[PATCH 2/2] arm: mm: drop VM_FAULT_BADMAP/VM_FAULT_BADACCESS

Kefeng Wang
2024-04-07T08:12:42Z

If bad map or access, directly set si_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.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
arch/arm/mm/fault.c | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 5c4b417e24f9..cab24fb17c4b 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -226,9 +226,6 @@ void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
}

#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, unsigned int fsr, struct pt_regs *regs)
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 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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 +328,13 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
* 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)) {
+ 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
@@ -358,10 +360,8 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
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;

bad_area:
@@ -395,8 +395,6 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
* 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);
--
2.27.0