goto err_ret_no_kmem;
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}
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// Allocate page in virtual memory,
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// for convenience also directly accessible by kernel.
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struct page *pg = alloc_page(GFP_USER);
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if (!pg) {
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// Allocate kernel virtual page
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struct page *curr_pg = alloc_page(GFP_USER);
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if (!curr_pg) {
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mutex_unlock(&my_shmem_pages_mtx);
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goto err_ret_no_vmem;
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}
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get_page(pg);
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new_page->page = pg;
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pr_info("[%s] Allocated pfn: %ld, kernel vaddr: %px.\n",
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__func__, page_to_pfn(curr_pg), page_to_virt(curr_pg));
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get_page(curr_pg);
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new_page->page = curr_pg;
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// List maintenance: add and incr. size
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list_add(&new_page->list, &my_shmem_pages);
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my_shmem_page_count++;
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// Fill in allocated page entry
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// Bad for performance, but guarantees to be the last page entry
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// on out.
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vmf->page = new_page->page;
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_dbg_phys = page_to_phys(new_page->page);
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// Fill in last_pg for final return from page fault handler
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last_pg = curr_pg;
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}
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// Fill in vmf's page for return
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// get_page(last_pg);
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vmf->page = last_pg;
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_dbg_phys_of_page = page_to_phys(last_pg);
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mutex_unlock(&my_shmem_pages_mtx);
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goto ok_ret_allocated;
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@ -146,27 +158,10 @@ err_ret_no_vmem:
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__func__);
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return VM_FAULT_OOM;
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ok_ret_remapped:
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if (vmf->vma->vm_mm) {
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rcu_read_lock();
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struct task_struct *fault_owner = vmf->vma->vm_mm->owner;
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pr_info("[%s] Remapped phys: 0x%llx -> virt@PID(%d): 0x%lx.\n",
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__func__, _dbg_phys, fault_owner->pid, vmf->address);
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rcu_read_unlock();
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}
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return 0;
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ok_ret_allocated:
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if (vmf->vma->vm_mm){
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rcu_read_lock();
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struct task_struct *fault_owner = vmf->vma->vm_mm->owner;
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pr_info("[%s] Allocated phys: 0x%llx -> virt@PID(%d): 0x%lx.\n",
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__func__, _dbg_phys, fault_owner->pid, vmf->address);
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rcu_read_unlock();
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}
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return 0;
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}
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static const struct vm_operations_struct my_shmem_vmops = {
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.close = my_shmem_vmops_close,
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.fault = my_shmem_vmops_fault,
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@ -279,7 +274,7 @@ static void __exit my_shmem_exit(void)
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mutex_lock(&my_shmem_pages_mtx);
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list_for_each_entry_safe(page_entry, tmp, &my_shmem_pages, list) {
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put_page(page_entry->page);
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kfree(page_to_virt(page_entry->page));
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free_page((ulong) page_to_virt(page_entry->page));
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my_shmem_page_count--;
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list_del(&page_entry->list);
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