Merge branch 'fixes' of git://git.linaro.org/people/rmk/linux-arm

Pull arm fixes fixes from Russell King:
 "This fixes a couple of problems with commit 48be69a0 ("ARM: move
  signal handlers into a vdso-like page"), one of which was originally
  discovered via my testing originally, but the fix for it was never
  actually committed.

  The other shows up on noMMU builds, and such platforms are extremely
  rare and as such are not part of my nightly testing"

* 'fixes' of git://git.linaro.org/people/rmk/linux-arm:
  ARM: fix nommu builds with 48be69a0 (ARM: move signal handlers into a vdso-like page)
  ARM: fix a cockup in 48be69a0 (ARM: move signal handlers into a vdso-like page)

arch/arm/include/asm/elf.h

@@ -130,8 +130,10 @@ struct mm_struct;
 extern unsigned long arch_randomize_brk(struct mm_struct *mm);
 #define arch_randomize_brk arch_randomize_brk
 
+#ifdef CONFIG_MMU
 #define ARCH_HAS_SETUP_ADDITIONAL_PAGES 1
 struct linux_binprm;
 int arch_setup_additional_pages(struct linux_binprm *, int);
+#endif
 
 #endif

arch/arm/kernel/process.c

@@ -474,17 +474,18 @@ const char *arch_vma_name(struct vm_area_struct *vma)
 		 "[sigpage]" : NULL;
 }
 
+static struct page *signal_page;
 extern struct page *get_signal_page(void);
 
 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 {
 	struct mm_struct *mm = current->mm;
-	struct page *page;
 	unsigned long addr;
 	int ret;
 
-	page = get_signal_page();
-	if (!page)
+	if (!signal_page)
+		signal_page = get_signal_page();
+	if (!signal_page)
 		return -ENOMEM;
 
 	down_write(&mm->mmap_sem);
@@ -496,7 +497,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 
 	ret = install_special_mapping(mm, addr, PAGE_SIZE,
 		VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
-		&page);
+		&signal_page);
 
 	if (ret == 0)
 		mm->context.sigpage = addr;

arch/arm/kernel/signal.c

@@ -402,7 +402,8 @@ setup_return(struct pt_regs *regs, struct ksignal *ksig,
 		    __put_user(sigreturn_codes[idx+1], rc+1))
 			return 1;
 
-		if ((cpsr & MODE32_BIT) && !IS_ENABLED(CONFIG_ARM_MPU)) {
+#ifdef CONFIG_MMU
+		if (cpsr & MODE32_BIT) {
 			struct mm_struct *mm = current->mm;
 
 			/*
@@ -412,7 +413,9 @@ setup_return(struct pt_regs *regs, struct ksignal *ksig,
 			 */
 			retcode = mm->context.sigpage + signal_return_offset +
 				  (idx << 2) + thumb;
-		} else {
+		} else
+#endif
+		{
 			/*
 			 * Ensure that the instruction cache sees
 			 * the return code written onto the stack.
@@ -614,21 +617,19 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
 	return 0;
 }
 
-static struct page *signal_page;
-
 struct page *get_signal_page(void)
 {
-	if (!signal_page) {
 	unsigned long ptr;
 	unsigned offset;
+	struct page *page;
 	void *addr;
 
-		signal_page = alloc_pages(GFP_KERNEL, 0);
+	page = alloc_pages(GFP_KERNEL, 0);
 
-		if (!signal_page)
+	if (!page)
 		return NULL;
 
-		addr = page_address(signal_page);
+	addr = page_address(page);
 
 	/* Give the signal return code some randomness */
 	offset = 0x200 + (get_random_int() & 0x7fc);
@@ -642,7 +643,6 @@ struct page *get_signal_page(void)
 
 	ptr = (unsigned long)addr + offset;
 	flush_icache_range(ptr, ptr + sizeof(sigreturn_codes));
-	}
 
-	return signal_page;
+	return page;
 }