X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fum%2Fkernel%2Fskas%2Fmmu.c;h=2c6d090a2e872b11d891c2510a1e4f55ef52dd17;hb=refs%2Fheads%2Fvserver;hp=5911cdd0c0b792c41fcf2190beeda1ce561066db;hpb=5273a3df6485dc2ad6aa7ddd441b9a21970f003b;p=linux-2.6.git

diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 5911cdd0c..2c6d090a2 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -7,40 +7,152 @@
 #include "linux/list.h"
 #include "linux/spinlock.h"
 #include "linux/slab.h"
+#include "linux/errno.h"
+#include "linux/mm.h"
 #include "asm/current.h"
 #include "asm/segment.h"
 #include "asm/mmu.h"
+#include "asm/pgalloc.h"
+#include "asm/pgtable.h"
+#include "asm/ldt.h"
 #include "os.h"
 #include "skas.h"
 
-int init_new_context_skas(struct task_struct *task, struct mm_struct *mm)
+extern int __syscall_stub_start;
+
+static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
+			 unsigned long kernel)
 {
-	int from;
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	pgd = pgd_offset(mm, proc);
+	pud = pud_alloc(mm, pgd, proc);
+	if (!pud)
+		goto out;
 
-	if((current->mm != NULL) && (current->mm != &init_mm))
-		from = current->mm->context.skas.mm_fd;
-	else from = -1;
+	pmd = pmd_alloc(mm, pud, proc);
+	if (!pmd)
+		goto out_pmd;
 
-	mm->context.skas.mm_fd = new_mm(from);
-	if(mm->context.skas.mm_fd < 0)
-		panic("init_new_context_skas - new_mm failed, errno = %d\n",
-		      mm->context.skas.mm_fd);
+	pte = pte_alloc_map(mm, pmd, proc);
+	if (!pte)
+		goto out_pte;
 
+	/* There's an interaction between the skas0 stub pages, stack
+	 * randomization, and the BUG at the end of exit_mmap.  exit_mmap
+         * checks that the number of page tables freed is the same as had
+         * been allocated.  If the stack is on the last page table page,
+	 * then the stack pte page will be freed, and if not, it won't.  To
+	 * avoid having to know where the stack is, or if the process mapped
+	 * something at the top of its address space for some other reason,
+	 * we set TASK_SIZE to end at the start of the last page table.
+	 * This keeps exit_mmap off the last page, but introduces a leak
+	 * of that page.  So, we hang onto it here and free it in
+	 * destroy_context_skas.
+	 */
+
+        mm->context.skas.last_page_table = pmd_page_vaddr(*pmd);
+#ifdef CONFIG_3_LEVEL_PGTABLES
+        mm->context.skas.last_pmd = (unsigned long) __va(pud_val(*pud));
+#endif
+
+	*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
+	*pte = pte_mkread(*pte);
 	return(0);
+
+ out_pmd:
+	pud_free(pud);
+ out_pte:
+	pmd_free(pmd);
+ out:
+	return(-ENOMEM);
 }
 
-void destroy_context_skas(struct mm_struct *mm)
+int init_new_context_skas(struct task_struct *task, struct mm_struct *mm)
 {
-	os_close_file(mm->context.skas.mm_fd);
+ 	struct mmu_context_skas *from_mm = NULL;
+	struct mmu_context_skas *to_mm = &mm->context.skas;
+	unsigned long stack = 0;
+	int ret = -ENOMEM;
+
+	if(skas_needs_stub){
+		stack = get_zeroed_page(GFP_KERNEL);
+		if(stack == 0)
+			goto out;
+
+		/* This zeros the entry that pgd_alloc didn't, needed since
+		 * we are about to reinitialize it, and want mm.nr_ptes to
+		 * be accurate.
+		 */
+		mm->pgd[USER_PTRS_PER_PGD] = __pgd(0);
+
+		ret = init_stub_pte(mm, CONFIG_STUB_CODE,
+				    (unsigned long) &__syscall_stub_start);
+		if(ret)
+			goto out_free;
+
+		ret = init_stub_pte(mm, CONFIG_STUB_DATA, stack);
+		if(ret)
+			goto out_free;
+
+		mm->nr_ptes--;
+	}
+
+	to_mm->id.stack = stack;
+	if(current->mm != NULL && current->mm != &init_mm)
+		from_mm = &current->mm->context.skas;
+
+	if(proc_mm){
+		ret = new_mm(stack);
+		if(ret < 0){
+			printk("init_new_context_skas - new_mm failed, "
+			       "errno = %d\n", ret);
+			goto out_free;
+		}
+		to_mm->id.u.mm_fd = ret;
+	}
+	else {
+		if(from_mm)
+			to_mm->id.u.pid = copy_context_skas0(stack,
+							     from_mm->id.u.pid);
+		else to_mm->id.u.pid = start_userspace(stack);
+	}
+
+	ret = init_new_ldt(to_mm, from_mm);
+	if(ret < 0){
+		printk("init_new_context_skas - init_ldt"
+		       " failed, errno = %d\n", ret);
+		goto out_free;
+	}
+
+	return 0;
+
+ out_free:
+	if(to_mm->id.stack != 0)
+		free_page(to_mm->id.stack);
+ out:
+	return ret;
 }
 
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */
+void destroy_context_skas(struct mm_struct *mm)
+{
+	struct mmu_context_skas *mmu = &mm->context.skas;
+
+	if(proc_mm)
+		os_close_file(mmu->id.u.mm_fd);
+	else
+		os_kill_ptraced_process(mmu->id.u.pid, 1);
+
+	if(!proc_mm || !ptrace_faultinfo){
+		free_page(mmu->id.stack);
+		pte_lock_deinit(virt_to_page(mmu->last_page_table));
+		pte_free_kernel((pte_t *) mmu->last_page_table);
+		dec_zone_page_state(virt_to_page(mmu->last_page_table), NR_PAGETABLE);
+#ifdef CONFIG_3_LEVEL_PGTABLES
+		pmd_free((pmd_t *) mmu->last_pmd);
+#endif
+	}
+}