linux-kernel - [PATCH] x86/vdso: Change return type to vm_fault

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Message-ID: <20180625155750.GA14306@jordon-HP-15-Notebook-PC>
Date:   Mon, 25 Jun 2018 21:27:50 +0530
From:   Souptick Joarder <jrdr.linux@...il.com>
To:     willy@...radead.org, luto@...capital.net, tglx@...utronix.de,
        mingo@...hat.com, hpa@...or.com, x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, brajeswar.linux@...il.com,
        sabyasachi.linux@...il.com
Subject: [PATCH] x86/vdso: Change return type to vm_fault_t for fault handlers

Use new return type vm_fault_t for fault handler. For
now, this is just documenting that the function returns
a VM_FAULT value rather than an errno. Once all instances
are converted, vm_fault_t will become a distinct type.

Ref-> commit 1c8f422059ae ("mm: change return type to vm_fault_t")

Previously vm_insert_pfn() returns err which has to
mapped into VM_FAULT_* type. The new function
vmf_insert_pfn() will replace this inefficiency by
returning VM_FAULT_* type.

Signed-off-by: Souptick Joarder <jrdr.linux@...il.com>
---
 arch/x86/entry/vdso/vma.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index 5b8b556..3679885 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/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;
@@ -84,15 +84,15 @@ 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;
+	vm_fault_t ret = VM_FAULT_SIGBUS;
 
 	if (!image)
-		return VM_FAULT_SIGBUS;
+		return ret;
 
 	sym_offset = (long)(vmf->pgoff << PAGE_SHIFT) +
 		image->sym_vvar_start;
@@ -105,10 +105,10 @@ static int vvar_fault(const struct vm_special_mapping *sm,
 	 * the page past the end of the vvar mapping.
 	 */
 	if (sym_offset == 0)
-		return VM_FAULT_SIGBUS;
+		return ret;
 
 	if (sym_offset == image->sym_vvar_page) {
-		ret = vm_insert_pfn(vma, vmf->address,
+		ret = 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 =
@@ -124,14 +124,11 @@ static int vvar_fault(const struct vm_special_mapping *sm,
 		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,
+			ret = vmf_insert_pfn(vma, vmf->address,
 					    vmalloc_to_pfn(tsc_pg));
 	}
 
-	if (ret == 0 || ret == -EBUSY)
-		return VM_FAULT_NOPAGE;
-
-	return VM_FAULT_SIGBUS;
+	return ret;
 }
 
 static const struct vm_special_mapping vdso_mapping = {
-- 
1.9.1