by Hi Linus,
This patch allows to write vmalloc space via /dev/kmem. Without it is
only readable. Writing is useful for example to change debugging variables
in modules.
The patch is originally from Marc Boucher.
Patch against 2.5.3.
Please consider applying it.
Thanks,
-Andi
--- linux/drivers/char/mem.c-KMEM Wed Jan 23 12:27:33 2002
size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
+ ssize_t wrote = 0;
+ ssize_t virtr = 0;
+ char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
- if (p >= (unsigned long) high_memory)
- return 0;
- if (count > (unsigned long) high_memory - p)
- count = (unsigned long) high_memory - p;
- return do_write_mem(file, (void*)p, p, buf, count, ppos);
+ if (p < (unsigned long) high_memory) {
+ wrote = count;
+ if (count > (unsigned long) high_memory - p)
+ wrote = (unsigned long) high_memory - p;
+
+ wrote = do_write_mem(file, (void*)p, p, buf, wrote, ppos);
+
+ p += wrote;
+ buf += wrote;
+ count -= wrote;
+ }
+
+ if (count > 0) {
+ kbuf = (char *)__get_free_page(GFP_KERNEL);
+ if (!kbuf)
+ return -ENOMEM;
+ while (count > 0) {
+ int len = count;
+
+ if (len > PAGE_SIZE)
+ len = PAGE_SIZE;
+ if (len && copy_from_user(kbuf, buf, len)) {
+ free_page((unsigned long)kbuf);
+ return -EFAULT;
+ }
+ len = vwrite(kbuf, (char *)p, len);
+ count -= len;
+ buf += len;
+ virtr += len;
+ p += len;
+ }
+ free_page((unsigned long)kbuf);
+ }
+
+ *ppos = p;
+ return virtr + wrote;
}
#if !defined(__mc68000__)
--- linux/include/linux/vmalloc.h-KMEM Sun Feb 3 11:15:37 2002
extern void vfree(void * addr);
extern void * __vmalloc (unsigned long size, int gfp_mask, pgprot_t prot);
extern long vread(char *buf, char *addr, unsigned long count);
+extern long vwrite(char *buf, char *addr, unsigned long count);
extern void vmfree_area_pages(unsigned long address, unsigned long size);
extern int vmalloc_area_pages(unsigned long address, unsigned long size,
int gfp_mask, pgprot_t prot);
--- linux/mm/vmalloc.c-KMEM Tue Jan 15 06:18:19 2002
*/
+#include <linux/config.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
if (count == 0)
goto finished;
*buf = *addr;
+ buf++;
+ addr++;
+ count--;
+ } while (--n > 0);
+ }
+finished:
+ read_unlock(&vmlist_lock);
+ return buf - buf_start;
+}
+
+long vwrite(char *buf, char *addr, unsigned long count)
+{
+ struct vm_struct *tmp;
+ char *vaddr, *buf_start = buf;
+ unsigned long n;
+
+ /* Don't allow overflow */
+ if ((unsigned long) addr + count < count)
+ count = -(unsigned long) addr;
+
+ read_lock(&vmlist_lock);
+ for (tmp = vmlist; tmp; tmp = tmp->next) {
+ vaddr = (char *) tmp->addr;
+ if (addr >= vaddr + tmp->size - PAGE_SIZE)
+ continue;
+ while (addr < vaddr) {
+ if (count == 0)
+ goto finished;
+ buf++;
+ addr++;
+ count--;
+ }
+ n = vaddr + tmp->size - PAGE_SIZE - addr;
+ do {
+ if (count == 0)
+ goto finished;
+ *addr = *buf;
buf++;
addr++;
count--;
-
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