4 files changed, 6 insertions, 105 deletions

diff --git a/arch/um/kernel/exec.c b/arch/um/kernel/exec.c
index e8fd5d540b05..4d8498100341 100644
--- a/arch/um/kernel/exec.c
+++ b/arch/um/kernel/exec.c
@@ -26,9 +26,7 @@ void flush_thread(void)
 
 	arch_flush_thread(&current->thread.arch);
 
-	ret = unmap(&current->mm->context.id, 0, STUB_START, 0, &data);
-	ret = ret || unmap(&current->mm->context.id, STUB_END,
-			   host_task_size - STUB_END, 1, &data);
+	ret = unmap(&current->mm->context.id, 0, TASK_SIZE, 1, &data);
 	if (ret) {
 		printk(KERN_ERR "flush_thread - clearing address space failed, "
 		       "err = %d\n", ret);
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index d9961163da66..125df465e8ea 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -14,47 +14,6 @@
 #include <os.h>
 #include <skas.h>
 
-static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
-			 unsigned long kernel)
-{
-	pgd_t *pgd;
-	p4d_t *p4d;
-	pud_t *pud;
-	pmd_t *pmd;
-	pte_t *pte;
-
-	pgd = pgd_offset(mm, proc);
-
-	p4d = p4d_alloc(mm, pgd, proc);
-	if (!p4d)
-		goto out;
-
-	pud = pud_alloc(mm, p4d, proc);
-	if (!pud)
-		goto out_pud;
-
-	pmd = pmd_alloc(mm, pud, proc);
-	if (!pmd)
-		goto out_pmd;
-
-	pte = pte_alloc_map(mm, pmd, proc);
-	if (!pte)
-		goto out_pte;
-
-	*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
-	*pte = pte_mkread(*pte);
-	return 0;
-
- out_pte:
-	pmd_free(mm, pmd);
- out_pmd:
-	pud_free(mm, pud);
- out_pud:
-	p4d_free(mm, p4d);
- out:
-	return -ENOMEM;
-}
-
 int init_new_context(struct task_struct *task, struct mm_struct *mm)
 {
  	struct mm_context *from_mm = NULL;
@@ -98,52 +57,6 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
 	return ret;
 }
 
-void uml_setup_stubs(struct mm_struct *mm)
-{
-	int err, ret;
-
-	ret = init_stub_pte(mm, STUB_CODE,
-			    (unsigned long) __syscall_stub_start);
-	if (ret)
-		goto out;
-
-	ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
-	if (ret)
-		goto out;
-
-	mm->context.stub_pages[0] = virt_to_page(__syscall_stub_start);
-	mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
-
-	/* dup_mmap already holds mmap_lock */
-	err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
-				      VM_READ | VM_MAYREAD | VM_EXEC |
-				      VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
-				      mm->context.stub_pages);
-	if (err) {
-		printk(KERN_ERR "install_special_mapping returned %d\n", err);
-		goto out;
-	}
-	return;
-
-out:
-	force_sigsegv(SIGSEGV);
-}
-
-void arch_exit_mmap(struct mm_struct *mm)
-{
-	pte_t *pte;
-
-	pte = virt_to_pte(mm, STUB_CODE);
-	if (pte != NULL)
-		pte_clear(mm, STUB_CODE, pte);
-
-	pte = virt_to_pte(mm, STUB_DATA);
-	if (pte == NULL)
-		return;
-
-	pte_clear(mm, STUB_DATA, pte);
-}
-
 void destroy_context(struct mm_struct *mm)
 {
 	struct mm_context *mmu = &mm->context;
diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index 5be1b0da9f3b..bc38f79ca3a3 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -125,9 +125,6 @@ static int add_mmap(unsigned long virt, unsigned long phys, unsigned long len,
 	struct host_vm_op *last;
 	int fd = -1, ret = 0;
 
-	if (virt + len > STUB_START && virt < STUB_END)
-		return -EINVAL;
-
 	if (hvc->userspace)
 		fd = phys_mapping(phys, &offset);
 	else
@@ -165,9 +162,6 @@ static int add_munmap(unsigned long addr, unsigned long len,
 	struct host_vm_op *last;
 	int ret = 0;
 
-	if (addr + len > STUB_START && addr < STUB_END)
-		return -EINVAL;
-
 	if (hvc->index != 0) {
 		last = &hvc->ops[hvc->index - 1];
 		if ((last->type == MUNMAP) &&
@@ -195,9 +189,6 @@ static int add_mprotect(unsigned long addr, unsigned long len,
 	struct host_vm_op *last;
 	int ret = 0;
 
-	if (addr + len > STUB_START && addr < STUB_END)
-		return -EINVAL;
-
 	if (hvc->index != 0) {
 		last = &hvc->ops[hvc->index - 1];
 		if ((last->type == MPROTECT) &&
@@ -232,9 +223,6 @@ static inline int update_pte_range(pmd_t *pmd, unsigned long addr,
 
 	pte = pte_offset_kernel(pmd, addr);
 	do {
-		if ((addr >= STUB_START) && (addr < STUB_END))
-			continue;
-
 		r = pte_read(*pte);
 		w = pte_write(*pte);
 		x = pte_exec(*pte);
@@ -478,9 +466,6 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
 
 	address &= PAGE_MASK;
 
-	if (address >= STUB_START && address < STUB_END)
-		goto kill;
-
 	pgd = pgd_offset(mm, address);
 	if (!pgd_present(*pgd))
 		goto kill;
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 80e2660782a0..74e07e748a9b 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -249,6 +249,7 @@ void uml_finishsetup(void)
 }
 
 /* Set during early boot */
+unsigned long stub_start;
 unsigned long task_size;
 EXPORT_SYMBOL(task_size);
 
@@ -283,6 +284,10 @@ int __init linux_main(int argc, char **argv)
 		add_arg(DEFAULT_COMMAND_LINE_CONSOLE);
 
 	host_task_size = os_get_top_address();
+	/* reserve two pages for the stubs */
+	host_task_size -= 2 * PAGE_SIZE;
+	stub_start = host_task_size;
+
 	/*
 	 * TASK_SIZE needs to be PGDIR_SIZE aligned or else exit_mmap craps
 	 * out