x86: convert vdso to use vm_fault_t

Return vm_fault_t codes directly from the appropriate mm routines instead
of converting from errnos ourselves.  Fixes a minor bug where we'd return
SIGBUS instead of the correct OOM code if we ran out of memory allocating
page tables.

Link: http://lkml.kernel.org/r/20180828145728.11873-5-willy@infradead.org
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/entry/vdso/vma.c

@@ -39,7 +39,7 @@ void __init init_vdso_image(const struct vdso_image *image)
 
 struct linux_binprm;
 
-static int vdso_fault(const struct vm_special_mapping *sm,
+static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
 		      struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	const struct vdso_image *image = vma->vm_mm->context.vdso_image;
@@ -84,12 +84,11 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
 	return 0;
 }
 
-static int vvar_fault(const struct vm_special_mapping *sm,
+static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 		      struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	const struct vdso_image *image = vma->vm_mm->context.vdso_image;
 	long sym_offset;
-	int ret = -EFAULT;
 
 	if (!image)
 		return VM_FAULT_SIGBUS;
@@ -108,29 +107,24 @@ static int vvar_fault(const struct vm_special_mapping *sm,
 		return VM_FAULT_SIGBUS;
 
 	if (sym_offset == image->sym_vvar_page) {
-		ret = vm_insert_pfn(vma, vmf->address,
-				    __pa_symbol(&__vvar_page) >> PAGE_SHIFT);
+		return vmf_insert_pfn(vma, vmf->address,
+				__pa_symbol(&__vvar_page) >> PAGE_SHIFT);
 	} else if (sym_offset == image->sym_pvclock_page) {
 		struct pvclock_vsyscall_time_info *pvti =
 			pvclock_get_pvti_cpu0_va();
 		if (pvti && vclock_was_used(VCLOCK_PVCLOCK)) {
-			ret = vm_insert_pfn_prot(
-				vma,
-				vmf->address,
-				__pa(pvti) >> PAGE_SHIFT,
-				pgprot_decrypted(vma->vm_page_prot));
+			return vmf_insert_pfn_prot(vma, vmf->address,
+					__pa(pvti) >> PAGE_SHIFT,
+					pgprot_decrypted(vma->vm_page_prot));
 		}
 	} else if (sym_offset == image->sym_hvclock_page) {
 		struct ms_hyperv_tsc_page *tsc_pg = hv_get_tsc_page();
 
 		if (tsc_pg && vclock_was_used(VCLOCK_HVCLOCK))
-			ret = vm_insert_pfn(vma, vmf->address,
-					    vmalloc_to_pfn(tsc_pg));
+			return vmf_insert_pfn(vma, vmf->address,
+					vmalloc_to_pfn(tsc_pg));
 	}
 
-	if (ret == 0 || ret == -EBUSY)
-		return VM_FAULT_NOPAGE;
-
 	return VM_FAULT_SIGBUS;
 }