+ arm-mm-drop-vm_fault_badmap-vm_fault_badaccess.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: arm: mm: drop VM_FAULT_BADMAP/VM_FAULT_BADACCESS
has been added to the -mm mm-unstable branch.  Its filename is
     arm-mm-drop-vm_fault_badmap-vm_fault_badaccess.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/arm-mm-drop-vm_fault_badmap-vm_fault_badaccess.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Kefeng Wang <wangkefeng.wang@huawei.com>
Subject: arm: mm: drop VM_FAULT_BADMAP/VM_FAULT_BADACCESS
Date: Thu, 11 Apr 2024 21:09:25 +0800

If bad map or access, directly set code to SEGV_MAPRR or SEGV_ACCERR, also
set fault to 0 and goto error handling, which make us to drop the arch's
special vm fault reason.

Link: https://lkml.kernel.org/r/20240411130925.73281-3-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Aishwarya TCV <aishwarya.tcv@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Cristian Marussi <cristian.marussi@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/arm/mm/fault.c |   30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

--- a/arch/arm/mm/fault.c~arm-mm-drop-vm_fault_badmap-vm_fault_badaccess
+++ a/arch/arm/mm/fault.c
@@ -226,9 +226,6 @@ void do_bad_area(unsigned long addr, uns
 }
 
 #ifdef CONFIG_MMU
-#define VM_FAULT_BADMAP		((__force vm_fault_t)0x010000)
-#define VM_FAULT_BADACCESS	((__force vm_fault_t)0x020000)
-
 static inline bool is_permission_fault(unsigned int fsr)
 {
 	int fs = fsr_fs(fsr);
@@ -295,7 +292,8 @@ do_page_fault(unsigned long addr, unsign
 	if (!(vma->vm_flags & vm_flags)) {
 		vma_end_read(vma);
 		count_vm_vma_lock_event(VMA_LOCK_SUCCESS);
-		fault = VM_FAULT_BADACCESS;
+		fault = 0;
+		code = SEGV_ACCERR;
 		goto bad_area;
 	}
 	fault = handle_mm_fault(vma, addr, flags | FAULT_FLAG_VMA_LOCK, regs);
@@ -321,7 +319,8 @@ lock_mmap:
 retry:
 	vma = lock_mm_and_find_vma(mm, addr, regs);
 	if (unlikely(!vma)) {
-		fault = VM_FAULT_BADMAP;
+		fault = 0;
+		code = SEGV_MAPERR;
 		goto bad_area;
 	}
 
@@ -329,10 +328,14 @@ retry:
 	 * ok, we have a good vm_area for this memory access, check the
 	 * permissions on the VMA allow for the fault which occurred.
 	 */
-	if (!(vma->vm_flags & vm_flags))
-		fault = VM_FAULT_BADACCESS;
-	else
-		fault = handle_mm_fault(vma, addr & PAGE_MASK, flags, regs);
+	if (!(vma->vm_flags & vm_flags)) {
+		mmap_read_unlock(mm);
+		fault = 0;
+		code = SEGV_ACCERR;
+		goto bad_area;
+	}
+
+	fault = handle_mm_fault(vma, addr & PAGE_MASK, flags, regs);
 
 	/* If we need to retry but a fatal signal is pending, handle the
 	 * signal first. We do not need to release the mmap_lock because
@@ -358,12 +361,11 @@ retry:
 	mmap_read_unlock(mm);
 done:
 
-	/*
-	 * Handle the "normal" case first - VM_FAULT_MAJOR
-	 */
-	if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
+	/* Handle the "normal" case first */
+	if (likely(!(fault & VM_FAULT_ERROR)))
 		return 0;
 
+        code = SEGV_MAPERR;
 bad_area:
 	/*
 	 * If we are in kernel mode at this point, we
@@ -395,8 +397,6 @@ bad_area:
 		 * isn't in our memory map..
 		 */
 		sig = SIGSEGV;
-		code = fault == VM_FAULT_BADACCESS ?
-			SEGV_ACCERR : SEGV_MAPERR;
 	}
 
 	__do_user_fault(addr, fsr, sig, code, regs);
_

Patches currently in -mm which might be from wangkefeng.wang@huawei.com are

mm-backing-dev-use-group-allocation-free-of-per-cpu-counters-api.patch
mm-remove-__set_page_dirty_nobuffers.patch
arm64-mm-cleanup-__do_page_fault.patch
arm64-mm-accelerate-pagefault-when-vm_fault_badaccess.patch
arm-mm-accelerate-pagefault-when-vm_fault_badaccess.patch
powerpc-mm-accelerate-pagefault-when-badaccess.patch
riscv-mm-accelerate-pagefault-when-badaccess.patch
riscv-mm-accelerate-pagefault-when-badaccess-fix.patch
s390-mm-accelerate-pagefault-when-badaccess.patch
x86-mm-accelerate-pagefault-when-badaccess.patch
arm64-mm-drop-vm_fault_badmap-vm_fault_badaccess.patch
arm-mm-drop-vm_fault_badmap-vm_fault_badaccess.patch