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ARM: 9127/1: mm: Cleanup access_error()

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Now the write fault check in do_page_fault() and access_error() twice,
we can cleanup access_error(), and make the fault check and vma flags set
into do_page_fault() directly, then pass the vma flags to __do_page_fault.

No functional change.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Wang Kefeng 2021-09-22 14:56:29 +01:00 committed by Russell King (Oracle)
parent 488cab12c3
commit f177b06ed7
1 changed files with 14 additions and 24 deletions
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38
arch/arm/mm/fault.c
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@ -183,26 +183,9 @@ void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
#define VM_FAULT_BADMAP 0x010000
#define VM_FAULT_BADACCESS 0x020000
/*
* Check that the permissions on the VMA allow for the fault which occurred.
* If we encountered a write fault, we must have write permission, otherwise
* we allow any permission.
*/
static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
{
unsigned int mask = VM_ACCESS_FLAGS;
if ((fsr & FSR_WRITE) && !(fsr & FSR_CM))
mask = VM_WRITE;
if (fsr & FSR_LNX_PF)
mask = VM_EXEC;
return vma->vm_flags & mask ? false : true;
}
static vm_fault_t __kprobes
__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
unsigned int flags, struct pt_regs *regs)
__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int flags,
unsigned long vma_flags, struct pt_regs *regs)
{
struct vm_area_struct *vma = find_vma(mm, addr);
if (unlikely(!vma))
@ -218,10 +201,10 @@ __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
}
/*
* Ok, we have a good vm_area for this
* memory access, so we can handle it.
* ok, we have a good vm_area for this memory access, check the
* permissions on the VMA allow for the fault which occurred.
*/
if (access_error(fsr, vma))
if (!(vma->vm_flags & vma_flags))
return VM_FAULT_BADACCESS;
return handle_mm_fault(vma, addr & PAGE_MASK, flags, regs);
@ -234,6 +217,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
int sig, code;
vm_fault_t fault;
unsigned int flags = FAULT_FLAG_DEFAULT;
unsigned long vm_flags = VM_ACCESS_FLAGS;
if (kprobe_page_fault(regs, fsr))
return 0;
@ -252,8 +236,14 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
if ((fsr & FSR_WRITE) && !(fsr & FSR_CM))
if ((fsr & FSR_WRITE) && !(fsr & FSR_CM)) {
flags |= FAULT_FLAG_WRITE;
vm_flags = VM_WRITE;
}
if (fsr & FSR_LNX_PF)
vm_flags = VM_EXEC;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
@ -281,7 +271,7 @@ retry:
#endif
}
fault = __do_page_fault(mm, addr, fsr, flags, regs);
fault = __do_page_fault(mm, addr, flags, vm_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