2.4.13-ac8

 kernel

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla/kernel/ptrace.c linux.ac/kernel/ptrace.c
--- linux.vanilla/kernel/ptrace.c   Wed Sep 19 00:32:16 2001
+++ linux.ac/kernel/ptrace.c   Fri Nov  2 14:31:33 2001
@@ -85,119 +85,17 @@
 }
 
 /*
- * Access another process' address space, one page at a time.
+ * Access another process' address space.
+ * Source/target buffer must be kernel space, 
+ * Do not walk the page table directly, use get_user_pages
  */
-static int access_one_page(struct mm_struct * mm, struct vm_area_struct * vma, unsigned long addr, void *buf, int len, int write)
-{
-   pgd_t * pgdir;
-   pmd_t * pgmiddle;
-   pte_t * pgtable;
-   char *maddr; 
-   struct page *page;
-
-repeat:
-   spin_lock(&mm->page_table_lock);
-   pgdir = pgd_offset(vma->vm_mm, addr);
-   if (pgd_none(*pgdir))
-      goto fault_in_page;
-   if (pgd_bad(*pgdir))
-      goto bad_pgd;
-   pgmiddle = pmd_offset(pgdir, addr);
-   if (pmd_none(*pgmiddle))
-      goto fault_in_page;
-   if (pmd_bad(*pgmiddle))
-      goto bad_pmd;
-   pgtable = pte_offset(pgmiddle, addr);
-   if (!pte_present(*pgtable))
-      goto fault_in_page;
-   if (write && (!pte_write(*pgtable) || !pte_dirty(*pgtable)))
-      goto fault_in_page;
-   page = pte_page(*pgtable);
-
-   /* ZERO_PAGE is special: reads from it are ok even though it's marked reserved */
-   if (page != ZERO_PAGE(addr) || write) {
-      if ((!VALID_PAGE(page)) || PageReserved(page)) {
-         spin_unlock(&mm->page_table_lock);
-         return 0;
-      }
-   }
-   get_page(page);
-   spin_unlock(&mm->page_table_lock);
-   flush_cache_page(vma, addr);
-
-   if (write) {
-      maddr = kmap(page);
-      memcpy(maddr + (addr & ~PAGE_MASK), buf, len);
-      flush_page_to_ram(page);
-      flush_icache_page(vma, page);
-      kunmap(page);
-   } else {
-      maddr = kmap(page);
-      memcpy(buf, maddr + (addr & ~PAGE_MASK), len);
-      flush_page_to_ram(page);
-      kunmap(page);
-   }
-   put_page(page);
-   return len;
-
-fault_in_page:
-   spin_unlock(&mm->page_table_lock);
-   /* -1: out of memory. 0 - unmapped page */
-   if (handle_mm_fault(mm, vma, addr, write) > 0)
-      goto repeat;
-   return 0;
-
-bad_pgd:
-   spin_unlock(&mm->page_table_lock);
-   pgd_ERROR(*pgdir);
-   return 0;
-
-bad_pmd:
-   spin_unlock(&mm->page_table_lock);
-   pmd_ERROR(*pgmiddle);
-   return 0;
-}
-
-static int access_mm(struct mm_struct *mm, struct vm_area_struct * vma, unsigned long addr, void *buf, int len, int write)
-{
-   int copied = 0;
-
-   for (;;) {
-      unsigned long offset = addr & ~PAGE_MASK;
-      int this_len = PAGE_SIZE - offset;
-      int retval;
-
-      if (this_len > len)
-         this_len = len;
-      retval = access_one_page(mm, vma, addr, buf, this_len, write);
-      copied += retval;
-      if (retval != this_len)
-         break;
-
-      len -= retval;
-      if (!len)
-         break;
-
-      addr += retval;
-      buf += retval;
-
-      if (addr < vma->vm_end)
-         continue;   
-      if (!vma->vm_next)
-         break;
-      if (vma->vm_next->vm_start != vma->vm_end)
-         break;
-   
-      vma = vma->vm_next;
-   }
-   return copied;
-}
 
 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
 {
-   int copied;
    struct mm_struct *mm;
-   struct vm_area_struct * vma;
+   struct vm_area_struct *vma;
+   struct page *page;
+   void *old_buf = buf;
 
    /* Worry about races with exit() */
    task_lock(tsk);
@@ -209,14 +107,41 @@
       return 0;
 
    down_read(&mm->mmap_sem);
-   vma = find_extend_vma(mm, addr);
-   copied = 0;
-   if (vma)
-      copied = access_mm(mm, vma, addr, buf, len, write);
+   /* ignore errors, just check how much was sucessfully transfered */
+   while (len) {
+      int bytes, ret, offset;
+      void *maddr;
+
+      ret = get_user_pages(current, mm, addr, 1,
+            write, 1, &page, &vma);
+      if (ret <= 0)
+         break;
+
+      bytes = len;
+      offset = addr & (PAGE_SIZE-1);
+      if (bytes > PAGE_SIZE-offset)
+         bytes = PAGE_SIZE-offset;
 
+      flush_cache_page(vma, addr);
+
+      maddr = kmap(page);
+      if (write) {
+         memcpy(maddr + offset, buf, bytes);
+         flush_page_to_ram(page);
+         flush_icache_page(vma, page);
+      } else {
+         memcpy(buf, maddr + offset, bytes);
+         flush_page_to_ram(page);
+      }
+      kunmap(page);
+      put_page(page);
+      len -= bytes;
+      buf += bytes;
+   }
    up_read(&mm->mmap_sem);
    mmput(mm);
-   return copied;
+   
+   return buf - old_buf;
 }
 
 int ptrace_readdata(struct task_struct *tsk, unsigned long src, char *dst, int len)